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      1 //===-- X86ISelLowering.h - X86 DAG Lowering Interface ----------*- C++ -*-===//
      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 file defines the interfaces that X86 uses to lower LLVM code into a
     11 // selection DAG.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef X86ISELLOWERING_H
     16 #define X86ISELLOWERING_H
     17 
     18 #include "X86Subtarget.h"
     19 #include "X86RegisterInfo.h"
     20 #include "X86MachineFunctionInfo.h"
     21 #include "llvm/Target/TargetLowering.h"
     22 #include "llvm/Target/TargetOptions.h"
     23 #include "llvm/CodeGen/FastISel.h"
     24 #include "llvm/CodeGen/SelectionDAG.h"
     25 #include "llvm/CodeGen/CallingConvLower.h"
     26 
     27 namespace llvm {
     28   namespace X86ISD {
     29     // X86 Specific DAG Nodes
     30     enum NodeType {
     31       // Start the numbering where the builtin ops leave off.
     32       FIRST_NUMBER = ISD::BUILTIN_OP_END,
     33 
     34       /// BSF - Bit scan forward.
     35       /// BSR - Bit scan reverse.
     36       BSF,
     37       BSR,
     38 
     39       /// SHLD, SHRD - Double shift instructions. These correspond to
     40       /// X86::SHLDxx and X86::SHRDxx instructions.
     41       SHLD,
     42       SHRD,
     43 
     44       /// FAND - Bitwise logical AND of floating point values. This corresponds
     45       /// to X86::ANDPS or X86::ANDPD.
     46       FAND,
     47 
     48       /// FOR - Bitwise logical OR of floating point values. This corresponds
     49       /// to X86::ORPS or X86::ORPD.
     50       FOR,
     51 
     52       /// FXOR - Bitwise logical XOR of floating point values. This corresponds
     53       /// to X86::XORPS or X86::XORPD.
     54       FXOR,
     55 
     56       /// FSRL - Bitwise logical right shift of floating point values. These
     57       /// corresponds to X86::PSRLDQ.
     58       FSRL,
     59 
     60       /// CALL - These operations represent an abstract X86 call
     61       /// instruction, which includes a bunch of information.  In particular the
     62       /// operands of these node are:
     63       ///
     64       ///     #0 - The incoming token chain
     65       ///     #1 - The callee
     66       ///     #2 - The number of arg bytes the caller pushes on the stack.
     67       ///     #3 - The number of arg bytes the callee pops off the stack.
     68       ///     #4 - The value to pass in AL/AX/EAX (optional)
     69       ///     #5 - The value to pass in DL/DX/EDX (optional)
     70       ///
     71       /// The result values of these nodes are:
     72       ///
     73       ///     #0 - The outgoing token chain
     74       ///     #1 - The first register result value (optional)
     75       ///     #2 - The second register result value (optional)
     76       ///
     77       CALL,
     78 
     79       /// RDTSC_DAG - This operation implements the lowering for
     80       /// readcyclecounter
     81       RDTSC_DAG,
     82 
     83       /// X86 compare and logical compare instructions.
     84       CMP, COMI, UCOMI,
     85 
     86       /// X86 bit-test instructions.
     87       BT,
     88 
     89       /// X86 SetCC. Operand 0 is condition code, and operand 1 is the EFLAGS
     90       /// operand, usually produced by a CMP instruction.
     91       SETCC,
     92 
     93       // Same as SETCC except it's materialized with a sbb and the value is all
     94       // one's or all zero's.
     95       SETCC_CARRY,  // R = carry_bit ? ~0 : 0
     96 
     97       /// X86 FP SETCC, implemented with CMP{cc}SS/CMP{cc}SD.
     98       /// Operands are two FP values to compare; result is a mask of
     99       /// 0s or 1s.  Generally DTRT for C/C++ with NaNs.
    100       FSETCCss, FSETCCsd,
    101 
    102       /// X86 MOVMSK{pd|ps}, extracts sign bits of two or four FP values,
    103       /// result in an integer GPR.  Needs masking for scalar result.
    104       FGETSIGNx86,
    105 
    106       /// X86 conditional moves. Operand 0 and operand 1 are the two values
    107       /// to select from. Operand 2 is the condition code, and operand 3 is the
    108       /// flag operand produced by a CMP or TEST instruction. It also writes a
    109       /// flag result.
    110       CMOV,
    111 
    112       /// X86 conditional branches. Operand 0 is the chain operand, operand 1
    113       /// is the block to branch if condition is true, operand 2 is the
    114       /// condition code, and operand 3 is the flag operand produced by a CMP
    115       /// or TEST instruction.
    116       BRCOND,
    117 
    118       /// Return with a flag operand. Operand 0 is the chain operand, operand
    119       /// 1 is the number of bytes of stack to pop.
    120       RET_FLAG,
    121 
    122       /// REP_STOS - Repeat fill, corresponds to X86::REP_STOSx.
    123       REP_STOS,
    124 
    125       /// REP_MOVS - Repeat move, corresponds to X86::REP_MOVSx.
    126       REP_MOVS,
    127 
    128       /// GlobalBaseReg - On Darwin, this node represents the result of the popl
    129       /// at function entry, used for PIC code.
    130       GlobalBaseReg,
    131 
    132       /// Wrapper - A wrapper node for TargetConstantPool,
    133       /// TargetExternalSymbol, and TargetGlobalAddress.
    134       Wrapper,
    135 
    136       /// WrapperRIP - Special wrapper used under X86-64 PIC mode for RIP
    137       /// relative displacements.
    138       WrapperRIP,
    139 
    140       /// MOVDQ2Q - Copies a 64-bit value from the low word of an XMM vector
    141       /// to an MMX vector.  If you think this is too close to the previous
    142       /// mnemonic, so do I; blame Intel.
    143       MOVDQ2Q,
    144 
    145       /// PEXTRB - Extract an 8-bit value from a vector and zero extend it to
    146       /// i32, corresponds to X86::PEXTRB.
