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
isGuard(const User * U)18 bool llvm::isGuard(const User *U) {
19 return match(U, m_Intrinsic<Intrinsic::experimental_guard>());
20 }
21
isWidenableBranch(const User * U)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
isGuardAsWidenableBranch(const User * U)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
parseWidenableBranch(const User * U,Value * & Condition,Value * & WidenableCondition,BasicBlock * & IfTrueBB,BasicBlock * & IfFalseBB)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
parseWidenableBranch(User * U,Use * & C,Use * & WC,BasicBlock * & IfTrueBB,BasicBlock * & IfFalseBB)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