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 20namespace 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. 30class 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; 37public: 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 50 // Public query interface. 51 52 /// Determine whether the specified value comparison with a constant is known 53 /// to be true or false on the specified CFG edge. 54 /// Pred is a CmpInst predicate. 55 Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, 56 BasicBlock *FromBB, BasicBlock *ToBB, 57 Instruction *CxtI = nullptr); 58 59 /// Determine whether the specified value comparison with a constant is known 60 /// to be true or false at the specified instruction 61 /// (from an assume intrinsic). Pred is a CmpInst predicate. 62 Tristate getPredicateAt(unsigned Pred, Value *V, Constant *C, 63 Instruction *CxtI); 64 65 /// Determine whether the specified value is known to be a 66 /// constant at the end of the specified block. Return null if not. 67 Constant *getConstant(Value *V, BasicBlock *BB, Instruction *CxtI = nullptr); 68 69 /// Determine whether the specified value is known to be a 70 /// constant on the specified edge. Return null if not. 71 Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB, 72 Instruction *CxtI = nullptr); 73 74 /// Inform the analysis cache that we have threaded an edge from 75 /// PredBB to OldSucc to be from PredBB to NewSucc instead. 76 void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc); 77 78 /// Inform the analysis cache that we have erased a block. 79 void eraseBlock(BasicBlock *BB); 80 81 // Implementation boilerplate. 82 83 void getAnalysisUsage(AnalysisUsage &AU) const override; 84 void releaseMemory() override; 85 bool runOnFunction(Function &F) override; 86}; 87 88} // end namespace llvm 89 90#endif 91 92