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//===-- Instrumentation.cpp - TransformUtils Infrastructure ---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the common initialization infrastructure for the
// Instrumentation library.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/Instrumentation.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/TargetParser/Triple.h"
using namespace llvm;
static cl::opt<bool> ClIgnoreRedundantInstrumentation(
"ignore-redundant-instrumentation",
cl::desc("Ignore redundant instrumentation"), cl::Hidden, cl::init(false));
/// Check if module has flag attached, if not add the flag.
bool llvm::checkIfAlreadyInstrumented(Module &M, StringRef Flag) {
if (!M.getModuleFlag(Flag)) {
M.addModuleFlag(Module::ModFlagBehavior::Override, Flag, 1);
return false;
}
if (ClIgnoreRedundantInstrumentation)
return true;
std::string diagInfo =
"Redundant instrumentation detected, with module flag: " +
std::string(Flag);
M.getContext().diagnose(
DiagnosticInfoInstrumentation(diagInfo, DiagnosticSeverity::DS_Warning));
return true;
}
/// Moves I before IP. Returns new insert point.
static BasicBlock::iterator moveBeforeInsertPoint(BasicBlock::iterator I,
BasicBlock::iterator IP) {
// If I is IP, move the insert point down.
if (I == IP) {
++IP;
} else {
// Otherwise, move I before IP and return IP.
I->moveBefore(IP);
}
return IP;
}
/// Instrumentation passes often insert conditional checks into entry blocks.
/// Call this function before splitting the entry block to move instructions
/// that must remain in the entry block up before the split point. Static
/// allocas and llvm.localescape calls, for example, must remain in the entry
/// block.
BasicBlock::iterator llvm::PrepareToSplitEntryBlock(BasicBlock &BB,
BasicBlock::iterator IP) {
assert(&BB.getParent()->getEntryBlock() == &BB);
for (auto I = IP, E = BB.end(); I != E; ++I) {
bool KeepInEntry = false;
if (auto *AI = dyn_cast<AllocaInst>(I)) {
if (AI->isStaticAlloca())
KeepInEntry = true;
} else if (auto *II = dyn_cast<IntrinsicInst>(I)) {
if (II->getIntrinsicID() == llvm::Intrinsic::localescape)
KeepInEntry = true;
}
if (KeepInEntry)
IP = moveBeforeInsertPoint(I, IP);
}
return IP;
}
// Create a constant for Str so that we can pass it to the run-time lib.
GlobalVariable *llvm::createPrivateGlobalForString(Module &M, StringRef Str,
bool AllowMerging,
Twine NamePrefix) {
Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
// We use private linkage for module-local strings. If they can be merged
// with another one, we set the unnamed_addr attribute.
GlobalVariable *GV =
new GlobalVariable(M, StrConst->getType(), true,
GlobalValue::PrivateLinkage, StrConst, NamePrefix);
if (AllowMerging)
GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
GV->setAlignment(Align(1)); // Strings may not be merged w/o setting
// alignment explicitly.
return GV;
}
Comdat *llvm::getOrCreateFunctionComdat(Function &F, Triple &T) {
if (auto Comdat = F.getComdat())
return Comdat;
assert(F.hasName());
Module *M = F.getParent();
// Make a new comdat for the function. Use the "no duplicates" selection kind
// if the object file format supports it. For COFF we restrict it to non-weak
// symbols.
Comdat *C = M->getOrInsertComdat(F.getName());
if (T.isOSBinFormatELF() || (T.isOSBinFormatCOFF() && !F.isWeakForLinker()))
C->setSelectionKind(Comdat::NoDeduplicate);
F.setComdat(C);
return C;
}
void llvm::setGlobalVariableLargeSection(const Triple &TargetTriple,
GlobalVariable &GV) {
// Limit to x86-64 ELF.
if (TargetTriple.getArch() != Triple::x86_64 ||
TargetTriple.getObjectFormat() != Triple::ELF)
return;
// Limit to medium/large code models.
std::optional<CodeModel::Model> CM = GV.getParent()->getCodeModel();
if (!CM || (*CM != CodeModel::Medium && *CM != CodeModel::Large))
return;
GV.setCodeModel(CodeModel::Large);
}
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