1 //===- AssumeBundleQueries.h - utilis to query 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 query into assume bundles. assume bundles can be 10 // built using utilities from Transform/Utils/AssumeBundleBuilder.h 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ANALYSIS_ASSUMEBUNDLEQUERIES_H 15 #define LLVM_ANALYSIS_ASSUMEBUNDLEQUERIES_H 16 17 #include "llvm/ADT/DenseMap.h" 18 #include "llvm/IR/IntrinsicInst.h" 19 20 namespace llvm { 21 class AssumptionCache; 22 class DominatorTree; 23 class Instruction; 24 class Value; 25 26 /// Index of elements in the operand bundle. 27 /// If the element exist it is guaranteed to be what is specified in this enum 28 /// but it may not exist. 29 enum AssumeBundleArg { 30 ABA_WasOn = 0, 31 ABA_Argument = 1, 32 }; 33 34 /// Query the operand bundle of an llvm.assume to find a single attribute of 35 /// the specified kind applied on a specified Value. 36 /// 37 /// This has a non-constant complexity. It should only be used when a single 38 /// attribute is going to be queried. 39 /// 40 /// Return true iff the queried attribute was found. 41 /// If ArgVal is set. the argument will be stored to ArgVal. 42 bool hasAttributeInAssume(AssumeInst &Assume, Value *IsOn, StringRef AttrName, 43 uint64_t *ArgVal = nullptr); 44 inline bool hasAttributeInAssume(AssumeInst &Assume, Value *IsOn, 45 Attribute::AttrKind Kind, 46 uint64_t *ArgVal = nullptr) { 47 return hasAttributeInAssume(Assume, IsOn, 48 Attribute::getNameFromAttrKind(Kind), ArgVal); 49 } 50 51 template<> struct DenseMapInfo<Attribute::AttrKind> { 52 static Attribute::AttrKind getEmptyKey() { 53 return Attribute::EmptyKey; 54 } 55 static Attribute::AttrKind getTombstoneKey() { 56 return Attribute::TombstoneKey; 57 } 58 static unsigned getHashValue(Attribute::AttrKind AK) { 59 return hash_combine(AK); 60 } 61 static bool isEqual(Attribute::AttrKind LHS, Attribute::AttrKind RHS) { 62 return LHS == RHS; 63 } 64 }; 65 66 /// The map Key contains the Value on for which the attribute is valid and 67 /// the Attribute that is valid for that value. 68 /// If the Attribute is not on any value, the Value is nullptr. 69 using RetainedKnowledgeKey = std::pair<Value *, Attribute::AttrKind>; 70 71 struct MinMax { 72 uint64_t Min; 73 uint64_t Max; 74 }; 75 76 /// A mapping from intrinsics (=`llvm.assume` calls) to a value range 77 /// (=knowledge) that is encoded in them. How the value range is interpreted 78 /// depends on the RetainedKnowledgeKey that was used to get this out of the 79 /// RetainedKnowledgeMap. 80 using Assume2KnowledgeMap = DenseMap<AssumeInst *, MinMax>; 81 82 using RetainedKnowledgeMap = 83 DenseMap<RetainedKnowledgeKey, Assume2KnowledgeMap>; 84 85 /// Insert into the map all the informations contained in the operand bundles of 86 /// the llvm.assume. This should be used instead of hasAttributeInAssume when 87 /// many queries are going to be made on the same llvm.assume. 88 /// String attributes are not inserted in the map. 89 /// If the IR changes the map will be outdated. 90 void fillMapFromAssume(AssumeInst &Assume, RetainedKnowledgeMap &Result); 91 92 /// Represent one information held inside an operand bundle of an llvm.assume. 93 /// AttrKind is the property that holds. 94 /// WasOn if not null is that Value for which AttrKind holds. 95 /// ArgValue is optionally an argument of the attribute. 96 /// For example if we know that %P has an alignment of at least four: 97 /// - AttrKind will be Attribute::Alignment. 