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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/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
static void appendToGlobalArray(const char *Array, Module &M, Function *F,
int Priority, Constant *Data) {
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)) {
ArrayType *ATy = cast<ArrayType>(GVCtor->getValueType());
StructType *OldEltTy = cast<StructType>(ATy->getElementType());
// Upgrade a 2-field global array type to the new 3-field format if needed.
if (Data && OldEltTy->getNumElements() < 3)
EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
IRB.getInt8PtrTy());
else
EltTy = OldEltTy;
if (Constant *Init = GVCtor->getInitializer()) {
unsigned n = Init->getNumOperands();
CurrentCtors.reserve(n + 1);
for (unsigned i = 0; i != n; ++i) {
auto Ctor = cast<Constant>(Init->getOperand(i));
if (EltTy != OldEltTy)
Ctor =
ConstantStruct::get(EltTy, Ctor->getAggregateElement((unsigned)0),
Ctor->getAggregateElement(1),
Constant::getNullValue(IRB.getInt8PtrTy()));
CurrentCtors.push_back(Ctor);
}
}
GVCtor->eraseFromParent();
} else {
// Use the new three-field struct if there isn't one already.
EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
IRB.getInt8PtrTy());
}
// 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] = Data ? ConstantExpr::getPointerCast(Data, IRB.getInt8PtrTy())
: 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, Constant *Data) {
appendToGlobalArray("llvm.global_ctors", M, F, Priority, Data);
}
void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *Data) {
appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
}
static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *> Values) {
GlobalVariable *GV = M.getGlobalVariable(Name);
SmallPtrSet<Constant *, 16> InitAsSet;
SmallVector<Constant *, 16> Init;
if (GV) {
ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
for (auto &Op : CA->operands()) {
Constant *C = cast_or_null<Constant>(Op);
if (InitAsSet.insert(C).second)
Init.push_back(C);
}
GV->eraseFromParent();
}
Type *Int8PtrTy = llvm::Type::getInt8PtrTy(M.getContext());
for (auto *V : Values) {
Constant *C = ConstantExpr::getBitCast(V, Int8PtrTy);
if (InitAsSet.insert(C).second)
Init.push_back(C);
}
if (Init.empty())
return;
ArrayType *ATy = ArrayType::get(Int8PtrTy, Init.size());
GV = new llvm::GlobalVariable(M, ATy, false, GlobalValue::AppendingLinkage,
ConstantArray::get(ATy, Init), Name);
GV->setSection("llvm.metadata");
}
void llvm::appendToUsed(Module &M, ArrayRef<GlobalValue *> Values) {
appendToUsedList(M, "llvm.used", Values);
}
void llvm::appendToCompilerUsed(Module &M, ArrayRef<GlobalValue *> Values) {
appendToUsedList(M, "llvm.compiler.used", Values);
}
Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
if (isa<Function>(FuncOrBitcast))
return cast<Function>(FuncOrBitcast);
FuncOrBitcast->print(errs());
errs() << '\n';
std::string Err;
raw_string_ostream Stream(Err);
Stream << "Sanitizer interface function redefined: " << *FuncOrBitcast;
report_fatal_error(Err);
}
Function *llvm::declareSanitizerInitFunction(Module &M, StringRef InitName,
ArrayRef<Type *> InitArgTypes) {
assert(!InitName.empty() && "Expected init function name");
Function *F = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
InitName,
FunctionType::get(Type::getVoidTy(M.getContext()), InitArgTypes, false),
AttributeList()));
F->setLinkage(Function::ExternalLinkage);
return F;
}
std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
Module &M, StringRef CtorName, StringRef InitName,
ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
StringRef VersionCheckName) {
assert(!InitName.empty() && "Expected init function name");
assert(InitArgs.size() == InitArgTypes.size() &&
"Sanitizer's init function expects different number of arguments");
Function *InitFunction =
declareSanitizerInitFunction(M, InitName, InitArgTypes);
Function *Ctor = Function::Create(
FunctionType::get(Type::getVoidTy(M.getContext()), false),
GlobalValue::InternalLinkage, CtorName, &M);
BasicBlock *CtorBB = BasicBlock::Create(M.getContext(), "", Ctor);
IRBuilder<> IRB(ReturnInst::Create(M.getContext(), CtorBB));
IRB.CreateCall(InitFunction, InitArgs);
if (!VersionCheckName.empty()) {
Function *VersionCheckFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
VersionCheckName, FunctionType::get(IRB.getVoidTy(), {}, false),
AttributeList()));
IRB.CreateCall(VersionCheckFunction, {});
}
return std::make_pair(Ctor, InitFunction);
}
void llvm::filterDeadComdatFunctions(
Module &M, SmallVectorImpl<Function *> &DeadComdatFunctions) {
// Build a map from the comdat to the number of entries in that comdat we
// think are dead. If this fully covers the comdat group, then the entire
// group is dead. If we find another entry in the comdat group though, we'll
// have to preserve the whole group.
SmallDenseMap<Comdat *, int, 16> ComdatEntriesCovered;
for (Function *F : DeadComdatFunctions) {
Comdat *C = F->getComdat();
assert(C && "Expected all input GVs to be in a comdat!");
ComdatEntriesCovered[C] += 1;
}
auto CheckComdat = [&](Comdat &C) {
auto CI = ComdatEntriesCovered.find(&C);
if (CI == ComdatEntriesCovered.end())
return;
// If this could have been covered by a dead entry, just subtract one to
// account for it.
if (CI->second > 0) {
CI->second -= 1;
return;
}
// If we've already accounted for all the entries that were dead, the
// entire comdat is alive so remove it from the map.
ComdatEntriesCovered.erase(CI);
};
auto CheckAllComdats = [&] {
for (Function &F : M.functions())
if (Comdat *C = F.getComdat()) {
CheckComdat(*C);
if (ComdatEntriesCovered.empty())
return;
}
for (GlobalVariable &GV : M.globals())
if (Comdat *C = GV.getComdat()) {
CheckComdat(*C);
if (ComdatEntriesCovered.empty())
return;
}
for (GlobalAlias &GA : M.aliases())
if (Comdat *C = GA.getComdat()) {
CheckComdat(*C);
if (ComdatEntriesCovered.empty())
return;
}
};
CheckAllComdats();
if (ComdatEntriesCovered.empty()) {
DeadComdatFunctions.clear();
return;
}
// Remove the entries that were not covering.
erase_if(DeadComdatFunctions, [&](GlobalValue *GV) {
return ComdatEntriesCovered.find(GV->getComdat()) ==
ComdatEntriesCovered.end();
});
}
std::string llvm::getUniqueModuleId(Module *M) {
MD5 Md5;
bool ExportsSymbols = false;
auto AddGlobal = [&](GlobalValue &GV) {
if (GV.isDeclaration() || GV.getName().startswith("llvm.") ||
!GV.hasExternalLinkage() || GV.hasComdat())
return;
ExportsSymbols = true;
Md5.update(GV.getName());
Md5.update(ArrayRef<uint8_t>{0});
};
for (auto &F : *M)
AddGlobal(F);
for (auto &GV : M->globals())
AddGlobal(GV);
for (auto &GA : M->aliases())
AddGlobal(GA);
for (auto &IF : M->ifuncs())
AddGlobal(IF);
if (!ExportsSymbols)
return "";
MD5::MD5Result R;
Md5.final(R);
SmallString<32> Str;
MD5::stringifyResult(R, Str);
return ("$" + Str).str();
}