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 22 #define DEBUG_TYPE "instcombine" 23 #include "llvm/Transforms/Utils/InstructionWorklist.h" 24 25 namespace llvm { 26 27 class InstCombinePass : public PassInfoMixin<InstCombinePass> { 28 InstructionWorklist Worklist; 29 const unsigned MaxIterations; 30 31 public: 32 explicit InstCombinePass(); 33 explicit InstCombinePass(unsigned MaxIterations); 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 InstructionWorklist Worklist; 44 const unsigned MaxIterations; 45 46 public: 47 static char ID; // Pass identification, replacement for typeid 48 49 explicit InstructionCombiningPass(); 50 explicit InstructionCombiningPass(unsigned MaxIterations); 51 52 void getAnalysisUsage(AnalysisUsage &AU) const override; 53 bool runOnFunction(Function &F) override; 54 }; 55 56 //===----------------------------------------------------------------------===// 57 // 58 // InstructionCombining - Combine instructions to form fewer, simple 59 // instructions. This pass does not modify the CFG, and has a tendency to make 60 // instructions dead, so a subsequent DCE pass is useful. 61 // 62 // This pass combines things like: 63 // %Y = add int 1, %X 64 // %Z = add int 1, %Y 65 // into: 66 // %Z = add int 2, %X 67 // 68 FunctionPass *createInstructionCombiningPass(); 69 FunctionPass *createInstructionCombiningPass(unsigned MaxIterations); 70 } 71 72 #undef DEBUG_TYPE 73 74 #endif 75