InstCombine.h

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//===- InstCombine.h - InstCombine pass -------------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file provides the primary interface to the instcombine pass. This pass
/// is suitable for use in the new pass manager. For a pass that works with the
/// legacy pass manager, use \c createInstructionCombiningPass().
///
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
#define LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
 
#include "llvm/IR/Function.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
 
#define DEBUG_TYPE "instcombine"
#include "llvm/Transforms/Utils/InstructionWorklist.h"
 
namespace llvm {
 
static constexpr unsigned InstCombineDefaultMaxIterations = 1000;
 
struct InstCombineOptions {
  bool UseLoopInfo = false;
  unsigned MaxIterations = InstCombineDefaultMaxIterations;
 
  InstCombineOptions() = default;
 
  InstCombineOptions &setUseLoopInfo(bool Value) {
    UseLoopInfo = Value;
    return *this;
  }
 
  InstCombineOptions &setMaxIterations(unsigned Value) {
    MaxIterations = Value;
    return *this;
  }
};
 
class InstCombinePass : public PassInfoMixin<InstCombinePass> {
private:
  InstructionWorklist Worklist;
  InstCombineOptions Options;
 
public:
  explicit InstCombinePass(InstCombineOptions Opts = {});
  void printPipeline(raw_ostream &OS,
                     function_ref<StringRef(StringRef)> MapClassName2PassName);
 
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
};
 
/// The legacy pass manager's instcombine pass.
///
/// This is a basic whole-function wrapper around the instcombine utility. It
/// will try to combine all instructions in the function.
class InstructionCombiningPass : public FunctionPass {
  InstructionWorklist Worklist;
  const unsigned MaxIterations;
 
public:
  static char ID; // Pass identification, replacement for typeid
 
  explicit InstructionCombiningPass();
  explicit InstructionCombiningPass(unsigned MaxIterations);
 
  void getAnalysisUsage(AnalysisUsage &AU) const override;
  bool runOnFunction(Function &F) override;
};
 
//===----------------------------------------------------------------------===//
//
// InstructionCombining - Combine instructions to form fewer, simple
// instructions. This pass does not modify the CFG, and has a tendency to make
// instructions dead, so a subsequent DCE pass is useful.
//
// This pass combines things like:
//    %Y = add int 1, %X
//    %Z = add int 1, %Y
// into:
//    %Z = add int 2, %X
//
FunctionPass *createInstructionCombiningPass();
FunctionPass *createInstructionCombiningPass(unsigned MaxIterations);
}
 
#undef DEBUG_TYPE
 
#endif