    147       PEXTRB,
    148 
    149       /// PEXTRW - Extract a 16-bit value from a vector and zero extend it to
    150       /// i32, corresponds to X86::PEXTRW.
    151       PEXTRW,
    152 
    153       /// INSERTPS - Insert any element of a 4 x float vector into any element
    154       /// of a destination 4 x floatvector.
    155       INSERTPS,
    156 
    157       /// PINSRB - Insert the lower 8-bits of a 32-bit value to a vector,
    158       /// corresponds to X86::PINSRB.
    159       PINSRB,
    160 
    161       /// PINSRW - Insert the lower 16-bits of a 32-bit value to a vector,
    162       /// corresponds to X86::PINSRW.
    163       PINSRW, MMX_PINSRW,
    164 
    165       /// PSHUFB - Shuffle 16 8-bit values within a vector.
    166       PSHUFB,
    167 
    168       /// ANDNP - Bitwise Logical AND NOT of Packed FP values.
    169       ANDNP,
    170 
    171       /// PSIGN - Copy integer sign.
    172       PSIGN,
    173 
    174       /// BLENDV - Blend where the selector is an XMM.
    175       BLENDV,
    176 
    177       /// BLENDxx - Blend where the selector is an immediate.
    178       BLENDPW,
    179       BLENDPS,
    180       BLENDPD,
    181 
    182       /// HADD - Integer horizontal add.
    183       HADD,
    184 
    185       /// HSUB - Integer horizontal sub.
    186       HSUB,
    187 
    188       /// FHADD - Floating point horizontal add.
    189       FHADD,
    190 
    191       /// FHSUB - Floating point horizontal sub.
    192       FHSUB,
    193 
    194       /// FMAX, FMIN - Floating point max and min.
    195       ///
    196       FMAX, FMIN,
    197 
    198       /// FMAXC, FMINC - Commutative FMIN and FMAX.
    199       FMAXC, FMINC,
    200 
    201       /// FRSQRT, FRCP - Floating point reciprocal-sqrt and reciprocal
    202       /// approximation.  Note that these typically require refinement
    203       /// in order to obtain suitable precision.
    204       FRSQRT, FRCP,
    205 
    206       // TLSADDR - Thread Local Storage.
    207       TLSADDR,
    208 
    209       // TLSBASEADDR - Thread Local Storage. A call to get the start address
    210       // of the TLS block for the current module.
    211       TLSBASEADDR,
    212 
    213       // TLSCALL - Thread Local Storage.  When calling to an OS provided
    214       // thunk at the address from an earlier relocation.
    215       TLSCALL,
    216 
    217       // EH_RETURN - Exception Handling helpers.
    218       EH_RETURN,
    219 
    220       /// TC_RETURN - Tail call return.
    221       ///   operand #0 chain
    222       ///   operand #1 callee (register or absolute)
    223       ///   operand #2 stack adjustment
    224       ///   operand #3 optional in flag
    225       TC_RETURN,
    226 
    227       // VZEXT_MOVL - Vector move low and zero extend.
    228       VZEXT_MOVL,
    229 
    230       // VSEXT_MOVL - Vector move low and sign extend.
    231       VSEXT_MOVL,
    232 
    233       // VFPEXT - Vector FP extend.
    234       VFPEXT,
    235 
    236       // VSHL, VSRL - 128-bit vector logical left / right shift
    237       VSHLDQ, VSRLDQ,
    238 
    239       // VSHL, VSRL, VSRA - Vector shift elements
    240       VSHL, VSRL, VSRA,
    241 
    242       // VSHLI, VSRLI, VSRAI - Vector shift elements by immediate
    243       VSHLI, VSRLI, VSRAI,
    244 
    245       // CMPP - Vector packed double/float comparison.
    246       CMPP,
    247 
    248       // PCMP* - Vector integer comparisons.
    249       PCMPEQ, PCMPGT,
    250 
    251       // ADD, SUB, SMUL, etc. - Arithmetic operations with FLAGS results.
    252       ADD, SUB, ADC, SBB, SMUL,
    253       INC, DEC, OR, XOR, AND,
    254 
    255       ANDN, // ANDN - Bitwise AND NOT with FLAGS results.
    256 
    257       BLSI,   // BLSI - Extract lowest set isolated bit
    258       BLSMSK, // BLSMSK - Get mask up to lowest set bit
    259       BLSR,   // BLSR - Reset lowest set bit
    260 
    261       UMUL, // LOW, HI, FLAGS = umul LHS, RHS
    262 
    263       // MUL_IMM - X86 specific multiply by immediate.
    264       MUL_IMM,
    265 
    266       // PTEST - Vector bitwise comparisons
    267       PTEST,
    268 
    269       // TESTP - Vector packed fp sign bitwise comparisons
    270       TESTP,
    271 
    272       // Several flavors of instructions with vector shuffle behaviors.
    273       PALIGN,
    274       PSHUFD,
    275       PSHUFHW,
    276       PSHUFLW,
    277       SHUFP,
    278       MOVDDUP,
    279       MOVSHDUP,
    280       MOVSLDUP,
    281       MOVLHPS,
    282       MOVLHPD,
    283       MOVHLPS,
    284       MOVLPS,
    285       MOVLPD,
    286       MOVSD,
    287       MOVSS,
    288       UNPCKL,
    289       UNPCKH,
    290       VPERMILP,
    291       VPERMV,
    292       VPERMI,
    293       VPERM2X128,
    294       VBROADCAST,
    295 
    296       // PMULUDQ - Vector multiply packed unsigned doubleword integers
    297       PMULUDQ,
    298 
    299       // FMA nodes
    300       FMADD,
    301       FNMADD,
    302       FMSUB,
    303       FNMSUB,
    304       FMADDSUB,
    305       FMSUBADD,
    306 
    307       // VASTART_SAVE_XMM_REGS - Save xmm argument registers to the stack,
    308       // according to %al. An operator is needed so that this can be expanded
    309       // with control flow.
