3a0c95fb50
After replacing the branch condition, this was calling simplifyCFG to perform the cleanups of the branch. This is far too heavy of a hammer. We do not want all of the extra optimizations in simplifyCFG, and this could also leave behind dead code. Instead, minimally fold the terminator and try to delete the newly dead code. This is pretty much a direct copy of what bugpoint does.
77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
//===- ReduceUsingSimplifyCFG.h - Specialized Delta Pass ------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a function which calls the Generic Delta pass in order
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// to call SimplifyCFG on individual basic blocks.
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//
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//===----------------------------------------------------------------------===//
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#include "ReduceUsingSimplifyCFG.h"
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#include "Utils.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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void llvm::reduceUsingSimplifyCFGDeltaPass(Oracle &O,
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ReducerWorkItem &WorkItem) {
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Module &Program = WorkItem.getModule();
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SmallVector<BasicBlock *, 16> ToSimplify;
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for (auto &F : Program)
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for (auto &BB : F)
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if (!O.shouldKeep())
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ToSimplify.push_back(&BB);
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TargetTransformInfo TTI(Program.getDataLayout());
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for (auto *BB : ToSimplify)
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simplifyCFG(BB, TTI);
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}
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static void reduceConditionals(Oracle &O, ReducerWorkItem &WorkItem,
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bool Direction) {
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Module &M = WorkItem.getModule();
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LLVMContext &Ctx = M.getContext();
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ConstantInt *ConstValToSet =
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Direction ? ConstantInt::getTrue(Ctx) : ConstantInt::getFalse(Ctx);
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for (Function &F : M) {
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if (F.isDeclaration())
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continue;
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SmallVector<BasicBlock *, 16> ToSimplify;
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for (auto &BB : F) {
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auto *BR = dyn_cast<BranchInst>(BB.getTerminator());
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if (!BR || !BR->isConditional() || BR->getCondition() == ConstValToSet ||
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O.shouldKeep())
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continue;
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BR->setCondition(ConstValToSet);
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ToSimplify.push_back(&BB);
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}
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if (!ToSimplify.empty()) {
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// TODO: Should probably leave MergeBlockIntoPredecessor for a separate
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// reduction
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simpleSimplifyCFG(F, ToSimplify);
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}
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}
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}
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void llvm::reduceConditionalsTrueDeltaPass(Oracle &O,
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ReducerWorkItem &WorkItem) {
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reduceConditionals(O, WorkItem, true);
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}
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void llvm::reduceConditionalsFalseDeltaPass(Oracle &O,
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ReducerWorkItem &WorkItem) {
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reduceConditionals(O, WorkItem, false);
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}
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