include/llvm/Transforms/InstCombine/InstCombine.h

   1 //===- InstCombine.h - InstCombine pass -------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 /// \file
   9 ///
  10 /// This file provides the primary interface to the instcombine pass. This pass
  11 /// is suitable for use in the new pass manager. For a pass that works with the
  12 /// legacy pass manager, use \c createInstructionCombiningPass().
  13 ///
  14 //===----------------------------------------------------------------------===//
  15
  16 #ifndef LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
  17 #define LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
  18
  19 #include "llvm/IR/Function.h"
  20 #include "llvm/IR/PassManager.h"
  21 #include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
  22
  23 namespace llvm {
  24
  25 class InstCombinePass : public PassInfoMixin<InstCombinePass> {
  26   InstCombineWorklist Worklist;
  27   bool ExpensiveCombines;
  28
  29 public:
  30   static StringRef name() { return "InstCombinePass"; }
  31
  32   explicit InstCombinePass(bool ExpensiveCombines = true)
  33       : ExpensiveCombines(ExpensiveCombines) {}
  34
  35   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  36 };
  37
  38 /// The legacy pass manager's instcombine pass.
  39 ///
  40 /// This is a basic whole-function wrapper around the instcombine utility. It
  41 /// will try to combine all instructions in the function.
  42 class InstructionCombiningPass : public FunctionPass {
  43   InstCombineWorklist Worklist;
  44   const bool ExpensiveCombines;
  45
  46 public:
  47   static char ID; // Pass identification, replacement for typeid
  48
  49   InstructionCombiningPass(bool ExpensiveCombines = true)
  50       : FunctionPass(ID), ExpensiveCombines(ExpensiveCombines) {
  51     initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
  52   }
  53
  54   void getAnalysisUsage(AnalysisUsage &AU) const override;
  55   bool runOnFunction(Function &F) override;
  56 };
  57
  58 //===----------------------------------------------------------------------===//
  59 //
  60 // InstructionCombining - Combine instructions to form fewer, simple
  61 // instructions. This pass does not modify the CFG, and has a tendency to make
  62 // instructions dead, so a subsequent DCE pass is useful.
  63 //
  64 // This pass combines things like:
  65 //    %Y = add int 1, %X
  66 //    %Z = add int 1, %Y
  67 // into:
  68 //    %Z = add int 2, %X
  69 //
  70 FunctionPass *createInstructionCombiningPass(bool ExpensiveCombines = true);
  71 }
  72
  73 #endif