LCOV - code coverage report
Current view: top level - lib/Target - TargetMachine.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 81 86 94.2 %
Date: 2018-09-23 13:06:45 Functions: 14 16 87.5 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===-- TargetMachine.cpp - General Target 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 describes the general parts of a Target machine.
      11             : //
      12             : //===----------------------------------------------------------------------===//
      13             : 
      14             : #include "llvm/Target/TargetMachine.h"
      15             : #include "llvm/Analysis/TargetTransformInfo.h"
      16             : #include "llvm/IR/Function.h"
      17             : #include "llvm/IR/GlobalAlias.h"
      18             : #include "llvm/IR/GlobalValue.h"
      19             : #include "llvm/IR/GlobalVariable.h"
      20             : #include "llvm/IR/LegacyPassManager.h"
      21             : #include "llvm/IR/Mangler.h"
      22             : #include "llvm/MC/MCAsmInfo.h"
      23             : #include "llvm/MC/MCContext.h"
      24             : #include "llvm/MC/MCInstrInfo.h"
      25             : #include "llvm/MC/MCSectionMachO.h"
      26             : #include "llvm/MC/MCTargetOptions.h"
      27             : #include "llvm/MC/SectionKind.h"
      28             : #include "llvm/Target/TargetLoweringObjectFile.h"
      29             : using namespace llvm;
      30             : 
      31             : //---------------------------------------------------------------------------
      32             : // TargetMachine Class
      33             : //
      34             : 
      35       41847 : TargetMachine::TargetMachine(const Target &T, StringRef DataLayoutString,
      36             :                              const Triple &TT, StringRef CPU, StringRef FS,
      37       41847 :                              const TargetOptions &Options)
      38             :     : TheTarget(T), DL(DataLayoutString), TargetTriple(TT), TargetCPU(CPU),
      39             :       TargetFS(FS), AsmInfo(nullptr), MRI(nullptr), MII(nullptr), STI(nullptr),
      40       83695 :       RequireStructuredCFG(false), DefaultOptions(Options), Options(Options) {
      41       41847 : }
      42             : 
      43       33945 : TargetMachine::~TargetMachine() {
      44       33945 :   delete AsmInfo;
      45       67887 :   delete MRI;
      46       33944 :   delete MII;
      47       33944 :   delete STI;
      48       33945 : }
      49           0 : 
      50             : bool TargetMachine::isPositionIndependent() const {
      51             :   return getRelocationModel() == Reloc::PIC_;
      52             : }
      53             : 
      54           0 : /// Reset the target options based on the function's attributes.
      55       33945 : // FIXME: This function needs to go away for a number of reasons:
      56       33945 : // a) global state on the TargetMachine is terrible in general,
      57       67887 : // b) these target options should be passed only on the function
      58       33944 : //    and not on the TargetMachine (via TargetOptions) at all.
      59       33944 : void TargetMachine::resetTargetOptions(const Function &F) const {
      60       33945 : #define RESET_OPTION(X, Y)                                                     \
      61             :   do {                                                                         \
      62     6945692 :     if (F.hasFnAttribute(Y))                                                   \
      63     6945692 :       Options.X = (F.getFnAttribute(Y).getValueAsString() == "true");          \
      64             :     else                                                                       \
      65             :       Options.X = DefaultOptions.X;                                            \
      66             :   } while (0)
      67             : 
      68             :   RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
      69             :   RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
      70             :   RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
      71      457909 :   RESET_OPTION(NoSignedZerosFPMath, "no-signed-zeros-fp-math");
      72             :   RESET_OPTION(NoTrappingFPMath, "no-trapping-math");
      73             : 
      74             :   StringRef Denormal =
      75             :     F.getFnAttribute("denormal-fp-math").getValueAsString();
      76             :   if (Denormal == "ieee")
      77             :     Options.FPDenormalMode = FPDenormal::IEEE;
      78             :   else if (Denormal == "preserve-sign")
      79             :     Options.FPDenormalMode = FPDenormal::PreserveSign;
      80      943747 :   else if (Denormal == "positive-zero")
      81      941559 :     Options.FPDenormalMode = FPDenormal::PositiveZero;
      82      942051 :   else
      83      938299 :     Options.FPDenormalMode = DefaultOptions.FPDenormalMode;
      84      937687 : }
      85             : 
      86             : /// Returns the code generation relocation model. The choices are static, PIC,
      87      457909 : /// and dynamic-no-pic.
      88             : Reloc::Model TargetMachine::getRelocationModel() const { return RM; }
      89          12 : 
      90             : /// Returns the code model. The choices are small, kernel, medium, large, and
      91          10 : /// target default.
      92             : CodeModel::Model TargetMachine::getCodeModel() const { return CMModel; }
      93           3 : 
      94             : /// Get the IR-specified TLS model for Var.
