1 //===- LazyValueInfo.h - Value constraint analysis --------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines the interface for lazy computation of value constraint 11 // information. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_ANALYSIS_LAZYVALUEINFO_H 16 #define LLVM_ANALYSIS_LAZYVALUEINFO_H 17 18 #include "llvm/Pass.h" 19 20 namespace llvm { 21 class AssumptionCache; 22 class Constant; 23 class DataLayout; 24 class DominatorTree; 25 class Instruction; 26 class TargetLibraryInfo; 27 class Value; 28 29 /// This pass computes, caches, and vends lazy value constraint information. 30 class LazyValueInfo : public FunctionPass { 31 AssumptionCache *AC; 32 class TargetLibraryInfo *TLI; 33 DominatorTree *DT; 34 void *PImpl; 35 LazyValueInfo(const LazyValueInfo&) = delete; 36 void operator=(const LazyValueInfo&) = delete; 37 public: 38 static char ID; 39 LazyValueInfo() : FunctionPass(ID), PImpl(nullptr) { 40 initializeLazyValueInfoPass(*PassRegistry::getPassRegistry()); 41 } 42 ~LazyValueInfo() override { assert(!PImpl && "releaseMemory not called"); } 43 44 /// This is used to return true/false/dunno results. 45 enum Tristate { 46 Unknown = -1, False = 0, True = 1 47 }; 48 49 // Public query interface. 50 51 /// Determine whether the specified value comparison with a constant is known 52 /// to be true or false on the specified CFG edge. 53 /// Pred is a CmpInst predicate. 54 Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, 55 BasicBlock *FromBB, BasicBlock *ToBB, 56 Instruction *CxtI = nullptr); 57 58 /// Determine whether the specified value comparison with a constant is known 59 /// to be true or false at the specified instruction 60 /// (from an assume intrinsic). Pred is a CmpInst predicate. 61 Tristate getPredicateAt(unsigned Pred, Value *V, Constant *C, 62 Instruction *CxtI); 63 64 /// Determine whether the specified value is known to be a 65 /// constant at the end of the specified block. Return null if not. 66 Constant *getConstant(Value *V, BasicBlock *BB, Instruction *CxtI = nullptr); 67 68 /// Determine whether the specified value is known to be a 69 /// constant on the specified edge. Return null if not. 70 Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB, 71 Instruction *CxtI = nullptr); 72 73 /// Inform the analysis cache that we have threaded an edge from 74 /// PredBB to OldSucc to be from PredBB to NewSucc instead. 75 void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc); 76 77 /// Inform the analysis cache that we have erased a block. 78 void eraseBlock(BasicBlock *BB); 79 80 // Implementation boilerplate. 81 82 void getAnalysisUsage(AnalysisUsage &AU) const override; 83 void releaseMemory() override; 84 bool runOnFunction(Function &F) override; 85 }; 86 87 } // end namespace llvm 88 89 #endif 90 91