    310       VASTART_SAVE_XMM_REGS,
    311 
    312       // WIN_ALLOCA - Windows's _chkstk call to do stack probing.
    313       WIN_ALLOCA,
    314 
    315       // SEG_ALLOCA - For allocating variable amounts of stack space when using
    316       // segmented stacks. Check if the current stacklet has enough space, and
    317       // falls back to heap allocation if not.
    318       SEG_ALLOCA,
    319 
    320       // WIN_FTOL - Windows's _ftol2 runtime routine to do fptoui.
    321       WIN_FTOL,
    322 
    323       // Memory barrier
    324       MEMBARRIER,
    325       MFENCE,
    326       SFENCE,
    327       LFENCE,
    328 
    329       // FNSTSW16r - Store FP status word into i16 register.
    330       FNSTSW16r,
    331 
    332       // SAHF - Store contents of %ah into %eflags.
    333       SAHF,
    334 
    335       // RDRAND - Get a random integer and indicate whether it is valid in CF.
    336       RDRAND,
    337 
    338       // PCMP*STRI
    339       PCMPISTRI,
    340       PCMPESTRI,
    341 
    342       // ATOMADD64_DAG, ATOMSUB64_DAG, ATOMOR64_DAG, ATOMAND64_DAG,
    343       // ATOMXOR64_DAG, ATOMNAND64_DAG, ATOMSWAP64_DAG -
    344       // Atomic 64-bit binary operations.
    345       ATOMADD64_DAG = ISD::FIRST_TARGET_MEMORY_OPCODE,
    346       ATOMSUB64_DAG,
    347       ATOMOR64_DAG,
    348       ATOMXOR64_DAG,
    349       ATOMAND64_DAG,
    350       ATOMNAND64_DAG,
    351       ATOMSWAP64_DAG,
    352 
    353       // LCMPXCHG_DAG, LCMPXCHG8_DAG, LCMPXCHG16_DAG - Compare and swap.
    354       LCMPXCHG_DAG,
    355       LCMPXCHG8_DAG,
    356       LCMPXCHG16_DAG,
    357 
    358       // VZEXT_LOAD - Load, scalar_to_vector, and zero extend.
    359       VZEXT_LOAD,
    360 
    361       // FNSTCW16m - Store FP control world into i16 memory.
    362       FNSTCW16m,
    363 
    364       /// FP_TO_INT*_IN_MEM - This instruction implements FP_TO_SINT with the
    365       /// integer destination in memory and a FP reg source.  This corresponds
    366       /// to the X86::FIST*m instructions and the rounding mode change stuff. It
    367       /// has two inputs (token chain and address) and two outputs (int value
    368       /// and token chain).
    369       FP_TO_INT16_IN_MEM,
    370       FP_TO_INT32_IN_MEM,
    371       FP_TO_INT64_IN_MEM,
    372 
    373       /// FILD, FILD_FLAG - This instruction implements SINT_TO_FP with the
    374       /// integer source in memory and FP reg result.  This corresponds to the
    375       /// X86::FILD*m instructions. It has three inputs (token chain, address,
    376       /// and source type) and two outputs (FP value and token chain). FILD_FLAG
    377       /// also produces a flag).
    378       FILD,
    379       FILD_FLAG,
    380 
    381       /// FLD - This instruction implements an extending load to FP stack slots.
    382       /// This corresponds to the X86::FLD32m / X86::FLD64m. It takes a chain
    383       /// operand, ptr to load from, and a ValueType node indicating the type
    384       /// to load to.
    385       FLD,
    386 
    387       /// FST - This instruction implements a truncating store to FP stack
    388       /// slots. This corresponds to the X86::FST32m / X86::FST64m. It takes a
    389       /// chain operand, value to store, address, and a ValueType to store it
    390       /// as.
    391       FST,
    392 
    393       /// VAARG_64 - This instruction grabs the address of the next argument
    394       /// from a va_list. (reads and modifies the va_list in memory)
    395       VAARG_64
    396 
    397       // WARNING: Do not add anything in the end unless you want the node to
    398       // have memop! In fact, starting from ATOMADD64_DAG all opcodes will be
    399       // thought as target memory ops!
    400     };
    401   }
    402 
    403   /// Define some predicates that are used for node matching.
    404   namespace X86 {
    405     /// isVEXTRACTF128Index - Return true if the specified
    406     /// EXTRACT_SUBVECTOR operand specifies a vector extract that is
    407     /// suitable for input to VEXTRACTF128.
    408     bool isVEXTRACTF128Index(SDNode *N);
    409 
    410     /// isVINSERTF128Index - Return true if the specified
    411     /// INSERT_SUBVECTOR operand specifies a subvector insert that is
    412     /// suitable for input to VINSERTF128.
    413     bool isVINSERTF128Index(SDNode *N);
    414 
    415     /// getExtractVEXTRACTF128Immediate - Return the appropriate
    416     /// immediate to extract the specified EXTRACT_SUBVECTOR index
    417     /// with VEXTRACTF128 instructions.
    418     unsigned getExtractVEXTRACTF128Immediate(SDNode *N);
    419 
    420     /// getInsertVINSERTF128Immediate - Return the appropriate
    421     /// immediate to insert at the specified INSERT_SUBVECTOR index
    422     /// with VINSERTF128 instructions.
    423     unsigned getInsertVINSERTF128Immediate(SDNode *N);
    424 
    425     /// isZeroNode - Returns true if Elt is a constant zero or a floating point
    426     /// constant +0.0.
    427     bool isZeroNode(SDValue Elt);
    428 
    429     /// isOffsetSuitableForCodeModel - Returns true of the given offset can be
    430     /// fit into displacement field of the instruction.
    431     bool isOffsetSuitableForCodeModel(int64_t Offset, CodeModel::Model M,
    432                                       bool hasSymbolicDisplacement = true);
    433 
    434 
    435     /// isCalleePop - Determines whether the callee is required to pop its
    436     /// own arguments. Callee pop is necessary to support tail calls.
