LLVM 19.0.0git
GuardUtils.cpp
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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
14
15using namespace llvm;
16using namespace llvm::PatternMatch;
17
18bool llvm::isGuard(const User *U) {
19 return match(U, m_Intrinsic<Intrinsic::experimental_guard>());
20}
21
23 return match(V, m_Intrinsic<Intrinsic::experimental_widenable_condition>());
24}
25
27 Value *Condition, *WidenableCondition;
28 BasicBlock *GuardedBB, *DeoptBB;
29 return parseWidenableBranch(U, Condition, WidenableCondition, GuardedBB,
30 DeoptBB);
31}
32
34 if (!isWidenableBranch(U))
35 return false;
36 BasicBlock *DeoptBB = cast<BranchInst>(U)->getSuccessor(1);
38 Visited.insert(DeoptBB);
39 do {
40 for (auto &Insn : *DeoptBB) {
41 if (match(&Insn, m_Intrinsic<Intrinsic::experimental_deoptimize>()))
42 return true;
43 if (Insn.mayHaveSideEffects())
44 return false;
45 }
46 DeoptBB = DeoptBB->getUniqueSuccessor();
47 if (!DeoptBB)
48 return false;
49 } while (Visited.insert(DeoptBB).second);
50 return false;
51}
52
53bool llvm::parseWidenableBranch(const User *U, Value *&Condition,
54 Value *&WidenableCondition,
55 BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB) {
56
57 Use *C, *WC;
58 if (parseWidenableBranch(const_cast<User*>(U), C, WC, IfTrueBB, IfFalseBB)) {
59 if (C)
60 Condition = C->get();
61 else
62 Condition = ConstantInt::getTrue(IfTrueBB->getContext());
63 WidenableCondition = WC->get();
64 return true;
65 }
66 return false;
67}
68
70 BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB) {
71
72 auto *BI = dyn_cast<BranchInst>(U);
73 if (!BI || !BI->isConditional())
74 return false;
75 auto *Cond = BI->getCondition();
76 if (!Cond->hasOneUse())
77 return false;
78
79 IfTrueBB = BI->getSuccessor(0);
80 IfFalseBB = BI->getSuccessor(1);
81
82 if (match(Cond, m_Intrinsic<Intrinsic::experimental_widenable_condition>())) {
83 WC = &BI->getOperandUse(0);
84 C = nullptr;
85 return true;
86 }
87
88 // Check for two cases:
89 // 1) br (i1 (and A, WC())), label %IfTrue, label %IfFalse
90 // 2) br (i1 (and WC(), B)), label %IfTrue, label %IfFalse
91 // We do not check for more generalized and trees as we should canonicalize
92 // to the form above in instcombine. (TODO)
93 Value *A, *B;
94 if (!match(Cond, m_And(m_Value(A), m_Value(B))))
95 return false;
96 auto *And = dyn_cast<Instruction>(Cond);
97 if (!And)
98 // Could be a constexpr
99 return false;
100
101 if (match(A, m_Intrinsic<Intrinsic::experimental_widenable_condition>()) &&
102 A->hasOneUse()) {
103 WC = &And->getOperandUse(0);
104 C = &And->getOperandUse(1);
105 return true;
106 }
107
108 if (match(B, m_Intrinsic<Intrinsic::experimental_widenable_condition>()) &&
109 B->hasOneUse()) {
110 WC = &And->getOperandUse(1);
111 C = &And->getOperandUse(0);
112 return true;
113 }
114 return false;
115}
116
117template <typename CallbackType>
118static void parseCondition(Value *Condition,
119 CallbackType RecordCheckOrWidenableCond) {
120 SmallVector<Value *, 4> Worklist(1, Condition);
122 Visited.insert(Condition);
123 do {
124 Value *Check = Worklist.pop_back_val();
125 Value *LHS, *RHS;
126 if (match(Check, m_And(m_Value(LHS), m_Value(RHS)))) {
127 if (Visited.insert(LHS).second)
128 Worklist.push_back(LHS);
129 if (Visited.insert(RHS).second)
130 Worklist.push_back(RHS);
131 continue;
132 }
133 if (!RecordCheckOrWidenableCond(Check))
134 break;
135 } while (!Worklist.empty());
136}
137
140 assert((isGuard(U) || isWidenableBranch(U)) && "Should be");
141 Value *Condition = isGuard(U) ? cast<IntrinsicInst>(U)->getArgOperand(0)
142 : cast<BranchInst>(U)->getCondition();
143
144 parseCondition(Condition, [&](Value *Check) {
146 Checks.push_back(Check);
147 return true;
148 });
149}
150
152 auto *BI = dyn_cast<BranchInst>(U);
153 if (!BI || !BI->isConditional())
154 return nullptr;
155
156 auto Condition = BI->getCondition();
157 if (!Condition->hasOneUse())
158 return nullptr;
159
160 Value *WidenableCondition = nullptr;
161 parseCondition(Condition, [&](Value *Check) {
162 // We require widenable_condition has only one use, otherwise we don't
163 // consider appropriate branch as widenable.
164 if (isWidenableCondition(Check) && Check->hasOneUse()) {
165 WidenableCondition = Check;
166 return false;
167 }
168 return true;
169 });
170 return WidenableCondition;
171}
SmallVector< AArch64_IMM::ImmInsnModel, 4 > Insn
static void parseCondition(Value *Condition, CallbackType RecordCheckOrWidenableCond)
Definition: GuardUtils.cpp:118
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
#define Check(C,...)
const SmallVectorImpl< MachineOperand > & Cond
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Value * RHS
Value * LHS
LLVM Basic Block Representation.
Definition: BasicBlock.h:60
LLVMContext & getContext() const
Get the context in which this basic block lives.
Definition: BasicBlock.cpp:168
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:852
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:342
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements.
Definition: SmallPtrSet.h:427
bool empty() const
Definition: SmallVector.h:94
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:586
void push_back(const T &Elt)
Definition: SmallVector.h:426
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1209
A Use represents the edge between a Value definition and its users.
Definition: Use.h:43
LLVM Value Representation.
Definition: Value.h:74
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:92
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
Value * extractWidenableCondition(const User *U)
Definition: GuardUtils.cpp:151
void parseWidenableGuard(const User *U, llvm::SmallVectorImpl< Value * > &Checks)
Definition: GuardUtils.cpp:138
bool isGuard(const User *U)
Returns true iff U has semantics of a guard expressed in a form of call of llvm.experimental....
Definition: GuardUtils.cpp:18
bool isWidenableCondition(const Value *V)
Returns true iff V has semantics of llvm.experimental.widenable.condition call.
Definition: GuardUtils.cpp:22
bool parseWidenableBranch(const User *U, Value *&Condition, Value *&WidenableCondition, BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB)
If U is widenable branch looking like: cond = ... wc = call i1 @llvm.experimental....
Definition: GuardUtils.cpp:53
bool isWidenableBranch(const User *U)
Returns true iff U is a widenable branch (that is, extractWidenableCondition returns widenable condit...
Definition: GuardUtils.cpp:26
bool isGuardAsWidenableBranch(const User *U)
Returns true iff U has semantics of a guard expressed in a form of a widenable conditional branch to ...
Definition: GuardUtils.cpp:33
@ And
Bitwise or logical AND of integers.