C++ global_iterator::getInitializer方法代码示例

void PIC16AsmPrinter::EmitUnInitData (Module &M)
{
  SwitchToSection(TAI->getBSSSection_());
  const TargetData *TD = TM.getTargetData();

  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I) {
    if (!I->hasInitializer())   // External global require no code.
      continue;

    Constant *C = I->getInitializer();
    if (C->isNullValue()) {

      if (EmitSpecialLLVMGlobal(I))
        continue;

      // Any variables reaching here with "." in its name is a local scope
      // variable and should not be printed in global data section.
      std::string name = Mang->getValueName(I);
      if (name.find(".") != std::string::npos)
        continue;

      I->setSection(TAI->getBSSSection_()->getName());

      const Type *Ty = C->getType();
      unsigned Size = TD->getTypePaddedSize(Ty);

      O << name << " " <<"RES"<< " " << Size ;
      O << "\n";
    }
  }
}

void Preparer::replaceUndefsWithNull(Module &M) {
  ValueSet Replaced;
  for (Module::global_iterator GI = M.global_begin(); GI != M.global_end();
       ++GI) {
    if (GI->hasInitializer()) {
      replaceUndefsWithNull(GI->getInitializer(), Replaced);
    }
  }
  for (Module::iterator F = M.begin(); F != M.end(); ++F) {
    for (Function::iterator BB = F->begin(); BB != F->end(); ++BB) {
      for (BasicBlock::iterator Ins = BB->begin(); Ins != BB->end(); ++Ins) {
        replaceUndefsWithNull(Ins, Replaced);
      }
    }
  }
}

void CaptureConstraints::identify_fixed_integers(Module &M) {
	ExecOnce &EO = getAnalysis<ExecOnce>();
	
	fixed_integers.clear();
	// Global variables. 
	for (Module::global_iterator gi = M.global_begin();
			gi != M.global_end(); ++gi) {
		if (isa<IntegerType>(gi->getType()) || isa<PointerType>(gi->getType())) {
			fixed_integers.insert(gi);
			if (gi->hasInitializer())
				extract_from_consts(gi->getInitializer());
		}
	}
	
	// Instructions and their constant operands. 
	forallinst(M, ii) {
		if (EO.not_executed(ii))
			continue;
		if (!EO.executed_once(ii))
			continue;
		if (isa<IntegerType>(ii->getType()) || isa<PointerType>(ii->getType())) {
			fixed_integers.insert(ii);
		}
		// No matter reachable or not, capture its constant operands. 
		for (unsigned i = 0; i < ii->getNumOperands(); ++i) {
			if (Constant *c = dyn_cast<Constant>(ii->getOperand(i)))
				extract_from_consts(c);
		}
	}
	
	// Function parameters. 
	forallfunc(M, f) {
		if (EO.not_executed(f))
			continue;
		if (!EO.executed_once(f))
			continue;
		for (Function::arg_iterator ai = f->arg_begin();
				ai != f->arg_end(); ++ai) {
			if (isa<IntegerType>(ai->getType()) || isa<PointerType>(ai->getType()))
				fixed_integers.insert(ai);
		}
	}
}

static int runCompilePasses(Module *ModuleRef,
                            unsigned ModuleIndex,
                            ThreadedFunctionQueue *FuncQueue,
                            const Triple &TheTriple,
                            TargetMachine &Target,
                            StringRef ProgramName,
                            raw_pwrite_stream &OS){
  PNaClABIErrorReporter ABIErrorReporter;

