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      1 //===-- TargetLowering.cpp - Implement the TargetLowering class -----------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This implements the TargetLowering class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/Target/TargetLowering.h"
     15 #include "llvm/MC/MCAsmInfo.h"
     16 #include "llvm/MC/MCExpr.h"
     17 #include "llvm/Target/TargetData.h"
     18 #include "llvm/Target/TargetLoweringObjectFile.h"
     19 #include "llvm/Target/TargetMachine.h"
     20 #include "llvm/Target/TargetRegisterInfo.h"
     21 #include "llvm/GlobalVariable.h"
     22 #include "llvm/DerivedTypes.h"
     23 #include "llvm/CodeGen/Analysis.h"
     24 #include "llvm/CodeGen/MachineFrameInfo.h"
     25 #include "llvm/CodeGen/MachineJumpTableInfo.h"
     26 #include "llvm/CodeGen/MachineFunction.h"
     27 #include "llvm/CodeGen/SelectionDAG.h"
     28 #include "llvm/ADT/STLExtras.h"
     29 #include "llvm/Support/CommandLine.h"
     30 #include "llvm/Support/ErrorHandling.h"
     31 #include "llvm/Support/MathExtras.h"
     32 #include <cctype>
     33 using namespace llvm;
     34 
     35 /// We are in the process of implementing a new TypeLegalization action
     36 /// - the promotion of vector elements. This feature is disabled by default
     37 /// and only enabled using this flag.
     38 static cl::opt<bool>
     39 AllowPromoteIntElem("promote-elements", cl::Hidden,
     40   cl::desc("Allow promotion of integer vector element types"));
     41 
     42 namespace llvm {
     43 TLSModel::Model getTLSModel(const GlobalValue *GV, Reloc::Model reloc) {
     44   bool isLocal = GV->hasLocalLinkage();
     45   bool isDeclaration = GV->isDeclaration();
     46   // FIXME: what should we do for protected and internal visibility?
     47   // For variables, is internal different from hidden?
     48   bool isHidden = GV->hasHiddenVisibility();
     49 
     50   if (reloc == Reloc::PIC_) {
     51     if (isLocal || isHidden)
     52       return TLSModel::LocalDynamic;
     53     else
     54       return TLSModel::GeneralDynamic;
     55   } else {
     56     if (!isDeclaration || isHidden)
     57       return TLSModel::LocalExec;
     58     else
     59       return TLSModel::InitialExec;
     60   }
     61 }
     62 }
     63 
     64 /// InitLibcallNames - Set default libcall names.
     65 ///
     66 static void InitLibcallNames(const char **Names) {
     67   Names[RTLIB::SHL_I16] = "__ashlhi3";
     68   Names[RTLIB::SHL_I32] = "__ashlsi3";
     69   Names[RTLIB::SHL_I64] = "__ashldi3";
     70   Names[RTLIB::SHL_I128] = "__ashlti3";
     71   Names[RTLIB::SRL_I16] = "__lshrhi3";
     72   Names[RTLIB::SRL_I32] = "__lshrsi3";
     73   Names[RTLIB::SRL_I64] = "__lshrdi3";
     74   Names[RTLIB::SRL_I128] = "__lshrti3";
     75   Names[RTLIB::SRA_I16] = "__ashrhi3";
     76   Names[RTLIB::SRA_I32] = "__ashrsi3";
     77   Names[RTLIB::SRA_I64] = "__ashrdi3";
     78   Names[RTLIB::SRA_I128] = "__ashrti3";
     79   Names[RTLIB::MUL_I8] = "__mulqi3";
     80   Names[RTLIB::MUL_I16] = "__mulhi3";
     81   Names[RTLIB::MUL_I32] = "__mulsi3";
     82   Names[RTLIB::MUL_I64] = "__muldi3";
     83   Names[RTLIB::MUL_I128] = "__multi3";
     84   Names[RTLIB::MULO_I32] = "__mulosi4";
     85   Names[RTLIB::MULO_I64] = "__mulodi4";
     86   Names[RTLIB::MULO_I128] = "__muloti4";
     87   Names[RTLIB::SDIV_I8] = "__divqi3";
     88   Names[RTLIB::SDIV_I16] = "__divhi3";
     89   Names[RTLIB::SDIV_I32] = "__divsi3";
     90   Names[RTLIB::SDIV_I64] = "__divdi3";
     91   Names[RTLIB::SDIV_I128] = "__divti3";
     92   Names[RTLIB::UDIV_I8] = "__udivqi3";
     93   Names[RTLIB::UDIV_I16] = "__udivhi3";
     94   Names[RTLIB::UDIV_I32] = "__udivsi3";
     95   Names[RTLIB::UDIV_I64] = "__udivdi3";
     96   Names[RTLIB::UDIV_I128] = "__udivti3";
     97   Names[RTLIB::SREM_I8] = "__modqi3";
     98   Names[RTLIB::SREM_I16] = "__modhi3";
     99   Names[RTLIB::SREM_I32] = "__modsi3";
    100   Names[RTLIB::SREM_I64] = "__moddi3";
    101   Names[RTLIB::SREM_I128] = "__modti3";
    102   Names[RTLIB::UREM_I8] = "__umodqi3";
    103   Names[RTLIB::UREM_I16] = "__umodhi3";
    104   Names[RTLIB::UREM_I32] = "__umodsi3";
    105   Names[RTLIB::UREM_I64] = "__umoddi3";
    106   Names[RTLIB::UREM_I128] = "__umodti3";
    107 
    108   // These are generally not available.
    109   Names[RTLIB::SDIVREM_I8] = 0;
    110   Names[RTLIB::SDIVREM_I16] = 0;
    111   Names[RTLIB::SDIVREM_I32] = 0;
    112   Names[RTLIB::SDIVREM_I64] = 0;
    113   Names[RTLIB::SDIVREM_I128] = 0;
    114   Names[RTLIB::UDIVREM_I8] = 0;
    115   Names[RTLIB::UDIVREM_I16] = 0;
    116   Names[RTLIB::UDIVREM_I32] = 0;
    117   Names[RTLIB::UDIVREM_I64] = 0;
    118   Names[RTLIB::UDIVREM_I128] = 0;
    119 
    120   Names[RTLIB::NEG_I32] = "__negsi2";
    121   Names[RTLIB::NEG_I64] = "__negdi2";
    122   Names[RTLIB::ADD_F32] = "__addsf3";
    123   Names[RTLIB::ADD_F64] = "__adddf3";
    124   Names[RTLIB::ADD_F80] = "__addxf3";
    125   Names[RTLIB::ADD_PPCF128] = "__gcc_qadd";
    126   Names[RTLIB::SUB_F32] = "__subsf3";
    127   Names[RTLIB::SUB_F64] = "__subdf3";
    128   Names[RTLIB::SUB_F80] = "__subxf3";
    129   Names[RTLIB::SUB_PPCF128] = "__gcc_qsub";
    130   Names[RTLIB::MUL_F32] = "__mulsf3";
    131   Names[RTLIB::MUL_F64] = "__muldf3";
    132   Names[RTLIB::MUL_F80] = "__mulxf3";
    133   Names[RTLIB::MUL_PPCF128] = "__gcc_qmul";
    134   Names[RTLIB::DIV_F32] = "__divsf3";
    135   Names[RTLIB::DIV_F64] = "__divdf3";
    136   Names[RTLIB::DIV_F80] = "__divxf3";
    137   Names[RTLIB::DIV_PPCF128] = "__gcc_qdiv";
    138   Names[RTLIB::REM_F32] = "fmodf";
    139   Names[RTLIB::REM_F64] = "fmod";
    140   Names[RTLIB::REM_F80] = "fmodl";
    141   Names[RTLIB::REM_PPCF128] = "fmodl";
    142   Names[RTLIB::FMA_F32] = "fmaf";
    143   Names[RTLIB::FMA_F64] = "fma";
    144   Names[RTLIB::FMA_F80] = "fmal";
    145   Names[RTLIB::FMA_PPCF128] = "fmal";
    146   Names[RTLIB::POWI_F32] = "__powisf2";
    147   Names[RTLIB::POWI_F64] = "__powidf2";
    148   Names[RTLIB::POWI_F80] = "__powixf2";
    149   Names[RTLIB::POWI_PPCF128] = "__powitf2";
    150   Names[RTLIB::SQRT_F32] = "sqrtf";
    151   Names[RTLIB::SQRT_F64] = "sqrt";
    152   Names[RTLIB::SQRT_F80] = "sqrtl";
    153   Names[RTLIB::SQRT_PPCF128] = "sqrtl";
    154   Names[RTLIB::LOG_F32] = "logf";
    155   Names[RTLIB::LOG_F64] = "log";
    156   Names[RTLIB::LOG_F80] = "logl";
    157   Names[RTLIB::LOG_PPCF128] = "logl";
    158   Names[RTLIB::LOG2_F32] = "log2f";
    159   Names[RTLIB::LOG2_F64] = "log2";
    160   Names[RTLIB::LOG2_F80] = "log2l";
    161   Names[RTLIB::LOG2_PPCF128] = "log2l";
    162   Names[RTLIB::LOG10_F32] = "log10f";
    163   Names[RTLIB::LOG10_F64] = "log10";
    164   Names[RTLIB::LOG10_F80] = "log10l";
    165   Names[RTLIB::LOG10_PPCF128] = "log10l";
    166   Names[RTLIB::EXP_F32] = "expf";
    167   Names[RTLIB::EXP_F64] = "exp";
    168   Names[RTLIB::EXP_F80] = "expl";
    169   Names[RTLIB::EXP_PPCF128] = "expl";
    170   Names[RTLIB::EXP2_F32] = "exp2f";
    171   Names[RTLIB::EXP2_F64] = "exp2";
    172   Names[RTLIB::EXP2_F80] = "exp2l";
    173   Names[RTLIB::EXP2_PPCF128] = "exp2l";
    174   Names[RTLIB::SIN_F32] = "sinf";
    175   Names[RTLIB::SIN_F64] = "sin";
    176   Names[RTLIB::SIN_F80] = "sinl";
    177   Names[RTLIB::SIN_PPCF128] = "sinl";
    178   Names[RTLIB::COS_F32] = "cosf";
    179   Names[RTLIB::COS_F64] = "cos";
    180   Names[RTLIB::COS_F80] = "cosl";
    181   Names[RTLIB::COS_PPCF128] = "cosl";
    182   Names[RTLIB::POW_F32] = "powf";
    183   Names[RTLIB::POW_F64] = "pow";
    184   Names[RTLIB::POW_F80] = "powl";
    185   Names[RTLIB::POW_PPCF128] = "powl";
    186   Names[RTLIB::CEIL_F32] = "ceilf";
    187   Names[RTLIB::CEIL_F64] = "ceil";
    188   Names[RTLIB::CEIL_F80] = "ceill";
    189   Names[RTLIB::CEIL_PPCF128] = "ceill";
    190   Names[RTLIB::TRUNC_F32] = "truncf";
    191   Names[RTLIB::TRUNC_F64] = "trunc";
    192   Names[RTLIB::TRUNC_F80] = "truncl";
    193   Names[RTLIB::TRUNC_PPCF128] = "truncl";
    194   Names[RTLIB::RINT_F32] = "rintf";
    195   Names[RTLIB::RINT_F64] = "rint";
    196   Names[RTLIB::RINT_F80] = "rintl";
    197   Names[RTLIB::RINT_PPCF128] = "rintl";
    198   Names[RTLIB::NEARBYINT_F32] = "nearbyintf";
    199   Names[RTLIB::NEARBYINT_F64] = "nearbyint";
    200   Names[RTLIB::NEARBYINT_F80] = "nearbyintl";
    201   Names[RTLIB::NEARBYINT_PPCF128] = "nearbyintl";
    202   Names[RTLIB::FLOOR_F32] = "floorf";
    203   Names[RTLIB::FLOOR_F64] = "floor";
    204   Names[RTLIB::FLOOR_F80] = "floorl";
    205   Names[RTLIB::FLOOR_PPCF128] = "floorl";
    206   Names[RTLIB::COPYSIGN_F32] = "copysignf";
    207   Names[RTLIB::COPYSIGN_F64] = "copysign";
    208   Names[RTLIB::COPYSIGN_F80] = "copysignl";
    209   Names[RTLIB::COPYSIGN_PPCF128] = "copysignl";
    210   Names[RTLIB::FPEXT_F32_F64] = "__extendsfdf2";
    211   Names[RTLIB::FPEXT_F16_F32] = "__gnu_h2f_ieee";
    212   Names[RTLIB::FPROUND_F32_F16] = "__gnu_f2h_ieee";
    213   Names[RTLIB::FPROUND_F64_F32] = "__truncdfsf2";
    214   Names[RTLIB::FPROUND_F80_F32] = "__truncxfsf2";
    215   Names[RTLIB::FPROUND_PPCF128_F32] = "__trunctfsf2";
    216   Names[RTLIB::FPROUND_F80_F64] = "__truncxfdf2";
    217   Names[RTLIB::FPROUND_PPCF128_F64] = "__trunctfdf2";
    218   Names[RTLIB::FPTOSINT_F32_I8] = "__fixsfqi";
    219   Names[RTLIB::FPTOSINT_F32_I16] = "__fixsfhi";
    220   Names[RTLIB::FPTOSINT_F32_I32] = "__fixsfsi";
    221   Names[RTLIB::FPTOSINT_F32_I64] = "__fixsfdi";
    222   Names[RTLIB::FPTOSINT_F32_I128] = "__fixsfti";
    223   Names[RTLIB::FPTOSINT_F64_I8] = "__fixdfqi";
    224   Names[RTLIB::FPTOSINT_F64_I16] = "__fixdfhi";
    225   Names[RTLIB::FPTOSINT_F64_I32] = "__fixdfsi";
    226   Names[RTLIB::FPTOSINT_F64_I64] = "__fixdfdi";
    227   Names[RTLIB::FPTOSINT_F64_I128] = "__fixdfti";
    228   Names[RTLIB::FPTOSINT_F80_I32] = "__fixxfsi";
    229   Names[RTLIB::FPTOSINT_F80_I64] = "__fixxfdi";
    230   Names[RTLIB::FPTOSINT_F80_I128] = "__fixxfti";
    231   Names[RTLIB::FPTOSINT_PPCF128_I32] = "__fixtfsi";
    232   Names[RTLIB::FPTOSINT_PPCF128_I64] = "__fixtfdi";
    233   Names[RTLIB::FPTOSINT_PPCF128_I128] = "__fixtfti";
    234   Names[RTLIB::FPTOUINT_F32_I8] = "__fixunssfqi";
    235   Names[RTLIB::FPTOUINT_F32_I16] = "__fixunssfhi";
    236   Names[RTLIB::FPTOUINT_F32_I32] = "__fixunssfsi";
    237   Names[RTLIB::FPTOUINT_F32_I64] = "__fixunssfdi";
    238   Names[RTLIB::FPTOUINT_F32_I128] = "__fixunssfti";
    239   Names[RTLIB::FPTOUINT_F64_I8] = "__fixunsdfqi";
    240   Names[RTLIB::FPTOUINT_F64_I16] = "__fixunsdfhi";
    241   Names[RTLIB::FPTOUINT_F64_I32] = "__fixunsdfsi";
    242   Names[RTLIB::FPTOUINT_F64_I64] = "__fixunsdfdi";
    243   Names[RTLIB::FPTOUINT_F64_I128] = "__fixunsdfti";
    244   Names[RTLIB::FPTOUINT_F80_I32] = "__fixunsxfsi";
    245   Names[RTLIB::FPTOUINT_F80_I64] = "__fixunsxfdi";
    246   Names[RTLIB::FPTOUINT_F80_I128] = "__fixunsxfti";
    247   Names[RTLIB::FPTOUINT_PPCF128_I32] = "__fixunstfsi";
    248   Names[RTLIB::FPTOUINT_PPCF128_I64] = "__fixunstfdi";
    249   Names[RTLIB::FPTOUINT_PPCF128_I128] = "__fixunstfti";
    250   Names[RTLIB::SINTTOFP_I32_F32] = "__floatsisf";
    251   Names[RTLIB::SINTTOFP_I32_F64] = "__floatsidf";
    252   Names[RTLIB::SINTTOFP_I32_F80] = "__floatsixf";
    253   Names[RTLIB::SINTTOFP_I32_PPCF128] = "__floatsitf";
    254   Names[RTLIB::SINTTOFP_I64_F32] = "__floatdisf";
    255   Names[RTLIB::SINTTOFP_I64_F64] = "__floatdidf";
    256   Names[RTLIB::SINTTOFP_I64_F80] = "__floatdixf";
    257   Names[RTLIB::SINTTOFP_I64_PPCF128] = "__floatditf";
    258   Names[RTLIB::SINTTOFP_I128_F32] = "__floattisf";
    259   Names[RTLIB::SINTTOFP_I128_F64] = "__floattidf";
    260   Names[RTLIB::SINTTOFP_I128_F80] = "__floattixf";
    261   Names[RTLIB::SINTTOFP_I128_PPCF128] = "__floattitf";
    262   Names[RTLIB::UINTTOFP_I32_F32] = "__floatunsisf";
    263   Names[RTLIB::UINTTOFP_I32_F64] = "__floatunsidf";
    264   Names[RTLIB::UINTTOFP_I32_F80] = "__floatunsixf";
    265   Names[RTLIB::UINTTOFP_I32_PPCF128] = "__floatunsitf";
    266   Names[RTLIB::UINTTOFP_I64_F32] = "__floatundisf";
    267   Names[RTLIB::UINTTOFP_I64_F64] = "__floatundidf";
    268   Names[RTLIB::UINTTOFP_I64_F80] = "__floatundixf";
    269   Names[RTLIB::UINTTOFP_I64_PPCF128] = "__floatunditf";
    270   Names[RTLIB::UINTTOFP_I128_F32] = "__floatuntisf";
    271   Names[RTLIB::UINTTOFP_I128_F64] = "__floatuntidf";
    272   Names[RTLIB::UINTTOFP_I128_F80] = "__floatuntixf";
    273   Names[RTLIB::UINTTOFP_I128_PPCF128] = "__floatuntitf";
    274   Names[RTLIB::OEQ_F32] = "__eqsf2";
    275   Names[RTLIB::OEQ_F64] = "__eqdf2";
    276   Names[RTLIB::UNE_F32] = "__nesf2";
    277   Names[RTLIB::UNE_F64] = "__nedf2";
    278   Names[RTLIB::OGE_F32] = "__gesf2";
    279   Names[RTLIB::OGE_F64] = "__gedf2";
    280   Names[RTLIB::OLT_F32] = "__ltsf2";
    281   Names[RTLIB::OLT_F64] = "__ltdf2";
    282   Names[RTLIB::OLE_F32] = "__lesf2";
    283   Names[RTLIB::OLE_F64] = "__ledf2";
    284   Names[RTLIB::OGT_F32] = "__gtsf2";
    285   Names[RTLIB::OGT_F64] = "__gtdf2";
    286   Names[RTLIB::UO_F32] = "__unordsf2";
    287   Names[RTLIB::UO_F64] = "__unorddf2";
    288   Names[RTLIB::O_F32] = "__unordsf2";
    289   Names[RTLIB::O_F64] = "__unorddf2";
    290   Names[RTLIB::MEMCPY] = "memcpy";
    291   Names[RTLIB::MEMMOVE] = "memmove";
    292   Names[RTLIB::MEMSET] = "memset";
    293   Names[RTLIB::UNWIND_RESUME] = "_Unwind_Resume";
    294   Names[RTLIB::SYNC_VAL_COMPARE_AND_SWAP_1] = "__sync_val_compare_and_swap_1";
    295   Names[RTLIB::SYNC_VAL_COMPARE_AND_SWAP_2] = "__sync_val_compare_and_swap_2";
    296   Names[RTLIB::SYNC_VAL_COMPARE_AND_SWAP_4] = "__sync_val_compare_and_swap_4";
    297   Names[RTLIB::SYNC_VAL_COMPARE_AND_SWAP_8] = "__sync_val_compare_and_swap_8";
    298   Names[RTLIB::SYNC_LOCK_TEST_AND_SET_1] = "__sync_lock_test_and_set_1";
    299   Names[RTLIB::SYNC_LOCK_TEST_AND_SET_2] = "__sync_lock_test_and_set_2";
    300   Names[RTLIB::SYNC_LOCK_TEST_AND_SET_4] = "__sync_lock_test_and_set_4";
    301   Names[RTLIB::SYNC_LOCK_TEST_AND_SET_8] = "__sync_lock_test_and_set_8";
    302   Names[RTLIB::SYNC_FETCH_AND_ADD_1] = "__sync_fetch_and_add_1";
    303   Names[RTLIB::SYNC_FETCH_AND_ADD_2] = "__sync_fetch_and_add_2";
    304   Names[RTLIB::SYNC_FETCH_AND_ADD_4] = "__sync_fetch_and_add_4";
    305   Names[RTLIB::SYNC_FETCH_AND_ADD_8] = "__sync_fetch_and_add_8";
    306   Names[RTLIB::SYNC_FETCH_AND_SUB_1] = "__sync_fetch_and_sub_1";
    307   Names[RTLIB::SYNC_FETCH_AND_SUB_2] = "__sync_fetch_and_sub_2";
    308   Names[RTLIB::SYNC_FETCH_AND_SUB_4] = "__sync_fetch_and_sub_4";
    309   Names[RTLIB::SYNC_FETCH_AND_SUB_8] = "__sync_fetch_and_sub_8";
    310   Names[RTLIB::SYNC_FETCH_AND_AND_1] = "__sync_fetch_and_and_1";
    311   Names[RTLIB::SYNC_FETCH_AND_AND_2] = "__sync_fetch_and_and_2";
    312   Names[RTLIB::SYNC_FETCH_AND_AND_4] = "__sync_fetch_and_and_4";
    313   Names[RTLIB::SYNC_FETCH_AND_AND_8] = "__sync_fetch_and_and_8";
    314   Names[RTLIB::SYNC_FETCH_AND_OR_1] = "__sync_fetch_and_or_1";
    315   Names[RTLIB::SYNC_FETCH_AND_OR_2] = "__sync_fetch_and_or_2";
    316   Names[RTLIB::SYNC_FETCH_AND_OR_4] = "__sync_fetch_and_or_4";
    317   Names[RTLIB::SYNC_FETCH_AND_OR_8] = "__sync_fetch_and_or_8";
    318   Names[RTLIB::SYNC_FETCH_AND_XOR_1] = "__sync_fetch_and_xor_1";
    319   Names[RTLIB::SYNC_FETCH_AND_XOR_2] = "__sync_fetch_and_xor_2";
    320   Names[RTLIB::SYNC_FETCH_AND_XOR_4] = "__sync_fetch_and-xor_4";
    321   Names[RTLIB::SYNC_FETCH_AND_XOR_8] = "__sync_fetch_and_xor_8";
    322   Names[RTLIB::SYNC_FETCH_AND_NAND_1] = "__sync_fetch_and_nand_1";
    323   Names[RTLIB::SYNC_FETCH_AND_NAND_2] = "__sync_fetch_and_nand_2";
    324   Names[RTLIB::SYNC_FETCH_AND_NAND_4] = "__sync_fetch_and_nand_4";
    325   Names[RTLIB::SYNC_FETCH_AND_NAND_8] = "__sync_fetch_and_nand_8";
    326 }
    327 
    328 /// InitLibcallCallingConvs - Set default libcall CallingConvs.
