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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
72 lines
1.9 KiB
C++
72 lines
1.9 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/STLExtras.h"
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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/RestoreExtractValuesPass.h"
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#include "revng-c/Support/FunctionTags.h"
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using namespace llvm;
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char RestoreExtractValues::ID = 0;
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using Reg = RegisterPass<RestoreExtractValues>;
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static Reg X("restore-extractvalues",
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"Substitute extractvalue() calls with actual extractvalues",
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true,
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true);
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static bool isOpaqueExtractValue(llvm::Instruction *I) {
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if (auto *Call = llvm::dyn_cast<llvm::CallInst>(I))
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if (auto *CalledFunc = Call->getCalledFunction())
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return FunctionTags::OpaqueExtractValue.isTagOf(CalledFunc);
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return false;
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}
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bool RestoreExtractValues::runOnFunction(llvm::Function &F) {
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using namespace llvm;
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// Collect all ExtractValues
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SmallVector<CallInst *, 16> ToReplace;
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for (auto &BB : F)
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for (auto &I : BB)
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if (isOpaqueExtractValue(&I))
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ToReplace.push_back(llvm::cast<CallInst>(&I));
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if (ToReplace.empty())
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return false;
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llvm::LLVMContext &LLVMCtx = F.getContext();
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IRBuilder<> Builder(LLVMCtx);
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for (CallInst *I : ToReplace) {
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Builder.SetInsertPoint(I);
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// Collect the indices values
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SmallVector<unsigned int, 8> Indexes;
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for (auto &Op : llvm::drop_begin(I->arg_operands())) {
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uint64_t Idx = llvm::cast<ConstantInt>(&Op)->getValue().getLimitedValue();
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Indexes.push_back(Idx);
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}
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// Emit extractvalue
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auto *Injected = Builder.CreateExtractValue(I->getArgOperand(0), Indexes);
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I->replaceAllUsesWith(Injected);
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I->eraseFromParent();
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}
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return true;
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}
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