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/Attributes.h"
21 #include "llvm/IR/Instruction.h"
22 #include "llvm/IR/PassManager.h"
23 
24 namespace llvm {
25 class IntrinsicInst;
26 class AssumptionCache;
27 class DominatorTree;
28 
29 /// Build a call to llvm.assume to preserve informations that can be derived
30 /// from the given instruction.
31 /// If no information derived from \p I, this call returns null.
32 /// The returned instruction is not inserted anywhere.
33 AssumeInst *buildAssumeFromInst(Instruction *I);
34 
35 /// Calls BuildAssumeFromInst and if the resulting llvm.assume is valid insert
36 /// if before I. This is usually what need to be done to salvage the knowledge
37 /// contained in the instruction I.
38 /// The AssumptionCache must be provided if it is available or the cache may
39 /// become silently be invalid.
40 /// The DominatorTree can optionally be provided to enable cross-block
41 /// reasoning.
42 void salvageKnowledge(Instruction *I, AssumptionCache *AC = nullptr,
43                       DominatorTree *DT = nullptr);
44 
45 /// Build and return a new assume created from the provided knowledge
46 /// if the knowledge in the assume is fully redundant this will return nullptr
47 AssumeInst *buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge,
48                                      Instruction *CtxI,
49                                      AssumptionCache *AC = nullptr,
50                                      DominatorTree *DT = nullptr);
51 
52 /// This pass attempts to minimize the number of assume without loosing any
53 /// information.
54 struct AssumeSimplifyPass : public PassInfoMixin<AssumeSimplifyPass> {
55   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
56 };
57 
58 FunctionPass *createAssumeSimplifyPass();
59 
60 /// This pass will try to build an llvm.assume for every instruction in the
61 /// function. Its main purpose is testing.
62 struct AssumeBuilderPass : public PassInfoMixin<AssumeBuilderPass> {
63   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
64 };
65 
66 /// canonicalize the RetainedKnowledge RK. it is assumed that RK is part of
67 /// Assume. This will return an empty RetainedKnowledge if the knowledge is
68 /// useless.
69 RetainedKnowledge simplifyRetainedKnowledge(AssumeInst *Assume,
70                                             RetainedKnowledge RK,
71                                             AssumptionCache *AC,
72                                             DominatorTree *DT);
73 
74 } // namespace llvm
75 
76 #endif
77