    329 ///
    330 static void InitLibcallCallingConvs(CallingConv::ID *CCs) {
    331   for (int i = 0; i < RTLIB::UNKNOWN_LIBCALL; ++i) {
    332     CCs[i] = CallingConv::C;
    333   }
    334 }
    335 
    336 /// getFPEXT - Return the FPEXT_*_* value for the given types, or
    337 /// UNKNOWN_LIBCALL if there is none.
    338 RTLIB::Libcall RTLIB::getFPEXT(EVT OpVT, EVT RetVT) {
    339   if (OpVT == MVT::f32) {
    340     if (RetVT == MVT::f64)
    341       return FPEXT_F32_F64;
    342   }
    343 
    344   return UNKNOWN_LIBCALL;
    345 }
    346 
    347 /// getFPROUND - Return the FPROUND_*_* value for the given types, or
    348 /// UNKNOWN_LIBCALL if there is none.
    349 RTLIB::Libcall RTLIB::getFPROUND(EVT OpVT, EVT RetVT) {
    350   if (RetVT == MVT::f32) {
    351     if (OpVT == MVT::f64)
    352       return FPROUND_F64_F32;
    353     if (OpVT == MVT::f80)
    354       return FPROUND_F80_F32;
    355     if (OpVT == MVT::ppcf128)
    356       return FPROUND_PPCF128_F32;
    357   } else if (RetVT == MVT::f64) {
    358     if (OpVT == MVT::f80)
    359       return FPROUND_F80_F64;
    360     if (OpVT == MVT::ppcf128)
    361       return FPROUND_PPCF128_F64;
    362   }
    363 
    364   return UNKNOWN_LIBCALL;
    365 }
    366 
    367 /// getFPTOSINT - Return the FPTOSINT_*_* value for the given types, or
    368 /// UNKNOWN_LIBCALL if there is none.
    369 RTLIB::Libcall RTLIB::getFPTOSINT(EVT OpVT, EVT RetVT) {
    370   if (OpVT == MVT::f32) {
    371     if (RetVT == MVT::i8)
    372       return FPTOSINT_F32_I8;
    373     if (RetVT == MVT::i16)
    374       return FPTOSINT_F32_I16;
    375     if (RetVT == MVT::i32)
    376       return FPTOSINT_F32_I32;
    377     if (RetVT == MVT::i64)
    378       return FPTOSINT_F32_I64;
    379     if (RetVT == MVT::i128)
    380       return FPTOSINT_F32_I128;
    381   } else if (OpVT == MVT::f64) {
    382     if (RetVT == MVT::i8)
    383       return FPTOSINT_F64_I8;
    384     if (RetVT == MVT::i16)
    385       return FPTOSINT_F64_I16;
    386     if (RetVT == MVT::i32)
    387       return FPTOSINT_F64_I32;
    388     if (RetVT == MVT::i64)
    389       return FPTOSINT_F64_I64;
    390     if (RetVT == MVT::i128)
    391       return FPTOSINT_F64_I128;
    392   } else if (OpVT == MVT::f80) {
    393     if (RetVT == MVT::i32)
    394       return FPTOSINT_F80_I32;
    395     if (RetVT == MVT::i64)
    396       return FPTOSINT_F80_I64;
    397     if (RetVT == MVT::i128)
    398       return FPTOSINT_F80_I128;
    399   } else if (OpVT == MVT::ppcf128) {
    400     if (RetVT == MVT::i32)
    401       return FPTOSINT_PPCF128_I32;
    402     if (RetVT == MVT::i64)
    403       return FPTOSINT_PPCF128_I64;
    404     if (RetVT == MVT::i128)
    405       return FPTOSINT_PPCF128_I128;
    406   }
    407   return UNKNOWN_LIBCALL;
    408 }
    409 
    410 /// getFPTOUINT - Return the FPTOUINT_*_* value for the given types, or
    411 /// UNKNOWN_LIBCALL if there is none.
    412 RTLIB::Libcall RTLIB::getFPTOUINT(EVT OpVT, EVT RetVT) {
    413   if (OpVT == MVT::f32) {
    414     if (RetVT == MVT::i8)
    415       return FPTOUINT_F32_I8;
    416     if (RetVT == MVT::i16)
    417       return FPTOUINT_F32_I16;
    418     if (RetVT == MVT::i32)
    419       return FPTOUINT_F32_I32;
    420     if (RetVT == MVT::i64)
    421       return FPTOUINT_F32_I64;
    422     if (RetVT == MVT::i128)
    423       return FPTOUINT_F32_I128;
    424   } else if (OpVT == MVT::f64) {
    425     if (RetVT == MVT::i8)
    426       return FPTOUINT_F64_I8;
    427     if (RetVT == MVT::i16)
    428       return FPTOUINT_F64_I16;
    429     if (RetVT == MVT::i32)
    430       return FPTOUINT_F64_I32;
    431     if (RetVT == MVT::i64)
    432       return FPTOUINT_F64_I64;
    433     if (RetVT == MVT::i128)
    434       return FPTOUINT_F64_I128;
    435   } else if (OpVT == MVT::f80) {
    436     if (RetVT == MVT::i32)
    437       return FPTOUINT_F80_I32;
    438     if (RetVT == MVT::i64)
    439       return FPTOUINT_F80_I64;
    440     if (RetVT == MVT::i128)
    441       return FPTOUINT_F80_I128;
    442   } else if (OpVT == MVT::ppcf128) {
    443     if (RetVT == MVT::i32)
    444       return FPTOUINT_PPCF128_I32;
    445     if (RetVT == MVT::i64)
    446       return FPTOUINT_PPCF128_I64;
    447     if (RetVT == MVT::i128)
    448       return FPTOUINT_PPCF128_I128;
    449   }
    450   return UNKNOWN_LIBCALL;
    451 }
    452 
    453 /// getSINTTOFP - Return the SINTTOFP_*_* value for the given types, or
    454 /// UNKNOWN_LIBCALL if there is none.
    455 RTLIB::Libcall RTLIB::getSINTTOFP(EVT OpVT, EVT RetVT) {
    456   if (OpVT == MVT::i32) {
    457     if (RetVT == MVT::f32)
    458       return SINTTOFP_I32_F32;
    459     else if (RetVT == MVT::f64)
    460       return SINTTOFP_I32_F64;
    461     else if (RetVT == MVT::f80)
    462       return SINTTOFP_I32_F80;
    463     else if (RetVT == MVT::ppcf128)
    464       return SINTTOFP_I32_PPCF128;
    465   } else if (OpVT == MVT::i64) {
    466     if (RetVT == MVT::f32)
    467       return SINTTOFP_I64_F32;
    468     else if (RetVT == MVT::f64)
    469       return SINTTOFP_I64_F64;
    470     else if (RetVT == MVT::f80)
    471       return SINTTOFP_I64_F80;
    472     else if (RetVT == MVT::ppcf128)
    473       return SINTTOFP_I64_PPCF128;
    474   } else if (OpVT == MVT::i128) {
    475     if (RetVT == MVT::f32)
    476       return SINTTOFP_I128_F32;
    477     else if (RetVT == MVT::f64)
    478       return SINTTOFP_I128_F64;
    479     else if (RetVT == MVT::f80)
    480       return SINTTOFP_I128_F80;
    481     else if (RetVT == MVT::ppcf128)
    482       return SINTTOFP_I128_PPCF128;
    483   }
    484   return UNKNOWN_LIBCALL;
    485 }
    486 
    487 /// getUINTTOFP - Return the UINTTOFP_*_* value for the given types, or
    488 /// UNKNOWN_LIBCALL if there is none.
    489 RTLIB::Libcall RTLIB::getUINTTOFP(EVT OpVT, EVT RetVT) {
    490   if (OpVT == MVT::i32) {
    491     if (RetVT == MVT::f32)
    492       return UINTTOFP_I32_F32;
    493     else if (RetVT == MVT::f64)
    494       return UINTTOFP_I32_F64;
    495     else if (RetVT == MVT::f80)
    496       return UINTTOFP_I32_F80;
    497     else if (RetVT == MVT::ppcf128)
    498       return UINTTOFP_I32_PPCF128;
    499   } else if (OpVT == MVT::i64) {
    500     if (RetVT == MVT::f32)
    501       return UINTTOFP_I64_F32;
    502     else if (RetVT == MVT::f64)
    503       return UINTTOFP_I64_F64;
    504     else if (RetVT == MVT::f80)
    505       return UINTTOFP_I64_F80;
    506     else if (RetVT == MVT::ppcf128)
    507       return UINTTOFP_I64_PPCF128;
    508   } else if (OpVT == MVT::i128) {
    509     if (RetVT == MVT::f32)
    510       return UINTTOFP_I128_F32;
    511     else if (RetVT == MVT::f64)
    512       return UINTTOFP_I128_F64;
    513     else if (RetVT == MVT::f80)
    514       return UINTTOFP_I128_F80;
    515     else if (RetVT == MVT::ppcf128)
    516       return UINTTOFP_I128_PPCF128;
    517   }
    518   return UNKNOWN_LIBCALL;
    519 }
    520 
    521 /// InitCmpLibcallCCs - Set default comparison libcall CC.
    522 ///
    523 static void InitCmpLibcallCCs(ISD::CondCode *CCs) {
    524   memset(CCs, ISD::SETCC_INVALID, sizeof(ISD::CondCode)*RTLIB::UNKNOWN_LIBCALL);
    525   CCs[RTLIB::OEQ_F32] = ISD::SETEQ;
    526   CCs[RTLIB::OEQ_F64] = ISD::SETEQ;
    527   CCs[RTLIB::UNE_F32] = ISD::SETNE;
    528   CCs[RTLIB::UNE_F64] = ISD::SETNE;
    529   CCs[RTLIB::OGE_F32] = ISD::SETGE;
    530   CCs[RTLIB::OGE_F64] = ISD::SETGE;
    531   CCs[RTLIB::OLT_F32] = ISD::SETLT;
    532   CCs[RTLIB::OLT_F64] = ISD::SETLT;
    533   CCs[RTLIB::OLE_F32] = ISD::SETLE;
    534   CCs[RTLIB::OLE_F64] = ISD::SETLE;
    535   CCs[RTLIB::OGT_F32] = ISD::SETGT;
    536   CCs[RTLIB::OGT_F64] = ISD::SETGT;
    537   CCs[RTLIB::UO_F32] = ISD::SETNE;
    538   CCs[RTLIB::UO_F64] = ISD::SETNE;
    539   CCs[RTLIB::O_F32] = ISD::SETEQ;
    540   CCs[RTLIB::O_F64] = ISD::SETEQ;
    541 }
    542 
    543 /// NOTE: The constructor takes ownership of TLOF.
    544 TargetLowering::TargetLowering(const TargetMachine &tm,
    545                                const TargetLoweringObjectFile *tlof)
    546   : TM(tm), TD(TM.getTargetData()), TLOF(*tlof),
    547   mayPromoteElements(AllowPromoteIntElem) {
    548   // All operations default to being supported.
    549   memset(OpActions, 0, sizeof(OpActions));
    550   memset(LoadExtActions, 0, sizeof(LoadExtActions));
    551   memset(TruncStoreActions, 0, sizeof(TruncStoreActions));
    552   memset(IndexedModeActions, 0, sizeof(IndexedModeActions));
    553   memset(CondCodeActions, 0, sizeof(CondCodeActions));
    554 
    555   // Set default actions for various operations.
    556   for (unsigned VT = 0; VT != (unsigned)MVT::LAST_VALUETYPE; ++VT) {
    557     // Default all indexed load / store to expand.
    558     for (unsigned IM = (unsigned)ISD::PRE_INC;
    559          IM != (unsigned)ISD::LAST_INDEXED_MODE; ++IM) {
    560       setIndexedLoadAction(IM, (MVT::SimpleValueType)VT, Expand);
    561       setIndexedStoreAction(IM, (MVT::SimpleValueType)VT, Expand);
    562     }
    563 
    564     // These operations default to expand.
    565     setOperationAction(ISD::FGETSIGN, (MVT::SimpleValueType)VT, Expand);
    566     setOperationAction(ISD::CONCAT_VECTORS, (MVT::SimpleValueType)VT, Expand);
    567   }
    568 
    569   // Most targets ignore the @llvm.prefetch intrinsic.
    570   setOperationAction(ISD::PREFETCH, MVT::Other, Expand);
    571 
    572   // ConstantFP nodes default to expand.  Targets can either change this to
    573   // Legal, in which case all fp constants are legal, or use isFPImmLegal()
    574   // to optimize expansions for certain constants.
    575   setOperationAction(ISD::ConstantFP, MVT::f32, Expand);
    576   setOperationAction(ISD::ConstantFP, MVT::f64, Expand);
    577   setOperationAction(ISD::ConstantFP, MVT::f80, Expand);
    578 
    579   // These library functions default to expand.
    580   setOperationAction(ISD::FLOG , MVT::f64, Expand);
    581   setOperationAction(ISD::FLOG2, MVT::f64, Expand);
    582   setOperationAction(ISD::FLOG10,MVT::f64, Expand);
    583   setOperationAction(ISD::FEXP , MVT::f64, Expand);
    584   setOperationAction(ISD::FEXP2, MVT::f64, Expand);
    585   setOperationAction(ISD::FLOG , MVT::f32, Expand);
    586   setOperationAction(ISD::FLOG2, MVT::f32, Expand);
    587   setOperationAction(ISD::FLOG10,MVT::f32, Expand);
    588   setOperationAction(ISD::FEXP , MVT::f32, Expand);
    589   setOperationAction(ISD::FEXP2, MVT::f32, Expand);
    590 
    591   // Default ISD::TRAP to expand (which turns it into abort).
    592   setOperationAction(ISD::TRAP, MVT::Other, Expand);
    593 
    594   IsLittleEndian = TD->isLittleEndian();
    595   PointerTy = MVT::getIntegerVT(8*TD->getPointerSize());
    596   memset(RegClassForVT, 0,MVT::LAST_VALUETYPE*sizeof(TargetRegisterClass*));
    597   memset(TargetDAGCombineArray, 0, array_lengthof(TargetDAGCombineArray));
    598   maxStoresPerMemset = maxStoresPerMemcpy = maxStoresPerMemmove = 8;
    599   maxStoresPerMemsetOptSize = maxStoresPerMemcpyOptSize
    600     = maxStoresPerMemmoveOptSize = 4;
    601   benefitFromCodePlacementOpt = false;
    602   UseUnderscoreSetJmp = false;
    603   UseUnderscoreLongJmp = false;
    604   SelectIsExpensive = false;
    605   IntDivIsCheap = false;
    606   Pow2DivIsCheap = false;
    607   JumpIsExpensive = false;
    608   StackPointerRegisterToSaveRestore = 0;
    609   ExceptionPointerRegister = 0;
    610   ExceptionSelectorRegister = 0;
    611   BooleanContents = UndefinedBooleanContent;
    612   SchedPreferenceInfo = Sched::Latency;
    613   JumpBufSize = 0;
    614   JumpBufAlignment = 0;
    615   MinFunctionAlignment = 0;
    616   PrefFunctionAlignment = 0;
    617   PrefLoopAlignment = 0;
    618   MinStackArgumentAlignment = 1;
    619   ShouldFoldAtomicFences = false;
    620 
    621   InitLibcallNames(LibcallRoutineNames);
    622   InitCmpLibcallCCs(CmpLibcallCCs);
    623   InitLibcallCallingConvs(LibcallCallingConvs);
    624 }
    625 
    626 TargetLowering::~TargetLowering() {
    627   delete &TLOF;
    628 }
    629 
    630 MVT TargetLowering::getShiftAmountTy(EVT LHSTy) const {
    631   return MVT::getIntegerVT(8*TD->getPointerSize());
    632 }
    633 
    634 /// canOpTrap - Returns true if the operation can trap for the value type.
    635 /// VT must be a legal type.
    636 bool TargetLowering::canOpTrap(unsigned Op, EVT VT) const {
    637   assert(isTypeLegal(VT));
    638   switch (Op) {
    639   default:
    640     return false;
    641   case ISD::FDIV:
    642   case ISD::FREM:
    643   case ISD::SDIV:
    644   case ISD::UDIV:
    645   case ISD::SREM:
    646   case ISD::UREM:
    647     return true;
    648   }
    649 }
    650 
    651 
    652 static unsigned getVectorTypeBreakdownMVT(MVT VT, MVT &IntermediateVT,
    653                                           unsigned &NumIntermediates,
    654                                           EVT &RegisterVT,
    655                                           TargetLowering *TLI) {
    656   // Figure out the right, legal destination reg to copy into.
    657   unsigned NumElts = VT.getVectorNumElements();
    658   MVT EltTy = VT.getVectorElementType();
    659 
    660   unsigned NumVectorRegs = 1;
    661 
    662   // FIXME: We don't support non-power-of-2-sized vectors for now.  Ideally we
    663   // could break down into LHS/RHS like LegalizeDAG does.
    664   if (!isPowerOf2_32(NumElts)) {
    665     NumVectorRegs = NumElts;
    666     NumElts = 1;
    667   }
    668 
    669   // Divide the input until we get to a supported size.  This will always
    670   // end with a scalar if the target doesn't support vectors.
    671   while (NumElts > 1 && !TLI->isTypeLegal(MVT::getVectorVT(EltTy, NumElts))) {
    672     NumElts >>= 1;
    673     NumVectorRegs <<= 1;
    674   }
    675 
    676   NumIntermediates = NumVectorRegs;
    677 
    678   MVT NewVT = MVT::getVectorVT(EltTy, NumElts);
    679   if (!TLI->isTypeLegal(NewVT))
    680     NewVT = EltTy;
    681   IntermediateVT = NewVT;
    682 
    683   unsigned NewVTSize = NewVT.getSizeInBits();
    684 
    685   // Convert sizes such as i33 to i64.
    686   if (!isPowerOf2_32(NewVTSize))
    687     NewVTSize = NextPowerOf2(NewVTSize);
    688 
    689   EVT DestVT = TLI->getRegisterType(NewVT);
    690   RegisterVT = DestVT;
    691   if (EVT(DestVT).bitsLT(NewVT))    // Value is expanded, e.g. i64 -> i16.
    692     return NumVectorRegs*(NewVTSize/DestVT.getSizeInBits());
    693 
    694   // Otherwise, promotion or legal types use the same number of registers as
    695   // the vector decimated to the appropriate level.
    696   return NumVectorRegs;
    697 }
    698 
    699 /// isLegalRC - Return true if the value types that can be represented by the
    700 /// specified register class are all legal.
    701 bool TargetLowering::isLegalRC(const TargetRegisterClass *RC) const {
    702   for (TargetRegisterClass::vt_iterator I = RC->vt_begin(), E = RC->vt_end();
    703        I != E; ++I) {
    704     if (isTypeLegal(*I))
    705       return true;
    706   }
    707   return false;
    708 }
    709 
    710 /// hasLegalSuperRegRegClasses - Return true if the specified register class
    711 /// has one or more super-reg register classes that are legal.
    712 bool
    713 TargetLowering::hasLegalSuperRegRegClasses(const TargetRegisterClass *RC) const{
    714   if (*RC->superregclasses_begin() == 0)
    715     return false;
    716   for (TargetRegisterInfo::regclass_iterator I = RC->superregclasses_begin(),
    717          E = RC->superregclasses_end(); I != E; ++I) {
    718     const TargetRegisterClass *RRC = *I;
    719     if (isLegalRC(RRC))
    720       return true;
    721   }
    722   return false;
    723 }
    724 
    725 /// findRepresentativeClass - Return the largest legal super-reg register class
    726 /// of the register class for the specified type and its associated "cost".
    727 std::pair<const TargetRegisterClass*, uint8_t>
    728 TargetLowering::findRepresentativeClass(EVT VT) const {
    729   const TargetRegisterClass *RC = RegClassForVT[VT.getSimpleVT().SimpleTy];
    730   if (!RC)
    731     return std::make_pair(RC, 0);
    732   const TargetRegisterClass *BestRC = RC;
    733   for (TargetRegisterInfo::regclass_iterator I = RC->superregclasses_begin(),
    734          E = RC->superregclasses_end(); I != E; ++I) {
    735     const TargetRegisterClass *RRC = *I;
    736     if (RRC->isASubClass() || !isLegalRC(RRC))
    737       continue;
    738     if (!hasLegalSuperRegRegClasses(RRC))
    739       return std::make_pair(RRC, 1);
    740     BestRC = RRC;
    741   }
    742   return std::make_pair(BestRC, 1);
    743 }
    744 
    745 
    746 /// computeRegisterProperties - Once all of the register classes are added,
    747 /// this allows us to compute derived properties we expose.
