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 static constexpr unsigned InstCombineDefaultMaxIterations = 1; 29 30 struct InstCombineOptions { 31 // Verify that a fix point has been reached after MaxIterations. 32 bool VerifyFixpoint = false; 33 unsigned MaxIterations = InstCombineDefaultMaxIterations; 34 35 InstCombineOptions() = default; 36 37 InstCombineOptions &setVerifyFixpoint(bool Value) { 38 VerifyFixpoint = Value; 39 return *this; 40 } 41 42 InstCombineOptions &setMaxIterations(unsigned Value) { 43 MaxIterations = Value; 44 return *this; 45 } 46 }; 47 48 class InstCombinePass : public PassInfoMixin<InstCombinePass> { 49 private: 50 InstructionWorklist Worklist; 51 InstCombineOptions Options; 52 static char ID; 53 54 public: 55 explicit InstCombinePass(InstCombineOptions Opts = {}); 56 void printPipeline(raw_ostream &OS, 57 function_ref<StringRef(StringRef)> MapClassName2PassName); 58 59 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 60 }; 61 62 /// The legacy pass manager's instcombine pass. 63 /// 64 /// This is a basic whole-function wrapper around the instcombine utility. It 65 /// will try to combine all instructions in the function. 66 class InstructionCombiningPass : public FunctionPass { 67 InstructionWorklist Worklist; 68 69 public: 70 static char ID; // Pass identification, replacement for typeid 71 72 explicit InstructionCombiningPass(); 73 74 void getAnalysisUsage(AnalysisUsage &AU) const override; 75 bool runOnFunction(Function &F) override; 76 }; 77 78 //===----------------------------------------------------------------------===// 79 // 80 // InstructionCombining - Combine instructions to form fewer, simple 81 // instructions. This pass does not modify the CFG, and has a tendency to make 82 // instructions dead, so a subsequent DCE pass is useful. 83 // 84 // This pass combines things like: 85 // %Y = add int 1, %X 86 // %Z = add int 1, %Y 87 // into: 88 // %Z = add int 2, %X 89 // 90 FunctionPass *createInstructionCombiningPass(); 91 } 92 93 #undef DEBUG_TYPE 94 95 #endif 96