llvm/llvm/lib/Transforms/Scalar/DCE.cpp

//===- DCE.cpp - Code to perform dead code elimination --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements dead inst elimination and dead code elimination.
//
// Dead Inst Elimination performs a single pass over the function removing
// instructions that are obviously dead.  Dead Code Elimination is similar, but
// it rechecks instructions that were used by removed instructions to see if
// they are newly dead.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Scalar/DCE.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/DebugCounter.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
usingnamespacellvm;

#define DEBUG_TYPE …

STATISTIC(DCEEliminated, "Number of insts removed");
DEBUG_COUNTER(DCECounter, "dce-transform",
              "Controls which instructions are eliminated");

PreservedAnalyses
RedundantDbgInstEliminationPass::run(Function &F, FunctionAnalysisManager &AM) { … }

//===--------------------------------------------------------------------===//
// DeadCodeElimination pass implementation
//

static bool DCEInstruction(Instruction *I,
                           SmallSetVector<Instruction *, 16> &WorkList,
                           const TargetLibraryInfo *TLI) { … }

static bool eliminateDeadCode(Function &F, TargetLibraryInfo *TLI) { … }

PreservedAnalyses DCEPass::run(Function &F, FunctionAnalysisManager &AM) { … }

namespace {
struct DCELegacyPass : public FunctionPass { … };
}

char DCELegacyPass::ID = …;
INITIALIZE_PASS(…)

FunctionPass *llvm::createDeadCodeEliminationPass() { … }