    437     bool isCalleePop(CallingConv::ID CallingConv,
    438                      bool is64Bit, bool IsVarArg, bool TailCallOpt);
    439   }
    440 
    441   //===--------------------------------------------------------------------===//
    442   //  X86TargetLowering - X86 Implementation of the TargetLowering interface
    443   class X86TargetLowering : public TargetLowering {
    444   public:
    445     explicit X86TargetLowering(X86TargetMachine &TM);
    446 
    447     virtual unsigned getJumpTableEncoding() const;
    448 
    449     virtual MVT getShiftAmountTy(EVT LHSTy) const { return MVT::i8; }
    450 
    451     virtual const MCExpr *
    452     LowerCustomJumpTableEntry(const MachineJumpTableInfo *MJTI,
    453                               const MachineBasicBlock *MBB, unsigned uid,
    454                               MCContext &Ctx) const;
    455 
    456     /// getPICJumpTableRelocaBase - Returns relocation base for the given PIC
    457     /// jumptable.
    458     virtual SDValue getPICJumpTableRelocBase(SDValue Table,
    459                                              SelectionDAG &DAG) const;
    460     virtual const MCExpr *
    461     getPICJumpTableRelocBaseExpr(const MachineFunction *MF,
    462                                  unsigned JTI, MCContext &Ctx) const;
    463 
    464     /// getStackPtrReg - Return the stack pointer register we are using: either
    465     /// ESP or RSP.
    466     unsigned getStackPtrReg() const { return X86StackPtr; }
    467 
    468     /// getByValTypeAlignment - Return the desired alignment for ByVal aggregate
    469     /// function arguments in the caller parameter area. For X86, aggregates
    470     /// that contains are placed at 16-byte boundaries while the rest are at
    471     /// 4-byte boundaries.
    472     virtual unsigned getByValTypeAlignment(Type *Ty) const;
    473 
    474     /// getOptimalMemOpType - Returns the target specific optimal type for load
    475     /// and store operations as a result of memset, memcpy, and memmove
    476     /// lowering. If DstAlign is zero that means it's safe to destination
    477     /// alignment can satisfy any constraint. Similarly if SrcAlign is zero it
    478     /// means there isn't a need to check it against alignment requirement,
    479     /// probably because the source does not need to be loaded. If
    480     /// 'IsZeroVal' is true, that means it's safe to return a
    481     /// non-scalar-integer type, e.g. empty string source, constant, or loaded
    482     /// from memory. 'MemcpyStrSrc' indicates whether the memcpy source is
    483     /// constant so it does not need to be loaded.
    484     /// It returns EVT::Other if the type should be determined using generic
    485     /// target-independent logic.
    486     virtual EVT
    487     getOptimalMemOpType(uint64_t Size, unsigned DstAlign, unsigned SrcAlign,
    488                         bool IsZeroVal, bool MemcpyStrSrc,
    489                         MachineFunction &MF) const;
    490 
    491     /// allowsUnalignedMemoryAccesses - Returns true if the target allows
    492     /// unaligned memory accesses. of the specified type.
    493     virtual bool allowsUnalignedMemoryAccesses(EVT VT) const {
    494       return true;
    495     }
    496 
    497     /// LowerOperation - Provide custom lowering hooks for some operations.
    498     ///
    499     virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const;
    500 
    501     /// ReplaceNodeResults - Replace the results of node with an illegal result
    502     /// type with new values built out of custom code.
    503     ///
    504     virtual void ReplaceNodeResults(SDNode *N, SmallVectorImpl<SDValue>&Results,
    505                                     SelectionDAG &DAG) const;
    506 
    507 
    508     virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
    509 
    510     /// isTypeDesirableForOp - Return true if the target has native support for
    511     /// the specified value type and it is 'desirable' to use the type for the
    512     /// given node type. e.g. On x86 i16 is legal, but undesirable since i16
    513     /// instruction encodings are longer and some i16 instructions are slow.
    514     virtual bool isTypeDesirableForOp(unsigned Opc, EVT VT) const;
    515 
    516     /// isTypeDesirable - Return true if the target has native support for the
    517     /// specified value type and it is 'desirable' to use the type. e.g. On x86
    518     /// i16 is legal, but undesirable since i16 instruction encodings are longer
    519     /// and some i16 instructions are slow.
    520     virtual bool IsDesirableToPromoteOp(SDValue Op, EVT &PVT) const;
    521 
    522     virtual MachineBasicBlock *
    523       EmitInstrWithCustomInserter(MachineInstr *MI,
    524                                   MachineBasicBlock *MBB) const;
    525 
    526 
    527     /// getTargetNodeName - This method returns the name of a target specific
    528     /// DAG node.
    529     virtual const char *getTargetNodeName(unsigned Opcode) const;
    530 
    531     /// getSetCCResultType - Return the value type to use for ISD::SETCC.
    532     virtual EVT getSetCCResultType(EVT VT) const;
    533 
    534     /// computeMaskedBitsForTargetNode - Determine which of the bits specified
    535     /// in Mask are known to be either zero or one and return them in the
    536     /// KnownZero/KnownOne bitsets.
    537     virtual void computeMaskedBitsForTargetNode(const SDValue Op,
    538                                                 APInt &KnownZero,
    539                                                 APInt &KnownOne,
    540                                                 const SelectionDAG &DAG,
    541                                                 unsigned Depth = 0) const;
    542 
    543     // ComputeNumSignBitsForTargetNode - Determine the number of bits in the
    544     // operation that are sign bits.
    545     virtual unsigned ComputeNumSignBitsForTargetNode(SDValue Op,
    546                                                      unsigned Depth) const;
    547 
    548     virtual bool
    549     isGAPlusOffset(SDNode *N, const GlobalValue* &GA, int64_t &Offset) const;
    550 
    551     SDValue getReturnAddressFrameIndex(SelectionDAG &DAG) const;
    552 
    553     virtual bool ExpandInlineAsm(CallInst *CI) const;
    554 
    555     ConstraintType getConstraintType(const std::string &Constraint) const;
    556 
    557     /// Examine constraint string and operand type and determine a weight value.
