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/*========================== begin_copyright_notice ============================
Copyright (C) 2023 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "Compiler/Optimizer/OpenCLPasses/StackOverflowDetection/StackOverflowDetection.hpp"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/CISACodeGen/helper.h"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/MetaDataApi/IGCMetaDataHelper.h"
#include "common/LLVMWarningsPush.hpp"
#include <llvm/IR/Module.h>
#include <llvm/IR/Instructions.h>
#include "common/LLVMWarningsPop.hpp"
using namespace llvm;
using namespace IGC;
// Register pass to igc-opt
#define PASS_FLAG "igc-stackoverflow-detection"
#define PASS_DESCRIPTION "Insert calls to stack overflow detection builtins."
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(StackOverflowDetectionPass, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_END(StackOverflowDetectionPass, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
char StackOverflowDetectionPass::ID = 0;
StackOverflowDetectionPass::StackOverflowDetectionPass() : ModulePass(ID) {
initializeStackOverflowDetectionPassPass(*PassRegistry::getPassRegistry());
}
StackOverflowDetectionPass::StackOverflowDetectionPass(Mode mode_) : StackOverflowDetectionPass() { mode = mode_; }
bool StackOverflowDetectionPass::removeDummyCalls(Module &M) {
std::vector<llvm::Instruction *> ToDeleteInstructions;
for (Function &F : M) {
for (auto &&BB : F) {
for (auto &I : BB) {
if (auto callI = llvm::dyn_cast<llvm::CallInst>(&I)) {
Function *callFunction = callI->getCalledFunction();
if (callFunction) {
auto callFunctionName = callFunction->getName();
if (callFunctionName.startswith(STACK_OVERFLOW_INIT_BUILTIN_NAME) ||
callFunctionName.startswith(STACK_OVERFLOW_DETECTION_BUILTIN_NAME)) {
ToDeleteInstructions.push_back(&I);
}
}
}
}
}
}
for (auto I : ToDeleteInstructions) {
I->eraseFromParent();
}
return !ToDeleteInstructions.empty();
}
bool StackOverflowDetectionPass::removeCallsAndFunctionsIfNoStackCallsOrVLA(Module &M, IGCMD::MetaDataUtils *pMdUtils,
ModuleMetaData *pModMD) {
bool changed = false;
bool HasStackCallsOrVLA = std::any_of(M.getFunctionList().begin(), M.getFunctionList().end(), [](auto &F) {
return F.hasFnAttribute("visaStackCall") || F.hasFnAttribute("hasVLA");
});
if (!HasStackCallsOrVLA) {
for (auto FuncName : {STACK_OVERFLOW_INIT_BUILTIN_NAME, STACK_OVERFLOW_DETECTION_BUILTIN_NAME}) {
if (auto F = M.getFunction(FuncName)) {
std::vector<llvm::CallInst *> CallersToDelete;
for (auto User : F->users()) {
if (auto I = dyn_cast<llvm::CallInst>(User)) {
CallersToDelete.push_back(I);
}
}
std::for_each(CallersToDelete.begin(), CallersToDelete.end(),
[](auto CallInst) { CallInst->eraseFromParent(); });
changed = true;
IGCMD::IGCMetaDataHelper::removeFunction(*pMdUtils, *pModMD, F);
F->removeDeadConstantUsers();
F->eraseFromParent();
}
}
}
return changed;
}
bool StackOverflowDetectionPass::runOnModule(Module &M) {
if (IGC_IS_FLAG_DISABLED(StackOverflowDetection)) {
return false;
}
bool changed = false;
auto &MDUWAnalysis = getAnalysis<MetaDataUtilsWrapper>();
auto pMdUtils = MDUWAnalysis.getMetaDataUtils();
auto pModMD = MDUWAnalysis.getModuleMetaData();
const bool isLibraryCompilation = pModMD->compOpt.IsLibraryCompilation;
// The pass is designed to be run at least two times.
// In the first run (Mode::Initialize) it inserts the detection functions
// to entry points without analysis if they are really needed,
// as it is not possible at this stage - it is meant to be called before BIImport
// and PrintfResoulution passes, as the implementation of the detection functions is in the
// builtin module. So the first run is before inlining and we are not sure if stack calls will be present.
// Also VLAs can be optimized later in the compilation.
//
// The next run (Mode::AnalyzeAndCleanup) of this pass is meant to cleanup the calls if they are not really needed.
//
// Third run (Mode::RemoveDummyCalls) removes previously inserted calls to __stackoverflow_init and
// __stackoverflow_detection. These will be inserted again in EmitVisaPass and it's impossible to do it
// correctly before this pass.
// Two dummy calls that we insterted in Mode::Initialize run were there to prevent dead code elimination
// of __stackoverflow_init and __stackoverflow_detection implementations before reaching EmitVisaPass.
if (mode == Mode::RemoveDummyCalls || mode == Mode::AnalyzeAndCleanup) {
if (mode == Mode::RemoveDummyCalls) {
changed = removeDummyCalls(M);
} else {
changed = removeCallsAndFunctionsIfNoStackCallsOrVLA(M, pMdUtils, pModMD);
}
if (changed) {
CodeGenContext *pContext = getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
pMdUtils->save(*pContext->getLLVMContext());
}
return changed;
}
IGC_ASSERT(mode == Mode::Initialize);
for (Function &F : M) {
const bool isEntryFunction = isEntryFunc(pMdUtils, &F);
if (isEntryFunction || isLibraryCompilation) {
if (F.isDeclaration())
continue;
IGCLLVM::IRBuilder<> builder(&*F.begin()->begin());
if (isEntryFunction) {
auto StackOverflowInitFunc = M.getOrInsertFunction(
STACK_OVERFLOW_INIT_BUILTIN_NAME, FunctionType::get(Type::getVoidTy(M.getContext()), {}, false));
Function *Callee = cast<Function>(StackOverflowInitFunc.getCallee());
IGC_ASSERT(Callee);
auto InitCall = builder.CreateCall(Callee);
InitCall->setCallingConv(CallingConv::SPIR_FUNC);
}
auto StackOverflowDetectionFunc = M.getOrInsertFunction(
STACK_OVERFLOW_DETECTION_BUILTIN_NAME, FunctionType::get(Type::getVoidTy(M.getContext()), {}, false));
Function *Callee = cast<Function>(StackOverflowDetectionFunc.getCallee());
IGC_ASSERT(Callee);
auto CallInst = builder.CreateCall(Callee);
CallInst->setCallingConv(CallingConv::SPIR_FUNC);
changed = true;
}
}
return changed;
}
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