forked from OSchip/llvm-project
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, SmallPtrSetImpl<GlobalValue *> &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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