    748 void TargetLowering::computeRegisterProperties() {
    749   assert(MVT::LAST_VALUETYPE <= MVT::MAX_ALLOWED_VALUETYPE &&
    750          "Too many value types for ValueTypeActions to hold!");
    751 
    752   // Everything defaults to needing one register.
    753   for (unsigned i = 0; i != MVT::LAST_VALUETYPE; ++i) {
    754     NumRegistersForVT[i] = 1;
    755     RegisterTypeForVT[i] = TransformToType[i] = (MVT::SimpleValueType)i;
    756   }
    757   // ...except isVoid, which doesn't need any registers.
    758   NumRegistersForVT[MVT::isVoid] = 0;
    759 
    760   // Find the largest integer register class.
    761   unsigned LargestIntReg = MVT::LAST_INTEGER_VALUETYPE;
    762   for (; RegClassForVT[LargestIntReg] == 0; --LargestIntReg)
    763     assert(LargestIntReg != MVT::i1 && "No integer registers defined!");
    764 
    765   // Every integer value type larger than this largest register takes twice as
    766   // many registers to represent as the previous ValueType.
    767   for (unsigned ExpandedReg = LargestIntReg + 1; ; ++ExpandedReg) {
    768     EVT ExpandedVT = (MVT::SimpleValueType)ExpandedReg;
    769     if (!ExpandedVT.isInteger())
    770       break;
    771     NumRegistersForVT[ExpandedReg] = 2*NumRegistersForVT[ExpandedReg-1];
    772     RegisterTypeForVT[ExpandedReg] = (MVT::SimpleValueType)LargestIntReg;
    773     TransformToType[ExpandedReg] = (MVT::SimpleValueType)(ExpandedReg - 1);
    774     ValueTypeActions.setTypeAction(ExpandedVT, TypeExpandInteger);
    775   }
    776 
    777   // Inspect all of the ValueType's smaller than the largest integer
    778   // register to see which ones need promotion.
    779   unsigned LegalIntReg = LargestIntReg;
    780   for (unsigned IntReg = LargestIntReg - 1;
    781        IntReg >= (unsigned)MVT::i1; --IntReg) {
    782     EVT IVT = (MVT::SimpleValueType)IntReg;
    783     if (isTypeLegal(IVT)) {
    784       LegalIntReg = IntReg;
    785     } else {
    786       RegisterTypeForVT[IntReg] = TransformToType[IntReg] =
    787         (MVT::SimpleValueType)LegalIntReg;
    788       ValueTypeActions.setTypeAction(IVT, TypePromoteInteger);
    789     }
    790   }
    791 
    792   // ppcf128 type is really two f64's.
    793   if (!isTypeLegal(MVT::ppcf128)) {
    794     NumRegistersForVT[MVT::ppcf128] = 2*NumRegistersForVT[MVT::f64];
    795     RegisterTypeForVT[MVT::ppcf128] = MVT::f64;
    796     TransformToType[MVT::ppcf128] = MVT::f64;
    797     ValueTypeActions.setTypeAction(MVT::ppcf128, TypeExpandFloat);
    798   }
    799 
    800   // Decide how to handle f64. If the target does not have native f64 support,
    801   // expand it to i64 and we will be generating soft float library calls.
    802   if (!isTypeLegal(MVT::f64)) {
    803     NumRegistersForVT[MVT::f64] = NumRegistersForVT[MVT::i64];
    804     RegisterTypeForVT[MVT::f64] = RegisterTypeForVT[MVT::i64];
    805     TransformToType[MVT::f64] = MVT::i64;
    806     ValueTypeActions.setTypeAction(MVT::f64, TypeSoftenFloat);
    807   }
    808 
    809   // Decide how to handle f32. If the target does not have native support for
    810   // f32, promote it to f64 if it is legal. Otherwise, expand it to i32.
    811   if (!isTypeLegal(MVT::f32)) {
    812     if (isTypeLegal(MVT::f64)) {
    813       NumRegistersForVT[MVT::f32] = NumRegistersForVT[MVT::f64];
    814       RegisterTypeForVT[MVT::f32] = RegisterTypeForVT[MVT::f64];
    815       TransformToType[MVT::f32] = MVT::f64;
    816       ValueTypeActions.setTypeAction(MVT::f32, TypePromoteInteger);
    817     } else {
    818       NumRegistersForVT[MVT::f32] = NumRegistersForVT[MVT::i32];
    819       RegisterTypeForVT[MVT::f32] = RegisterTypeForVT[MVT::i32];
    820       TransformToType[MVT::f32] = MVT::i32;
    821       ValueTypeActions.setTypeAction(MVT::f32, TypeSoftenFloat);
    822     }
    823   }
    824 
    825   // Loop over all of the vector value types to see which need transformations.
    826   for (unsigned i = MVT::FIRST_VECTOR_VALUETYPE;
    827        i <= (unsigned)MVT::LAST_VECTOR_VALUETYPE; ++i) {
    828     MVT VT = (MVT::SimpleValueType)i;
    829     if (isTypeLegal(VT)) continue;
    830 
    831     // Determine if there is a legal wider type.  If so, we should promote to
    832     // that wider vector type.
    833     EVT EltVT = VT.getVectorElementType();
    834     unsigned NElts = VT.getVectorNumElements();
    835     if (NElts != 1) {
    836       bool IsLegalWiderType = false;
    837       // If we allow the promotion of vector elements using a flag,
    838       // then return TypePromoteInteger on vector elements.
    839       // First try to promote the elements of integer vectors. If no legal
    840       // promotion was found, fallback to the widen-vector method.
    841       if (mayPromoteElements)
    842       for (unsigned nVT = i+1; nVT <= MVT::LAST_VECTOR_VALUETYPE; ++nVT) {
    843         EVT SVT = (MVT::SimpleValueType)nVT;
    844         // Promote vectors of integers to vectors with the same number
    845         // of elements, with a wider element type.
    846         if (SVT.getVectorElementType().getSizeInBits() > EltVT.getSizeInBits()
    847             && SVT.getVectorNumElements() == NElts &&
    848             isTypeLegal(SVT) && SVT.getScalarType().isInteger()) {
    849           TransformToType[i] = SVT;
    850           RegisterTypeForVT[i] = SVT;
    851           NumRegistersForVT[i] = 1;
    852           ValueTypeActions.setTypeAction(VT, TypePromoteInteger);
    853           IsLegalWiderType = true;
    854           break;
    855         }
    856       }
    857 
    858       if (IsLegalWiderType) continue;
    859 
    860       // Try to widen the vector.
    861       for (unsigned nVT = i+1; nVT <= MVT::LAST_VECTOR_VALUETYPE; ++nVT) {
    862         EVT SVT = (MVT::SimpleValueType)nVT;
    863         if (SVT.getVectorElementType() == EltVT &&
    864             SVT.getVectorNumElements() > NElts &&
    865             isTypeLegal(SVT)) {
    866           TransformToType[i] = SVT;
    867           RegisterTypeForVT[i] = SVT;
    868           NumRegistersForVT[i] = 1;
    869           ValueTypeActions.setTypeAction(VT, TypeWidenVector);
    870           IsLegalWiderType = true;
    871           break;
    872         }
    873       }
    874       if (IsLegalWiderType) continue;
    875     }
    876 
    877     MVT IntermediateVT;
    878     EVT RegisterVT;
    879     unsigned NumIntermediates;
    880     NumRegistersForVT[i] =
    881       getVectorTypeBreakdownMVT(VT, IntermediateVT, NumIntermediates,
    882                                 RegisterVT, this);
    883     RegisterTypeForVT[i] = RegisterVT;
    884 
    885     EVT NVT = VT.getPow2VectorType();
    886     if (NVT == VT) {
    887       // Type is already a power of 2.  The default action is to split.
    888       TransformToType[i] = MVT::Other;
    889       unsigned NumElts = VT.getVectorNumElements();
    890       ValueTypeActions.setTypeAction(VT,
    891             NumElts > 1 ? TypeSplitVector : TypeScalarizeVector);
    892     } else {
    893       TransformToType[i] = NVT;
    894       ValueTypeActions.setTypeAction(VT, TypeWidenVector);
    895     }
    896   }
    897 
    898   // Determine the 'representative' register class for each value type.
    899   // An representative register class is the largest (meaning one which is
    900   // not a sub-register class / subreg register class) legal register class for
    901   // a group of value types. For example, on i386, i8, i16, and i32
    902   // representative would be GR32; while on x86_64 it's GR64.
    903   for (unsigned i = 0; i != MVT::LAST_VALUETYPE; ++i) {
    904     const TargetRegisterClass* RRC;
    905     uint8_t Cost;
    906     tie(RRC, Cost) =  findRepresentativeClass((MVT::SimpleValueType)i);
    907     RepRegClassForVT[i] = RRC;
    908     RepRegClassCostForVT[i] = Cost;
    909   }
    910 }
    911 
    912 const char *TargetLowering::getTargetNodeName(unsigned Opcode) const {
    913   return NULL;
    914 }
    915 
    916 
    917 MVT::SimpleValueType TargetLowering::getSetCCResultType(EVT VT) const {
    918   return PointerTy.SimpleTy;
    919 }
    920 
    921 MVT::SimpleValueType TargetLowering::getCmpLibcallReturnType() const {
    922   return MVT::i32; // return the default value
    923 }
    924 
    925 /// getVectorTypeBreakdown - Vector types are broken down into some number of
    926 /// legal first class types.  For example, MVT::v8f32 maps to 2 MVT::v4f32
    927 /// with Altivec or SSE1, or 8 promoted MVT::f64 values with the X86 FP stack.
    928 /// Similarly, MVT::v2i64 turns into 4 MVT::i32 values with both PPC and X86.
    929 ///
    930 /// This method returns the number of registers needed, and the VT for each
    931 /// register.  It also returns the VT and quantity of the intermediate values
    932 /// before they are promoted/expanded.
    933 ///
    934 unsigned TargetLowering::getVectorTypeBreakdown(LLVMContext &Context, EVT VT,
    935                                                 EVT &IntermediateVT,
    936                                                 unsigned &NumIntermediates,
    937                                                 EVT &RegisterVT) const {
    938   unsigned NumElts = VT.getVectorNumElements();
    939 
    940   // If there is a wider vector type with the same element type as this one,
    941   // we should widen to that legal vector type.  This handles things like
    942   // <2 x float> -> <4 x float>.
    943   if (NumElts != 1 && getTypeAction(Context, VT) == TypeWidenVector) {
    944     RegisterVT = getTypeToTransformTo(Context, VT);
    945     if (isTypeLegal(RegisterVT)) {
    946       IntermediateVT = RegisterVT;
    947       NumIntermediates = 1;
    948       return 1;
    949     }
    950   }
    951 
    952   // Figure out the right, legal destination reg to copy into.
    953   EVT EltTy = VT.getVectorElementType();
    954 
    955   unsigned NumVectorRegs = 1;
    956 
    957   // FIXME: We don't support non-power-of-2-sized vectors for now.  Ideally we
    958   // could break down into LHS/RHS like LegalizeDAG does.
    959   if (!isPowerOf2_32(NumElts)) {
    960     NumVectorRegs = NumElts;
    961     NumElts = 1;
    962   }
    963 
    964   // Divide the input until we get to a supported size.  This will always
    965   // end with a scalar if the target doesn't support vectors.
    966   while (NumElts > 1 && !isTypeLegal(
    967                                    EVT::getVectorVT(Context, EltTy, NumElts))) {
    968     NumElts >>= 1;
    969     NumVectorRegs <<= 1;
    970   }
    971 
    972   NumIntermediates = NumVectorRegs;
    973 
    974   EVT NewVT = EVT::getVectorVT(Context, EltTy, NumElts);
    975   if (!isTypeLegal(NewVT))
    976     NewVT = EltTy;
    977   IntermediateVT = NewVT;
    978 
    979   EVT DestVT = getRegisterType(Context, NewVT);
    980   RegisterVT = DestVT;
    981   unsigned NewVTSize = NewVT.getSizeInBits();
    982 
    983   // Convert sizes such as i33 to i64.
    984   if (!isPowerOf2_32(NewVTSize))
    985     NewVTSize = NextPowerOf2(NewVTSize);
    986 
    987   if (DestVT.bitsLT(NewVT))   // Value is expanded, e.g. i64 -> i16.
    988     return NumVectorRegs*(NewVTSize/DestVT.getSizeInBits());
    989 
    990   // Otherwise, promotion or legal types use the same number of registers as
    991   // the vector decimated to the appropriate level.
    992   return NumVectorRegs;
    993 }
    994 
    995 /// Get the EVTs and ArgFlags collections that represent the legalized return
    996 /// type of the given function.  This does not require a DAG or a return value,
    997 /// and is suitable for use before any DAGs for the function are constructed.
    998 /// TODO: Move this out of TargetLowering.cpp.
    999 void llvm::GetReturnInfo(Type* ReturnType, Attributes attr,
   1000                          SmallVectorImpl<ISD::OutputArg> &Outs,
   1001                          const TargetLowering &TLI,
   1002                          SmallVectorImpl<uint64_t> *Offsets) {
   1003   SmallVector<EVT, 4> ValueVTs;
   1004   ComputeValueVTs(TLI, ReturnType, ValueVTs);
   1005   unsigned NumValues = ValueVTs.size();
   1006   if (NumValues == 0) return;
   1007   unsigned Offset = 0;
   1008 
   1009   for (unsigned j = 0, f = NumValues; j != f; ++j) {
   1010     EVT VT = ValueVTs[j];
   1011     ISD::NodeType ExtendKind = ISD::ANY_EXTEND;
   1012 
   1013     if (attr & Attribute::SExt)
   1014       ExtendKind = ISD::SIGN_EXTEND;
   1015     else if (attr & Attribute::ZExt)
   1016       ExtendKind = ISD::ZERO_EXTEND;
   1017 
   1018     // FIXME: C calling convention requires the return type to be promoted to
   1019     // at least 32-bit. But this is not necessary for non-C calling
   1020     // conventions. The frontend should mark functions whose return values
   1021     // require promoting with signext or zeroext attributes.
   1022     if (ExtendKind != ISD::ANY_EXTEND && VT.isInteger()) {
   1023       EVT MinVT = TLI.getRegisterType(ReturnType->getContext(), MVT::i32);
   1024       if (VT.bitsLT(MinVT))
   1025         VT = MinVT;
   1026     }
   1027 
   1028     unsigned NumParts = TLI.getNumRegisters(ReturnType->getContext(), VT);
   1029     EVT PartVT = TLI.getRegisterType(ReturnType->getContext(), VT);
   1030     unsigned PartSize = TLI.getTargetData()->getTypeAllocSize(
   1031                         PartVT.getTypeForEVT(ReturnType->getContext()));
   1032 
   1033     // 'inreg' on function refers to return value
   1034     ISD::ArgFlagsTy Flags = ISD::ArgFlagsTy();
   1035     if (attr & Attribute::InReg)
   1036       Flags.setInReg();
   1037 
   1038     // Propagate extension type if any
   1039     if (attr & Attribute::SExt)
   1040       Flags.setSExt();
   1041     else if (attr & Attribute::ZExt)
   1042       Flags.setZExt();
   1043 
   1044     for (unsigned i = 0; i < NumParts; ++i) {
   1045       Outs.push_back(ISD::OutputArg(Flags, PartVT, /*isFixed=*/true));
   1046       if (Offsets) {
   1047         Offsets->push_back(Offset);
   1048         Offset += PartSize;
   1049       }
   1050     }
   1051   }
   1052 }
   1053 
   1054 /// getByValTypeAlignment - Return the desired alignment for ByVal aggregate
   1055 /// function arguments in the caller parameter area.  This is the actual
   1056 /// alignment, not its logarithm.
   1057 unsigned TargetLowering::getByValTypeAlignment(Type *Ty) const {
   1058   return TD->getCallFrameTypeAlignment(Ty);
   1059 }
   1060 
   1061 /// getJumpTableEncoding - Return the entry encoding for a jump table in the
   1062 /// current function.  The returned value is a member of the
   1063 /// MachineJumpTableInfo::JTEntryKind enum.
   1064 unsigned TargetLowering::getJumpTableEncoding() const {
   1065   // In non-pic modes, just use the address of a block.
   1066   if (getTargetMachine().getRelocationModel() != Reloc::PIC_)
   1067     return MachineJumpTableInfo::EK_BlockAddress;
   1068 
   1069   // In PIC mode, if the target supports a GPRel32 directive, use it.
   1070   if (getTargetMachine().getMCAsmInfo()->getGPRel32Directive() != 0)
   1071     return MachineJumpTableInfo::EK_GPRel32BlockAddress;
   1072 
   1073   // Otherwise, use a label difference.
   1074   return MachineJumpTableInfo::EK_LabelDifference32;
   1075 }
   1076 
   1077 SDValue TargetLowering::getPICJumpTableRelocBase(SDValue Table,
   1078                                                  SelectionDAG &DAG) const {
   1079   // If our PIC model is GP relative, use the global offset table as the base.
   1080   if (getJumpTableEncoding() == MachineJumpTableInfo::EK_GPRel32BlockAddress)
   1081     return DAG.getGLOBAL_OFFSET_TABLE(getPointerTy());
   1082   return Table;
   1083 }
   1084 
   1085 /// getPICJumpTableRelocBaseExpr - This returns the relocation base for the
   1086 /// given PIC jumptable, the same as getPICJumpTableRelocBase, but as an
   1087 /// MCExpr.
   1088 const MCExpr *
   1089 TargetLowering::getPICJumpTableRelocBaseExpr(const MachineFunction *MF,
   1090                                              unsigned JTI,MCContext &Ctx) const{
   1091   // The normal PIC reloc base is the label at the start of the jump table.
   1092   return MCSymbolRefExpr::Create(MF->getJTISymbol(JTI, Ctx), Ctx);
   1093 }
   1094 
   1095 bool
   1096 TargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
   1097   // Assume that everything is safe in static mode.
   1098   if (getTargetMachine().getRelocationModel() == Reloc::Static)
   1099     return true;
   1100 
   1101   // In dynamic-no-pic mode, assume that known defined values are safe.
   1102   if (getTargetMachine().getRelocationModel() == Reloc::DynamicNoPIC &&
   1103       GA &&
   1104       !GA->getGlobal()->isDeclaration() &&
   1105       !GA->getGlobal()->isWeakForLinker())
   1106     return true;
   1107 
   1108   // Otherwise assume nothing is safe.
   1109   return false;
   1110 }
   1111 
   1112 //===----------------------------------------------------------------------===//
   1113 //  Optimization Methods
   1114 //===----------------------------------------------------------------------===//
   1115 
   1116 /// ShrinkDemandedConstant - Check to see if the specified operand of the
   1117 /// specified instruction is a constant integer.  If so, check to see if there
   1118 /// are any bits set in the constant that are not demanded.  If so, shrink the
   1119 /// constant and return true.
   1120 bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDValue Op,
   1121                                                         const APInt &Demanded) {
   1122   DebugLoc dl = Op.getDebugLoc();
   1123 
   1124   // FIXME: ISD::SELECT, ISD::SELECT_CC
   1125   switch (Op.getOpcode()) {
   1126   default: break;
   1127   case ISD::XOR:
   1128   case ISD::AND:
   1129   case ISD::OR: {
   1130     ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
   1131     if (!C) return false;
   1132 
   1133     if (Op.getOpcode() == ISD::XOR &&
   1134         (C->getAPIntValue() | (~Demanded)).isAllOnesValue())
   1135       return false;
   1136 
   1137     // if we can expand it to have all bits set, do it
   1138     if (C->getAPIntValue().intersects(~Demanded)) {
   1139       EVT VT = Op.getValueType();
   1140       SDValue New = DAG.getNode(Op.getOpcode(), dl, VT, Op.getOperand(0),
   1141                                 DAG.getConstant(Demanded &
   1142                                                 C->getAPIntValue(),
   1143                                                 VT));
   1144       return CombineTo(Op, New);
   1145     }
   1146 
   1147     break;
   1148   }
   1149   }
   1150 
   1151   return false;
   1152 }
   1153 
   1154 /// ShrinkDemandedOp - Convert x+y to (VT)((SmallVT)x+(SmallVT)y) if the
   1155 /// casts are free.  This uses isZExtFree and ZERO_EXTEND for the widening
   1156 /// cast, but it could be generalized for targets with other types of
   1157 /// implicit widening casts.
   1158 bool
   1159 TargetLowering::TargetLoweringOpt::ShrinkDemandedOp(SDValue Op,
   1160                                                     unsigned BitWidth,
   1161                                                     const APInt &Demanded,
   1162                                                     DebugLoc dl) {
   1163   assert(Op.getNumOperands() == 2 &&
   1164          "ShrinkDemandedOp only supports binary operators!");
   1165   assert(Op.getNode()->getNumValues() == 1 &&
   1166          "ShrinkDemandedOp only supports nodes with one result!");
   1167 
   1168   // Don't do this if the node has another user, which may require the
   1169   // full value.
   1170   if (!Op.getNode()->hasOneUse())
   1171     return false;
   1172 
   1173   // Search for the smallest integer type with free casts to and from
   1174   // Op's type. For expedience, just check power-of-2 integer types.
   1175   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   1176   unsigned SmallVTBits = BitWidth - Demanded.countLeadingZeros();
   1177   if (!isPowerOf2_32(SmallVTBits))
   1178     SmallVTBits = NextPowerOf2(SmallVTBits);
   1179   for (; SmallVTBits < BitWidth; SmallVTBits = NextPowerOf2(SmallVTBits)) {
   1180     EVT SmallVT = EVT::getIntegerVT(*DAG.getContext(), SmallVTBits);
   1181     if (TLI.isTruncateFree(Op.getValueType(), SmallVT) &&
   1182         TLI.isZExtFree(SmallVT, Op.getValueType())) {
   1183       // We found a type with free casts.