  if (SplitModuleCount > 1 || ExternalizeAll) {
    // Add function and global names, and give them external linkage.
    // This relies on LLVM's consistent auto-generation of names, we could
    // maybe do our own in case something changes there.
    for (Function &F : *ModuleRef) {
      if (!F.hasName())
        F.setName("Function");
      if (F.hasInternalLinkage())
        F.setLinkage(GlobalValue::ExternalLinkage);
    }
    for (Module::global_iterator GI = ModuleRef->global_begin(),
         GE = ModuleRef->global_end();
         GI != GE; ++GI) {
      if (!GI->hasName())
        GI->setName("Global");
      if (GI->hasInternalLinkage())
        GI->setLinkage(GlobalValue::ExternalLinkage);
    }
    if (ModuleIndex > 0) {
      // Remove the initializers for all global variables, turning them into
      // declarations.
      for (Module::global_iterator GI = ModuleRef->global_begin(),
          GE = ModuleRef->global_end();
          GI != GE; ++GI) {
        assert(GI->hasInitializer() && "Global variable missing initializer");
        Constant *Init = GI->getInitializer();
        GI->setInitializer(nullptr);
        if (Init->getNumUses() == 0)
          Init->destroyConstant();
      }
    }
  }

  // Make all non-weak symbols hidden for better code. We cannot do
  // this for weak symbols. The linker complains when some weak
  // symbols are not resolved.
  for (Function &F : *ModuleRef) {
    if (!F.isWeakForLinker() && !F.hasLocalLinkage())
      F.setVisibility(GlobalValue::HiddenVisibility);
  }
  for (Module::global_iterator GI = ModuleRef->global_begin(),
           GE = ModuleRef->global_end();
       GI != GE; ++GI) {
    if (!GI->isWeakForLinker() && !GI->hasLocalLinkage())
      GI->setVisibility(GlobalValue::HiddenVisibility);
  }

  // Build up all of the passes that we want to do to the module.
  std::unique_ptr<legacy::PassManagerBase> PM;
  if (LazyBitcode)
    PM.reset(new legacy::FunctionPassManager(ModuleRef));
  else
    PM.reset(new legacy::PassManager());

  // Add the target data from the target machine, if it exists, or the module.
  if (const DataLayout *DL = Target.getDataLayout())
    ModuleRef->setDataLayout(*DL);

  // For conformance with llc, we let the user disable LLVM IR verification with
  // -disable-verify. Unlike llc, when LLVM IR verification is enabled we only
  // run it once, before PNaCl ABI verification.
  if (!NoVerify)
    PM->add(createVerifierPass());

  // Add the ABI verifier pass before the analysis and code emission passes.
  if (PNaClABIVerify)
    PM->add(createPNaClABIVerifyFunctionsPass(&ABIErrorReporter));

  // Add the intrinsic resolution pass. It assumes ABI-conformant code.
  PM->add(createResolvePNaClIntrinsicsPass());

  // Add an appropriate TargetLibraryInfo pass for the module's triple.
  TargetLibraryInfoImpl TLII(TheTriple);

  // The -disable-simplify-libcalls flag actually disables all builtin optzns.
  if (DisableSimplifyLibCalls)
    TLII.disableAllFunctions();
  PM->add(new TargetLibraryInfoWrapperPass(TLII));

  // Allow subsequent passes and the backend to better optimize instructions
  // that were simplified for PNaCl's ABI. This pass uses the TargetLibraryInfo
  // above.
  PM->add(createBackendCanonicalizePass());

  // Ask the target to add backend passes as necessary. We explicitly ask it
  // not to add the verifier pass because we added it earlier.
  if (Target.addPassesToEmitFile(*PM, OS, FileType,
                                 /* DisableVerify */ true)) {
    errs() << ProgramName
    << ": target does not support generation of this file type!\n";
    return 1;
//.........这里部分代码省略.........

bool GlobalDCE::runOnModule(Module &M) {
  bool Changed = false;

  // Remove empty functions from the global ctors list.
  Changed |= optimizeGlobalCtorsList(M, isEmptyFunction);

  // Loop over the module, adding globals which are obviously necessary.
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
    Changed |= RemoveUnusedGlobalValue(*I);
    // Functions with external linkage are needed if they have a body
    if (!I->isDeclaration() && !I->hasAvailableExternallyLinkage()) {
      if (!I->isDiscardableIfUnused())
        GlobalIsNeeded(I);
    }
  }

