Home | History | Annotate | Download | only in X86 
      1 //===-- X86Subtarget.cpp - X86 Subtarget Information ----------------------===//
      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 implements the X86 specific subclass of TargetSubtargetInfo.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "X86Subtarget.h"
     15 #include "X86InstrInfo.h"
     16 #include "llvm/IR/Attributes.h"
     17 #include "llvm/IR/Function.h"
     18 #include "llvm/IR/GlobalValue.h"
     19 #include "llvm/Support/CommandLine.h"
     20 #include "llvm/Support/Debug.h"
     21 #include "llvm/Support/ErrorHandling.h"
     22 #include "llvm/Support/Host.h"
     23 #include "llvm/Support/raw_ostream.h"
     24 #include "llvm/Target/TargetMachine.h"
     25 #include "llvm/Target/TargetOptions.h"
     26 
     27 #if defined(_MSC_VER)
     28 #include <intrin.h>
     29 #endif
     30 
     31 using namespace llvm;
     32 
     33 #define DEBUG_TYPE "subtarget"
     34 
     35 #define GET_SUBTARGETINFO_TARGET_DESC
     36 #define GET_SUBTARGETINFO_CTOR
     37 #include "X86GenSubtargetInfo.inc"
     38 
     39 // Temporary option to control early if-conversion for x86 while adding machine
     40 // models.
     41 static cl::opt<bool>
     42 X86EarlyIfConv("x86-early-ifcvt", cl::Hidden,
     43                cl::desc("Enable early if-conversion on X86"));
     44 
     45 
     46 /// ClassifyBlockAddressReference - Classify a blockaddress reference for the
     47 /// current subtarget according to how we should reference it in a non-pcrel
     48 /// context.
     49 unsigned char X86Subtarget::ClassifyBlockAddressReference() const {
     50   if (isPICStyleGOT())    // 32-bit ELF targets.
     51     return X86II::MO_GOTOFF;
     52 
     53   if (isPICStyleStubPIC())   // Darwin/32 in PIC mode.
     54     return X86II::MO_PIC_BASE_OFFSET;
     55 
     56   // Direct static reference to label.
     57   return X86II::MO_NO_FLAG;
     58 }
     59 
     60 /// ClassifyGlobalReference - Classify a global variable reference for the
     61 /// current subtarget according to how we should reference it in a non-pcrel
     62 /// context.
     63 unsigned char X86Subtarget::
     64 ClassifyGlobalReference(const GlobalValue *GV, const TargetMachine &TM) const {
     65   // DLLImport only exists on windows, it is implemented as a load from a
     66   // DLLIMPORT stub.
     67   if (GV->hasDLLImportStorageClass())
     68     return X86II::MO_DLLIMPORT;
     69 
     70   // Determine whether this is a reference to a definition or a declaration.
     71   // Materializable GVs (in JIT lazy compilation mode) do not require an extra
     72   // load from stub.
     73   bool isDecl = GV->hasAvailableExternallyLinkage();
     74   if (GV->isDeclaration() && !GV->isMaterializable())
     75     isDecl = true;
     76 
     77   // X86-64 in PIC mode.
     78   if (isPICStyleRIPRel()) {
     79     // Large model never uses stubs.
     80     if (TM.getCodeModel() == CodeModel::Large)
     81       return X86II::MO_NO_FLAG;
     82 
     83     if (isTargetDarwin()) {
     84       // If symbol visibility is hidden, the extra load is not needed if
     85       // target is x86-64 or the symbol is definitely defined in the current
     86       // translation unit.
     87       if (GV->hasDefaultVisibility() &&
     88           (isDecl || GV->isWeakForLinker()))
     89         return X86II::MO_GOTPCREL;
     90     } else if (!isTargetWin64()) {
     91       assert(isTargetELF() && "Unknown rip-relative target");
     92 
     93       // Extra load is needed for all externally visible.
     94       if (!GV->hasLocalLinkage() && GV->hasDefaultVisibility())
     95         return X86II::MO_GOTPCREL;
     96     }
     97 
     98     return X86II::MO_NO_FLAG;
     99   }
    100 
    101   if (isPICStyleGOT()) {   // 32-bit ELF targets.
