mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Pietro Fezzardi
105 lines
3.1 KiB
C++
105 lines
3.1 KiB
C++
//
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// Copyright (c) rev.ng Srls. See LICENSE.md for details.
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//
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/InstIterator.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/Casting.h"
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#include "revng/Model/LoadModelPass.h"
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#include "revng/Support/FunctionTags.h"
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#include "revng-c/Decompiler/MarkForSerialization.h"
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struct AddSCEVBarrierPass : public llvm::FunctionPass {
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static char ID;
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AddSCEVBarrierPass() : llvm::FunctionPass(ID) {}
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bool runOnFunction(llvm::Function &F) override;
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void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
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AU.addRequired<LoadModelWrapperPass>();
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AU.addUsedIfAvailable<MarkForSerializationPass>();
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AU.setPreservesAll();
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}
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};
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char AddSCEVBarrierPass::ID = 0;
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using Pass = AddSCEVBarrierPass;
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using llvm::RegisterPass;
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static RegisterPass<Pass> X("add-scev-barrier", "Pass to add SCEV barriers");
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static std::string makeTypeName(const llvm::Type *Ty) {
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std::string Name;
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if (auto *PtrTy = llvm::dyn_cast<llvm::PointerType>(Ty)) {
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Name = "ptr_to_" + makeTypeName(PtrTy->getElementType());
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} else if (auto *IntTy = llvm::dyn_cast<llvm::IntegerType>(Ty)) {
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Name = "i" + std::to_string(IntTy->getBitWidth());
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} else {
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revng_unreachable("cannot build Type name");
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}
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return Name;
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}
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std::string makeSCEVBarrierName(const llvm::Type *Ty) {
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return "revng_scev_barrier_" + makeTypeName(Ty);
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}
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bool AddSCEVBarrierPass::runOnFunction(llvm::Function &F) {
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// Skip non-isolated functions
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auto FTags = FunctionTags::TagsSet::from(&F);
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if (not FTags.contains(FunctionTags::Lifted))
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return false;
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// If the MarkForSerializationPass was not executed, we have nothing to do.
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auto *MarkPass = getAnalysisIfAvailable<MarkForSerializationPass>();
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if (not MarkPass)
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return false;
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const auto &MarkMap = MarkPass->getMap();
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llvm::Module *M = F.getParent();
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llvm::IRBuilder<> Builder(M->getContext());
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bool Changed = false;
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for (auto &I : llvm::instructions(&F)) {
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// Check if I was marked for serialization, and skip it if it wasn't marked.
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auto MarkIt = MarkMap.find(&I);
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if (MarkIt == MarkMap.end())
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continue;
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// If it was marked for serialization, see how.
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const SerializationFlags &Flags = MarkIt->second;
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auto *IType = I.getType();
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if (SerializationFlags::mustBeSerialized(Flags) and IType->isIntOrPtrTy()) {
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// Get the SCEV barrier function associated with IType
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auto BarrierName = makeSCEVBarrierName(IType);
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auto SCEVBarrierF = M->getOrInsertFunction(BarrierName, IType, IType);
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// Insert a call to the SCEV barrier right after I. For now the call to
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// barrier has an undef argument, that will be fixed later.
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Builder.SetInsertPoint(I.getParent(), std::next(I.getIterator()));
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auto *Undef = llvm::UndefValue::get(IType);
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auto *Call = Builder.CreateCall(SCEVBarrierF, Undef);
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// Replace all uses of I with the new call.
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I.replaceAllUsesWith(Call);
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// Now Fix the call to use I as argument.
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Call->setArgOperand(0, &I);
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Changed = true;
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}
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}
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return Changed;
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}
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