1 //===- LazyValueInfo.h - Value constraint analysis --------------*- 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 defines the interface for lazy computation of value constraint 10 // information. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ANALYSIS_LAZYVALUEINFO_H 15 #define LLVM_ANALYSIS_LAZYVALUEINFO_H 16 17 #include "llvm/IR/PassManager.h" 18 #include "llvm/Pass.h" 19 20 namespace llvm { 21 class AssumptionCache; 22 class Constant; 23 class ConstantRange; 24 class DataLayout; 25 class DominatorTree; 26 class Instruction; 27 class TargetLibraryInfo; 28 class Value; 29 30 /// This pass computes, caches, and vends lazy value constraint information. 31 class LazyValueInfo { 32 friend class LazyValueInfoWrapperPass; 33 AssumptionCache *AC = nullptr; 34 const DataLayout *DL = nullptr; 35 class TargetLibraryInfo *TLI = nullptr; 36 void *PImpl = nullptr; 37 LazyValueInfo(const LazyValueInfo&) = delete; 38 void operator=(const LazyValueInfo&) = delete; 39 public: 40 ~LazyValueInfo(); 41 LazyValueInfo() = default; 42 LazyValueInfo(AssumptionCache *AC_, const DataLayout *DL_, 43 TargetLibraryInfo *TLI_) 44 : AC(AC_), DL(DL_), TLI(TLI_) {} 45 LazyValueInfo(LazyValueInfo &&Arg) 46 : AC(Arg.AC), DL(Arg.DL), TLI(Arg.TLI), PImpl(Arg.PImpl) { 47 Arg.PImpl = nullptr; 48 } 49 LazyValueInfo &operator=(LazyValueInfo &&Arg) { 50 releaseMemory(); 51 AC = Arg.AC; 52 DL = Arg.DL; 53 TLI = Arg.TLI; 54 PImpl = Arg.PImpl; 55 Arg.PImpl = nullptr; 56 return *this; 57 } 58 59 /// This is used to return true/false/dunno results. 60 enum Tristate { 61 Unknown = -1, False = 0, True = 1 62 }; 63 64 // Public query interface. 65 66 /// Determine whether the specified value comparison with a constant is known 67 /// to be true or false on the specified CFG edge. 68 /// Pred is a CmpInst predicate. 69 Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, 70 BasicBlock *FromBB, BasicBlock *ToBB, 71 Instruction *CxtI = nullptr); 72 73 /// Determine whether the specified value comparison with a constant is known 74 /// to be true or false at the specified instruction. 75 /// \p Pred is a CmpInst predicate. If \p UseBlockValue is true, the block 76 /// value is also taken into account. 77 Tristate getPredicateAt(unsigned Pred, Value *V, Constant *C, 78 Instruction *CxtI, bool UseBlockValue); 79 80 /// Determine whether the specified value comparison is known to be true 81 /// or false at the specified instruction. While this takes two Value's, 82 /// it still requires that one of them is a constant. 83 /// \p Pred is a CmpInst predicate. 84 /// If \p UseBlockValue is true, the block value is also taken into account. 85 Tristate getPredicateAt(unsigned Pred, Value *LHS, Value *RHS, 86 Instruction *CxtI, bool UseBlockValue); 87 88 /// Determine whether the specified value is known to be a constant at the 89 /// specified instruction. Return null if not. 90 Constant *getConstant(Value *V, Instruction *CxtI); 91 92 /// Return the ConstantRange constraint that is known to hold for the 93 /// specified value at the specified instruction. This may only be called 94 /// on integer-typed Values. 95 ConstantRange getConstantRange(Value *V, Instruction *CxtI, 96 bool UndefAllowed = true); 97 98 /// Determine whether the specified value is known to be a 99 /// constant on the specified edge. Return null if not. 100 Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB, 101 Instruction *CxtI = nullptr); 102 103 /// Return the ConstantRage constraint that is known to hold for the 104 /// specified value on the specified edge. This may be only be called 105 /// on integer-typed Values. 106 ConstantRange getConstantRangeOnEdge(Value *V, BasicBlock *FromBB, 107 BasicBlock *ToBB, 108 Instruction *CxtI = nullptr); 109 110 /// Inform the analysis cache that we have threaded an edge from 111 /// PredBB to OldSucc to be from PredBB to NewSucc instead. 112 void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc); 113 114 /// Inform the analysis cache that we have erased a block. 115 void eraseBlock(BasicBlock *BB); 116 117 /// Complete flush all previously computed values 118 void clear(const Module *M); 119 120 /// Print the \LazyValueInfo Analysis. 121 /// We pass in the DTree that is required for identifying which basic blocks 122 /// we can solve/print for, in the LVIPrinter. 123 void printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS); 124 125 // For old PM pass. Delete once LazyValueInfoWrapperPass is gone. 126 void releaseMemory(); 127 128 /// Handle invalidation events in the new pass manager. 129 bool invalidate(Function &F, const PreservedAnalyses &PA, 130 FunctionAnalysisManager::Invalidator &Inv); 131 }; 132 133 /// Analysis to compute lazy value information. 134 class LazyValueAnalysis : public AnalysisInfoMixin<LazyValueAnalysis> { 135 public: 136 typedef LazyValueInfo Result; 137 Result run(Function &F, FunctionAnalysisManager &FAM); 138 139 private: 140 static AnalysisKey Key; 141 friend struct AnalysisInfoMixin<LazyValueAnalysis>; 142 }; 143 144 /// Wrapper around LazyValueInfo. 145 class LazyValueInfoWrapperPass : public FunctionPass { 146 LazyValueInfoWrapperPass(const LazyValueInfoWrapperPass&) = delete; 147 void operator=(const LazyValueInfoWrapperPass&) = delete; 148 public: 149 static char ID; 150 LazyValueInfoWrapperPass(); 151 ~LazyValueInfoWrapperPass() override { 152 assert(!Info.PImpl && "releaseMemory not called"); 153 } 154 155 LazyValueInfo &getLVI(); 156 157 void getAnalysisUsage(AnalysisUsage &AU) const override; 158 void releaseMemory() override; 159 bool runOnFunction(Function &F) override; 160 private: 161 LazyValueInfo Info; 162 }; 163 164 } // end namespace llvm 165 166 #endif 167 168