  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I) {
    Changed |= RemoveUnusedGlobalValue(*I);
    // Externally visible & appending globals are needed, if they have an
    // initializer.
    if (!I->isDeclaration() && !I->hasAvailableExternallyLinkage()) {
      if (!I->isDiscardableIfUnused())
        GlobalIsNeeded(I);
    }
  }

  for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
       I != E; ++I) {
    Changed |= RemoveUnusedGlobalValue(*I);
    // Externally visible aliases are needed.
    if (!I->isDiscardableIfUnused()) {
      GlobalIsNeeded(I);
    }
  }

  // Now that all globals which are needed are in the AliveGlobals set, we loop
  // through the program, deleting those which are not alive.
  //

  // The first pass is to drop initializers of global variables which are dead.
  std::vector<GlobalVariable*> DeadGlobalVars;   // Keep track of dead globals
  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I)
    if (!AliveGlobals.count(I)) {
      DeadGlobalVars.push_back(I);         // Keep track of dead globals
      if (I->hasInitializer()) {
        Constant *Init = I->getInitializer();
        I->setInitializer(nullptr);
        if (isSafeToDestroyConstant(Init))
          Init->destroyConstant();
      }
    }

  // The second pass drops the bodies of functions which are dead...
  std::vector<Function*> DeadFunctions;
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    if (!AliveGlobals.count(I)) {
      DeadFunctions.push_back(I);         // Keep track of dead globals
      if (!I->isDeclaration())
        I->deleteBody();
    }

  // The third pass drops targets of aliases which are dead...
  std::vector<GlobalAlias*> DeadAliases;
  for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); I != E;
       ++I)
    if (!AliveGlobals.count(I)) {
      DeadAliases.push_back(I);
      I->setAliasee(nullptr);
    }

  if (!DeadFunctions.empty()) {
    // Now that all interferences have been dropped, delete the actual objects
    // themselves.
    for (unsigned i = 0, e = DeadFunctions.size(); i != e; ++i) {
      RemoveUnusedGlobalValue(*DeadFunctions[i]);
      M.getFunctionList().erase(DeadFunctions[i]);
    }
    NumFunctions += DeadFunctions.size();
    Changed = true;
  }

  if (!DeadGlobalVars.empty()) {
    for (unsigned i = 0, e = DeadGlobalVars.size(); i != e; ++i) {
      RemoveUnusedGlobalValue(*DeadGlobalVars[i]);
      M.getGlobalList().erase(DeadGlobalVars[i]);
    }
    NumVariables += DeadGlobalVars.size();
    Changed = true;
  }

  // Now delete any dead aliases.
  if (!DeadAliases.empty()) {
    for (unsigned i = 0, e = DeadAliases.size(); i != e; ++i) {
      RemoveUnusedGlobalValue(*DeadAliases[i]);
      M.getAliasList().erase(DeadAliases[i]);
    }
    NumAliases += DeadAliases.size();
    Changed = true;
//.........这里部分代码省略.........

static PointerType *buildTlsTemplate(Module &M, std::vector<VarInfo> *TlsVars) {
  std::vector<Type*> FieldBssTypes;
  std::vector<Type*> FieldInitTypes;
  std::vector<Constant*> FieldInitValues;
  PassState State(&M);