      95      457884 : static TLSModel::Model getSelectedTLSModel(const GlobalValue *GV) {
      96      457909 :   switch (GV->getThreadLocalMode()) {
      97             :   case GlobalVariable::NotThreadLocal:
      98             :     llvm_unreachable("getSelectedTLSModel for non-TLS variable");
      99             :     break;
     100     7735155 :   case GlobalVariable::GeneralDynamicTLSModel:
     101             :     return TLSModel::GeneralDynamic;
     102             :   case GlobalVariable::LocalDynamicTLSModel:
     103             :     return TLSModel::LocalDynamic;
     104    20463118 :   case GlobalVariable::InitialExecTLSModel:
     105             :     return TLSModel::InitialExec;
     106             :   case GlobalVariable::LocalExecTLSModel:
     107             :     return TLSModel::LocalExec;
     108         614 :   }
     109             :   llvm_unreachable("invalid TLS model");
     110             : }
     111             : 
     112             : bool TargetMachine::shouldAssumeDSOLocal(const Module &M,
     113             :                                          const GlobalValue *GV) const {
     114             :   // If the IR producer requested that this GV be treated as dso local, obey.
     115             :   if (GV && GV->isDSOLocal())
     116             :     return true;
     117             : 
     118             :   // If we are not supossed to use a PLT, we cannot assume that intrinsics are
     119             :   // local since the linker can convert some direct access to access via plt.
     120             :   if (M.getRtLibUseGOT() && !GV)
     121           0 :     return false;
     122             : 
     123             :   // According to the llvm language reference, we should be able to
     124     5822792 :   // just return false in here if we have a GV, as we know it is
     125             :   // dso_preemptable.  At this point in time, the various IR producers
     126             :   // have not been transitioned to always produce a dso_local when it
     127     5822792 :   // is possible to do so.
     128             :   // In the case of intrinsics, GV is null and there is nowhere to put
     129             :   // dso_local. Returning false for those will produce worse code in some
     130             :   // architectures. For example, on x86 the caller has to set ebx before calling
     131             :   // a plt.
     132      242474 :   // As a result we still have some logic in here to improve the quality of the
     133             :   // generated code.
     134             :   // FIXME: Add a module level metadata for whether intrinsics should be assumed
     135             :   // local.
     136             : 
     137             :   Reloc::Model RM = getRelocationModel();
     138             :   const Triple &TT = getTargetTriple();
     139             : 
     140             :   // DLLImport explicitly marks the GV as external.
     141             :   if (GV && GV->hasDLLImportStorageClass())
     142             :     return false;
     143             : 
     144             :   // On MinGW, variables that haven't been declared with DLLImport may still
     145             :   // end up automatically imported by the linker. To make this feasible,
     146             :   // don't assume the variables to be DSO local unless we actually know
     147             :   // that for sure. This only has to be done for variables; for functions
     148             :   // the linker can insert thunks for calling functions from another DLL.
     149      242470 :   if (TT.isWindowsGNUEnvironment() && GV && GV->isDeclarationForLinker() &&
     150             :       isa<GlobalVariable>(GV))
     151             :     return false;
     152             : 
     153      242470 :   // Every other GV is local on COFF.
     154             :   // Make an exception for windows OS in the triple: Some firmware builds use
     155             :   // *-win32-macho triples. This (accidentally?) produced windows relocations
     156             :   // without GOT tables in older clang versions; Keep this behaviour.
     157             :   if (TT.isOSBinFormatCOFF() || (TT.isOSWindows() && TT.isOSBinFormatMachO()))
     158             :     return true;
     159             : 
     160             :   // Most PIC code sequences that assume that a symbol is local cannot
     161         995 :   // produce a 0 if it turns out the symbol is undefined. While this
     162             :   // is ABI and relocation depended, it seems worth it to handle it
     163             :   // here.
     164             :   if (GV && isPositionIndependent() && GV->hasExternalWeakLinkage())
     165             :     return false;
     166             : 
     167             :   if (GV && !GV->hasDefaultVisibility())
     168             :     return true;
     169      242226 : 
     170             :   if (TT.isOSBinFormatMachO()) {
     171             :     if (RM == Reloc::Static)
     172             :       return true;
     173             :     return GV && GV->isStrongDefinitionForLinker();
     174             :   }
     175             : 
     176      239217 :   assert(TT.isOSBinFormatELF());
     177             :   assert(RM != Reloc::DynamicNoPIC);
     178             : 
     179      239177 :   bool IsExecutable =
     180             :       RM == Reloc::Static || M.getPIELevel() != PIELevel::Default;
     181             :   if (IsExecutable) {
     182      239169 :     // If the symbol is defined, it cannot be preempted.
     183       15727 :     if (GV && !GV->isDeclarationForLinker())
     184             :       return true;
     185       14799 : 
     186             :     // A symbol marked nonlazybind should not be accessed with a plt. If the
     187             :     // symbol turns out to be external, the linker will convert a direct
     188             :     // access to an access via the plt, so don't assume it is local.