    558     /// The operand object must already have been set up with the operand type.
    559     virtual ConstraintWeight getSingleConstraintMatchWeight(
    560       AsmOperandInfo &info, const char *constraint) const;
    561 
    562     virtual const char *LowerXConstraint(EVT ConstraintVT) const;
    563 
    564     /// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
    565     /// vector.  If it is invalid, don't add anything to Ops. If hasMemory is
    566     /// true it means one of the asm constraint of the inline asm instruction
    567     /// being processed is 'm'.
    568     virtual void LowerAsmOperandForConstraint(SDValue Op,
    569                                               std::string &Constraint,
    570                                               std::vector<SDValue> &Ops,
    571                                               SelectionDAG &DAG) const;
    572 
    573     /// getRegForInlineAsmConstraint - Given a physical register constraint
    574     /// (e.g. {edx}), return the register number and the register class for the
    575     /// register.  This should only be used for C_Register constraints.  On
    576     /// error, this returns a register number of 0.
    577     std::pair<unsigned, const TargetRegisterClass*>
    578       getRegForInlineAsmConstraint(const std::string &Constraint,
    579                                    EVT VT) const;
    580 
    581     /// isLegalAddressingMode - Return true if the addressing mode represented
    582     /// by AM is legal for this target, for a load/store of the specified type.
    583     virtual bool isLegalAddressingMode(const AddrMode &AM, Type *Ty)const;
    584 
    585     /// isLegalICmpImmediate - Return true if the specified immediate is legal
    586     /// icmp immediate, that is the target has icmp instructions which can
    587     /// compare a register against the immediate without having to materialize
    588     /// the immediate into a register.
    589     virtual bool isLegalICmpImmediate(int64_t Imm) const;
    590 
    591     /// isLegalAddImmediate - Return true if the specified immediate is legal
    592     /// add immediate, that is the target has add instructions which can
    593     /// add a register and the immediate without having to materialize
    594     /// the immediate into a register.
    595     virtual bool isLegalAddImmediate(int64_t Imm) const;
    596 
    597     /// isTruncateFree - Return true if it's free to truncate a value of
    598     /// type Ty1 to type Ty2. e.g. On x86 it's free to truncate a i32 value in
    599     /// register EAX to i16 by referencing its sub-register AX.
    600     virtual bool isTruncateFree(Type *Ty1, Type *Ty2) const;
    601     virtual bool isTruncateFree(EVT VT1, EVT VT2) const;
    602 
    603     /// isZExtFree - Return true if any actual instruction that defines a
    604     /// value of type Ty1 implicit zero-extends the value to Ty2 in the result
    605     /// register. This does not necessarily include registers defined in
    606     /// unknown ways, such as incoming arguments, or copies from unknown
    607     /// virtual registers. Also, if isTruncateFree(Ty2, Ty1) is true, this
    608     /// does not necessarily apply to truncate instructions. e.g. on x86-64,
    609     /// all instructions that define 32-bit values implicit zero-extend the
    610     /// result out to 64 bits.
    611     virtual bool isZExtFree(Type *Ty1, Type *Ty2) const;
    612     virtual bool isZExtFree(EVT VT1, EVT VT2) const;
    613 
    614     /// isFMAFasterThanMulAndAdd - Return true if an FMA operation is faster than
    615     /// a pair of mul and add instructions. fmuladd intrinsics will be expanded to
    616     /// FMAs when this method returns true (and FMAs are legal), otherwise fmuladd
    617     /// is expanded to mul + add.
    618     virtual bool isFMAFasterThanMulAndAdd(EVT) const { return true; }
    619 
    620     /// isNarrowingProfitable - Return true if it's profitable to narrow
    621     /// operations of type VT1 to VT2. e.g. on x86, it's profitable to narrow
    622     /// from i32 to i8 but not from i32 to i16.
    623     virtual bool isNarrowingProfitable(EVT VT1, EVT VT2) const;
    624 
    625     /// isFPImmLegal - Returns true if the target can instruction select the
    626     /// specified FP immediate natively. If false, the legalizer will
    627     /// materialize the FP immediate as a load from a constant pool.
    628     virtual bool isFPImmLegal(const APFloat &Imm, EVT VT) const;
    629 
    630     /// isShuffleMaskLegal - Targets can use this to indicate that they only
    631     /// support *some* VECTOR_SHUFFLE operations, those with specific masks.
    632     /// By default, if a target supports the VECTOR_SHUFFLE node, all mask
    633     /// values are assumed to be legal.
    634     virtual bool isShuffleMaskLegal(const SmallVectorImpl<int> &Mask,
    635                                     EVT VT) const;
    636 
    637     /// isVectorClearMaskLegal - Similar to isShuffleMaskLegal. This is
    638     /// used by Targets can use this to indicate if there is a suitable
    639     /// VECTOR_SHUFFLE that can be used to replace a VAND with a constant
    640     /// pool entry.
    641     virtual bool isVectorClearMaskLegal(const SmallVectorImpl<int> &Mask,
    642                                         EVT VT) const;
    643 
    644     /// ShouldShrinkFPConstant - If true, then instruction selection should
    645     /// seek to shrink the FP constant of the specified type to a smaller type
    646     /// in order to save space and / or reduce runtime.
    647     virtual bool ShouldShrinkFPConstant(EVT VT) const {
    648       // Don't shrink FP constpool if SSE2 is available since cvtss2sd is more
    649       // expensive than a straight movsd. On the other hand, it's important to
    650       // shrink long double fp constant since fldt is very slow.
    651       return !X86ScalarSSEf64 || VT == MVT::f80;
    652     }
    653 
    654     const X86Subtarget* getSubtarget() const {
    655       return Subtarget;
    656     }
    657 
    658     /// isScalarFPTypeInSSEReg - Return true if the specified scalar FP type is
    659     /// computed in an SSE register, not on the X87 floating point stack.
