1 //===- AssumeBundleBuilder.h - utils to build assume bundles ----*- 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 // 9 // This file contain tools to preserve informations. They should be used before 10 // performing a transformation that may move and delete instructions as those 11 // transformation may destroy or worsen information that can be derived from the 12 // IR. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_TRANSFORMS_UTILS_ASSUMEBUNDLEBUILDER_H 17 #define LLVM_TRANSFORMS_UTILS_ASSUMEBUNDLEBUILDER_H 18 19 #include "llvm/Analysis/AssumeBundleQueries.h" 20 #include "llvm/IR/PassManager.h" 21 #include "llvm/Support/CommandLine.h" 22 23 namespace llvm { 24 class AssumeInst; 25 class Function; 26 class Instruction; 27 class AssumptionCache; 28 class DominatorTree; 29 30 extern cl::opt<bool> EnableKnowledgeRetention; 31 32 /// Build a call to llvm.assume to preserve informations that can be derived 33 /// from the given instruction. 34 /// If no information derived from \p I, this call returns null. 35 /// The returned instruction is not inserted anywhere. 36 AssumeInst *buildAssumeFromInst(Instruction *I); 37 38 /// Calls BuildAssumeFromInst and if the resulting llvm.assume is valid insert 39 /// if before I. This is usually what need to be done to salvage the knowledge 40 /// contained in the instruction I. 41 /// The AssumptionCache must be provided if it is available or the cache may 42 /// become silently be invalid. 43 /// The DominatorTree can optionally be provided to enable cross-block 44 /// reasoning. 45 /// This returns if a change was made. 46 bool salvageKnowledge(Instruction *I, AssumptionCache *AC = nullptr, 47 DominatorTree *DT = nullptr); 48 49 /// Build and return a new assume created from the provided knowledge 50 /// if the knowledge in the assume is fully redundant this will return nullptr 51 AssumeInst *buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge, 52 Instruction *CtxI, 53 AssumptionCache *AC = nullptr, 54 DominatorTree *DT = nullptr); 55 56 /// This pass attempts to minimize the number of assume without loosing any 57 /// information. 58 struct AssumeSimplifyPass : public PassInfoMixin<AssumeSimplifyPass> { 59 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 60 }; 61 62 /// This pass will try to build an llvm.assume for every instruction in the 63 /// function. Its main purpose is testing. 64 struct AssumeBuilderPass : public PassInfoMixin<AssumeBuilderPass> { 65 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 66 }; 67 68 /// canonicalize the RetainedKnowledge RK. it is assumed that RK is part of 69 /// Assume. This will return an empty RetainedKnowledge if the knowledge is 70 /// useless. 71 RetainedKnowledge simplifyRetainedKnowledge(AssumeInst *Assume, 72 RetainedKnowledge RK, 73 AssumptionCache *AC, 74 DominatorTree *DT); 75 76 } // namespace llvm 77 78 #endif 79