   1184       SDValue X = DAG.getNode(Op.getOpcode(), dl, SmallVT,
   1185                               DAG.getNode(ISD::TRUNCATE, dl, SmallVT,
   1186                                           Op.getNode()->getOperand(0)),
   1187                               DAG.getNode(ISD::TRUNCATE, dl, SmallVT,
   1188                                           Op.getNode()->getOperand(1)));
   1189       SDValue Z = DAG.getNode(ISD::ZERO_EXTEND, dl, Op.getValueType(), X);
   1190       return CombineTo(Op, Z);
   1191     }
   1192   }
   1193   return false;
   1194 }
   1195 
   1196 /// SimplifyDemandedBits - Look at Op.  At this point, we know that only the
   1197 /// DemandedMask bits of the result of Op are ever used downstream.  If we can
   1198 /// use this information to simplify Op, create a new simplified DAG node and
   1199 /// return true, returning the original and new nodes in Old and New. Otherwise,
   1200 /// analyze the expression and return a mask of KnownOne and KnownZero bits for
   1201 /// the expression (used to simplify the caller).  The KnownZero/One bits may
   1202 /// only be accurate for those bits in the DemandedMask.
   1203 bool TargetLowering::SimplifyDemandedBits(SDValue Op,
   1204                                           const APInt &DemandedMask,
   1205                                           APInt &KnownZero,
   1206                                           APInt &KnownOne,
   1207                                           TargetLoweringOpt &TLO,
   1208                                           unsigned Depth) const {
   1209   unsigned BitWidth = DemandedMask.getBitWidth();
   1210   assert(Op.getValueType().getScalarType().getSizeInBits() == BitWidth &&
   1211          "Mask size mismatches value type size!");
   1212   APInt NewMask = DemandedMask;
   1213   DebugLoc dl = Op.getDebugLoc();
   1214 
   1215   // Don't know anything.
   1216   KnownZero = KnownOne = APInt(BitWidth, 0);
   1217 
   1218   // Other users may use these bits.
   1219   if (!Op.getNode()->hasOneUse()) {
   1220     if (Depth != 0) {
   1221       // If not at the root, Just compute the KnownZero/KnownOne bits to
   1222       // simplify things downstream.
   1223       TLO.DAG.ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
   1224       return false;
   1225     }
   1226     // If this is the root being simplified, allow it to have multiple uses,
   1227     // just set the NewMask to all bits.
   1228     NewMask = APInt::getAllOnesValue(BitWidth);
   1229   } else if (DemandedMask == 0) {
   1230     // Not demanding any bits from Op.
   1231     if (Op.getOpcode() != ISD::UNDEF)
   1232       return TLO.CombineTo(Op, TLO.DAG.getUNDEF(Op.getValueType()));
   1233     return false;
   1234   } else if (Depth == 6) {        // Limit search depth.
   1235     return false;
   1236   }
   1237 
   1238   APInt KnownZero2, KnownOne2, KnownZeroOut, KnownOneOut;
   1239   switch (Op.getOpcode()) {
   1240   case ISD::Constant:
   1241     // We know all of the bits for a constant!
   1242     KnownOne = cast<ConstantSDNode>(Op)->getAPIntValue() & NewMask;
   1243     KnownZero = ~KnownOne & NewMask;
   1244     return false;   // Don't fall through, will infinitely loop.
   1245   case ISD::AND:
   1246     // If the RHS is a constant, check to see if the LHS would be zero without
   1247     // using the bits from the RHS.  Below, we use knowledge about the RHS to
   1248     // simplify the LHS, here we're using information from the LHS to simplify
   1249     // the RHS.
   1250     if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
   1251       APInt LHSZero, LHSOne;
   1252       // Do not increment Depth here; that can cause an infinite loop.
   1253       TLO.DAG.ComputeMaskedBits(Op.getOperand(0), NewMask,
   1254                                 LHSZero, LHSOne, Depth);
   1255       // If the LHS already has zeros where RHSC does, this and is dead.
   1256       if ((LHSZero & NewMask) == (~RHSC->getAPIntValue() & NewMask))
   1257         return TLO.CombineTo(Op, Op.getOperand(0));
   1258       // If any of the set bits in the RHS are known zero on the LHS, shrink
   1259       // the constant.
   1260       if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & NewMask))
   1261         return true;
   1262     }
   1263 
   1264     if (SimplifyDemandedBits(Op.getOperand(1), NewMask, KnownZero,
   1265                              KnownOne, TLO, Depth+1))
   1266       return true;
   1267     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1268     if (SimplifyDemandedBits(Op.getOperand(0), ~KnownZero & NewMask,
   1269                              KnownZero2, KnownOne2, TLO, Depth+1))
   1270       return true;
   1271     assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
   1272 
   1273     // If all of the demanded bits are known one on one side, return the other.
   1274     // These bits cannot contribute to the result of the 'and'.
   1275     if ((NewMask & ~KnownZero2 & KnownOne) == (~KnownZero2 & NewMask))
   1276       return TLO.CombineTo(Op, Op.getOperand(0));
   1277     if ((NewMask & ~KnownZero & KnownOne2) == (~KnownZero & NewMask))
   1278       return TLO.CombineTo(Op, Op.getOperand(1));
   1279     // If all of the demanded bits in the inputs are known zeros, return zero.
   1280     if ((NewMask & (KnownZero|KnownZero2)) == NewMask)
   1281       return TLO.CombineTo(Op, TLO.DAG.getConstant(0, Op.getValueType()));
   1282     // If the RHS is a constant, see if we can simplify it.
   1283     if (TLO.ShrinkDemandedConstant(Op, ~KnownZero2 & NewMask))
   1284       return true;
   1285     // If the operation can be done in a smaller type, do so.
   1286     if (TLO.ShrinkDemandedOp(Op, BitWidth, NewMask, dl))
   1287       return true;
   1288 
   1289     // Output known-1 bits are only known if set in both the LHS & RHS.
   1290     KnownOne &= KnownOne2;
   1291     // Output known-0 are known to be clear if zero in either the LHS | RHS.
   1292     KnownZero |= KnownZero2;
   1293     break;
   1294   case ISD::OR:
   1295     if (SimplifyDemandedBits(Op.getOperand(1), NewMask, KnownZero,
   1296                              KnownOne, TLO, Depth+1))
   1297       return true;
   1298     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1299     if (SimplifyDemandedBits(Op.getOperand(0), ~KnownOne & NewMask,
   1300                              KnownZero2, KnownOne2, TLO, Depth+1))
   1301       return true;
   1302     assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
   1303 
   1304     // If all of the demanded bits are known zero on one side, return the other.
   1305     // These bits cannot contribute to the result of the 'or'.
   1306     if ((NewMask & ~KnownOne2 & KnownZero) == (~KnownOne2 & NewMask))
   1307       return TLO.CombineTo(Op, Op.getOperand(0));
   1308     if ((NewMask & ~KnownOne & KnownZero2) == (~KnownOne & NewMask))
   1309       return TLO.CombineTo(Op, Op.getOperand(1));
   1310     // If all of the potentially set bits on one side are known to be set on
   1311     // the other side, just use the 'other' side.
   1312     if ((NewMask & ~KnownZero & KnownOne2) == (~KnownZero & NewMask))
   1313       return TLO.CombineTo(Op, Op.getOperand(0));
   1314     if ((NewMask & ~KnownZero2 & KnownOne) == (~KnownZero2 & NewMask))
   1315       return TLO.CombineTo(Op, Op.getOperand(1));
   1316     // If the RHS is a constant, see if we can simplify it.
   1317     if (TLO.ShrinkDemandedConstant(Op, NewMask))
   1318       return true;
   1319     // If the operation can be done in a smaller type, do so.
   1320     if (TLO.ShrinkDemandedOp(Op, BitWidth, NewMask, dl))
   1321       return true;
   1322 
   1323     // Output known-0 bits are only known if clear in both the LHS & RHS.
   1324     KnownZero &= KnownZero2;
   1325     // Output known-1 are known to be set if set in either the LHS | RHS.
   1326     KnownOne |= KnownOne2;
   1327     break;
   1328   case ISD::XOR:
   1329     if (SimplifyDemandedBits(Op.getOperand(1), NewMask, KnownZero,
   1330                              KnownOne, TLO, Depth+1))
   1331       return true;
   1332     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1333     if (SimplifyDemandedBits(Op.getOperand(0), NewMask, KnownZero2,
   1334                              KnownOne2, TLO, Depth+1))
   1335       return true;
   1336     assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
   1337 
   1338     // If all of the demanded bits are known zero on one side, return the other.
   1339     // These bits cannot contribute to the result of the 'xor'.
   1340     if ((KnownZero & NewMask) == NewMask)
   1341       return TLO.CombineTo(Op, Op.getOperand(0));
   1342     if ((KnownZero2 & NewMask) == NewMask)
   1343       return TLO.CombineTo(Op, Op.getOperand(1));
   1344     // If the operation can be done in a smaller type, do so.
   1345     if (TLO.ShrinkDemandedOp(Op, BitWidth, NewMask, dl))
   1346       return true;
   1347 
   1348     // If all of the unknown bits are known to be zero on one side or the other
   1349     // (but not both) turn this into an *inclusive* or.
   1350     //    e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
   1351     if ((NewMask & ~KnownZero & ~KnownZero2) == 0)
   1352       return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, dl, Op.getValueType(),
   1353                                                Op.getOperand(0),
   1354                                                Op.getOperand(1)));
   1355 
   1356     // Output known-0 bits are known if clear or set in both the LHS & RHS.
   1357     KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
   1358     // Output known-1 are known to be set if set in only one of the LHS, RHS.
   1359     KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
   1360 
   1361     // If all of the demanded bits on one side are known, and all of the set
   1362     // bits on that side are also known to be set on the other side, turn this
   1363     // into an AND, as we know the bits will be cleared.
   1364     //    e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
   1365     if ((NewMask & (KnownZero|KnownOne)) == NewMask) { // all known
   1366       if ((KnownOne & KnownOne2) == KnownOne) {
   1367         EVT VT = Op.getValueType();
   1368         SDValue ANDC = TLO.DAG.getConstant(~KnownOne & NewMask, VT);
   1369         return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::AND, dl, VT,
   1370                                                  Op.getOperand(0), ANDC));
   1371       }
   1372     }
   1373 
   1374     // If the RHS is a constant, see if we can simplify it.
   1375     // for XOR, we prefer to force bits to 1 if they will make a -1.
   1376     // if we can't force bits, try to shrink constant
   1377     if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
   1378       APInt Expanded = C->getAPIntValue() | (~NewMask);
   1379       // if we can expand it to have all bits set, do it
   1380       if (Expanded.isAllOnesValue()) {
   1381         if (Expanded != C->getAPIntValue()) {
   1382           EVT VT = Op.getValueType();
   1383           SDValue New = TLO.DAG.getNode(Op.getOpcode(), dl,VT, Op.getOperand(0),
   1384                                           TLO.DAG.getConstant(Expanded, VT));
   1385           return TLO.CombineTo(Op, New);
   1386         }
   1387         // if it already has all the bits set, nothing to change
   1388         // but don't shrink either!
   1389       } else if (TLO.ShrinkDemandedConstant(Op, NewMask)) {
   1390         return true;
   1391       }
   1392     }
   1393 
   1394     KnownZero = KnownZeroOut;
   1395     KnownOne  = KnownOneOut;
   1396     break;
   1397   case ISD::SELECT:
   1398     if (SimplifyDemandedBits(Op.getOperand(2), NewMask, KnownZero,
   1399                              KnownOne, TLO, Depth+1))
   1400       return true;
   1401     if (SimplifyDemandedBits(Op.getOperand(1), NewMask, KnownZero2,
   1402                              KnownOne2, TLO, Depth+1))
   1403       return true;
   1404     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1405     assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
   1406 
   1407     // If the operands are constants, see if we can simplify them.
   1408     if (TLO.ShrinkDemandedConstant(Op, NewMask))
   1409       return true;
   1410 
   1411     // Only known if known in both the LHS and RHS.
   1412     KnownOne &= KnownOne2;
   1413     KnownZero &= KnownZero2;
   1414     break;
   1415   case ISD::SELECT_CC:
   1416     if (SimplifyDemandedBits(Op.getOperand(3), NewMask, KnownZero,
   1417                              KnownOne, TLO, Depth+1))
   1418       return true;
   1419     if (SimplifyDemandedBits(Op.getOperand(2), NewMask, KnownZero2,
   1420                              KnownOne2, TLO, Depth+1))
   1421       return true;
   1422     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1423     assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
   1424 
   1425     // If the operands are constants, see if we can simplify them.
   1426     if (TLO.ShrinkDemandedConstant(Op, NewMask))
   1427       return true;
   1428 
   1429     // Only known if known in both the LHS and RHS.
   1430     KnownOne &= KnownOne2;
   1431     KnownZero &= KnownZero2;
   1432     break;
   1433   case ISD::SHL:
   1434     if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
   1435       unsigned ShAmt = SA->getZExtValue();
   1436       SDValue InOp = Op.getOperand(0);
   1437 
   1438       // If the shift count is an invalid immediate, don't do anything.
   1439       if (ShAmt >= BitWidth)
   1440         break;
   1441 
   1442       // If this is ((X >>u C1) << ShAmt), see if we can simplify this into a
   1443       // single shift.  We can do this if the bottom bits (which are shifted
   1444       // out) are never demanded.
   1445       if (InOp.getOpcode() == ISD::SRL &&
   1446           isa<ConstantSDNode>(InOp.getOperand(1))) {
   1447         if (ShAmt && (NewMask & APInt::getLowBitsSet(BitWidth, ShAmt)) == 0) {
   1448           unsigned C1= cast<ConstantSDNode>(InOp.getOperand(1))->getZExtValue();
   1449           unsigned Opc = ISD::SHL;
   1450           int Diff = ShAmt-C1;
   1451           if (Diff < 0) {
   1452             Diff = -Diff;
   1453             Opc = ISD::SRL;
   1454           }
   1455 
   1456           SDValue NewSA =
   1457             TLO.DAG.getConstant(Diff, Op.getOperand(1).getValueType());
   1458           EVT VT = Op.getValueType();
   1459           return TLO.CombineTo(Op, TLO.DAG.getNode(Opc, dl, VT,
   1460                                                    InOp.getOperand(0), NewSA));
   1461         }
   1462       }
   1463 
   1464       if (SimplifyDemandedBits(InOp, NewMask.lshr(ShAmt),
   1465                                KnownZero, KnownOne, TLO, Depth+1))
   1466         return true;
   1467 
   1468       // Convert (shl (anyext x, c)) to (anyext (shl x, c)) if the high bits
   1469       // are not demanded. This will likely allow the anyext to be folded away.
   1470       if (InOp.getNode()->getOpcode() == ISD::ANY_EXTEND) {
   1471         SDValue InnerOp = InOp.getNode()->getOperand(0);
   1472         EVT InnerVT = InnerOp.getValueType();
   1473         if ((APInt::getHighBitsSet(BitWidth,
   1474                                    BitWidth - InnerVT.getSizeInBits()) &
   1475                DemandedMask) == 0 &&
   1476             isTypeDesirableForOp(ISD::SHL, InnerVT)) {
   1477           EVT ShTy = getShiftAmountTy(InnerVT);
   1478           if (!APInt(BitWidth, ShAmt).isIntN(ShTy.getSizeInBits()))
   1479             ShTy = InnerVT;
   1480           SDValue NarrowShl =
   1481             TLO.DAG.getNode(ISD::SHL, dl, InnerVT, InnerOp,
   1482                             TLO.DAG.getConstant(ShAmt, ShTy));
   1483           return
   1484             TLO.CombineTo(Op,
   1485                           TLO.DAG.getNode(ISD::ANY_EXTEND, dl, Op.getValueType(),
   1486                                           NarrowShl));
   1487         }
   1488       }
   1489 
   1490       KnownZero <<= SA->getZExtValue();
   1491       KnownOne  <<= SA->getZExtValue();
   1492       // low bits known zero.
   1493       KnownZero |= APInt::getLowBitsSet(BitWidth, SA->getZExtValue());
   1494     }
   1495     break;
   1496   case ISD::SRL:
   1497     if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
   1498       EVT VT = Op.getValueType();
   1499       unsigned ShAmt = SA->getZExtValue();
   1500       unsigned VTSize = VT.getSizeInBits();
   1501       SDValue InOp = Op.getOperand(0);
   1502 
   1503       // If the shift count is an invalid immediate, don't do anything.
   1504       if (ShAmt >= BitWidth)
   1505         break;
   1506 
   1507       // If this is ((X << C1) >>u ShAmt), see if we can simplify this into a
   1508       // single shift.  We can do this if the top bits (which are shifted out)
   1509       // are never demanded.
   1510       if (InOp.getOpcode() == ISD::SHL &&
   1511           isa<ConstantSDNode>(InOp.getOperand(1))) {
   1512         if (ShAmt && (NewMask & APInt::getHighBitsSet(VTSize, ShAmt)) == 0) {
   1513           unsigned C1= cast<ConstantSDNode>(InOp.getOperand(1))->getZExtValue();
   1514           unsigned Opc = ISD::SRL;
   1515           int Diff = ShAmt-C1;
   1516           if (Diff < 0) {
   1517             Diff = -Diff;
   1518             Opc = ISD::SHL;
   1519           }
   1520 
   1521           SDValue NewSA =
   1522             TLO.DAG.getConstant(Diff, Op.getOperand(1).getValueType());
   1523           return TLO.CombineTo(Op, TLO.DAG.getNode(Opc, dl, VT,
   1524                                                    InOp.getOperand(0), NewSA));
   1525         }
   1526       }
   1527 
   1528       // Compute the new bits that are at the top now.
   1529       if (SimplifyDemandedBits(InOp, (NewMask << ShAmt),
   1530                                KnownZero, KnownOne, TLO, Depth+1))
   1531         return true;
   1532       assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1533       KnownZero = KnownZero.lshr(ShAmt);
   1534       KnownOne  = KnownOne.lshr(ShAmt);
   1535 
   1536       APInt HighBits = APInt::getHighBitsSet(BitWidth, ShAmt);
   1537       KnownZero |= HighBits;  // High bits known zero.
   1538     }
   1539     break;
   1540   case ISD::SRA:
   1541     // If this is an arithmetic shift right and only the low-bit is set, we can
   1542     // always convert this into a logical shr, even if the shift amount is
   1543     // variable.  The low bit of the shift cannot be an input sign bit unless
   1544     // the shift amount is >= the size of the datatype, which is undefined.
   1545     if (DemandedMask == 1)
   1546       return TLO.CombineTo(Op,
   1547                            TLO.DAG.getNode(ISD::SRL, dl, Op.getValueType(),
   1548                                            Op.getOperand(0), Op.getOperand(1)));
   1549 
   1550     if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
   1551       EVT VT = Op.getValueType();
   1552       unsigned ShAmt = SA->getZExtValue();
   1553 
   1554       // If the shift count is an invalid immediate, don't do anything.
   1555       if (ShAmt >= BitWidth)
   1556         break;
   1557 
   1558       APInt InDemandedMask = (NewMask << ShAmt);
   1559 
   1560       // If any of the demanded bits are produced by the sign extension, we also
   1561       // demand the input sign bit.
   1562       APInt HighBits = APInt::getHighBitsSet(BitWidth, ShAmt);
   1563       if (HighBits.intersects(NewMask))
   1564         InDemandedMask |= APInt::getSignBit(VT.getScalarType().getSizeInBits());
   1565 
   1566       if (SimplifyDemandedBits(Op.getOperand(0), InDemandedMask,
   1567                                KnownZero, KnownOne, TLO, Depth+1))
   1568         return true;
   1569       assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1570       KnownZero = KnownZero.lshr(ShAmt);
   1571       KnownOne  = KnownOne.lshr(ShAmt);
   1572 
   1573       // Handle the sign bit, adjusted to where it is now in the mask.
   1574       APInt SignBit = APInt::getSignBit(BitWidth).lshr(ShAmt);
   1575 
   1576       // If the input sign bit is known to be zero, or if none of the top bits
   1577       // are demanded, turn this into an unsigned shift right.
   1578       if (KnownZero.intersects(SignBit) || (HighBits & ~NewMask) == HighBits) {
   1579         return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl, VT,
   1580                                                  Op.getOperand(0),
   1581                                                  Op.getOperand(1)));
   1582       } else if (KnownOne.intersects(SignBit)) { // New bits are known one.
   1583         KnownOne |= HighBits;
   1584       }
   1585     }
   1586     break;
   1587   case ISD::SIGN_EXTEND_INREG: {
   1588     EVT EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
   1589 
   1590     // Sign extension.  Compute the demanded bits in the result that are not
   1591     // present in the input.
   1592     APInt NewBits =
   1593       APInt::getHighBitsSet(BitWidth,
   1594                             BitWidth - EVT.getScalarType().getSizeInBits());
   1595 
   1596     // If none of the extended bits are demanded, eliminate the sextinreg.
   1597     if ((NewBits & NewMask) == 0)
   1598       return TLO.CombineTo(Op, Op.getOperand(0));
   1599 
   1600     APInt InSignBit =
   1601       APInt::getSignBit(EVT.getScalarType().getSizeInBits()).zext(BitWidth);
   1602     APInt InputDemandedBits =
   1603       APInt::getLowBitsSet(BitWidth,
   1604                            EVT.getScalarType().getSizeInBits()) &
   1605       NewMask;
   1606 
   1607     // Since the sign extended bits are demanded, we know that the sign
   1608     // bit is demanded.
   1609     InputDemandedBits |= InSignBit;
   1610 
   1611     if (SimplifyDemandedBits(Op.getOperand(0), InputDemandedBits,
   1612                              KnownZero, KnownOne, TLO, Depth+1))
   1613       return true;
   1614     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1615 
   1616     // If the sign bit of the input is known set or clear, then we know the
   1617     // top bits of the result.
   1618 
   1619     // If the input sign bit is known zero, convert this into a zero extension.
   1620     if (KnownZero.intersects(InSignBit))
   1621       return TLO.CombineTo(Op,
   1622                            TLO.DAG.getZeroExtendInReg(Op.getOperand(0),dl,EVT));
   1623 
   1624     if (KnownOne.intersects(InSignBit)) {    // Input sign bit known set
   1625       KnownOne |= NewBits;
   1626       KnownZero &= ~NewBits;
   1627     } else {                       // Input sign bit unknown
   1628       KnownZero &= ~NewBits;
   1629       KnownOne &= ~NewBits;
   1630     }
   1631     break;
   1632   }
   1633   case ISD::ZERO_EXTEND: {
   1634     unsigned OperandBitWidth =
   1635       Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
   1636     APInt InMask = NewMask.trunc(OperandBitWidth);
   1637 
   1638     // If none of the top bits are demanded, convert this into an any_extend.
