1 //===-- GuardUtils.cpp - Utils for work with guards -------------*- 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 // Utils that are used to perform analyzes related to guards and their 9 // conditions. 10 //===----------------------------------------------------------------------===// 11 12 #include "llvm/Analysis/GuardUtils.h" 13 #include "llvm/IR/PatternMatch.h" 14 15 using namespace llvm; 16 using namespace llvm::PatternMatch; 17 18 bool llvm::isGuard(const User *U) { 19 return match(U, m_Intrinsic<Intrinsic::experimental_guard>()); 20 } 21 22 bool llvm::isWidenableBranch(const User *U) { 23 Value *Condition, *WidenableCondition; 24 BasicBlock *GuardedBB, *DeoptBB; 25 return parseWidenableBranch(U, Condition, WidenableCondition, GuardedBB, 26 DeoptBB); 27 } 28 29 bool llvm::isGuardAsWidenableBranch(const User *U) { 30 Value *Condition, *WidenableCondition; 31 BasicBlock *GuardedBB, *DeoptBB; 32 if (!parseWidenableBranch(U, Condition, WidenableCondition, GuardedBB, 33 DeoptBB)) 34 return false; 35 for (auto &Insn : *DeoptBB) { 36 if (match(&Insn, m_Intrinsic<Intrinsic::experimental_deoptimize>())) 37 return true; 38 if (Insn.mayHaveSideEffects()) 39 return false; 40 } 41 return false; 42 } 43 44 bool llvm::parseWidenableBranch(const User *U, Value *&Condition, 45 Value *&WidenableCondition, 46 BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB) { 47 48 Use *C, *WC; 49 if (parseWidenableBranch(const_cast<User*>(U), C, WC, IfTrueBB, IfFalseBB)) { 50 if (C) 51 Condition = C->get(); 52 else 53 Condition = ConstantInt::getTrue(IfTrueBB->getContext()); 54 WidenableCondition = WC->get(); 55 return true; 56 } 57 return false; 58 } 59 60 bool llvm::parseWidenableBranch(User *U, Use *&C,Use *&WC, 61 BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB) { 62 63 auto *BI = dyn_cast<BranchInst>(U); 64 if (!BI || !BI->isConditional()) 65 return false; 66 auto *Cond = BI->getCondition(); 67 if (!Cond->hasOneUse()) 68 return false; 69 70 IfTrueBB = BI->getSuccessor(0); 71 IfFalseBB = BI->getSuccessor(1); 72 73 if (match(Cond, m_Intrinsic<Intrinsic::experimental_widenable_condition>())) { 74 WC = &BI->getOperandUse(0); 75 C = nullptr; 76 return true; 77 } 78 79 // Check for two cases: 80 // 1) br (i1 (and A, WC())), label %IfTrue, label %IfFalse 81 // 2) br (i1 (and WC(), B)), label %IfTrue, label %IfFalse 82 // We do not check for more generalized and trees as we should canonicalize 83 // to the form above in instcombine. (TODO) 84 Value *A, *B; 85 if (!match(Cond, m_And(m_Value(A), m_Value(B)))) 86 return false; 87 auto *And = dyn_cast<Instruction>(Cond); 88 if (!And) 89 // Could be a constexpr 90 return false; 91 92 if (match(A, m_Intrinsic<Intrinsic::experimental_widenable_condition>()) && 93 A->hasOneUse()) { 94 WC = &And->getOperandUse(0); 95 C = &And->getOperandUse(1); 96 return true; 97 } 98 99 if (match(B, m_Intrinsic<Intrinsic::experimental_widenable_condition>()) && 100 B->hasOneUse()) { 101 WC = &And->getOperandUse(1); 102 C = &And->getOperandUse(0); 103 return true; 104 } 105 return false; 106 } 107