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() {} 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 /// (from an assume intrinsic). Pred is a CmpInst predicate. 76 Tristate getPredicateAt(unsigned Pred, Value *V, Constant *C, 77 Instruction *CxtI); 78 79 /// Determine whether the specified value is known to be a 80 /// constant at the end of the specified block. Return null if not. 81 Constant *getConstant(Value *V, BasicBlock *BB, Instruction *CxtI = nullptr); 82 83 /// Return the ConstantRange constraint that is known to hold for the 84 /// specified value at the end of the specified block. This may only be called 85 /// on integer-typed Values. 86 ConstantRange getConstantRange(Value *V, BasicBlock *BB, 87 Instruction *CxtI = nullptr, 88 bool UndefAllowed = true); 89 90 /// Determine whether the specified value is known to be a 91 /// constant on the specified edge. Return null if not. 92 Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB, 93 Instruction *CxtI = nullptr); 94 95 /// Return the ConstantRage constraint that is known to hold for the 96 /// specified value on the specified edge. This may be only be called 97 /// on integer-typed Values. 98 ConstantRange getConstantRangeOnEdge(Value *V, BasicBlock *FromBB, 99 BasicBlock *ToBB, 100 Instruction *CxtI = nullptr); 101 102 /// Inform the analysis cache that we have threaded an edge from 103 /// PredBB to OldSucc to be from PredBB to NewSucc instead. 104 void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc); 105 106 /// Inform the analysis cache that we have erased a block. 107 void eraseBlock(BasicBlock *BB); 108 109 /// Print the \LazyValueInfo Analysis. 110 /// We pass in the DTree that is required for identifying which basic blocks 111 /// we can solve/print for, in the LVIPrinter. 112 void printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS); 113 114 // For old PM pass. Delete once LazyValueInfoWrapperPass is gone. 115 void releaseMemory(); 116 117 /// Handle invalidation events in the new pass manager. 118 bool invalidate(Function &F, const PreservedAnalyses &PA, 119 FunctionAnalysisManager::Invalidator &Inv); 120 }; 121 122 /// Analysis to compute lazy value information. 123 class LazyValueAnalysis : public AnalysisInfoMixin<LazyValueAnalysis> { 124 public: 125 typedef LazyValueInfo Result; 126 Result run(Function &F, FunctionAnalysisManager &FAM); 127 128 private: 129 static AnalysisKey Key; 130 friend struct AnalysisInfoMixin<LazyValueAnalysis>; 131 }; 132 133 /// Wrapper around LazyValueInfo. 134 class LazyValueInfoWrapperPass : public FunctionPass { 135 LazyValueInfoWrapperPass(const LazyValueInfoWrapperPass&) = delete; 136 void operator=(const LazyValueInfoWrapperPass&) = delete; 137 public: 138 static char ID; 139 LazyValueInfoWrapperPass(); 140 ~LazyValueInfoWrapperPass() override { 141 assert(!Info.PImpl && "releaseMemory not called"); 142 } 143 144 LazyValueInfo &getLVI(); 145 146 void getAnalysisUsage(AnalysisUsage &AU) const override; 147 void releaseMemory() override; 148 bool runOnFunction(Function &F) override; 149 private: 150 LazyValueInfo Info; 151 }; 152 153 } // end namespace llvm 154 155 #endif 156 157