    102     // Extra load is needed for all externally visible.
    103     if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
    104       return X86II::MO_GOTOFF;
    105     return X86II::MO_GOT;
    106   }
    107 
    108   if (isPICStyleStubPIC()) {  // Darwin/32 in PIC mode.
    109     // Determine whether we have a stub reference and/or whether the reference
    110     // is relative to the PIC base or not.
    111 
    112     // If this is a strong reference to a definition, it is definitely not
    113     // through a stub.
    114     if (!isDecl && !GV->isWeakForLinker())
    115       return X86II::MO_PIC_BASE_OFFSET;
    116 
    117     // Unless we have a symbol with hidden visibility, we have to go through a
    118     // normal $non_lazy_ptr stub because this symbol might be resolved late.
    119     if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
    120       return X86II::MO_DARWIN_NONLAZY_PIC_BASE;
    121 
    122     // If symbol visibility is hidden, we have a stub for common symbol
    123     // references and external declarations.
    124     if (isDecl || GV->hasCommonLinkage()) {
    125       // Hidden $non_lazy_ptr reference.
    126       return X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE;
    127     }
    128 
    129     // Otherwise, no stub.
    130     return X86II::MO_PIC_BASE_OFFSET;
    131   }
    132 
    133   if (isPICStyleStubNoDynamic()) {  // Darwin/32 in -mdynamic-no-pic mode.
    134     // Determine whether we have a stub reference.
    135 
    136     // If this is a strong reference to a definition, it is definitely not
    137     // through a stub.
    138     if (!isDecl && !GV->isWeakForLinker())
    139       return X86II::MO_NO_FLAG;
    140 
    141     // Unless we have a symbol with hidden visibility, we have to go through a
    142     // normal $non_lazy_ptr stub because this symbol might be resolved late.
    143     if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
    144       return X86II::MO_DARWIN_NONLAZY;
    145 
    146     // Otherwise, no stub.
    147     return X86II::MO_NO_FLAG;
    148   }
    149 
    150   // Direct static reference to global.
    151   return X86II::MO_NO_FLAG;
    152 }
    153 
    154 
    155 /// getBZeroEntry - This function returns the name of a function which has an
    156 /// interface like the non-standard bzero function, if such a function exists on
    157 /// the current subtarget and it is considered prefereable over memset with zero
    158 /// passed as the second argument. Otherwise it returns null.
    159 const char *X86Subtarget::getBZeroEntry() const {
    160   // Darwin 10 has a __bzero entry point for this purpose.
    161   if (getTargetTriple().isMacOSX() &&
    162       !getTargetTriple().isMacOSXVersionLT(10, 6))
    163     return "__bzero";
    164 
    165   return nullptr;
    166 }
    167 
    168 bool X86Subtarget::hasSinCos() const {
    169   return getTargetTriple().isMacOSX() &&
    170     !getTargetTriple().isMacOSXVersionLT(10, 9) &&
    171     is64Bit();
    172 }
    173 
    174 /// IsLegalToCallImmediateAddr - Return true if the subtarget allows calls
    175 /// to immediate address.
    176 bool X86Subtarget::IsLegalToCallImmediateAddr(const TargetMachine &TM) const {
    177   // FIXME: I386 PE/COFF supports PC relative calls using IMAGE_REL_I386_REL32
    178   // but WinCOFFObjectWriter::RecordRelocation cannot emit them.  Once it does,
    179   // the following check for Win32 should be removed.