   1639     APInt NewBits =
   1640       APInt::getHighBitsSet(BitWidth, BitWidth - OperandBitWidth) & NewMask;
   1641     if (!NewBits.intersects(NewMask))
   1642       return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND, dl,
   1643                                                Op.getValueType(),
   1644                                                Op.getOperand(0)));
   1645 
   1646     if (SimplifyDemandedBits(Op.getOperand(0), InMask,
   1647                              KnownZero, KnownOne, TLO, Depth+1))
   1648       return true;
   1649     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1650     KnownZero = KnownZero.zext(BitWidth);
   1651     KnownOne = KnownOne.zext(BitWidth);
   1652     KnownZero |= NewBits;
   1653     break;
   1654   }
   1655   case ISD::SIGN_EXTEND: {
   1656     EVT InVT = Op.getOperand(0).getValueType();
   1657     unsigned InBits = InVT.getScalarType().getSizeInBits();
   1658     APInt InMask    = APInt::getLowBitsSet(BitWidth, InBits);
   1659     APInt InSignBit = APInt::getBitsSet(BitWidth, InBits - 1, InBits);
   1660     APInt NewBits   = ~InMask & NewMask;
   1661 
   1662     // If none of the top bits are demanded, convert this into an any_extend.
   1663     if (NewBits == 0)
   1664       return TLO.CombineTo(Op,TLO.DAG.getNode(ISD::ANY_EXTEND, dl,
   1665                                               Op.getValueType(),
   1666                                               Op.getOperand(0)));
   1667 
   1668     // Since some of the sign extended bits are demanded, we know that the sign
   1669     // bit is demanded.
   1670     APInt InDemandedBits = InMask & NewMask;
   1671     InDemandedBits |= InSignBit;
   1672     InDemandedBits = InDemandedBits.trunc(InBits);
   1673 
   1674     if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, KnownZero,
   1675                              KnownOne, TLO, Depth+1))
   1676       return true;
   1677     KnownZero = KnownZero.zext(BitWidth);
   1678     KnownOne = KnownOne.zext(BitWidth);
   1679 
   1680     // If the sign bit is known zero, convert this to a zero extend.
   1681     if (KnownZero.intersects(InSignBit))
   1682       return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ZERO_EXTEND, dl,
   1683                                                Op.getValueType(),
   1684                                                Op.getOperand(0)));
   1685 
   1686     // If the sign bit is known one, the top bits match.
   1687     if (KnownOne.intersects(InSignBit)) {
   1688       KnownOne  |= NewBits;
   1689       KnownZero &= ~NewBits;
   1690     } else {   // Otherwise, top bits aren't known.
   1691       KnownOne  &= ~NewBits;
   1692       KnownZero &= ~NewBits;
   1693     }
   1694     break;
   1695   }
   1696   case ISD::ANY_EXTEND: {
   1697     unsigned OperandBitWidth =
   1698       Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
   1699     APInt InMask = NewMask.trunc(OperandBitWidth);
   1700     if (SimplifyDemandedBits(Op.getOperand(0), InMask,
   1701                              KnownZero, KnownOne, TLO, Depth+1))
   1702       return true;
   1703     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1704     KnownZero = KnownZero.zext(BitWidth);
   1705     KnownOne = KnownOne.zext(BitWidth);
   1706     break;
   1707   }
   1708   case ISD::TRUNCATE: {
   1709     // Simplify the input, using demanded bit information, and compute the known
   1710     // zero/one bits live out.
   1711     unsigned OperandBitWidth =
   1712       Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
   1713     APInt TruncMask = NewMask.zext(OperandBitWidth);
   1714     if (SimplifyDemandedBits(Op.getOperand(0), TruncMask,
   1715                              KnownZero, KnownOne, TLO, Depth+1))
   1716       return true;
   1717     KnownZero = KnownZero.trunc(BitWidth);
   1718     KnownOne = KnownOne.trunc(BitWidth);
   1719 
   1720     // If the input is only used by this truncate, see if we can shrink it based
   1721     // on the known demanded bits.
   1722     if (Op.getOperand(0).getNode()->hasOneUse()) {
   1723       SDValue In = Op.getOperand(0);
   1724       switch (In.getOpcode()) {
   1725       default: break;
   1726       case ISD::SRL:
   1727         // Shrink SRL by a constant if none of the high bits shifted in are
   1728         // demanded.
   1729         if (TLO.LegalTypes() &&
   1730             !isTypeDesirableForOp(ISD::SRL, Op.getValueType()))
   1731           // Do not turn (vt1 truncate (vt2 srl)) into (vt1 srl) if vt1 is
   1732           // undesirable.
   1733           break;
   1734         ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(In.getOperand(1));
   1735         if (!ShAmt)
   1736           break;
   1737         SDValue Shift = In.getOperand(1);
   1738         if (TLO.LegalTypes()) {
   1739           uint64_t ShVal = ShAmt->getZExtValue();
   1740           Shift =
   1741             TLO.DAG.getConstant(ShVal, getShiftAmountTy(Op.getValueType()));
   1742         }
   1743 
   1744         APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
   1745                                                OperandBitWidth - BitWidth);
   1746         HighBits = HighBits.lshr(ShAmt->getZExtValue()).trunc(BitWidth);
   1747 
   1748         if (ShAmt->getZExtValue() < BitWidth && !(HighBits & NewMask)) {
   1749           // None of the shifted in bits are needed.  Add a truncate of the
   1750           // shift input, then shift it.
   1751           SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl,
   1752                                              Op.getValueType(),
   1753                                              In.getOperand(0));
   1754           return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl,
   1755                                                    Op.getValueType(),
   1756                                                    NewTrunc,
   1757                                                    Shift));
   1758         }
   1759         break;
   1760       }
   1761     }
   1762 
   1763     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1764     break;
   1765   }
   1766   case ISD::AssertZext: {
   1767     // Demand all the bits of the input that are demanded in the output.
   1768     // The low bits are obvious; the high bits are demanded because we're
   1769     // asserting that they're zero here.
   1770     if (SimplifyDemandedBits(Op.getOperand(0), NewMask,
   1771                              KnownZero, KnownOne, TLO, Depth+1))
   1772       return true;
   1773     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
   1774 
   1775     EVT VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
   1776     APInt InMask = APInt::getLowBitsSet(BitWidth,
   1777                                         VT.getSizeInBits());
   1778     KnownZero |= ~InMask & NewMask;
   1779     break;
   1780   }
   1781   case ISD::BITCAST:
   1782     // If this is an FP->Int bitcast and if the sign bit is the only
   1783     // thing demanded, turn this into a FGETSIGN.
   1784     if (!Op.getOperand(0).getValueType().isVector() &&
   1785         NewMask == APInt::getSignBit(Op.getValueType().getSizeInBits()) &&
   1786         Op.getOperand(0).getValueType().isFloatingPoint()) {
   1787       bool OpVTLegal = isOperationLegalOrCustom(ISD::FGETSIGN, Op.getValueType());
   1788       bool i32Legal  = isOperationLegalOrCustom(ISD::FGETSIGN, MVT::i32);
   1789       if ((OpVTLegal || i32Legal) && Op.getValueType().isSimple()) {
   1790         EVT Ty = OpVTLegal ? Op.getValueType() : MVT::i32;
   1791         // Make a FGETSIGN + SHL to move the sign bit into the appropriate
   1792         // place.  We expect the SHL to be eliminated by other optimizations.
   1793         SDValue Sign = TLO.DAG.getNode(ISD::FGETSIGN, dl, Ty, Op.getOperand(0));
   1794         unsigned OpVTSizeInBits = Op.getValueType().getSizeInBits();
   1795         if (!OpVTLegal && OpVTSizeInBits > 32)
   1796           Sign = TLO.DAG.getNode(ISD::ZERO_EXTEND, dl, Op.getValueType(), Sign);
   1797         unsigned ShVal = Op.getValueType().getSizeInBits()-1;
   1798         SDValue ShAmt = TLO.DAG.getConstant(ShVal, Op.getValueType());
   1799         return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SHL, dl,
   1800                                                  Op.getValueType(),
   1801                                                  Sign, ShAmt));
   1802       }
   1803     }
   1804     break;
   1805   case ISD::ADD:
   1806   case ISD::MUL:
   1807   case ISD::SUB: {
   1808     // Add, Sub, and Mul don't demand any bits in positions beyond that
   1809     // of the highest bit demanded of them.
   1810     APInt LoMask = APInt::getLowBitsSet(BitWidth,
   1811                                         BitWidth - NewMask.countLeadingZeros());
   1812     if (SimplifyDemandedBits(Op.getOperand(0), LoMask, KnownZero2,
   1813                              KnownOne2, TLO, Depth+1))
   1814       return true;
   1815     if (SimplifyDemandedBits(Op.getOperand(1), LoMask, KnownZero2,
   1816                              KnownOne2, TLO, Depth+1))
   1817       return true;
   1818     // See if the operation should be performed at a smaller bit width.
   1819     if (TLO.ShrinkDemandedOp(Op, BitWidth, NewMask, dl))
   1820       return true;
   1821   }
   1822   // FALL THROUGH
   1823   default:
   1824     // Just use ComputeMaskedBits to compute output bits.
   1825     TLO.DAG.ComputeMaskedBits(Op, NewMask, KnownZero, KnownOne, Depth);
   1826     break;
   1827   }
   1828 
   1829   // If we know the value of all of the demanded bits, return this as a
   1830   // constant.
   1831   if ((NewMask & (KnownZero|KnownOne)) == NewMask)
   1832     return TLO.CombineTo(Op, TLO.DAG.getConstant(KnownOne, Op.getValueType()));
   1833 
   1834   return false;
   1835 }
   1836 
   1837 /// computeMaskedBitsForTargetNode - Determine which of the bits specified
   1838 /// in Mask are known to be either zero or one and return them in the
   1839 /// KnownZero/KnownOne bitsets.
   1840 void TargetLowering::computeMaskedBitsForTargetNode(const SDValue Op,
   1841                                                     const APInt &Mask,
   1842                                                     APInt &KnownZero,
   1843                                                     APInt &KnownOne,
   1844                                                     const SelectionDAG &DAG,
   1845                                                     unsigned Depth) const {
   1846   assert((Op.getOpcode() >= ISD::BUILTIN_OP_END ||
   1847           Op.getOpcode() == ISD::INTRINSIC_WO_CHAIN ||
   1848           Op.getOpcode() == ISD::INTRINSIC_W_CHAIN ||
   1849           Op.getOpcode() == ISD::INTRINSIC_VOID) &&
   1850          "Should use MaskedValueIsZero if you don't know whether Op"
   1851          " is a target node!");
   1852   KnownZero = KnownOne = APInt(Mask.getBitWidth(), 0);
   1853 }
   1854 
   1855 /// ComputeNumSignBitsForTargetNode - This method can be implemented by
   1856 /// targets that want to expose additional information about sign bits to the
   1857 /// DAG Combiner.
   1858 unsigned TargetLowering::ComputeNumSignBitsForTargetNode(SDValue Op,
   1859                                                          unsigned Depth) const {
   1860   assert((Op.getOpcode() >= ISD::BUILTIN_OP_END ||
   1861           Op.getOpcode() == ISD::INTRINSIC_WO_CHAIN ||
   1862           Op.getOpcode() == ISD::INTRINSIC_W_CHAIN ||
   1863           Op.getOpcode() == ISD::INTRINSIC_VOID) &&
   1864          "Should use ComputeNumSignBits if you don't know whether Op"
   1865          " is a target node!");
   1866   return 1;
   1867 }
   1868 
   1869 /// ValueHasExactlyOneBitSet - Test if the given value is known to have exactly
   1870 /// one bit set. This differs from ComputeMaskedBits in that it doesn't need to
   1871 /// determine which bit is set.
   1872 ///
   1873 static bool ValueHasExactlyOneBitSet(SDValue Val, const SelectionDAG &DAG) {
   1874   // A left-shift of a constant one will have exactly one bit set, because
   1875   // shifting the bit off the end is undefined.
   1876   if (Val.getOpcode() == ISD::SHL)
   1877     if (ConstantSDNode *C =
   1878          dyn_cast<ConstantSDNode>(Val.getNode()->getOperand(0)))
   1879       if (C->getAPIntValue() == 1)
   1880         return true;
   1881 
   1882   // Similarly, a right-shift of a constant sign-bit will have exactly
   1883   // one bit set.
   1884   if (Val.getOpcode() == ISD::SRL)
   1885     if (ConstantSDNode *C =
   1886          dyn_cast<ConstantSDNode>(Val.getNode()->getOperand(0)))
   1887       if (C->getAPIntValue().isSignBit())
   1888         return true;
   1889 
   1890   // More could be done here, though the above checks are enough
   1891   // to handle some common cases.
   1892 
   1893   // Fall back to ComputeMaskedBits to catch other known cases.
   1894   EVT OpVT = Val.getValueType();
   1895   unsigned BitWidth = OpVT.getScalarType().getSizeInBits();
   1896   APInt Mask = APInt::getAllOnesValue(BitWidth);
   1897   APInt KnownZero, KnownOne;
   1898   DAG.ComputeMaskedBits(Val, Mask, KnownZero, KnownOne);
   1899   return (KnownZero.countPopulation() == BitWidth - 1) &&
   1900          (KnownOne.countPopulation() == 1);
   1901 }
   1902 
   1903 /// SimplifySetCC - Try to simplify a setcc built with the specified operands
   1904 /// and cc. If it is unable to simplify it, return a null SDValue.
   1905 SDValue
   1906 TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
   1907                               ISD::CondCode Cond, bool foldBooleans,
   1908                               DAGCombinerInfo &DCI, DebugLoc dl) const {
   1909   SelectionDAG &DAG = DCI.DAG;
   1910 
   1911   // These setcc operations always fold.
   1912   switch (Cond) {
   1913   default: break;
   1914   case ISD::SETFALSE:
   1915   case ISD::SETFALSE2: return DAG.getConstant(0, VT);
   1916   case ISD::SETTRUE:
   1917   case ISD::SETTRUE2:  return DAG.getConstant(1, VT);
   1918   }
   1919 
   1920   // Ensure that the constant occurs on the RHS, and fold constant
   1921   // comparisons.
   1922   if (isa<ConstantSDNode>(N0.getNode()))
   1923     return DAG.getSetCC(dl, VT, N1, N0, ISD::getSetCCSwappedOperands(Cond));
   1924 
   1925   if (ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.getNode())) {
   1926     const APInt &C1 = N1C->getAPIntValue();
   1927 
   1928     // If the LHS is '(srl (ctlz x), 5)', the RHS is 0/1, and this is an
   1929     // equality comparison, then we're just comparing whether X itself is
   1930     // zero.
   1931     if (N0.getOpcode() == ISD::SRL && (C1 == 0 || C1 == 1) &&
   1932         N0.getOperand(0).getOpcode() == ISD::CTLZ &&
   1933         N0.getOperand(1).getOpcode() == ISD::Constant) {
   1934       const APInt &ShAmt
   1935         = cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
   1936       if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
   1937           ShAmt == Log2_32(N0.getValueType().getSizeInBits())) {
   1938         if ((C1 == 0) == (Cond == ISD::SETEQ)) {
   1939           // (srl (ctlz x), 5) == 0  -> X != 0
   1940           // (srl (ctlz x), 5) != 1  -> X != 0
   1941           Cond = ISD::SETNE;
   1942         } else {
   1943           // (srl (ctlz x), 5) != 0  -> X == 0
   1944           // (srl (ctlz x), 5) == 1  -> X == 0
   1945           Cond = ISD::SETEQ;
   1946         }
   1947         SDValue Zero = DAG.getConstant(0, N0.getValueType());
   1948         return DAG.getSetCC(dl, VT, N0.getOperand(0).getOperand(0),
   1949                             Zero, Cond);
   1950       }
   1951     }
   1952 
   1953     SDValue CTPOP = N0;
   1954     // Look through truncs that don't change the value of a ctpop.
   1955     if (N0.hasOneUse() && N0.getOpcode() == ISD::TRUNCATE)
   1956       CTPOP = N0.getOperand(0);
   1957 
   1958     if (CTPOP.hasOneUse() && CTPOP.getOpcode() == ISD::CTPOP &&
   1959         (N0 == CTPOP || N0.getValueType().getSizeInBits() >
   1960                         Log2_32_Ceil(CTPOP.getValueType().getSizeInBits()))) {
   1961       EVT CTVT = CTPOP.getValueType();
   1962       SDValue CTOp = CTPOP.getOperand(0);
   1963 
   1964       // (ctpop x) u< 2 -> (x & x-1) == 0
   1965       // (ctpop x) u> 1 -> (x & x-1) != 0
   1966       if ((Cond == ISD::SETULT && C1 == 2) || (Cond == ISD::SETUGT && C1 == 1)){
   1967         SDValue Sub = DAG.getNode(ISD::SUB, dl, CTVT, CTOp,
   1968                                   DAG.getConstant(1, CTVT));
   1969         SDValue And = DAG.getNode(ISD::AND, dl, CTVT, CTOp, Sub);
   1970         ISD::CondCode CC = Cond == ISD::SETULT ? ISD::SETEQ : ISD::SETNE;
   1971         return DAG.getSetCC(dl, VT, And, DAG.getConstant(0, CTVT), CC);
   1972       }
   1973 
   1974       // TODO: (ctpop x) == 1 -> x && (x & x-1) == 0 iff ctpop is illegal.
   1975     }
   1976 
   1977     // (zext x) == C --> x == (trunc C)
   1978     if (DCI.isBeforeLegalize() && N0->hasOneUse() &&
   1979         (Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
   1980       unsigned MinBits = N0.getValueSizeInBits();
   1981       SDValue PreZExt;
   1982       if (N0->getOpcode() == ISD::ZERO_EXTEND) {
   1983         // ZExt
   1984         MinBits = N0->getOperand(0).getValueSizeInBits();
   1985         PreZExt = N0->getOperand(0);
   1986       } else if (N0->getOpcode() == ISD::AND) {
   1987         // DAGCombine turns costly ZExts into ANDs
   1988         if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N0->getOperand(1)))
   1989           if ((C->getAPIntValue()+1).isPowerOf2()) {
   1990             MinBits = C->getAPIntValue().countTrailingOnes();
   1991             PreZExt = N0->getOperand(0);
   1992           }
   1993       } else if (LoadSDNode *LN0 = dyn_cast<LoadSDNode>(N0)) {
   1994         // ZEXTLOAD
   1995         if (LN0->getExtensionType() == ISD::ZEXTLOAD) {
   1996           MinBits = LN0->getMemoryVT().getSizeInBits();
   1997           PreZExt = N0;
   1998         }
   1999       }
   2000 
   2001       // Make sure we're not loosing bits from the constant.
   2002       if (MinBits < C1.getBitWidth() && MinBits > C1.getActiveBits()) {
   2003         EVT MinVT = EVT::getIntegerVT(*DAG.getContext(), MinBits);
   2004         if (isTypeDesirableForOp(ISD::SETCC, MinVT)) {
   2005           // Will get folded away.
   2006           SDValue Trunc = DAG.getNode(ISD::TRUNCATE, dl, MinVT, PreZExt);
   2007           SDValue C = DAG.getConstant(C1.trunc(MinBits), MinVT);
   2008           return DAG.getSetCC(dl, VT, Trunc, C, Cond);
   2009         }
   2010       }
   2011     }
   2012 
   2013     // If the LHS is '(and load, const)', the RHS is 0,
   2014     // the test is for equality or unsigned, and all 1 bits of the const are
   2015     // in the same partial word, see if we can shorten the load.
   2016     if (DCI.isBeforeLegalize() &&
   2017         N0.getOpcode() == ISD::AND && C1 == 0 &&
   2018         N0.getNode()->hasOneUse() &&
   2019         isa<LoadSDNode>(N0.getOperand(0)) &&
   2020         N0.getOperand(0).getNode()->hasOneUse() &&
   2021         isa<ConstantSDNode>(N0.getOperand(1))) {
   2022       LoadSDNode *Lod = cast<LoadSDNode>(N0.getOperand(0));
   2023       APInt bestMask;
   2024       unsigned bestWidth = 0, bestOffset = 0;
   2025       if (!Lod->isVolatile() && Lod->isUnindexed()) {
   2026         unsigned origWidth = N0.getValueType().getSizeInBits();
   2027         unsigned maskWidth = origWidth;
   2028         // We can narrow (e.g.) 16-bit extending loads on 32-bit target to
   2029         // 8 bits, but have to be careful...
   2030         if (Lod->getExtensionType() != ISD::NON_EXTLOAD)
   2031           origWidth = Lod->getMemoryVT().getSizeInBits();
   2032         const APInt &Mask =
   2033           cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
   2034         for (unsigned width = origWidth / 2; width>=8; width /= 2) {
   2035           APInt newMask = APInt::getLowBitsSet(maskWidth, width);
   2036           for (unsigned offset=0; offset<origWidth/width; offset++) {
   2037             if ((newMask & Mask) == Mask) {
   2038               if (!TD->isLittleEndian())
   2039                 bestOffset = (origWidth/width - offset - 1) * (width/8);
   2040               else
   2041                 bestOffset = (uint64_t)offset * (width/8);
   2042               bestMask = Mask.lshr(offset * (width/8) * 8);
   2043               bestWidth = width;
   2044               break;
   2045             }
   2046             newMask = newMask << width;
   2047           }
   2048         }
   2049       }
   2050       if (bestWidth) {
   2051         EVT newVT = EVT::getIntegerVT(*DAG.getContext(), bestWidth);
   2052         if (newVT.isRound()) {
   2053           EVT PtrType = Lod->getOperand(1).getValueType();
   2054           SDValue Ptr = Lod->getBasePtr();
   2055           if (bestOffset != 0)
   2056             Ptr = DAG.getNode(ISD::ADD, dl, PtrType, Lod->getBasePtr(),
   2057                               DAG.getConstant(bestOffset, PtrType));
   2058           unsigned NewAlign = MinAlign(Lod->getAlignment(), bestOffset);
   2059           SDValue NewLoad = DAG.getLoad(newVT, dl, Lod->getChain(), Ptr,
   2060                                 Lod->getPointerInfo().getWithOffset(bestOffset),
   2061                                         false, false, NewAlign);
   2062           return DAG.getSetCC(dl, VT,
   2063                               DAG.getNode(ISD::AND, dl, newVT, NewLoad,
   2064                                       DAG.getConstant(bestMask.trunc(bestWidth),
   2065                                                       newVT)),
   2066                               DAG.getConstant(0LL, newVT), Cond);
   2067         }
   2068       }
   2069     }
   2070 
   2071     // If the LHS is a ZERO_EXTEND, perform the comparison on the input.