  for (Module::global_iterator GV = M.global_begin();
       GV != M.global_end();
       ++GV) {
    if (GV->isThreadLocal()) {
      if (!GV->hasInitializer()) {
        // Since this is a whole-program transformation, "extern" TLS
        // variables are not allowed at this point.
        report_fatal_error(std::string("TLS variable without an initializer: ")
                           + GV->getName());
      }
      if (!GV->getInitializer()->isNullValue()) {
        addVarToTlsTemplate(&State, &FieldInitTypes,
                            &FieldInitValues, GV);
        VarInfo Info;
        Info.TlsVar = GV;
        Info.IsBss = false;
        Info.TemplateIndex = FieldInitTypes.size() - 1;
        TlsVars->push_back(Info);
      }
    }
  }
  // Handle zero-initialized TLS variables in a second pass, because
  // these should follow non-zero-initialized TLS variables.
  for (Module::global_iterator GV = M.global_begin();
       GV != M.global_end();
       ++GV) {
    if (GV->isThreadLocal() && GV->getInitializer()->isNullValue()) {
      addVarToTlsTemplate(&State, &FieldBssTypes, NULL, GV);
      VarInfo Info;
      Info.TlsVar = GV;
      Info.IsBss = true;
      Info.TemplateIndex = FieldBssTypes.size() - 1;
      TlsVars->push_back(Info);
    }
  }
  // Add final alignment padding so that
  //   (struct tls_struct *) __nacl_read_tp() - 1
  // gives the correct, aligned start of the TLS variables given the
  // x86-style layout we are using.  This requires some more bytes to
  // be memset() to zero at runtime.  This wastage doesn't seem
  // important gives that we're not trying to optimize packing by
  // reordering to put similarly-aligned variables together.
  padToAlignment(&State, &FieldBssTypes, NULL, State.Alignment);

  // We create the TLS template structs as "packed" because we insert
  // alignment padding ourselves, and LLVM's implicit insertion of
  // padding would interfere with ours.  tls_bss_template can start at
  // a non-aligned address immediately following the last field in
  // tls_init_template.
  StructType *InitTemplateType =
      StructType::create(M.getContext(), "tls_init_template");
  InitTemplateType->setBody(FieldInitTypes, /*isPacked=*/true);
  StructType *BssTemplateType =
      StructType::create(M.getContext(), "tls_bss_template");
  BssTemplateType->setBody(FieldBssTypes, /*isPacked=*/true);

  StructType *TemplateType = StructType::create(M.getContext(), "tls_struct");
  SmallVector<Type*, 2> TemplateTopFields;
  TemplateTopFields.push_back(InitTemplateType);
  TemplateTopFields.push_back(BssTemplateType);
  TemplateType->setBody(TemplateTopFields, /*isPacked=*/true);
  PointerType *TemplatePtrType = PointerType::get(TemplateType, 0);

  // We define the following symbols, which are the same as those
  // defined by NaCl's original customized binutils linker scripts:
  //   __tls_template_start
  //   __tls_template_tdata_end
  //   __tls_template_end
  // We also define __tls_template_alignment, which was not defined by
  // the original linker scripts.

  const char *StartSymbol = "__tls_template_start";
  Constant *TemplateData = ConstantStruct::get(InitTemplateType,
                                               FieldInitValues);
  GlobalVariable *TemplateDataVar =
      new GlobalVariable(M, InitTemplateType, /*isConstant=*/true,
                         GlobalValue::InternalLinkage, TemplateData);
  setGlobalVariableValue(M, StartSymbol, TemplateDataVar);
  TemplateDataVar->setName(StartSymbol);

  Constant *TdataEnd = ConstantExpr::getGetElementPtr(
      TemplateDataVar,
      ConstantInt::get(M.getContext(), APInt(32, 1)));
  setGlobalVariableValue(M, "__tls_template_tdata_end", TdataEnd);

  Constant *TotalEnd = ConstantExpr::getGetElementPtr(
      ConstantExpr::getBitCast(TemplateDataVar, TemplatePtrType),
      ConstantInt::get(M.getContext(), APInt(32, 1)));
  setGlobalVariableValue(M, "__tls_template_end", TotalEnd);

  const char *AlignmentSymbol = "__tls_template_alignment";
  Type *i32 = Type::getInt32Ty(M.getContext());
  GlobalVariable *AlignmentVar = new GlobalVariable(
      M, i32, /*isConstant=*/true,
//.........这里部分代码省略.........