    660     bool isScalarFPTypeInSSEReg(EVT VT) const {
    661       return (VT == MVT::f64 && X86ScalarSSEf64) || // f64 is when SSE2
    662       (VT == MVT::f32 && X86ScalarSSEf32);   // f32 is when SSE1
    663     }
    664 
    665     /// isTargetFTOL - Return true if the target uses the MSVC _ftol2 routine
    666     /// for fptoui.
    667     bool isTargetFTOL() const {
    668       return Subtarget->isTargetWindows() && !Subtarget->is64Bit();
    669     }
    670 
    671     /// isIntegerTypeFTOL - Return true if the MSVC _ftol2 routine should be
    672     /// used for fptoui to the given type.
    673     bool isIntegerTypeFTOL(EVT VT) const {
    674       return isTargetFTOL() && VT == MVT::i64;
    675     }
    676 
    677     /// createFastISel - This method returns a target specific FastISel object,
    678     /// or null if the target does not support "fast" ISel.
    679     virtual FastISel *createFastISel(FunctionLoweringInfo &funcInfo,
    680                                      const TargetLibraryInfo *libInfo) const;
    681 
    682     /// getStackCookieLocation - Return true if the target stores stack
    683     /// protector cookies at a fixed offset in some non-standard address
    684     /// space, and populates the address space and offset as
    685     /// appropriate.
    686     virtual bool getStackCookieLocation(unsigned &AddressSpace, unsigned &Offset) const;
    687 
    688     SDValue BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain, SDValue StackSlot,
    689                       SelectionDAG &DAG) const;
    690 
    691   protected:
    692     std::pair<const TargetRegisterClass*, uint8_t>
    693     findRepresentativeClass(EVT VT) const;
    694 
    695   private:
    696     /// Subtarget - Keep a pointer to the X86Subtarget around so that we can
    697     /// make the right decision when generating code for different targets.
    698     const X86Subtarget *Subtarget;
    699     const X86RegisterInfo *RegInfo;
    700     const TargetData *TD;
    701 
    702     /// X86StackPtr - X86 physical register used as stack ptr.
    703     unsigned X86StackPtr;
    704 
    705     /// X86ScalarSSEf32, X86ScalarSSEf64 - Select between SSE or x87
    706     /// floating point ops.
    707     /// When SSE is available, use it for f32 operations.
    708     /// When SSE2 is available, use it for f64 operations.
    709     bool X86ScalarSSEf32;
    710     bool X86ScalarSSEf64;
    711 
    712     /// LegalFPImmediates - A list of legal fp immediates.
    713     std::vector<APFloat> LegalFPImmediates;
    714 
    715     /// addLegalFPImmediate - Indicate that this x86 target can instruction
    716     /// select the specified FP immediate natively.
    717     void addLegalFPImmediate(const APFloat& Imm) {
    718       LegalFPImmediates.push_back(Imm);
    719     }
    720 
    721     SDValue LowerCallResult(SDValue Chain, SDValue InFlag,
    722                             CallingConv::ID CallConv, bool isVarArg,
    723                             const SmallVectorImpl<ISD::InputArg> &Ins,
    724                             DebugLoc dl, SelectionDAG &DAG,
    725                             SmallVectorImpl<SDValue> &InVals) const;
    726     SDValue LowerMemArgument(SDValue Chain,
    727                              CallingConv::ID CallConv,
    728                              const SmallVectorImpl<ISD::InputArg> &ArgInfo,
    729                              DebugLoc dl, SelectionDAG &DAG,
    730                              const CCValAssign &VA,  MachineFrameInfo *MFI,
    731                               unsigned i) const;
    732     SDValue LowerMemOpCallTo(SDValue Chain, SDValue StackPtr, SDValue Arg,
    733                              DebugLoc dl, SelectionDAG &DAG,
    734                              const CCValAssign &VA,
    735                              ISD::ArgFlagsTy Flags) const;
    736 
    737     // Call lowering helpers.
    738 
    739     /// IsEligibleForTailCallOptimization - Check whether the call is eligible
    740     /// for tail call optimization. Targets which want to do tail call
    741     /// optimization should implement this function.
    742     bool IsEligibleForTailCallOptimization(SDValue Callee,
    743                                            CallingConv::ID CalleeCC,
    744                                            bool isVarArg,
    745                                            bool isCalleeStructRet,
    746                                            bool isCallerStructRet,
    747                                     const SmallVectorImpl<ISD::OutputArg> &Outs,
    748                                     const SmallVectorImpl<SDValue> &OutVals,
    749                                     const SmallVectorImpl<ISD::InputArg> &Ins,
    750                                            SelectionDAG& DAG) const;
    751     bool IsCalleePop(bool isVarArg, CallingConv::ID CallConv) const;
    752     SDValue EmitTailCallLoadRetAddr(SelectionDAG &DAG, SDValue &OutRetAddr,
    753                                 SDValue Chain, bool IsTailCall, bool Is64Bit,
    754                                 int FPDiff, DebugLoc dl) const;
    755 
    756     unsigned GetAlignedArgumentStackSize(unsigned StackSize,
    757                                          SelectionDAG &DAG) const;
    758 
    759     std::pair<SDValue,SDValue> FP_TO_INTHelper(SDValue Op, SelectionDAG &DAG,
    760                                                bool isSigned,
    761                                                bool isReplace) const;
    762 
    763     SDValue LowerAsSplatVectorLoad(SDValue SrcOp, EVT VT, DebugLoc dl,
    764                                    SelectionDAG &DAG) const;
    765     SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) const;
    766     SDValue LowerCONCAT_VECTORS(SDValue Op, SelectionDAG &DAG) const;
    767     SDValue LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) const;
    768     SDValue LowerEXTRACT_VECTOR_ELT(SDValue Op, SelectionDAG &DAG) const;
    769     SDValue LowerEXTRACT_VECTOR_ELT_SSE4(SDValue Op, SelectionDAG &DAG) const;
    770     SDValue LowerINSERT_VECTOR_ELT(SDValue Op, SelectionDAG &DAG) const;
    771     SDValue LowerINSERT_VECTOR_ELT_SSE4(SDValue Op, SelectionDAG &DAG) const;
