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