mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Pietro Fezzardi
df3bd470a1
Various parts of revng replace `llvm::GlobalVariable`s representing CSVs with Allocal/Load/Store. In particular, these are PromoteCSV, RootAnalyzer and PromoteGlobalToLocalVars. Before this commit, those places were sloppy when replacing CSVs with Alloca/Load/Store, and did that iterating on a container sorted by pointers. This caused Alloca/Load/Store to be emitted in different order accross runs, which in turn caused more non-determinism down the pipeline. This commit fixes the non-deterministic behavior, sorting CSVs based on their names, which should always be present and deterministic.
54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
/// \file PromoteGlobalToLocalVars.cpp
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/// Promote CSVs in form of global variables to local variables.
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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/STLExtras.h"
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#include "llvm/IR/IRBuilder.h"
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#include "revng/EarlyFunctionAnalysis/PromoteGlobalToLocalVars.h"
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#include "revng/Support/IRHelpers.h"
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#include "revng/Support/OpaqueRegisterUser.h"
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using namespace llvm;
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llvm::PreservedAnalyses
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PromoteGlobalToLocalPass::run(llvm::Function &F,
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llvm::FunctionAnalysisManager &FAM) {
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// Collect the CSVs used by the current function.
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std::map<GlobalVariable *, Value *> CSVMap;
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for (auto &BB : F) {
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for (auto &I : BB) {
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Value *Pointer = nullptr;
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if (auto *Load = dyn_cast<LoadInst>(&I))
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Pointer = skipCasts(Load->getPointerOperand());
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else if (auto *Store = dyn_cast<StoreInst>(&I))
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Pointer = skipCasts(Store->getPointerOperand());
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else
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continue;
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if (auto *CSV = dyn_cast_or_null<GlobalVariable>(Pointer))
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CSVMap.try_emplace(CSV);
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}
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}
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// Create an equivalent local variable, replace all the uses of the CSV.
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IRBuilder<> Builder(&F.getEntryBlock().front());
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for (GlobalVariable *CSV : toSortedByName(llvm::make_first_range(CSVMap))) {
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auto *CSVTy = CSV->getValueType();
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auto *Alloca = Builder.CreateAlloca(CSVTy, nullptr, CSV->getName());
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replaceAllUsesInFunctionWith(&F, CSV, Alloca);
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CSVMap[CSV] = Alloca;
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}
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// Load all the CSVs and store their value onto the local variables.
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for (const auto &[CSV, Alloca] : CSVMap)
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Builder.CreateStore(createLoad(Builder, CSV), Alloca);
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return PreservedAnalyses::none();
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}
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