Transforms/Utils/AssumeBundleBuilder.h

0001 //===- AssumeBundleBuilder.h - utils to build assume bundles ----*- C++ -*-===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008 //
0009 // This file contain tools to preserve informations. They should be used before
0010 // performing a transformation that may move and delete instructions as those
0011 // transformation may destroy or worsen information that can be derived from the
0012 // IR.
0013 //
0014 //===----------------------------------------------------------------------===//
0015
0016 #ifndef LLVM_TRANSFORMS_UTILS_ASSUMEBUNDLEBUILDER_H
0017 #define LLVM_TRANSFORMS_UTILS_ASSUMEBUNDLEBUILDER_H
0018
0019 #include "llvm/Analysis/AssumeBundleQueries.h"
0020 #include "llvm/IR/PassManager.h"
0021 #include "llvm/Support/CommandLine.h"
0022
0023 namespace llvm {
0024 class AssumeInst;
0025 class Function;
0026 class Instruction;
0027 class AssumptionCache;
0028 class DominatorTree;
0029
0030 extern cl::opt<bool> EnableKnowledgeRetention;
0031
0032 /// Build a call to llvm.assume to preserve informations that can be derived
0033 /// from the given instruction.
0034 /// If no information derived from \p I, this call returns null.
0035 /// The returned instruction is not inserted anywhere.
0036 AssumeInst *buildAssumeFromInst(Instruction *I);
0037
0038 /// Calls BuildAssumeFromInst and if the resulting llvm.assume is valid insert
0039 /// if before I. This is usually what need to be done to salvage the knowledge
0040 /// contained in the instruction I.
0041 /// The AssumptionCache must be provided if it is available or the cache may
0042 /// become silently be invalid.
0043 /// The DominatorTree can optionally be provided to enable cross-block
0044 /// reasoning.
0045 /// This returns if a change was made.
0046 bool salvageKnowledge(Instruction *I, AssumptionCache *AC = nullptr,
0047                       DominatorTree *DT = nullptr);
0048
0049 /// Build and return a new assume created from the provided knowledge
0050 /// if the knowledge in the assume is fully redundant this will return nullptr
0051 AssumeInst *buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge,
0052                                      Instruction *CtxI,
0053                                      AssumptionCache *AC = nullptr,
0054                                      DominatorTree *DT = nullptr);
0055
0056 /// This pass attempts to minimize the number of assume without loosing any
0057 /// information.
0058 struct AssumeSimplifyPass : public PassInfoMixin<AssumeSimplifyPass> {
0059   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
0060 };
0061
0062 /// This pass will try to build an llvm.assume for every instruction in the
0063 /// function. Its main purpose is testing.
0064 struct AssumeBuilderPass : public PassInfoMixin<AssumeBuilderPass> {
0065   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
0066 };
0067
0068 /// canonicalize the RetainedKnowledge RK. it is assumed that RK is part of
0069 /// Assume. This will return an empty RetainedKnowledge if the knowledge is
0070 /// useless.
0071 RetainedKnowledge simplifyRetainedKnowledge(AssumeInst *Assume,
0072                                             RetainedKnowledge RK,
0073                                             AssumptionCache *AC,
0074                                             DominatorTree *DT);
0075
0076 } // namespace llvm
0077
0078 #endif