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https://github.com/revng/revng
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Alvise de Faveri
8230d91da7
* RemoveExtractValues transforms every `extractvalue` instruction into an opaque call. This prevents the optimization pipeline from moving around and optimizing `extractvalue`s, since they have a particular meaning in our IR * RestoreExtractValues transforms such opaque calls back to regular `extractvalue`s at the end of the pipeline
78 lines
2.4 KiB
C++
78 lines
2.4 KiB
C++
//
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// Copyright rev.ng Srls. See LICENSE.md for details.
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//
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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#include "revng/Support/Assert.h"
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#include "revng/Support/FunctionTags.h"
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#include "revng/Support/IRHelpers.h"
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#include "revng/Support/OpaqueFunctionsPool.h"
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#include "revng-c/RemoveExtractValues/RemoveExtractValuesPass.h"
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#include "revng-c/Support/FunctionTags.h"
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using namespace llvm;
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char RemoveExtractValues::ID = 0;
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using Reg = RegisterPass<RemoveExtractValues>;
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static Reg X("remove-extractvalues",
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"Substitute extractvalues with opaque calls so that they don't "
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"get optimized",
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true,
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true);
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bool RemoveExtractValues::runOnFunction(llvm::Function &F) {
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using namespace llvm;
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// Collect all ExtractValues
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SmallVector<ExtractValueInst *, 16> ToReplace;
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for (auto &BB : F)
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for (auto &I : BB)
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if (auto *ExtractVal = llvm::dyn_cast<llvm::ExtractValueInst>(&I))
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ToReplace.push_back(ExtractVal);
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if (ToReplace.empty())
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return false;
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// Create a pool of functions with the same behavior: we will need a different
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// function for each different struct
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OpaqueFunctionsPool<llvm::Type *>
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OpaqueEVPool(F.getParent(), /* PurgeOnDestruction */ false);
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initOpaqueEVPool(OpaqueEVPool);
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llvm::LLVMContext &LLVMCtx = F.getContext();
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IRBuilder<> Builder(LLVMCtx);
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for (ExtractValueInst *I : ToReplace) {
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Builder.SetInsertPoint(I);
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// Collect arguments of the ExtractValue
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SmallVector<Value *, 8> ArgValues = { I->getAggregateOperand() };
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for (auto Idx : I->indices()) {
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auto *IndexVal = ConstantInt::get(IntegerType::getInt64Ty(LLVMCtx), Idx);
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ArgValues.push_back(IndexVal);
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}
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// Get or generate the function
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auto *EVFunctionType = getOpaqueEVFunctionType(F.getContext(), I);
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auto *ExtractValueFunction = OpaqueEVPool.get(EVFunctionType,
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EVFunctionType,
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"OpaqueExtractvalue");
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// Emit a call to the new function
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CallInst *InjectedCall = Builder.CreateCall(ExtractValueFunction,
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ArgValues);
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I->replaceAllUsesWith(InjectedCall);
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InjectedCall->copyMetadata(*I);
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I->eraseFromParent();
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}
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return true;
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}
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