   2072     if (N0.getOpcode() == ISD::ZERO_EXTEND) {
   2073       unsigned InSize = N0.getOperand(0).getValueType().getSizeInBits();
   2074 
   2075       // If the comparison constant has bits in the upper part, the
   2076       // zero-extended value could never match.
   2077       if (C1.intersects(APInt::getHighBitsSet(C1.getBitWidth(),
   2078                                               C1.getBitWidth() - InSize))) {
   2079         switch (Cond) {
   2080         case ISD::SETUGT:
   2081         case ISD::SETUGE:
   2082         case ISD::SETEQ: return DAG.getConstant(0, VT);
   2083         case ISD::SETULT:
   2084         case ISD::SETULE:
   2085         case ISD::SETNE: return DAG.getConstant(1, VT);
   2086         case ISD::SETGT:
   2087         case ISD::SETGE:
   2088           // True if the sign bit of C1 is set.
   2089           return DAG.getConstant(C1.isNegative(), VT);
   2090         case ISD::SETLT:
   2091         case ISD::SETLE:
   2092           // True if the sign bit of C1 isn't set.
   2093           return DAG.getConstant(C1.isNonNegative(), VT);
   2094         default:
   2095           break;
   2096         }
   2097       }
   2098 
   2099       // Otherwise, we can perform the comparison with the low bits.
   2100       switch (Cond) {
   2101       case ISD::SETEQ:
   2102       case ISD::SETNE:
   2103       case ISD::SETUGT:
   2104       case ISD::SETUGE:
   2105       case ISD::SETULT:
   2106       case ISD::SETULE: {
   2107         EVT newVT = N0.getOperand(0).getValueType();
   2108         if (DCI.isBeforeLegalizeOps() ||
   2109             (isOperationLegal(ISD::SETCC, newVT) &&
   2110               getCondCodeAction(Cond, newVT)==Legal))
   2111           return DAG.getSetCC(dl, VT, N0.getOperand(0),
   2112                               DAG.getConstant(C1.trunc(InSize), newVT),
   2113                               Cond);
   2114         break;
   2115       }
   2116       default:
   2117         break;   // todo, be more careful with signed comparisons
   2118       }
   2119     } else if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG &&
   2120                (Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
   2121       EVT ExtSrcTy = cast<VTSDNode>(N0.getOperand(1))->getVT();
   2122       unsigned ExtSrcTyBits = ExtSrcTy.getSizeInBits();
   2123       EVT ExtDstTy = N0.getValueType();
   2124       unsigned ExtDstTyBits = ExtDstTy.getSizeInBits();
   2125 
   2126       // If the constant doesn't fit into the number of bits for the source of
   2127       // the sign extension, it is impossible for both sides to be equal.
   2128       if (C1.getMinSignedBits() > ExtSrcTyBits)
   2129         return DAG.getConstant(Cond == ISD::SETNE, VT);
   2130 
   2131       SDValue ZextOp;
   2132       EVT Op0Ty = N0.getOperand(0).getValueType();
   2133       if (Op0Ty == ExtSrcTy) {
   2134         ZextOp = N0.getOperand(0);
   2135       } else {
   2136         APInt Imm = APInt::getLowBitsSet(ExtDstTyBits, ExtSrcTyBits);
   2137         ZextOp = DAG.getNode(ISD::AND, dl, Op0Ty, N0.getOperand(0),
   2138                               DAG.getConstant(Imm, Op0Ty));
   2139       }
   2140       if (!DCI.isCalledByLegalizer())
   2141         DCI.AddToWorklist(ZextOp.getNode());
   2142       // Otherwise, make this a use of a zext.
   2143       return DAG.getSetCC(dl, VT, ZextOp,
   2144                           DAG.getConstant(C1 & APInt::getLowBitsSet(
   2145                                                               ExtDstTyBits,
   2146                                                               ExtSrcTyBits),
   2147                                           ExtDstTy),
   2148                           Cond);
   2149     } else if ((N1C->isNullValue() || N1C->getAPIntValue() == 1) &&
   2150                 (Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
   2151       // SETCC (SETCC), [0|1], [EQ|NE]  -> SETCC
   2152       if (N0.getOpcode() == ISD::SETCC &&
   2153           isTypeLegal(VT) && VT.bitsLE(N0.getValueType())) {
   2154         bool TrueWhenTrue = (Cond == ISD::SETEQ) ^ (N1C->getAPIntValue() != 1);
   2155         if (TrueWhenTrue)
   2156           return DAG.getNode(ISD::TRUNCATE, dl, VT, N0);
   2157         // Invert the condition.
   2158         ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
   2159         CC = ISD::getSetCCInverse(CC,
   2160                                   N0.getOperand(0).getValueType().isInteger());
   2161         return DAG.getSetCC(dl, VT, N0.getOperand(0), N0.getOperand(1), CC);
   2162       }
   2163 
   2164       if ((N0.getOpcode() == ISD::XOR ||
   2165            (N0.getOpcode() == ISD::AND &&
   2166             N0.getOperand(0).getOpcode() == ISD::XOR &&
   2167             N0.getOperand(1) == N0.getOperand(0).getOperand(1))) &&
   2168           isa<ConstantSDNode>(N0.getOperand(1)) &&
   2169           cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue() == 1) {
   2170         // If this is (X^1) == 0/1, swap the RHS and eliminate the xor.  We
   2171         // can only do this if the top bits are known zero.
   2172         unsigned BitWidth = N0.getValueSizeInBits();
   2173         if (DAG.MaskedValueIsZero(N0,
   2174                                   APInt::getHighBitsSet(BitWidth,
   2175                                                         BitWidth-1))) {
   2176           // Okay, get the un-inverted input value.
   2177           SDValue Val;
   2178           if (N0.getOpcode() == ISD::XOR)
   2179             Val = N0.getOperand(0);
   2180           else {
   2181             assert(N0.getOpcode() == ISD::AND &&
   2182                     N0.getOperand(0).getOpcode() == ISD::XOR);
   2183             // ((X^1)&1)^1 -> X & 1
   2184             Val = DAG.getNode(ISD::AND, dl, N0.getValueType(),
   2185                               N0.getOperand(0).getOperand(0),
   2186                               N0.getOperand(1));
   2187           }
   2188 
   2189           return DAG.getSetCC(dl, VT, Val, N1,
   2190                               Cond == ISD::SETEQ ? ISD::SETNE : ISD::SETEQ);
   2191         }
   2192       } else if (N1C->getAPIntValue() == 1 &&
   2193                  (VT == MVT::i1 ||
   2194                   getBooleanContents() == ZeroOrOneBooleanContent)) {
   2195         SDValue Op0 = N0;
   2196         if (Op0.getOpcode() == ISD::TRUNCATE)
   2197           Op0 = Op0.getOperand(0);
   2198 
   2199         if ((Op0.getOpcode() == ISD::XOR) &&
   2200             Op0.getOperand(0).getOpcode() == ISD::SETCC &&
   2201             Op0.getOperand(1).getOpcode() == ISD::SETCC) {
   2202           // (xor (setcc), (setcc)) == / != 1 -> (setcc) != / == (setcc)
   2203           Cond = (Cond == ISD::SETEQ) ? ISD::SETNE : ISD::SETEQ;
   2204           return DAG.getSetCC(dl, VT, Op0.getOperand(0), Op0.getOperand(1),
   2205                               Cond);
   2206         } else if (Op0.getOpcode() == ISD::AND &&
   2207                 isa<ConstantSDNode>(Op0.getOperand(1)) &&
   2208                 cast<ConstantSDNode>(Op0.getOperand(1))->getAPIntValue() == 1) {
   2209           // If this is (X&1) == / != 1, normalize it to (X&1) != / == 0.
   2210           if (Op0.getValueType().bitsGT(VT))
   2211             Op0 = DAG.getNode(ISD::AND, dl, VT,
   2212                           DAG.getNode(ISD::TRUNCATE, dl, VT, Op0.getOperand(0)),
   2213                           DAG.getConstant(1, VT));
   2214           else if (Op0.getValueType().bitsLT(VT))
   2215             Op0 = DAG.getNode(ISD::AND, dl, VT,
   2216                         DAG.getNode(ISD::ANY_EXTEND, dl, VT, Op0.getOperand(0)),
   2217                         DAG.getConstant(1, VT));
   2218 
   2219           return DAG.getSetCC(dl, VT, Op0,
   2220                               DAG.getConstant(0, Op0.getValueType()),
   2221                               Cond == ISD::SETEQ ? ISD::SETNE : ISD::SETEQ);
   2222         }
   2223       }
   2224     }
   2225 
   2226     APInt MinVal, MaxVal;
   2227     unsigned OperandBitSize = N1C->getValueType(0).getSizeInBits();
   2228     if (ISD::isSignedIntSetCC(Cond)) {
   2229       MinVal = APInt::getSignedMinValue(OperandBitSize);
   2230       MaxVal = APInt::getSignedMaxValue(OperandBitSize);
   2231     } else {
   2232       MinVal = APInt::getMinValue(OperandBitSize);
   2233       MaxVal = APInt::getMaxValue(OperandBitSize);
   2234     }
   2235 
   2236     // Canonicalize GE/LE comparisons to use GT/LT comparisons.
   2237     if (Cond == ISD::SETGE || Cond == ISD::SETUGE) {
   2238       if (C1 == MinVal) return DAG.getConstant(1, VT);   // X >= MIN --> true
   2239       // X >= C0 --> X > (C0-1)
   2240       return DAG.getSetCC(dl, VT, N0,
   2241                           DAG.getConstant(C1-1, N1.getValueType()),
   2242                           (Cond == ISD::SETGE) ? ISD::SETGT : ISD::SETUGT);
   2243     }
   2244 
   2245     if (Cond == ISD::SETLE || Cond == ISD::SETULE) {
   2246       if (C1 == MaxVal) return DAG.getConstant(1, VT);   // X <= MAX --> true
   2247       // X <= C0 --> X < (C0+1)
   2248       return DAG.getSetCC(dl, VT, N0,
   2249                           DAG.getConstant(C1+1, N1.getValueType()),
   2250                           (Cond == ISD::SETLE) ? ISD::SETLT : ISD::SETULT);
   2251     }
   2252 
   2253     if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal)
   2254       return DAG.getConstant(0, VT);      // X < MIN --> false
   2255     if ((Cond == ISD::SETGE || Cond == ISD::SETUGE) && C1 == MinVal)
   2256       return DAG.getConstant(1, VT);      // X >= MIN --> true
   2257     if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MaxVal)
   2258       return DAG.getConstant(0, VT);      // X > MAX --> false
   2259     if ((Cond == ISD::SETLE || Cond == ISD::SETULE) && C1 == MaxVal)
   2260       return DAG.getConstant(1, VT);      // X <= MAX --> true
   2261 
   2262     // Canonicalize setgt X, Min --> setne X, Min
   2263     if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MinVal)
   2264       return DAG.getSetCC(dl, VT, N0, N1, ISD::SETNE);
   2265     // Canonicalize setlt X, Max --> setne X, Max
   2266     if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MaxVal)
   2267       return DAG.getSetCC(dl, VT, N0, N1, ISD::SETNE);
   2268 
   2269     // If we have setult X, 1, turn it into seteq X, 0
   2270     if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal+1)
   2271       return DAG.getSetCC(dl, VT, N0,
   2272                           DAG.getConstant(MinVal, N0.getValueType()),
   2273                           ISD::SETEQ);
   2274     // If we have setugt X, Max-1, turn it into seteq X, Max
   2275     else if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MaxVal-1)
   2276       return DAG.getSetCC(dl, VT, N0,
   2277                           DAG.getConstant(MaxVal, N0.getValueType()),
   2278                           ISD::SETEQ);
   2279 
   2280     // If we have "setcc X, C0", check to see if we can shrink the immediate
   2281     // by changing cc.
   2282 
   2283     // SETUGT X, SINTMAX  -> SETLT X, 0
   2284     if (Cond == ISD::SETUGT &&
   2285         C1 == APInt::getSignedMaxValue(OperandBitSize))
   2286       return DAG.getSetCC(dl, VT, N0,
   2287                           DAG.getConstant(0, N1.getValueType()),
   2288                           ISD::SETLT);
   2289 
   2290     // SETULT X, SINTMIN  -> SETGT X, -1
   2291     if (Cond == ISD::SETULT &&
   2292         C1 == APInt::getSignedMinValue(OperandBitSize)) {
   2293       SDValue ConstMinusOne =
   2294           DAG.getConstant(APInt::getAllOnesValue(OperandBitSize),
   2295                           N1.getValueType());
   2296       return DAG.getSetCC(dl, VT, N0, ConstMinusOne, ISD::SETGT);
   2297     }
   2298 
   2299     // Fold bit comparisons when we can.
   2300     if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
   2301         (VT == N0.getValueType() ||
   2302          (isTypeLegal(VT) && VT.bitsLE(N0.getValueType()))) &&
   2303         N0.getOpcode() == ISD::AND)
   2304       if (ConstantSDNode *AndRHS =
   2305                   dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
   2306         EVT ShiftTy = DCI.isBeforeLegalize() ?
   2307           getPointerTy() : getShiftAmountTy(N0.getValueType());
   2308         if (Cond == ISD::SETNE && C1 == 0) {// (X & 8) != 0  -->  (X & 8) >> 3
   2309           // Perform the xform if the AND RHS is a single bit.
   2310           if (AndRHS->getAPIntValue().isPowerOf2()) {
   2311             return DAG.getNode(ISD::TRUNCATE, dl, VT,
   2312                               DAG.getNode(ISD::SRL, dl, N0.getValueType(), N0,
   2313                    DAG.getConstant(AndRHS->getAPIntValue().logBase2(), ShiftTy)));
   2314           }
   2315         } else if (Cond == ISD::SETEQ && C1 == AndRHS->getAPIntValue()) {
   2316           // (X & 8) == 8  -->  (X & 8) >> 3
   2317           // Perform the xform if C1 is a single bit.
   2318           if (C1.isPowerOf2()) {
   2319             return DAG.getNode(ISD::TRUNCATE, dl, VT,
   2320                                DAG.getNode(ISD::SRL, dl, N0.getValueType(), N0,
   2321                                       DAG.getConstant(C1.logBase2(), ShiftTy)));
   2322           }
   2323         }
   2324       }
   2325   }
   2326 
   2327   if (isa<ConstantFPSDNode>(N0.getNode())) {
   2328     // Constant fold or commute setcc.
   2329     SDValue O = DAG.FoldSetCC(VT, N0, N1, Cond, dl);
   2330     if (O.getNode()) return O;
   2331   } else if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1.getNode())) {
   2332     // If the RHS of an FP comparison is a constant, simplify it away in
   2333     // some cases.
   2334     if (CFP->getValueAPF().isNaN()) {
   2335       // If an operand is known to be a nan, we can fold it.
   2336       switch (ISD::getUnorderedFlavor(Cond)) {
   2337       default: llvm_unreachable("Unknown flavor!");
   2338       case 0:  // Known false.
   2339         return DAG.getConstant(0, VT);
   2340       case 1:  // Known true.
   2341         return DAG.getConstant(1, VT);
   2342       case 2:  // Undefined.
   2343         return DAG.getUNDEF(VT);
   2344       }
   2345     }
   2346 
   2347     // Otherwise, we know the RHS is not a NaN.  Simplify the node to drop the
   2348     // constant if knowing that the operand is non-nan is enough.  We prefer to
   2349     // have SETO(x,x) instead of SETO(x, 0.0) because this avoids having to
   2350     // materialize 0.0.
   2351     if (Cond == ISD::SETO || Cond == ISD::SETUO)
   2352       return DAG.getSetCC(dl, VT, N0, N0, Cond);
   2353 
   2354     // If the condition is not legal, see if we can find an equivalent one
   2355     // which is legal.
   2356     if (!isCondCodeLegal(Cond, N0.getValueType())) {
   2357       // If the comparison was an awkward floating-point == or != and one of
   2358       // the comparison operands is infinity or negative infinity, convert the
   2359       // condition to a less-awkward <= or >=.
   2360       if (CFP->getValueAPF().isInfinity()) {
   2361         if (CFP->getValueAPF().isNegative()) {
   2362           if (Cond == ISD::SETOEQ &&
   2363               isCondCodeLegal(ISD::SETOLE, N0.getValueType()))
   2364             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOLE);
   2365           if (Cond == ISD::SETUEQ &&
   2366               isCondCodeLegal(ISD::SETOLE, N0.getValueType()))
   2367             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETULE);
   2368           if (Cond == ISD::SETUNE &&
   2369               isCondCodeLegal(ISD::SETUGT, N0.getValueType()))
   2370             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETUGT);
   2371           if (Cond == ISD::SETONE &&
   2372               isCondCodeLegal(ISD::SETUGT, N0.getValueType()))
   2373             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOGT);
   2374         } else {
   2375           if (Cond == ISD::SETOEQ &&
   2376               isCondCodeLegal(ISD::SETOGE, N0.getValueType()))
   2377             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOGE);
   2378           if (Cond == ISD::SETUEQ &&
   2379               isCondCodeLegal(ISD::SETOGE, N0.getValueType()))
   2380             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETUGE);
   2381           if (Cond == ISD::SETUNE &&
   2382               isCondCodeLegal(ISD::SETULT, N0.getValueType()))
   2383             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETULT);
   2384           if (Cond == ISD::SETONE &&
   2385               isCondCodeLegal(ISD::SETULT, N0.getValueType()))
   2386             return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOLT);
   2387         }
   2388       }
   2389     }
   2390   }
   2391 
   2392   if (N0 == N1) {
   2393     // We can always fold X == X for integer setcc's.
   2394     if (N0.getValueType().isInteger())
   2395       return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);
   2396     unsigned UOF = ISD::getUnorderedFlavor(Cond);
   2397     if (UOF == 2)   // FP operators that are undefined on NaNs.
   2398       return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);
   2399     if (UOF == unsigned(ISD::isTrueWhenEqual(Cond)))
   2400       return DAG.getConstant(UOF, VT);
   2401     // Otherwise, we can't fold it.  However, we can simplify it to SETUO/SETO
   2402     // if it is not already.
   2403     ISD::CondCode NewCond = UOF == 0 ? ISD::SETO : ISD::SETUO;
   2404     if (NewCond != Cond)
   2405       return DAG.getSetCC(dl, VT, N0, N1, NewCond);
   2406   }
   2407 
   2408   if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
   2409       N0.getValueType().isInteger()) {
   2410     if (N0.getOpcode() == ISD::ADD || N0.getOpcode() == ISD::SUB ||
   2411         N0.getOpcode() == ISD::XOR) {
   2412       // Simplify (X+Y) == (X+Z) -->  Y == Z
   2413       if (N0.getOpcode() == N1.getOpcode()) {
   2414         if (N0.getOperand(0) == N1.getOperand(0))
   2415           return DAG.getSetCC(dl, VT, N0.getOperand(1), N1.getOperand(1), Cond);
   2416         if (N0.getOperand(1) == N1.getOperand(1))
   2417           return DAG.getSetCC(dl, VT, N0.getOperand(0), N1.getOperand(0), Cond);
   2418         if (DAG.isCommutativeBinOp(N0.getOpcode())) {
   2419           // If X op Y == Y op X, try other combinations.
   2420           if (N0.getOperand(0) == N1.getOperand(1))
   2421             return DAG.getSetCC(dl, VT, N0.getOperand(1), N1.getOperand(0),
   2422                                 Cond);
   2423           if (N0.getOperand(1) == N1.getOperand(0))
   2424             return DAG.getSetCC(dl, VT, N0.getOperand(0), N1.getOperand(1),
   2425                                 Cond);
   2426         }
   2427       }
   2428 
   2429       if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(N1)) {
   2430         if (ConstantSDNode *LHSR = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
   2431           // Turn (X+C1) == C2 --> X == C2-C1
   2432           if (N0.getOpcode() == ISD::ADD && N0.getNode()->hasOneUse()) {
   2433             return DAG.getSetCC(dl, VT, N0.getOperand(0),
   2434                                 DAG.getConstant(RHSC->getAPIntValue()-
   2435                                                 LHSR->getAPIntValue(),
   2436                                 N0.getValueType()), Cond);
   2437           }
   2438 
   2439           // Turn (X^C1) == C2 into X == C1^C2 iff X&~C1 = 0.
   2440           if (N0.getOpcode() == ISD::XOR)
   2441             // If we know that all of the inverted bits are zero, don't bother
   2442             // performing the inversion.