    772     SDValue LowerSCALAR_TO_VECTOR(SDValue Op, SelectionDAG &DAG) const;
    773     SDValue LowerEXTRACT_SUBVECTOR(SDValue Op, SelectionDAG &DAG) const;
    774     SDValue LowerINSERT_SUBVECTOR(SDValue Op, SelectionDAG &DAG) const;
    775     SDValue LowerConstantPool(SDValue Op, SelectionDAG &DAG) const;
    776     SDValue LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const;
    777     SDValue LowerGlobalAddress(const GlobalValue *GV, DebugLoc dl,
    778                                int64_t Offset, SelectionDAG &DAG) const;
    779     SDValue LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;
    780     SDValue LowerGlobalTLSAddress(SDValue Op, SelectionDAG &DAG) const;
    781     SDValue LowerExternalSymbol(SDValue Op, SelectionDAG &DAG) const;
    782     SDValue LowerShiftParts(SDValue Op, SelectionDAG &DAG) const;
    783     SDValue LowerBITCAST(SDValue op, SelectionDAG &DAG) const;
    784     SDValue LowerSINT_TO_FP(SDValue Op, SelectionDAG &DAG) const;
    785     SDValue LowerUINT_TO_FP(SDValue Op, SelectionDAG &DAG) const;
    786     SDValue LowerUINT_TO_FP_i64(SDValue Op, SelectionDAG &DAG) const;
    787     SDValue LowerUINT_TO_FP_i32(SDValue Op, SelectionDAG &DAG) const;
    788     SDValue LowerFP_TO_SINT(SDValue Op, SelectionDAG &DAG) const;
    789     SDValue LowerFP_TO_UINT(SDValue Op, SelectionDAG &DAG) const;
    790     SDValue LowerFABS(SDValue Op, SelectionDAG &DAG) const;
    791     SDValue LowerFNEG(SDValue Op, SelectionDAG &DAG) const;
    792     SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const;
    793     SDValue LowerFGETSIGN(SDValue Op, SelectionDAG &DAG) const;
    794     SDValue LowerToBT(SDValue And, ISD::CondCode CC,
    795                       DebugLoc dl, SelectionDAG &DAG) const;
    796     SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
    797     SDValue LowerVSETCC(SDValue Op, SelectionDAG &DAG) const;
    798     SDValue LowerSELECT(SDValue Op, SelectionDAG &DAG) const;
    799     SDValue LowerBRCOND(SDValue Op, SelectionDAG &DAG) const;
    800     SDValue LowerMEMSET(SDValue Op, SelectionDAG &DAG) const;
    801     SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;
    802     SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
    803     SDValue LowerVASTART(SDValue Op, SelectionDAG &DAG) const;
    804     SDValue LowerVAARG(SDValue Op, SelectionDAG &DAG) const;
    805     SDValue LowerVACOPY(SDValue Op, SelectionDAG &DAG) const;
    806     SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, SelectionDAG &DAG) const;
    807     SDValue LowerINTRINSIC_W_CHAIN(SDValue Op, SelectionDAG &DAG) const;
    808     SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;
    809     SDValue LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const;
    810     SDValue LowerFRAME_TO_ARGS_OFFSET(SDValue Op, SelectionDAG &DAG) const;
    811     SDValue LowerEH_RETURN(SDValue Op, SelectionDAG &DAG) const;
    812     SDValue LowerINIT_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
    813     SDValue LowerADJUST_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
    814     SDValue LowerFLT_ROUNDS_(SDValue Op, SelectionDAG &DAG) const;
    815     SDValue LowerCTLZ(SDValue Op, SelectionDAG &DAG) const;
    816     SDValue LowerCTLZ_ZERO_UNDEF(SDValue Op, SelectionDAG &DAG) const;
    817     SDValue LowerCTTZ(SDValue Op, SelectionDAG &DAG) const;
    818     SDValue LowerADD(SDValue Op, SelectionDAG &DAG) const;
    819     SDValue LowerSUB(SDValue Op, SelectionDAG &DAG) const;
    820     SDValue LowerMUL(SDValue Op, SelectionDAG &DAG) const;
    821     SDValue LowerShift(SDValue Op, SelectionDAG &DAG) const;
    822     SDValue LowerXALUO(SDValue Op, SelectionDAG &DAG) const;
    823 
    824     SDValue LowerCMP_SWAP(SDValue Op, SelectionDAG &DAG) const;
    825     SDValue LowerLOAD_SUB(SDValue Op, SelectionDAG &DAG) const;
    826     SDValue LowerREADCYCLECOUNTER(SDValue Op, SelectionDAG &DAG) const;
    827     SDValue LowerMEMBARRIER(SDValue Op, SelectionDAG &DAG) const;
    828     SDValue LowerATOMIC_FENCE(SDValue Op, SelectionDAG &DAG) const;
    829     SDValue LowerSIGN_EXTEND_INREG(SDValue Op, SelectionDAG &DAG) const;
    830     SDValue PerformTruncateCombine(SDNode* N, SelectionDAG &DAG, DAGCombinerInfo &DCI) const;
    831 
    832     // Utility functions to help LowerVECTOR_SHUFFLE
    833     SDValue LowerVECTOR_SHUFFLEv8i16(SDValue Op, SelectionDAG &DAG) const;
    834     SDValue LowerVectorBroadcast(SDValue &Op, SelectionDAG &DAG) const;
    835     SDValue NormalizeVectorShuffle(SDValue Op, SelectionDAG &DAG) const;
    836 
    837     SDValue LowerVectorFpExtend(SDValue &Op, SelectionDAG &DAG) const;
    838 
    839     virtual SDValue
    840       LowerFormalArguments(SDValue Chain,
    841                            CallingConv::ID CallConv, bool isVarArg,
    842                            const SmallVectorImpl<ISD::InputArg> &Ins,
    843                            DebugLoc dl, SelectionDAG &DAG,
    844                            SmallVectorImpl<SDValue> &InVals) const;
    845     virtual SDValue
    846       LowerCall(CallLoweringInfo &CLI,
    847                 SmallVectorImpl<SDValue> &InVals) const;
    848 
    849     virtual SDValue
    850       LowerReturn(SDValue Chain,
    851                   CallingConv::ID CallConv, bool isVarArg,
    852                   const SmallVectorImpl<ISD::OutputArg> &Outs,
    853                   const SmallVectorImpl<SDValue> &OutVals,
    854                   DebugLoc dl, SelectionDAG &DAG) const;
    855 
    856     virtual bool isUsedByReturnOnly(SDNode *N, SDValue &Chain) const;
    857 
    858     virtual bool mayBeEmittedAsTailCall(CallInst *CI) const;
    859 
    860     virtual EVT
    861     getTypeForExtArgOrReturn(LLVMContext &Context, EVT VT,
    862                              ISD::NodeType ExtendKind) const;
    863 
    864     virtual bool
    865     CanLowerReturn(CallingConv::ID CallConv, MachineFunction &MF,
    866                    bool isVarArg,
    867                    const SmallVectorImpl<ISD::OutputArg> &Outs,
    868                    LLVMContext &Context) const;
    869 
    870     /// Utility function to emit string processing sse4.2 instructions
    871     /// that return in xmm0.