    180   if (In64BitMode || isTargetWin32())
    181     return false;
    182   return isTargetELF() || TM.getRelocationModel() == Reloc::Static;
    183 }
    184 
    185 void X86Subtarget::resetSubtargetFeatures(const MachineFunction *MF) {
    186   AttributeSet FnAttrs = MF->getFunction()->getAttributes();
    187   Attribute CPUAttr =
    188       FnAttrs.getAttribute(AttributeSet::FunctionIndex, "target-cpu");
    189   Attribute FSAttr =
    190       FnAttrs.getAttribute(AttributeSet::FunctionIndex, "target-features");
    191   std::string CPU =
    192       !CPUAttr.hasAttribute(Attribute::None) ? CPUAttr.getValueAsString() : "";
    193   std::string FS =
    194       !FSAttr.hasAttribute(Attribute::None) ? FSAttr.getValueAsString() : "";
    195   if (!FS.empty()) {
    196     initializeEnvironment();
    197     resetSubtargetFeatures(CPU, FS);
    198   }
    199 }
    200 
    201 void X86Subtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
    202   std::string CPUName = CPU;
    203   if (CPUName.empty())
    204     CPUName = "generic";
    205 
    206   // Make sure 64-bit features are available in 64-bit mode. (But make sure
    207   // SSE2 can be turned off explicitly.)
    208   std::string FullFS = FS;
    209   if (In64BitMode) {
    210     if (!FullFS.empty())
    211       FullFS = "+64bit,+sse2," + FullFS;
    212     else
    213       FullFS = "+64bit,+sse2";
    214   }
    215 
    216   // If feature string is not empty, parse features string.
    217   ParseSubtargetFeatures(CPUName, FullFS);
    218 
    219   // Make sure the right MCSchedModel is used.
    220   InitCPUSchedModel(CPUName);
    221 
    222   if (X86ProcFamily == IntelAtom || X86ProcFamily == IntelSLM)
    223     PostRAScheduler = true;
    224 
    225   InstrItins = getInstrItineraryForCPU(CPUName);
    226 
    227   // It's important to keep the MCSubtargetInfo feature bits in sync with
    228   // target data structure which is shared with MC code emitter, etc.
    229   if (In64BitMode)
    230     ToggleFeature(X86::Mode64Bit);
    231   else if (In32BitMode)
    232     ToggleFeature(X86::Mode32Bit);
    233   else if (In16BitMode)
    234     ToggleFeature(X86::Mode16Bit);
    235   else
    236     llvm_unreachable("Not 16-bit, 32-bit or 64-bit mode!");
    237 
    238   DEBUG(dbgs() << "Subtarget features: SSELevel " << X86SSELevel
    239                << ", 3DNowLevel " << X863DNowLevel
    240                << ", 64bit " << HasX86_64 << "\n");
    241   assert((!In64BitMode || HasX86_64) &&
    242          "64-bit code requested on a subtarget that doesn't support it!");
    243 
    244   // Stack alignment is 16 bytes on Darwin, Linux and Solaris (both
    245   // 32 and 64 bit) and for all 64-bit targets.
    246   if (StackAlignOverride)
    247     stackAlignment = StackAlignOverride;
    248   else if (isTargetDarwin() || isTargetLinux() || isTargetSolaris() ||
    249            In64BitMode)
    250     stackAlignment = 16;
    251 }
    252 
    253 void X86Subtarget::initializeEnvironment() {
    254   X86SSELevel = NoMMXSSE;
    255   X863DNowLevel = NoThreeDNow;
    256   HasCMov = false;
    257   HasX86_64 = false;
    258   HasPOPCNT = false;
    259   HasSSE4A = false;
    260   HasAES = false;
    261   HasPCLMUL = false;
    262   HasFMA = false;
    263   HasFMA4 = false;
    264   HasXOP = false;
    265   HasTBM = false;
    266   HasMOVBE = false;
    267   HasRDRAND = false;
    268   HasF16C = false;
    269   HasFSGSBase = false;
    270   HasLZCNT = false;
    271   HasBMI = false;
    272   HasBMI2 = false;
    273   HasRTM = false;
    274   HasHLE = false;
    275   HasERI = false;
    276   HasCDI = false;
    277   HasPFI = false;
    278   HasADX = false;
    279   HasSHA = false;
    280   HasPRFCHW = false;
    281   HasRDSEED = false;
    282   IsBTMemSlow = false;
    283   IsSHLDSlow = false;
    284   IsUAMemFast = false;
    285   HasVectorUAMem = false;
    286   HasCmpxchg16b = false;
    287   UseLeaForSP = false;
    288   HasSlowDivide = false;
    289   PostRAScheduler = false;
    290   PadShortFunctions = false;
    291   CallRegIndirect = false;
    292   LEAUsesAG = false;
    293   SlowLEA = false;
    294   SlowIncDec = false;
    295   stackAlignment = 4;
    296   // FIXME: this is a known good value for Yonah. How about others?