   2443             if (DAG.MaskedValueIsZero(N0.getOperand(0), ~LHSR->getAPIntValue()))
   2444               return
   2445                 DAG.getSetCC(dl, VT, N0.getOperand(0),
   2446                              DAG.getConstant(LHSR->getAPIntValue() ^
   2447                                                RHSC->getAPIntValue(),
   2448                                              N0.getValueType()),
   2449                              Cond);
   2450         }
   2451 
   2452         // Turn (C1-X) == C2 --> X == C1-C2
   2453         if (ConstantSDNode *SUBC = dyn_cast<ConstantSDNode>(N0.getOperand(0))) {
   2454           if (N0.getOpcode() == ISD::SUB && N0.getNode()->hasOneUse()) {
   2455             return
   2456               DAG.getSetCC(dl, VT, N0.getOperand(1),
   2457                            DAG.getConstant(SUBC->getAPIntValue() -
   2458                                              RHSC->getAPIntValue(),
   2459                                            N0.getValueType()),
   2460                            Cond);
   2461           }
   2462         }
   2463       }
   2464 
   2465       // Simplify (X+Z) == X -->  Z == 0
   2466       if (N0.getOperand(0) == N1)
   2467         return DAG.getSetCC(dl, VT, N0.getOperand(1),
   2468                         DAG.getConstant(0, N0.getValueType()), Cond);
   2469       if (N0.getOperand(1) == N1) {
   2470         if (DAG.isCommutativeBinOp(N0.getOpcode()))
   2471           return DAG.getSetCC(dl, VT, N0.getOperand(0),
   2472                           DAG.getConstant(0, N0.getValueType()), Cond);
   2473         else if (N0.getNode()->hasOneUse()) {
   2474           assert(N0.getOpcode() == ISD::SUB && "Unexpected operation!");
   2475           // (Z-X) == X  --> Z == X<<1
   2476           SDValue SH = DAG.getNode(ISD::SHL, dl, N1.getValueType(),
   2477                                      N1,
   2478                        DAG.getConstant(1, getShiftAmountTy(N1.getValueType())));
   2479           if (!DCI.isCalledByLegalizer())
   2480             DCI.AddToWorklist(SH.getNode());
   2481           return DAG.getSetCC(dl, VT, N0.getOperand(0), SH, Cond);
   2482         }
   2483       }
   2484     }
   2485 
   2486     if (N1.getOpcode() == ISD::ADD || N1.getOpcode() == ISD::SUB ||
   2487         N1.getOpcode() == ISD::XOR) {
   2488       // Simplify  X == (X+Z) -->  Z == 0
   2489       if (N1.getOperand(0) == N0) {
   2490         return DAG.getSetCC(dl, VT, N1.getOperand(1),
   2491                         DAG.getConstant(0, N1.getValueType()), Cond);
   2492       } else if (N1.getOperand(1) == N0) {
   2493         if (DAG.isCommutativeBinOp(N1.getOpcode())) {
   2494           return DAG.getSetCC(dl, VT, N1.getOperand(0),
   2495                           DAG.getConstant(0, N1.getValueType()), Cond);
   2496         } else if (N1.getNode()->hasOneUse()) {
   2497           assert(N1.getOpcode() == ISD::SUB && "Unexpected operation!");
   2498           // X == (Z-X)  --> X<<1 == Z
   2499           SDValue SH = DAG.getNode(ISD::SHL, dl, N1.getValueType(), N0,
   2500                        DAG.getConstant(1, getShiftAmountTy(N0.getValueType())));
   2501           if (!DCI.isCalledByLegalizer())
   2502             DCI.AddToWorklist(SH.getNode());
   2503           return DAG.getSetCC(dl, VT, SH, N1.getOperand(0), Cond);
   2504         }
   2505       }
   2506     }
   2507 
   2508     // Simplify x&y == y to x&y != 0 if y has exactly one bit set.
   2509     // Note that where y is variable and is known to have at most
   2510     // one bit set (for example, if it is z&1) we cannot do this;
   2511     // the expressions are not equivalent when y==0.
   2512     if (N0.getOpcode() == ISD::AND)
   2513       if (N0.getOperand(0) == N1 || N0.getOperand(1) == N1) {
   2514         if (ValueHasExactlyOneBitSet(N1, DAG)) {
   2515           Cond = ISD::getSetCCInverse(Cond, /*isInteger=*/true);
   2516           SDValue Zero = DAG.getConstant(0, N1.getValueType());
   2517           return DAG.getSetCC(dl, VT, N0, Zero, Cond);
   2518         }
   2519       }
   2520     if (N1.getOpcode() == ISD::AND)
   2521       if (N1.getOperand(0) == N0 || N1.getOperand(1) == N0) {
   2522         if (ValueHasExactlyOneBitSet(N0, DAG)) {
   2523           Cond = ISD::getSetCCInverse(Cond, /*isInteger=*/true);
   2524           SDValue Zero = DAG.getConstant(0, N0.getValueType());
   2525           return DAG.getSetCC(dl, VT, N1, Zero, Cond);
   2526         }
   2527       }
   2528   }
   2529 
   2530   // Fold away ALL boolean setcc's.
   2531   SDValue Temp;
   2532   if (N0.getValueType() == MVT::i1 && foldBooleans) {
   2533     switch (Cond) {
   2534     default: llvm_unreachable("Unknown integer setcc!");
   2535     case ISD::SETEQ:  // X == Y  -> ~(X^Y)
   2536       Temp = DAG.getNode(ISD::XOR, dl, MVT::i1, N0, N1);
   2537       N0 = DAG.getNOT(dl, Temp, MVT::i1);
   2538       if (!DCI.isCalledByLegalizer())
   2539         DCI.AddToWorklist(Temp.getNode());
   2540       break;
   2541     case ISD::SETNE:  // X != Y   -->  (X^Y)
   2542       N0 = DAG.getNode(ISD::XOR, dl, MVT::i1, N0, N1);
   2543       break;
   2544     case ISD::SETGT:  // X >s Y   -->  X == 0 & Y == 1  -->  ~X & Y
   2545     case ISD::SETULT: // X <u Y   -->  X == 0 & Y == 1  -->  ~X & Y
   2546       Temp = DAG.getNOT(dl, N0, MVT::i1);
   2547       N0 = DAG.getNode(ISD::AND, dl, MVT::i1, N1, Temp);
   2548       if (!DCI.isCalledByLegalizer())
   2549         DCI.AddToWorklist(Temp.getNode());
   2550       break;
   2551     case ISD::SETLT:  // X <s Y   --> X == 1 & Y == 0  -->  ~Y & X
   2552     case ISD::SETUGT: // X >u Y   --> X == 1 & Y == 0  -->  ~Y & X
   2553       Temp = DAG.getNOT(dl, N1, MVT::i1);
   2554       N0 = DAG.getNode(ISD::AND, dl, MVT::i1, N0, Temp);
   2555       if (!DCI.isCalledByLegalizer())
   2556         DCI.AddToWorklist(Temp.getNode());
   2557       break;
   2558     case ISD::SETULE: // X <=u Y  --> X == 0 | Y == 1  -->  ~X | Y
   2559     case ISD::SETGE:  // X >=s Y  --> X == 0 | Y == 1  -->  ~X | Y
   2560       Temp = DAG.getNOT(dl, N0, MVT::i1);
   2561       N0 = DAG.getNode(ISD::OR, dl, MVT::i1, N1, Temp);
   2562       if (!DCI.isCalledByLegalizer())
   2563         DCI.AddToWorklist(Temp.getNode());
   2564       break;
   2565     case ISD::SETUGE: // X >=u Y  --> X == 1 | Y == 0  -->  ~Y | X
   2566     case ISD::SETLE:  // X <=s Y  --> X == 1 | Y == 0  -->  ~Y | X
   2567       Temp = DAG.getNOT(dl, N1, MVT::i1);
   2568       N0 = DAG.getNode(ISD::OR, dl, MVT::i1, N0, Temp);
   2569       break;
   2570     }
   2571     if (VT != MVT::i1) {
   2572       if (!DCI.isCalledByLegalizer())
   2573         DCI.AddToWorklist(N0.getNode());
   2574       // FIXME: If running after legalize, we probably can't do this.
   2575       N0 = DAG.getNode(ISD::ZERO_EXTEND, dl, VT, N0);
   2576     }
   2577     return N0;
   2578   }
   2579 
   2580   // Could not fold it.
   2581   return SDValue();
   2582 }
   2583 
   2584 /// isGAPlusOffset - Returns true (and the GlobalValue and the offset) if the
   2585 /// node is a GlobalAddress + offset.
   2586 bool TargetLowering::isGAPlusOffset(SDNode *N, const GlobalValue *&GA,
   2587                                     int64_t &Offset) const {
   2588   if (isa<GlobalAddressSDNode>(N)) {
   2589     GlobalAddressSDNode *GASD = cast<GlobalAddressSDNode>(N);
   2590     GA = GASD->getGlobal();
   2591     Offset += GASD->getOffset();
   2592     return true;
   2593   }
   2594 
   2595   if (N->getOpcode() == ISD::ADD) {
   2596     SDValue N1 = N->getOperand(0);
   2597     SDValue N2 = N->getOperand(1);
   2598     if (isGAPlusOffset(N1.getNode(), GA, Offset)) {
   2599       ConstantSDNode *V = dyn_cast<ConstantSDNode>(N2);
   2600       if (V) {
   2601         Offset += V->getSExtValue();
   2602         return true;
   2603       }
   2604     } else if (isGAPlusOffset(N2.getNode(), GA, Offset)) {
   2605       ConstantSDNode *V = dyn_cast<ConstantSDNode>(N1);
   2606       if (V) {
   2607         Offset += V->getSExtValue();
   2608         return true;
   2609       }
   2610     }
   2611   }
   2612 
   2613   return false;
   2614 }
   2615 
   2616 
   2617 SDValue TargetLowering::
   2618 PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const {
   2619   // Default implementation: no optimization.
   2620   return SDValue();
   2621 }
   2622 
   2623 //===----------------------------------------------------------------------===//
   2624 //  Inline Assembler Implementation Methods
   2625 //===----------------------------------------------------------------------===//
   2626 
   2627 
   2628 TargetLowering::ConstraintType
   2629 TargetLowering::getConstraintType(const std::string &Constraint) const {
   2630   if (Constraint.size() == 1) {
   2631     switch (Constraint[0]) {
   2632     default: break;
   2633     case 'r': return C_RegisterClass;
   2634     case 'm':    // memory
   2635     case 'o':    // offsetable
   2636     case 'V':    // not offsetable
   2637       return C_Memory;
   2638     case 'i':    // Simple Integer or Relocatable Constant
   2639     case 'n':    // Simple Integer
   2640     case 'E':    // Floating Point Constant
   2641     case 'F':    // Floating Point Constant
   2642     case 's':    // Relocatable Constant
   2643     case 'p':    // Address.
   2644     case 'X':    // Allow ANY value.
   2645     case 'I':    // Target registers.
   2646     case 'J':
   2647     case 'K':
   2648     case 'L':
   2649     case 'M':
   2650     case 'N':
   2651     case 'O':
   2652     case 'P':
   2653     case '<':
   2654     case '>':
   2655       return C_Other;
   2656     }
   2657   }
   2658 
   2659   if (Constraint.size() > 1 && Constraint[0] == '{' &&
   2660       Constraint[Constraint.size()-1] == '}')
   2661     return C_Register;
   2662   return C_Unknown;
   2663 }
   2664 
   2665 /// LowerXConstraint - try to replace an X constraint, which matches anything,
   2666 /// with another that has more specific requirements based on the type of the
   2667 /// corresponding operand.
   2668 const char *TargetLowering::LowerXConstraint(EVT ConstraintVT) const{
   2669   if (ConstraintVT.isInteger())
   2670     return "r";
   2671   if (ConstraintVT.isFloatingPoint())
   2672     return "f";      // works for many targets
   2673   return 0;
   2674 }
   2675 
   2676 /// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
   2677 /// vector.  If it is invalid, don't add anything to Ops.
   2678 void TargetLowering::LowerAsmOperandForConstraint(SDValue Op,
   2679                                                   std::string &Constraint,
   2680                                                   std::vector<SDValue> &Ops,
   2681                                                   SelectionDAG &DAG) const {
   2682 
   2683   if (Constraint.length() > 1) return;
   2684 
   2685   char ConstraintLetter = Constraint[0];
   2686   switch (ConstraintLetter) {
   2687   default: break;
   2688   case 'X':     // Allows any operand; labels (basic block) use this.
   2689     if (Op.getOpcode() == ISD::BasicBlock) {
   2690       Ops.push_back(Op);
   2691       return;
   2692     }
   2693     // fall through
   2694   case 'i':    // Simple Integer or Relocatable Constant
   2695   case 'n':    // Simple Integer
   2696   case 's': {  // Relocatable Constant
   2697     // These operands are interested in values of the form (GV+C), where C may
   2698     // be folded in as an offset of GV, or it may be explicitly added.  Also, it
   2699     // is possible and fine if either GV or C are missing.
   2700     ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op);
   2701     GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op);
   2702 
   2703     // If we have "(add GV, C)", pull out GV/C
   2704     if (Op.getOpcode() == ISD::ADD) {
   2705       C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
   2706       GA = dyn_cast<GlobalAddressSDNode>(Op.getOperand(0));
   2707       if (C == 0 || GA == 0) {
   2708         C = dyn_cast<ConstantSDNode>(Op.getOperand(0));
   2709         GA = dyn_cast<GlobalAddressSDNode>(Op.getOperand(1));
   2710       }
   2711       if (C == 0 || GA == 0)
   2712         C = 0, GA = 0;
   2713     }
   2714 
   2715     // If we find a valid operand, map to the TargetXXX version so that the
   2716     // value itself doesn't get selected.
   2717     if (GA) {   // Either &GV   or   &GV+C
   2718       if (ConstraintLetter != 'n') {
   2719         int64_t Offs = GA->getOffset();
   2720         if (C) Offs += C->getZExtValue();
   2721         Ops.push_back(DAG.getTargetGlobalAddress(GA->getGlobal(),
   2722                                                  C ? C->getDebugLoc() : DebugLoc(),
   2723                                                  Op.getValueType(), Offs));
   2724         return;
   2725       }
   2726     }
   2727     if (C) {   // just C, no GV.
   2728       // Simple constants are not allowed for 's'.
   2729       if (ConstraintLetter != 's') {
   2730         // gcc prints these as sign extended.  Sign extend value to 64 bits
   2731         // now; without this it would get ZExt'd later in
   2732         // ScheduleDAGSDNodes::EmitNode, which is very generic.
   2733         Ops.push_back(DAG.getTargetConstant(C->getAPIntValue().getSExtValue(),
   2734                                             MVT::i64));
   2735         return;
   2736       }
   2737     }
   2738     break;
   2739   }
   2740   }
   2741 }
   2742 
   2743 std::pair<unsigned, const TargetRegisterClass*> TargetLowering::
   2744 getRegForInlineAsmConstraint(const std::string &Constraint,
   2745                              EVT VT) const {
   2746   if (Constraint[0] != '{')
   2747     return std::make_pair(0u, static_cast<TargetRegisterClass*>(0));
   2748   assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
   2749 
   2750   // Remove the braces from around the name.
   2751   StringRef RegName(Constraint.data()+1, Constraint.size()-2);
   2752 
   2753   // Figure out which register class contains this reg.
   2754   const TargetRegisterInfo *RI = TM.getRegisterInfo();
   2755   for (TargetRegisterInfo::regclass_iterator RCI = RI->regclass_begin(),
   2756        E = RI->regclass_end(); RCI != E; ++RCI) {
   2757     const TargetRegisterClass *RC = *RCI;
   2758 
   2759     // If none of the value types for this register class are valid, we
   2760     // can't use it.  For example, 64-bit reg classes on 32-bit targets.
   2761     bool isLegal = false;
   2762     for (TargetRegisterClass::vt_iterator I = RC->vt_begin(), E = RC->vt_end();
   2763          I != E; ++I) {
   2764       if (isTypeLegal(*I)) {
   2765         isLegal = true;
   2766         break;
   2767       }
   2768     }
   2769 
   2770     if (!isLegal) continue;
   2771 
   2772     for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
   2773          I != E; ++I) {
   2774       if (RegName.equals_lower(RI->getName(*I)))
   2775         return std::make_pair(*I, RC);
   2776     }
   2777   }
   2778 
   2779   return std::make_pair(0u, static_cast<const TargetRegisterClass*>(0));
   2780 }
   2781 
   2782 //===----------------------------------------------------------------------===//
   2783 // Constraint Selection.
   2784 
   2785 /// isMatchingInputConstraint - Return true of this is an input operand that is
   2786 /// a matching constraint like "4".
   2787 bool TargetLowering::AsmOperandInfo::isMatchingInputConstraint() const {
   2788   assert(!ConstraintCode.empty() && "No known constraint!");
   2789   return isdigit(ConstraintCode[0]);
   2790 }
   2791 
   2792 /// getMatchedOperand - If this is an input matching constraint, this method
   2793 /// returns the output operand it matches.
   2794 unsigned TargetLowering::AsmOperandInfo::getMatchedOperand() const {
   2795   assert(!ConstraintCode.empty() && "No known constraint!");
   2796   return atoi(ConstraintCode.c_str());
   2797 }
   2798 
   2799 
   2800 /// ParseConstraints - Split up the constraint string from the inline
   2801 /// assembly value into the specific constraints and their prefixes,
   2802 /// and also tie in the associated operand values.
   2803 /// If this returns an empty vector, and if the constraint string itself
   2804 /// isn't empty, there was an error parsing.
   2805 TargetLowering::AsmOperandInfoVector TargetLowering::ParseConstraints(
   2806     ImmutableCallSite CS) const {
   2807   /// ConstraintOperands - Information about all of the constraints.
   2808   AsmOperandInfoVector ConstraintOperands;
   2809   const InlineAsm *IA = cast<InlineAsm>(CS.getCalledValue());
   2810   unsigned maCount = 0; // Largest number of multiple alternative constraints.
   2811 
   2812   // Do a prepass over the constraints, canonicalizing them, and building up the
   2813   // ConstraintOperands list.
   2814   InlineAsm::ConstraintInfoVector
   2815     ConstraintInfos = IA->ParseConstraints();
   2816 
   2817   unsigned ArgNo = 0;   // ArgNo - The argument of the CallInst.
   2818   unsigned ResNo = 0;   // ResNo - The result number of the next output.
   2819 
   2820   for (unsigned i = 0, e = ConstraintInfos.size(); i != e; ++i) {
   2821     ConstraintOperands.push_back(AsmOperandInfo(ConstraintInfos[i]));
   2822     AsmOperandInfo &OpInfo = ConstraintOperands.back();
   2823 
   2824     // Update multiple alternative constraint count.
   2825     if (OpInfo.multipleAlternatives.size() > maCount)
   2826       maCount = OpInfo.multipleAlternatives.size();
   2827 
   2828     OpInfo.ConstraintVT = MVT::Other;
   2829 
   2830     // Compute the value type for each operand.
   2831     switch (OpInfo.Type) {
   2832     case InlineAsm::isOutput:
   2833       // Indirect outputs just consume an argument.
   2834       if (OpInfo.isIndirect) {
   2835         OpInfo.CallOperandVal = const_cast<Value *>(CS.getArgument(ArgNo++));
   2836         break;
   2837       }
   2838 
   2839       // The return value of the call is this value.  As such, there is no
   2840       // corresponding argument.
   2841       assert(!CS.getType()->isVoidTy() &&
   2842              "Bad inline asm!");
   2843       if (StructType *STy = dyn_cast<StructType>(CS.getType())) {
   2844         OpInfo.ConstraintVT = getValueType(STy->getElementType(ResNo));
   2845       } else {
   2846         assert(ResNo == 0 && "Asm only has one result!");
   2847         OpInfo.ConstraintVT = getValueType(CS.getType());
   2848       }
   2849       ++ResNo;
   2850       break;
   2851     case InlineAsm::isInput:
   2852       OpInfo.CallOperandVal = const_cast<Value *>(CS.getArgument(ArgNo++));
   2853       break;
   2854     case InlineAsm::isClobber:
   2855       // Nothing to do.
   2856       break;
   2857     }
   2858 
   2859     if (OpInfo.CallOperandVal) {
   2860       llvm::Type *OpTy = OpInfo.CallOperandVal->getType();
   2861       if (OpInfo.isIndirect) {
   2862         llvm::PointerType *PtrTy = dyn_cast<PointerType>(OpTy);
   2863         if (!PtrTy)
   2864           report_fatal_error("Indirect operand for inline asm not a pointer!");
   2865         OpTy = PtrTy->getElementType();
   2866       }
   2867 
   2868       // Look for vector wrapped in a struct. e.g. { <16 x i8> }.
   2869       if (StructType *STy = dyn_cast<StructType>(OpTy))
   2870         if (STy->getNumElements() == 1)
   2871           OpTy = STy->getElementType(0);
   2872 
   2873       // If OpTy is not a single value, it may be a struct/union that we
   2874       // can tile with integers.
   2875       if (!OpTy->isSingleValueType() && OpTy->isSized()) {
   2876         unsigned BitSize = TD->getTypeSizeInBits(OpTy);
   2877         switch (BitSize) {
   2878         default: break;
   2879         case 1:
   2880         case 8:
   2881         case 16:
   2882         case 32:
   2883         case 64:
   2884         case 128:
   2885           OpInfo.ConstraintVT =
   2886               EVT::getEVT(IntegerType::get(OpTy->getContext(), BitSize), true);
   2887           break;
   2888         }
   2889       } else if (dyn_cast<PointerType>(OpTy)) {
   2890         OpInfo.ConstraintVT = MVT::getIntegerVT(8*TD->getPointerSize());
   2891       } else {
   2892         OpInfo.ConstraintVT = EVT::getEVT(OpTy, true);
   2893       }
   2894     }
   2895   }
   2896 
   2897   // If we have multiple alternative constraints, select the best alternative.
   2898   if (ConstraintInfos.size()) {
   2899     if (maCount) {
   2900       unsigned bestMAIndex = 0;
   2901       int bestWeight = -1;
   2902       // weight:  -1 = invalid match, and 0 = so-so match to 5 = good match.
   2903       int weight = -1;
   2904       unsigned maIndex;
   2905       // Compute the sums of the weights for each alternative, keeping track
   2906       // of the best (highest weight) one so far.
   2907       for (maIndex = 0; maIndex < maCount; ++maIndex) {
   2908         int weightSum = 0;
   2909         for (unsigned cIndex = 0, eIndex = ConstraintOperands.size();
   2910             cIndex != eIndex; ++cIndex) {
   2911           AsmOperandInfo& OpInfo = ConstraintOperands[cIndex];
   2912           if (OpInfo.Type == InlineAsm::isClobber)
   2913             continue;
   2914 
   2915           // If this is an output operand with a matching input operand,
   2916           // look up the matching input. If their types mismatch, e.g. one
   2917           // is an integer, the other is floating point, or their sizes are
   2918           // different, flag it as an maCantMatch.
