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fd1a7dfe04
This allows us to put dynamic initializers for weak data into the same comdat group as the data being initialized. This is necessary for MSVC ABI compatibility. Once we have comdats for guard variables, we can use the combination to help GlobalOpt fire more often for weak data with guarded initialization on other platforms. Reviewers: nlewycky Differential Revision: http://reviews.llvm.org/D3499 llvm-svn: 209015
96 lines
3.5 KiB
C++
96 lines
3.5 KiB
C++
//===-- ModuleUtils.cpp - Functions to manipulate Modules -----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This family of functions perform manipulations on Modules.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Module.h"
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using namespace llvm;
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static void appendToGlobalArray(const char *Array,
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Module &M, Function *F, int Priority) {
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IRBuilder<> IRB(M.getContext());
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FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
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// Get the current set of static global constructors and add the new ctor
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// to the list.
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SmallVector<Constant *, 16> CurrentCtors;
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StructType *EltTy;
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if (GlobalVariable *GVCtor = M.getNamedGlobal(Array)) {
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// If there is a global_ctors array, use the existing struct type, which can
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// have 2 or 3 fields.
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ArrayType *ATy = cast<ArrayType>(GVCtor->getType()->getElementType());
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EltTy = cast<StructType>(ATy->getElementType());
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if (Constant *Init = GVCtor->getInitializer()) {
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unsigned n = Init->getNumOperands();
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CurrentCtors.reserve(n + 1);
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for (unsigned i = 0; i != n; ++i)
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CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
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}
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GVCtor->eraseFromParent();
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} else {
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// Use a simple two-field struct if there isn't one already.
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EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
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nullptr);
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}
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// Build a 2 or 3 field global_ctor entry. We don't take a comdat key.
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Constant *CSVals[3];
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CSVals[0] = IRB.getInt32(Priority);
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CSVals[1] = F;
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// FIXME: Drop support for the two element form in LLVM 4.0.
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if (EltTy->getNumElements() >= 3)
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CSVals[2] = llvm::Constant::getNullValue(IRB.getInt8PtrTy());
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Constant *RuntimeCtorInit =
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ConstantStruct::get(EltTy, makeArrayRef(CSVals, EltTy->getNumElements()));
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CurrentCtors.push_back(RuntimeCtorInit);
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// Create a new initializer.
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ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
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Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
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// Create the new global variable and replace all uses of
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// the old global variable with the new one.
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(void)new GlobalVariable(M, NewInit->getType(), false,
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GlobalValue::AppendingLinkage, NewInit, Array);
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}
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void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
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appendToGlobalArray("llvm.global_ctors", M, F, Priority);
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}
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void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority) {
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appendToGlobalArray("llvm.global_dtors", M, F, Priority);
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}
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GlobalVariable *
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llvm::collectUsedGlobalVariables(Module &M, SmallPtrSet<GlobalValue *, 8> &Set,
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bool CompilerUsed) {
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const char *Name = CompilerUsed ? "llvm.compiler.used" : "llvm.used";
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GlobalVariable *GV = M.getGlobalVariable(Name);
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if (!GV || !GV->hasInitializer())
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return GV;
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const ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
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for (unsigned I = 0, E = Init->getNumOperands(); I != E; ++I) {
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Value *Op = Init->getOperand(I);
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GlobalValue *G = cast<GlobalValue>(Op->stripPointerCastsNoFollowAliases());
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Set.insert(G);
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}
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return GV;
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}
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