    872     /// This takes the instruction to expand, the associated machine basic
    873     /// block, the number of args, and whether or not the second arg is
    874     /// in memory or not.
    875     MachineBasicBlock *EmitPCMP(MachineInstr *BInstr, MachineBasicBlock *BB,
    876                                 unsigned argNum, bool inMem) const;
    877 
    878     /// Utility functions to emit monitor and mwait instructions. These
    879     /// need to make sure that the arguments to the intrinsic are in the
    880     /// correct registers.
    881     MachineBasicBlock *EmitMonitor(MachineInstr *MI,
    882                                    MachineBasicBlock *BB) const;
    883     MachineBasicBlock *EmitMwait(MachineInstr *MI, MachineBasicBlock *BB) const;
    884 
    885     /// Utility function to emit atomic bitwise operations (and, or, xor).
    886     /// It takes the bitwise instruction to expand, the associated machine basic
    887     /// block, and the associated X86 opcodes for reg/reg and reg/imm.
    888     MachineBasicBlock *EmitAtomicBitwiseWithCustomInserter(
    889                                                     MachineInstr *BInstr,
    890                                                     MachineBasicBlock *BB,
    891                                                     unsigned regOpc,
    892                                                     unsigned immOpc,
    893                                                     unsigned loadOpc,
    894                                                     unsigned cxchgOpc,
    895                                                     unsigned notOpc,
    896                                                     unsigned EAXreg,
    897                                               const TargetRegisterClass *RC,
    898                                                     bool Invert = false) const;
    899 
    900     MachineBasicBlock *EmitAtomicBit6432WithCustomInserter(
    901                                                     MachineInstr *BInstr,
    902                                                     MachineBasicBlock *BB,
    903                                                     unsigned regOpcL,
    904                                                     unsigned regOpcH,
    905                                                     unsigned immOpcL,
    906                                                     unsigned immOpcH,
    907                                                     bool Invert = false) const;
    908 
    909     /// Utility function to emit atomic min and max.  It takes the min/max
    910     /// instruction to expand, the associated basic block, and the associated
    911     /// cmov opcode for moving the min or max value.
    912     MachineBasicBlock *EmitAtomicMinMaxWithCustomInserter(MachineInstr *BInstr,
    913                                                           MachineBasicBlock *BB,
    914                                                         unsigned cmovOpc) const;
    915 
    916     // Utility function to emit the low-level va_arg code for X86-64.
    917     MachineBasicBlock *EmitVAARG64WithCustomInserter(
    918                        MachineInstr *MI,
    919                        MachineBasicBlock *MBB) const;
    920 
    921     /// Utility function to emit the xmm reg save portion of va_start.
    922     MachineBasicBlock *EmitVAStartSaveXMMRegsWithCustomInserter(
    923                                                    MachineInstr *BInstr,
    924                                                    MachineBasicBlock *BB) const;
    925 
    926     MachineBasicBlock *EmitLoweredSelect(MachineInstr *I,
    927                                          MachineBasicBlock *BB) const;
    928 
    929     MachineBasicBlock *EmitLoweredWinAlloca(MachineInstr *MI,
    930                                               MachineBasicBlock *BB) const;
    931 
    932     MachineBasicBlock *EmitLoweredSegAlloca(MachineInstr *MI,
    933                                             MachineBasicBlock *BB,
    934                                             bool Is64Bit) const;
    935 
    936     MachineBasicBlock *EmitLoweredTLSCall(MachineInstr *MI,
    937                                           MachineBasicBlock *BB) const;
    938 
    939     MachineBasicBlock *emitLoweredTLSAddr(MachineInstr *MI,
    940                                           MachineBasicBlock *BB) const;
    941 
    942     /// Emit nodes that will be selected as "test Op0,Op0", or something
    943     /// equivalent, for use with the given x86 condition code.
    944     SDValue EmitTest(SDValue Op0, unsigned X86CC, SelectionDAG &DAG) const;
    945 
    946     /// Emit nodes that will be selected as "cmp Op0,Op1", or something
    947     /// equivalent, for use with the given x86 condition code.
    948     SDValue EmitCmp(SDValue Op0, SDValue Op1, unsigned X86CC,
    949                     SelectionDAG &DAG) const;
    950 
    951     /// Convert a comparison if required by the subtarget.
    952     SDValue ConvertCmpIfNecessary(SDValue Cmp, SelectionDAG &DAG) const;
    953   };
    954 
    955   namespace X86 {
    956     FastISel *createFastISel(FunctionLoweringInfo &funcInfo,
    957                              const TargetLibraryInfo *libInfo);
    958   }
    959 }
    960 
    961 #endif    // X86ISELLOWERING_H
    962