1//===-- ModuleUtils.cpp - Functions to manipulate Modules -----------------===// 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 family of functions perform manipulations on Modules. 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/Transforms/Utils/ModuleUtils.h" 15#include "llvm/DerivedTypes.h" 16#include "llvm/Function.h" 17#include "llvm/IRBuilder.h" 18#include "llvm/Module.h" 19 20using namespace llvm; 21 22static void appendToGlobalArray(const char *Array, 23 Module &M, Function *F, int Priority) { 24 IRBuilder<> IRB(M.getContext()); 25 FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false); 26 StructType *Ty = StructType::get( 27 IRB.getInt32Ty(), PointerType::getUnqual(FnTy), NULL); 28 29 Constant *RuntimeCtorInit = ConstantStruct::get( 30 Ty, IRB.getInt32(Priority), F, NULL); 31 32 // Get the current set of static global constructors and add the new ctor 33 // to the list. 34 SmallVector<Constant *, 16> CurrentCtors; 35 if (GlobalVariable * GVCtor = M.getNamedGlobal(Array)) { 36 if (Constant *Init = GVCtor->getInitializer()) { 37 unsigned n = Init->getNumOperands(); 38 CurrentCtors.reserve(n + 1); 39 for (unsigned i = 0; i != n; ++i) 40 CurrentCtors.push_back(cast<Constant>(Init->getOperand(i))); 41 } 42 GVCtor->eraseFromParent(); 43 } 44 45 CurrentCtors.push_back(RuntimeCtorInit); 46 47 // Create a new initializer. 48 ArrayType *AT = ArrayType::get(RuntimeCtorInit->getType(), 49 CurrentCtors.size()); 50 Constant *NewInit = ConstantArray::get(AT, CurrentCtors); 51 52 // Create the new global variable and replace all uses of 53 // the old global variable with the new one. 54 (void)new GlobalVariable(M, NewInit->getType(), false, 55 GlobalValue::AppendingLinkage, NewInit, Array); 56} 57 58void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) { 59 appendToGlobalArray("llvm.global_ctors", M, F, Priority); 60} 61 62void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority) { 63 appendToGlobalArray("llvm.global_dtors", M, F, Priority); 64} 65