    297   MaxInlineSizeThreshold = 128;
    298 }
    299 
    300 static std::string computeDataLayout(const X86Subtarget &ST) {
    301   // X86 is little endian
    302   std::string Ret = "e";
    303 
    304   Ret += DataLayout::getManglingComponent(ST.getTargetTriple());
    305   // X86 and x32 have 32 bit pointers.
    306   if (ST.isTarget64BitILP32() || !ST.is64Bit())
    307     Ret += "-p:32:32";
    308 
    309   // Some ABIs align 64 bit integers and doubles to 64 bits, others to 32.
    310   if (ST.is64Bit() || ST.isOSWindows() || ST.isTargetNaCl())
    311     Ret += "-i64:64";
    312   else
    313     Ret += "-f64:32:64";
    314 
    315   // Some ABIs align long double to 128 bits, others to 32.
    316   if (ST.isTargetNaCl())
    317     ; // No f80
    318   else if (ST.is64Bit() || ST.isTargetDarwin())
    319     Ret += "-f80:128";
    320   else
    321     Ret += "-f80:32";
    322 
    323   // The registers can hold 8, 16, 32 or, in x86-64, 64 bits.
    324   if (ST.is64Bit())
    325     Ret += "-n8:16:32:64";
    326   else
    327     Ret += "-n8:16:32";
    328 
    329   // The stack is aligned to 32 bits on some ABIs and 128 bits on others.
    330   if (!ST.is64Bit() && ST.isOSWindows())
    331     Ret += "-S32";
    332   else
    333     Ret += "-S128";
    334 
    335   return Ret;
    336 }
    337 
    338 X86Subtarget &X86Subtarget::initializeSubtargetDependencies(StringRef CPU,
    339                                                             StringRef FS) {
    340   initializeEnvironment();
    341   resetSubtargetFeatures(CPU, FS);
    342   return *this;
    343 }
    344 
    345 X86Subtarget::X86Subtarget(const std::string &TT, const std::string &CPU,
    346                            const std::string &FS, X86TargetMachine &TM,
    347                            unsigned StackAlignOverride)
    348     : X86GenSubtargetInfo(TT, CPU, FS), X86ProcFamily(Others),
    349       PICStyle(PICStyles::None), TargetTriple(TT),
    350       StackAlignOverride(StackAlignOverride),
    351       In64BitMode(TargetTriple.getArch() == Triple::x86_64),
    352       In32BitMode(TargetTriple.getArch() == Triple::x86 &&
    353                   TargetTriple.getEnvironment() != Triple::CODE16),
    354       In16BitMode(TargetTriple.getArch() == Triple::x86 &&
    355                   TargetTriple.getEnvironment() == Triple::CODE16),
    356       DL(computeDataLayout(*this)), TSInfo(DL),
    357       InstrInfo(initializeSubtargetDependencies(CPU, FS)), TLInfo(TM),
    358       FrameLowering(TargetFrameLowering::StackGrowsDown, getStackAlignment(),
    359                     is64Bit() ? -8 : -4),
    360       JITInfo(hasSSE1()) {}
    361 
    362 bool
    363 X86Subtarget::enablePostRAScheduler(CodeGenOpt::Level OptLevel,
    364                                     TargetSubtargetInfo::AntiDepBreakMode &Mode,
    365                                     RegClassVector &CriticalPathRCs) const {
    366   Mode = TargetSubtargetInfo::ANTIDEP_CRITICAL;
    367   CriticalPathRCs.clear();
    368   return PostRAScheduler && OptLevel >= CodeGenOpt::Default;
    369 }
    370 
    371 bool
    372 X86Subtarget::enableEarlyIfConversion() const {
    373   return hasCMov() && X86EarlyIfConv;
    374 }
    375