   2919           if (OpInfo.hasMatchingInput()) {
   2920             AsmOperandInfo &Input = ConstraintOperands[OpInfo.MatchingInput];
   2921             if (OpInfo.ConstraintVT != Input.ConstraintVT) {
   2922               if ((OpInfo.ConstraintVT.isInteger() !=
   2923                    Input.ConstraintVT.isInteger()) ||
   2924                   (OpInfo.ConstraintVT.getSizeInBits() !=
   2925                    Input.ConstraintVT.getSizeInBits())) {
   2926                 weightSum = -1;  // Can't match.
   2927                 break;
   2928               }
   2929             }
   2930           }
   2931           weight = getMultipleConstraintMatchWeight(OpInfo, maIndex);
   2932           if (weight == -1) {
   2933             weightSum = -1;
   2934             break;
   2935           }
   2936           weightSum += weight;
   2937         }
   2938         // Update best.
   2939         if (weightSum > bestWeight) {
   2940           bestWeight = weightSum;
   2941           bestMAIndex = maIndex;
   2942         }
   2943       }
   2944 
   2945       // Now select chosen alternative in each constraint.
   2946       for (unsigned cIndex = 0, eIndex = ConstraintOperands.size();
   2947           cIndex != eIndex; ++cIndex) {
   2948         AsmOperandInfo& cInfo = ConstraintOperands[cIndex];
   2949         if (cInfo.Type == InlineAsm::isClobber)
   2950           continue;
   2951         cInfo.selectAlternative(bestMAIndex);
   2952       }
   2953     }
   2954   }
   2955 
   2956   // Check and hook up tied operands, choose constraint code to use.
   2957   for (unsigned cIndex = 0, eIndex = ConstraintOperands.size();
   2958       cIndex != eIndex; ++cIndex) {
   2959     AsmOperandInfo& OpInfo = ConstraintOperands[cIndex];
   2960 
   2961     // If this is an output operand with a matching input operand, look up the
   2962     // matching input. If their types mismatch, e.g. one is an integer, the
   2963     // other is floating point, or their sizes are different, flag it as an
   2964     // error.
   2965     if (OpInfo.hasMatchingInput()) {
   2966       AsmOperandInfo &Input = ConstraintOperands[OpInfo.MatchingInput];
   2967 
   2968       if (OpInfo.ConstraintVT != Input.ConstraintVT) {
   2969 	std::pair<unsigned, const TargetRegisterClass*> MatchRC =
   2970 	  getRegForInlineAsmConstraint(OpInfo.ConstraintCode, OpInfo.ConstraintVT);
   2971 	std::pair<unsigned, const TargetRegisterClass*> InputRC =
   2972 	  getRegForInlineAsmConstraint(Input.ConstraintCode, Input.ConstraintVT);
   2973         if ((OpInfo.ConstraintVT.isInteger() !=
   2974              Input.ConstraintVT.isInteger()) ||
   2975             (MatchRC.second != InputRC.second)) {
   2976           report_fatal_error("Unsupported asm: input constraint"
   2977                              " with a matching output constraint of"
   2978                              " incompatible type!");
   2979         }
   2980       }
   2981 
   2982     }
   2983   }
   2984 
   2985   return ConstraintOperands;
   2986 }
   2987 
   2988 
   2989 /// getConstraintGenerality - Return an integer indicating how general CT
   2990 /// is.
   2991 static unsigned getConstraintGenerality(TargetLowering::ConstraintType CT) {
   2992   switch (CT) {
   2993   default: llvm_unreachable("Unknown constraint type!");
   2994   case TargetLowering::C_Other:
   2995   case TargetLowering::C_Unknown:
   2996     return 0;
   2997   case TargetLowering::C_Register:
   2998     return 1;
   2999   case TargetLowering::C_RegisterClass:
   3000     return 2;
   3001   case TargetLowering::C_Memory:
   3002     return 3;
   3003   }
   3004 }
   3005 
   3006 /// Examine constraint type and operand type and determine a weight value.
   3007 /// This object must already have been set up with the operand type
   3008 /// and the current alternative constraint selected.
   3009 TargetLowering::ConstraintWeight
   3010   TargetLowering::getMultipleConstraintMatchWeight(
   3011     AsmOperandInfo &info, int maIndex) const {
   3012   InlineAsm::ConstraintCodeVector *rCodes;
   3013   if (maIndex >= (int)info.multipleAlternatives.size())
   3014     rCodes = &info.Codes;
   3015   else
   3016     rCodes = &info.multipleAlternatives[maIndex].Codes;
   3017   ConstraintWeight BestWeight = CW_Invalid;
   3018 
   3019   // Loop over the options, keeping track of the most general one.
   3020   for (unsigned i = 0, e = rCodes->size(); i != e; ++i) {
   3021     ConstraintWeight weight =
   3022       getSingleConstraintMatchWeight(info, (*rCodes)[i].c_str());
   3023     if (weight > BestWeight)
   3024       BestWeight = weight;
   3025   }
   3026 
   3027   return BestWeight;
   3028 }
   3029 
   3030 /// Examine constraint type and operand type and determine a weight value.
   3031 /// This object must already have been set up with the operand type
   3032 /// and the current alternative constraint selected.
   3033 TargetLowering::ConstraintWeight
   3034   TargetLowering::getSingleConstraintMatchWeight(
   3035     AsmOperandInfo &info, const char *constraint) const {
   3036   ConstraintWeight weight = CW_Invalid;
   3037   Value *CallOperandVal = info.CallOperandVal;
   3038     // If we don't have a value, we can't do a match,
   3039     // but allow it at the lowest weight.
   3040   if (CallOperandVal == NULL)
   3041     return CW_Default;
   3042   // Look at the constraint type.
   3043   switch (*constraint) {
   3044     case 'i': // immediate integer.
   3045     case 'n': // immediate integer with a known value.
   3046       if (isa<ConstantInt>(CallOperandVal))
   3047         weight = CW_Constant;
   3048       break;
   3049     case 's': // non-explicit intregal immediate.
   3050       if (isa<GlobalValue>(CallOperandVal))
   3051         weight = CW_Constant;
   3052       break;
   3053     case 'E': // immediate float if host format.
   3054     case 'F': // immediate float.
   3055       if (isa<ConstantFP>(CallOperandVal))
   3056         weight = CW_Constant;
   3057       break;
   3058     case '<': // memory operand with autodecrement.
   3059     case '>': // memory operand with autoincrement.
   3060     case 'm': // memory operand.
   3061     case 'o': // offsettable memory operand
   3062     case 'V': // non-offsettable memory operand
   3063       weight = CW_Memory;
   3064       break;
   3065     case 'r': // general register.
   3066     case 'g': // general register, memory operand or immediate integer.
   3067               // note: Clang converts "g" to "imr".
   3068       if (CallOperandVal->getType()->isIntegerTy())
   3069         weight = CW_Register;
   3070       break;
   3071     case 'X': // any operand.
   3072     default:
   3073       weight = CW_Default;
   3074       break;
   3075   }
   3076   return weight;
   3077 }
   3078 
   3079 /// ChooseConstraint - If there are multiple different constraints that we
   3080 /// could pick for this operand (e.g. "imr") try to pick the 'best' one.
   3081 /// This is somewhat tricky: constraints fall into four classes:
   3082 ///    Other         -> immediates and magic values
   3083 ///    Register      -> one specific register
   3084 ///    RegisterClass -> a group of regs
   3085 ///    Memory        -> memory
   3086 /// Ideally, we would pick the most specific constraint possible: if we have
   3087 /// something that fits into a register, we would pick it.  The problem here
   3088 /// is that if we have something that could either be in a register or in
   3089 /// memory that use of the register could cause selection of *other*
   3090 /// operands to fail: they might only succeed if we pick memory.  Because of
   3091 /// this the heuristic we use is:
   3092 ///
   3093 ///  1) If there is an 'other' constraint, and if the operand is valid for
   3094 ///     that constraint, use it.  This makes us take advantage of 'i'
   3095 ///     constraints when available.
   3096 ///  2) Otherwise, pick the most general constraint present.  This prefers
   3097 ///     'm' over 'r', for example.
   3098 ///
   3099 static void ChooseConstraint(TargetLowering::AsmOperandInfo &OpInfo,
   3100                              const TargetLowering &TLI,
   3101                              SDValue Op, SelectionDAG *DAG) {
   3102   assert(OpInfo.Codes.size() > 1 && "Doesn't have multiple constraint options");
   3103   unsigned BestIdx = 0;
   3104   TargetLowering::ConstraintType BestType = TargetLowering::C_Unknown;
   3105   int BestGenerality = -1;
   3106 
   3107   // Loop over the options, keeping track of the most general one.
   3108   for (unsigned i = 0, e = OpInfo.Codes.size(); i != e; ++i) {
   3109     TargetLowering::ConstraintType CType =
   3110       TLI.getConstraintType(OpInfo.Codes[i]);
   3111 
   3112     // If this is an 'other' constraint, see if the operand is valid for it.
   3113     // For example, on X86 we might have an 'rI' constraint.  If the operand
   3114     // is an integer in the range [0..31] we want to use I (saving a load
   3115     // of a register), otherwise we must use 'r'.
   3116     if (CType == TargetLowering::C_Other && Op.getNode()) {
   3117       assert(OpInfo.Codes[i].size() == 1 &&
   3118              "Unhandled multi-letter 'other' constraint");
   3119       std::vector<SDValue> ResultOps;
   3120       TLI.LowerAsmOperandForConstraint(Op, OpInfo.Codes[i],
   3121                                        ResultOps, *DAG);
   3122       if (!ResultOps.empty()) {
   3123         BestType = CType;
   3124         BestIdx = i;
   3125         break;
   3126       }
   3127     }
   3128 
   3129     // Things with matching constraints can only be registers, per gcc
   3130     // documentation.  This mainly affects "g" constraints.
   3131     if (CType == TargetLowering::C_Memory && OpInfo.hasMatchingInput())
   3132       continue;
   3133 
   3134     // This constraint letter is more general than the previous one, use it.
   3135     int Generality = getConstraintGenerality(CType);
   3136     if (Generality > BestGenerality) {
   3137       BestType = CType;
   3138       BestIdx = i;
   3139       BestGenerality = Generality;
   3140     }
   3141   }
   3142 
   3143   OpInfo.ConstraintCode = OpInfo.Codes[BestIdx];
   3144   OpInfo.ConstraintType = BestType;
   3145 }
   3146 
   3147 /// ComputeConstraintToUse - Determines the constraint code and constraint
   3148 /// type to use for the specific AsmOperandInfo, setting
   3149 /// OpInfo.ConstraintCode and OpInfo.ConstraintType.
   3150 void TargetLowering::ComputeConstraintToUse(AsmOperandInfo &OpInfo,
   3151                                             SDValue Op,
   3152                                             SelectionDAG *DAG) const {
   3153   assert(!OpInfo.Codes.empty() && "Must have at least one constraint");
   3154 
   3155   // Single-letter constraints ('r') are very common.
   3156   if (OpInfo.Codes.size() == 1) {
   3157     OpInfo.ConstraintCode = OpInfo.Codes[0];
   3158     OpInfo.ConstraintType = getConstraintType(OpInfo.ConstraintCode);
   3159   } else {
   3160     ChooseConstraint(OpInfo, *this, Op, DAG);
   3161   }
   3162 
   3163   // 'X' matches anything.
   3164   if (OpInfo.ConstraintCode == "X" && OpInfo.CallOperandVal) {
   3165     // Labels and constants are handled elsewhere ('X' is the only thing
   3166     // that matches labels).  For Functions, the type here is the type of
   3167     // the result, which is not what we want to look at; leave them alone.
   3168     Value *v = OpInfo.CallOperandVal;
   3169     if (isa<BasicBlock>(v) || isa<ConstantInt>(v) || isa<Function>(v)) {
   3170       OpInfo.CallOperandVal = v;
   3171       return;
   3172     }
   3173 
   3174     // Otherwise, try to resolve it to something we know about by looking at
   3175     // the actual operand type.
   3176     if (const char *Repl = LowerXConstraint(OpInfo.ConstraintVT)) {
   3177       OpInfo.ConstraintCode = Repl;
   3178       OpInfo.ConstraintType = getConstraintType(OpInfo.ConstraintCode);
   3179     }
   3180   }
   3181 }
   3182 
   3183 //===----------------------------------------------------------------------===//
   3184 //  Loop Strength Reduction hooks
   3185 //===----------------------------------------------------------------------===//
   3186 
   3187 /// isLegalAddressingMode - Return true if the addressing mode represented
   3188 /// by AM is legal for this target, for a load/store of the specified type.
   3189 bool TargetLowering::isLegalAddressingMode(const AddrMode &AM,
   3190                                            Type *Ty) const {
   3191   // The default implementation of this implements a conservative RISCy, r+r and
   3192   // r+i addr mode.
   3193 
   3194   // Allows a sign-extended 16-bit immediate field.
   3195   if (AM.BaseOffs <= -(1LL << 16) || AM.BaseOffs >= (1LL << 16)-1)
   3196     return false;
   3197 
   3198   // No global is ever allowed as a base.
   3199   if (AM.BaseGV)
   3200     return false;
   3201 
   3202   // Only support r+r,
   3203   switch (AM.Scale) {
   3204   case 0:  // "r+i" or just "i", depending on HasBaseReg.
   3205     break;
   3206   case 1:
   3207     if (AM.HasBaseReg && AM.BaseOffs)  // "r+r+i" is not allowed.
   3208       return false;
   3209     // Otherwise we have r+r or r+i.
   3210     break;
   3211   case 2:
   3212     if (AM.HasBaseReg || AM.BaseOffs)  // 2*r+r  or  2*r+i is not allowed.
   3213       return false;
   3214     // Allow 2*r as r+r.
   3215     break;
   3216   }
   3217 
   3218   return true;
   3219 }
   3220 
   3221 /// BuildExactDiv - Given an exact SDIV by a constant, create a multiplication
   3222 /// with the multiplicative inverse of the constant.
   3223 SDValue TargetLowering::BuildExactSDIV(SDValue Op1, SDValue Op2, DebugLoc dl,
   3224                                        SelectionDAG &DAG) const {
   3225   ConstantSDNode *C = cast<ConstantSDNode>(Op2);
   3226   APInt d = C->getAPIntValue();
   3227   assert(d != 0 && "Division by zero!");
   3228 
   3229   // Shift the value upfront if it is even, so the LSB is one.
   3230   unsigned ShAmt = d.countTrailingZeros();
   3231   if (ShAmt) {
   3232     // TODO: For UDIV use SRL instead of SRA.
   3233     SDValue Amt = DAG.getConstant(ShAmt, getShiftAmountTy(Op1.getValueType()));
   3234     Op1 = DAG.getNode(ISD::SRA, dl, Op1.getValueType(), Op1, Amt);
   3235     d = d.ashr(ShAmt);
   3236   }
   3237 
   3238   // Calculate the multiplicative inverse, using Newton's method.
   3239   APInt t, xn = d;
   3240   while ((t = d*xn) != 1)
   3241     xn *= APInt(d.getBitWidth(), 2) - t;
   3242 
   3243   Op2 = DAG.getConstant(xn, Op1.getValueType());
   3244   return DAG.getNode(ISD::MUL, dl, Op1.getValueType(), Op1, Op2);
   3245 }
   3246 
   3247 /// BuildSDIVSequence - Given an ISD::SDIV node expressing a divide by constant,
   3248 /// return a DAG expression to select that will generate the same value by
   3249 /// multiplying by a magic number.  See:
   3250 /// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
   3251 SDValue TargetLowering::BuildSDIV(SDNode *N, SelectionDAG &DAG,
   3252                                   std::vector<SDNode*>* Created) const {
   3253   EVT VT = N->getValueType(0);
   3254   DebugLoc dl= N->getDebugLoc();
   3255 
   3256   // Check to see if we can do this.
   3257   // FIXME: We should be more aggressive here.
   3258   if (!isTypeLegal(VT))
   3259     return SDValue();
   3260 
   3261   APInt d = cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
   3262   APInt::ms magics = d.magic();
   3263 
   3264   // Multiply the numerator (operand 0) by the magic value
   3265   // FIXME: We should support doing a MUL in a wider type
   3266   SDValue Q;
   3267   if (isOperationLegalOrCustom(ISD::MULHS, VT))
   3268     Q = DAG.getNode(ISD::MULHS, dl, VT, N->getOperand(0),
   3269                     DAG.getConstant(magics.m, VT));
   3270   else if (isOperationLegalOrCustom(ISD::SMUL_LOHI, VT))
   3271     Q = SDValue(DAG.getNode(ISD::SMUL_LOHI, dl, DAG.getVTList(VT, VT),
   3272                               N->getOperand(0),
   3273                               DAG.getConstant(magics.m, VT)).getNode(), 1);
   3274   else
   3275     return SDValue();       // No mulhs or equvialent
   3276   // If d > 0 and m < 0, add the numerator
   3277   if (d.isStrictlyPositive() && magics.m.isNegative()) {
   3278     Q = DAG.getNode(ISD::ADD, dl, VT, Q, N->getOperand(0));
   3279     if (Created)
   3280       Created->push_back(Q.getNode());
   3281   }
   3282   // If d < 0 and m > 0, subtract the numerator.
   3283   if (d.isNegative() && magics.m.isStrictlyPositive()) {
   3284     Q = DAG.getNode(ISD::SUB, dl, VT, Q, N->getOperand(0));
   3285     if (Created)
   3286       Created->push_back(Q.getNode());
   3287   }
   3288   // Shift right algebraic if shift value is nonzero
   3289   if (magics.s > 0) {
   3290     Q = DAG.getNode(ISD::SRA, dl, VT, Q,
   3291                  DAG.getConstant(magics.s, getShiftAmountTy(Q.getValueType())));
   3292     if (Created)
   3293       Created->push_back(Q.getNode());
   3294   }
   3295   // Extract the sign bit and add it to the quotient
   3296   SDValue T =
   3297     DAG.getNode(ISD::SRL, dl, VT, Q, DAG.getConstant(VT.getSizeInBits()-1,
   3298                                            getShiftAmountTy(Q.getValueType())));
   3299   if (Created)
   3300     Created->push_back(T.getNode());
   3301   return DAG.getNode(ISD::ADD, dl, VT, Q, T);
   3302 }
   3303 
   3304 /// BuildUDIVSequence - Given an ISD::UDIV node expressing a divide by constant,
   3305 /// return a DAG expression to select that will generate the same value by
   3306 /// multiplying by a magic number.  See:
   3307 /// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
   3308 SDValue TargetLowering::BuildUDIV(SDNode *N, SelectionDAG &DAG,
   3309                                   std::vector<SDNode*>* Created) const {
   3310   EVT VT = N->getValueType(0);
   3311   DebugLoc dl = N->getDebugLoc();
   3312 
   3313   // Check to see if we can do this.
   3314   // FIXME: We should be more aggressive here.
   3315   if (!isTypeLegal(VT))
   3316     return SDValue();
   3317 
   3318   // FIXME: We should use a narrower constant when the upper
   3319   // bits are known to be zero.
   3320   const APInt &N1C = cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
   3321   APInt::mu magics = N1C.magicu();
   3322 
   3323   SDValue Q = N->getOperand(0);
   3324 
   3325   // If the divisor is even, we can avoid using the expensive fixup by shifting
   3326   // the divided value upfront.
   3327   if (magics.a != 0 && !N1C[0]) {
   3328     unsigned Shift = N1C.countTrailingZeros();
   3329     Q = DAG.getNode(ISD::SRL, dl, VT, Q,
   3330                     DAG.getConstant(Shift, getShiftAmountTy(Q.getValueType())));
   3331     if (Created)
   3332       Created->push_back(Q.getNode());
   3333 
   3334     // Get magic number for the shifted divisor.
   3335     magics = N1C.lshr(Shift).magicu(Shift);
   3336     assert(magics.a == 0 && "Should use cheap fixup now");
   3337   }
   3338 
   3339   // Multiply the numerator (operand 0) by the magic value
   3340   // FIXME: We should support doing a MUL in a wider type
   3341   if (isOperationLegalOrCustom(ISD::MULHU, VT))
   3342     Q = DAG.getNode(ISD::MULHU, dl, VT, Q, DAG.getConstant(magics.m, VT));
   3343   else if (isOperationLegalOrCustom(ISD::UMUL_LOHI, VT))
   3344     Q = SDValue(DAG.getNode(ISD::UMUL_LOHI, dl, DAG.getVTList(VT, VT), Q,
   3345                             DAG.getConstant(magics.m, VT)).getNode(), 1);
   3346   else
   3347     return SDValue();       // No mulhu or equvialent
   3348   if (Created)
   3349     Created->push_back(Q.getNode());
   3350 
   3351   if (magics.a == 0) {
   3352     assert(magics.s < N1C.getBitWidth() &&
   3353            "We shouldn't generate an undefined shift!");
   3354     return DAG.getNode(ISD::SRL, dl, VT, Q,
   3355                  DAG.getConstant(magics.s, getShiftAmountTy(Q.getValueType())));
   3356   } else {
   3357     SDValue NPQ = DAG.getNode(ISD::SUB, dl, VT, N->getOperand(0), Q);
   3358     if (Created)
   3359       Created->push_back(NPQ.getNode());
   3360     NPQ = DAG.getNode(ISD::SRL, dl, VT, NPQ,
   3361                       DAG.getConstant(1, getShiftAmountTy(NPQ.getValueType())));
   3362     if (Created)
   3363       Created->push_back(NPQ.getNode());
   3364     NPQ = DAG.getNode(ISD::ADD, dl, VT, NPQ, Q);
   3365     if (Created)
   3366       Created->push_back(NPQ.getNode());
   3367     return DAG.getNode(ISD::SRL, dl, VT, NPQ,
   3368              DAG.getConstant(magics.s-1, getShiftAmountTy(NPQ.getValueType())));
   3369   }
   3370 }
   3371