mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Alessandro Di Federico
77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
/// \file RemoveHelperCalls.cpp
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/// Remove calls to helpers in a function and replaces them with stores of an
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/// opaque value onto the CSVs clobbered by the helper.
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//
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// This file is distributed under the MIT License. See LICENSE.md for details.
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//
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#include "llvm/ADT/SmallVector.h"
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#include "revng/BasicAnalyses/RemoveHelperCalls.h"
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#include "revng/Support/IRHelpers.h"
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#include "revng/Support/OpaqueRegisterUser.h"
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static bool isCallToAbort(const llvm::Instruction *I) {
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const llvm::Function *Callee = getCallee(I);
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return Callee and (Callee->getName() == AbortFunctionName);
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}
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llvm::PreservedAnalyses
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RemoveHelperCallsPass::run(llvm::Function &F,
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llvm::FunctionAnalysisManager &FAM) {
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using namespace llvm;
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// Get the result of the GCBI analysis
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GCBI = &(FAM.getResult<GeneratedCodeBasicInfoAnalysis>(F));
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revng_assert(GCBI != nullptr);
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SmallVector<Instruction *, 16> ToReplace;
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for (auto &BB : F)
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for (auto &I : BB)
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if (isCallToHelper(&I) and not isCallToAbort(&I))
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ToReplace.push_back(&I);
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bool Changed = not ToReplace.empty();
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if (!Changed)
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return PreservedAnalyses::all();
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OpaqueRegisterUser Clobberer(F.getParent());
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OpaqueFunctionsPool<Type *> OFPOriginalHelper(F.getParent(), false);
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OFPOriginalHelper.setMemoryEffects(MemoryEffects::readOnly());
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OFPOriginalHelper.addFnAttribute(Attribute::NoUnwind);
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OFPOriginalHelper.addFnAttribute(Attribute::WillReturn);
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OFPOriginalHelper.setTags({ &FunctionTags::UniquedByPrototype });
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// TODO: the checks should be enabled conditionally based on the user.
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revng::NonDebugInfoCheckingIRBuilder Builder(F.getContext());
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for (auto *I : ToReplace) {
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Builder.SetInsertPoint(I);
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// Assumption: helpers do not leave the stack altered, thus we can save the
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// stack pointer and restore it back later.
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auto *SP = createLoad(Builder, GCBI->spReg());
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auto *RetTy = cast<CallInst>(I)->getFunctionType()->getReturnType();
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auto *OriginalHelperMarker = OFPOriginalHelper.get(RetTy,
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RetTy,
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{},
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"original_helper");
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// Create opaque helper for the original helper and taint the registers
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// originally clobbered.
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CallInst *NewHelper = Builder.CreateCall(OriginalHelperMarker);
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for (auto *CSV : getCSVUsedByHelperCall(I).Written)
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Clobberer.clobber(Builder, CSV);
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// Restore stack pointer back.
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Builder.CreateStore(SP, GCBI->spReg());
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I->replaceAllUsesWith(NewHelper);
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I->eraseFromParent();
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}
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return PreservedAnalyses::none();
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}
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