98 /// - WasOn will be %P. 99 /// - ArgValue will be 4. 100 struct RetainedKnowledge { 101 Attribute::AttrKind AttrKind = Attribute::None; 102 uint64_t ArgValue = 0; 103 Value *WasOn = nullptr; 104 bool operator==(RetainedKnowledge Other) const { 105 return AttrKind == Other.AttrKind && WasOn == Other.WasOn && 106 ArgValue == Other.ArgValue; 107 } 108 bool operator!=(RetainedKnowledge Other) const { return !(*this == Other); } 109 /// This is only intended for use in std::min/std::max between attribute that 110 /// only differ in ArgValue. 111 bool operator<(RetainedKnowledge Other) const { 112 assert(((AttrKind == Other.AttrKind && WasOn == Other.WasOn) || 113 AttrKind == Attribute::None || Other.AttrKind == Attribute::None) && 114 "This is only intend for use in min/max to select the best for " 115 "RetainedKnowledge that is otherwise equal"); 116 return ArgValue < Other.ArgValue; 117 } 118 operator bool() const { return AttrKind != Attribute::None; } 119 static RetainedKnowledge none() { return RetainedKnowledge{}; } 120 }; 121 122 /// Retreive the information help by Assume on the operand at index Idx. 123 /// Assume should be an llvm.assume and Idx should be in the operand bundle. 124 RetainedKnowledge getKnowledgeFromOperandInAssume(AssumeInst &Assume, 125 unsigned Idx); 126 127 /// Retreive the information help by the Use U of an llvm.assume. the use should 128 /// be in the operand bundle. 129 inline RetainedKnowledge getKnowledgeFromUseInAssume(const Use *U) { 130 return getKnowledgeFromOperandInAssume(*cast<AssumeInst>(U->getUser()), 131 U->getOperandNo()); 132 } 133 134 /// Tag in operand bundle indicating that this bundle should be ignored. 135 constexpr StringRef IgnoreBundleTag = "ignore"; 136 137 /// Return true iff the operand bundles of the provided llvm.assume doesn't 138 /// contain any valuable information. This is true when: 139 /// - The operand bundle is empty 140 /// - The operand bundle only contains information about dropped values or 141 /// constant folded values. 142 /// 143 /// the argument to the call of llvm.assume may still be useful even if the 144 /// function returned true. 145 bool isAssumeWithEmptyBundle(const AssumeInst &Assume); 146 147 /// Return a valid Knowledge associated to the Use U if its Attribute kind is 148 /// in AttrKinds. 149 RetainedKnowledge getKnowledgeFromUse(const Use *U, 150 ArrayRef<Attribute::AttrKind> AttrKinds); 151 152 /// Return a valid Knowledge associated to the Value V if its Attribute kind is 153 /// in AttrKinds and it matches the Filter. 154 RetainedKnowledge getKnowledgeForValue( 155 const Value *V, ArrayRef<Attribute::AttrKind> AttrKinds, 156 AssumptionCache *AC = nullptr, 157 function_ref<bool(RetainedKnowledge, Instruction *, 158 const CallBase::BundleOpInfo *)> 159 Filter = [](auto...) { return true; }); 160 161 /// Return a valid Knowledge associated to the Value V if its Attribute kind is 162 /// in AttrKinds and the knowledge is suitable to be used in the context of 163 /// CtxI. 164 RetainedKnowledge getKnowledgeValidInContext( 165 const Value *V, ArrayRef<Attribute::AttrKind> AttrKinds, 166 const Instruction *CtxI, const DominatorTree *DT = nullptr, 167 AssumptionCache *AC = nullptr); 168 169 /// This extracts the Knowledge from an element of an operand bundle. 170 /// This is mostly for use in the assume builder. 171 RetainedKnowledge getKnowledgeFromBundle(AssumeInst &Assume, 172 const CallBase::BundleOpInfo &BOI); 173 174 } // namespace llvm 175 176 #endif 177