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/Pass.h" 22 23 #define DEBUG_TYPE "instcombine" 24 #include "llvm/Transforms/Utils/InstructionWorklist.h" 25 26 namespace llvm { 27 28 class InstCombinePass : public PassInfoMixin<InstCombinePass> { 29 InstructionWorklist Worklist; 30 const unsigned MaxIterations; 31 32 public: 33 explicit InstCombinePass(); 34 explicit InstCombinePass(unsigned MaxIterations); 35 36 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 37 }; 38 39 /// The legacy pass manager's instcombine pass. 40 /// 41 /// This is a basic whole-function wrapper around the instcombine utility. It 42 /// will try to combine all instructions in the function. 43 class InstructionCombiningPass : public FunctionPass { 44 InstructionWorklist Worklist; 45 const unsigned MaxIterations; 46 47 public: 48 static char ID; // Pass identification, replacement for typeid 49 50 explicit InstructionCombiningPass(); 51 explicit InstructionCombiningPass(unsigned MaxIterations); 52 53 void getAnalysisUsage(AnalysisUsage &AU) const override; 54 bool runOnFunction(Function &F) override; 55 }; 56 57 //===----------------------------------------------------------------------===// 58 // 59 // InstructionCombining - Combine instructions to form fewer, simple 60 // instructions. This pass does not modify the CFG, and has a tendency to make 61 // instructions dead, so a subsequent DCE pass is useful. 62 // 63 // This pass combines things like: 64 // %Y = add int 1, %X 65 // %Z = add int 1, %Y 66 // into: 67 // %Z = add int 2, %X 68 // 69 FunctionPass *createInstructionCombiningPass(); 70 FunctionPass *createInstructionCombiningPass(unsigned MaxIterations); 71 } 72 73 #undef DEBUG_TYPE 74 75 #endif 76