     189             :     const Function *F = dyn_cast_or_null<Function>(GV);
     190             :     if (F && F->hasFnAttribute(Attribute::NonLazyBind))
     191             :       return false;
     192      223442 : 
     193             :     bool IsTLS = GV && GV->isThreadLocal();
     194             :     bool IsAccessViaCopyRelocs =
     195      241569 :         GV && Options.MCOptions.MCPIECopyRelocations && isa<GlobalVariable>(GV);
     196             :     Triple::ArchType Arch = TT.getArch();
     197             :     bool IsPPC =
     198             :         Arch == Triple::ppc || Arch == Triple::ppc64 || Arch == Triple::ppc64le;
     199             :     // Check if we can use copy relocations. PowerPC has no copy relocations.
     200             :     if (!IsTLS && !IsPPC && (RM == Reloc::Static || IsAccessViaCopyRelocs))
     201             :       return true;
     202       86745 :   }
     203             : 
     204             :   // ELF supports preemption of other symbols.
     205      109427 :   return false;
     206             : }
     207      109427 : 
     208      109427 : bool TargetMachine::useEmulatedTLS() const {
     209             :   // Returns Options.EmulatedTLS if the -emulated-tls or -no-emulated-tls
     210      109427 :   // was specified explicitly; otherwise uses target triple to decide default.
     211             :   if (Options.ExplicitEmulatedTLS)
     212      109427 :     return Options.EmulatedTLS;
     213      108777 :   return getTargetTriple().hasDefaultEmulatedTLS();
     214             : }
     215             : 
     216             : TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const {
     217             :   bool IsPIE = GV->getParent()->getPIELevel() != PIELevel::Default;
     218             :   Reloc::Model RM = getRelocationModel();
     219             :   bool IsSharedLibrary = RM == Reloc::PIC_ && !IsPIE;
     220      321005 :   bool IsLocal = shouldAssumeDSOLocal(*GV->getParent(), GV);
     221             : 
     222             :   TLSModel::Model Model;
     223      321005 :   if (IsSharedLibrary) {
     224        1410 :     if (IsLocal)
     225             :       Model = TLSModel::LocalDynamic;
     226             :     else
     227             :       Model = TLSModel::GeneralDynamic;
     228         614 :   } else {
     229         614 :     if (IsLocal)
     230         614 :       Model = TLSModel::LocalExec;
     231         614 :     else
     232         614 :       Model = TLSModel::InitialExec;
     233             :   }
     234             : 
     235         614 :   // If the user specified a more specific model, use that.
     236         293 :   TLSModel::Model SelectedModel = getSelectedTLSModel(GV);
     237             :   if (SelectedModel > Model)
     238             :     return SelectedModel;
     239             : 
     240             :   return Model;
     241         321 : }
     242             : 
     243             : /// Returns the optimization level: None, Less, Default, or Aggressive.
     244             : CodeGenOpt::Level TargetMachine::getOptLevel() const { return OptLevel; }
     245             : 
     246             : void TargetMachine::setOptLevel(CodeGenOpt::Level Level) { OptLevel = Level; }
     247             : 
     248             : TargetTransformInfo TargetMachine::getTargetTransformInfo(const Function &F) {
     249         614 :   return TargetTransformInfo(F.getParent()->getDataLayout());
     250         102 : }
     251             : 
     252             : void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name,
     253             :                                       const GlobalValue *GV, Mangler &Mang,
     254             :                                       bool MayAlwaysUsePrivate) const {
     255             :   if (MayAlwaysUsePrivate || !GV->hasPrivateLinkage()) {
     256    10259395 :     // Simple case: If GV is not private, it is not important to find out if
     257             :     // private labels are legal in this case or not.
     258         344 :     Mang.getNameWithPrefix(Name, GV, false);
     259             :     return;
     260           0 :   }
     261           0 :   const TargetLoweringObjectFile *TLOF = getObjFileLowering();
     262             :   TLOF->getNameWithPrefix(Name, GV, *this);
     263             : }
     264     5347210 : 
     265             : MCSymbol *TargetMachine::getSymbol(const GlobalValue *GV) const {
     266             :   const TargetLoweringObjectFile *TLOF = getObjFileLowering();
     267     5347210 :   SmallString<128> NameStr;
     268             :   getNameWithPrefix(NameStr, GV, TLOF->getMangler());
     269             :   return TLOF->getContext().getOrCreateSymbol(NameStr);
     270     4192330 : }
     271     4192331 : 
     272             : TargetIRAnalysis TargetMachine::getTargetIRAnalysis() {
     273     1154880 :   // Since Analysis can't depend on Target, use a std::function to invert the
     274     1154880 :   // dependency.
     275             :   return TargetIRAnalysis(
     276             :       [this](const Function &F) { return this->getTargetTransformInfo(F); });
     277     1555475 : }

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