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//===-- GuardUtils.cpp - Utils for work with guards -------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Utils that are used to perform analyzes related to guards and their
// conditions.
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/GuardUtils.h"
#include "llvm/IR/PatternMatch.h"
using namespace llvm;
using namespace llvm::PatternMatch;
bool llvm::isGuard(const User *U) {
return match(U, m_Intrinsic<Intrinsic::experimental_guard>());
}
bool llvm::isWidenableCondition(const Value *V) {
return match(V, m_Intrinsic<Intrinsic::experimental_widenable_condition>());
}
bool llvm::isWidenableBranch(const User *U) {
Value *Condition, *WidenableCondition;
BasicBlock *GuardedBB, *DeoptBB;
return parseWidenableBranch(U, Condition, WidenableCondition, GuardedBB,
DeoptBB);
}
bool llvm::isGuardAsWidenableBranch(const User *U) {
if (!isWidenableBranch(U))
return false;
BasicBlock *DeoptBB = cast<BranchInst>(U)->getSuccessor(1);
SmallPtrSet<const BasicBlock *, 2> Visited;
Visited.insert(DeoptBB);
do {
for (auto &Insn : *DeoptBB) {
if (match(&Insn, m_Intrinsic<Intrinsic::experimental_deoptimize>()))
return true;
if (Insn.mayHaveSideEffects())
return false;
}
DeoptBB = DeoptBB->getUniqueSuccessor();
if (!DeoptBB)
return false;
} while (Visited.insert(DeoptBB).second);
return false;
}
bool llvm::parseWidenableBranch(const User *U, Value *&Condition,
Value *&WidenableCondition,
BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB) {
Use *C, *WC;
if (parseWidenableBranch(const_cast<User*>(U), C, WC, IfTrueBB, IfFalseBB)) {
if (C)
Condition = C->get();
else
Condition = ConstantInt::getTrue(IfTrueBB->getContext());
WidenableCondition = WC->get();
return true;
}
return false;
}
bool llvm::parseWidenableBranch(User *U, Use *&C,Use *&WC,
BasicBlock *&IfTrueBB, BasicBlock *&IfFalseBB) {
auto *BI = dyn_cast<BranchInst>(U);
if (!BI || !BI->isConditional())
return false;
auto *Cond = BI->getCondition();
if (!Cond->hasOneUse())
return false;
IfTrueBB = BI->getSuccessor(0);
IfFalseBB = BI->getSuccessor(1);
if (match(Cond, m_Intrinsic<Intrinsic::experimental_widenable_condition>())) {
WC = &BI->getOperandUse(0);
C = nullptr;
return true;
}
// Check for two cases:
// 1) br (i1 (and A, WC())), label %IfTrue, label %IfFalse
// 2) br (i1 (and WC(), B)), label %IfTrue, label %IfFalse
// We do not check for more generalized and trees as we should canonicalize
// to the form above in instcombine. (TODO)
Value *A, *B;
if (!match(Cond, m_And(m_Value(A), m_Value(B))))
return false;
auto *And = dyn_cast<Instruction>(Cond);
if (!And)
// Could be a constexpr
return false;
if (match(A, m_Intrinsic<Intrinsic::experimental_widenable_condition>()) &&
A->hasOneUse()) {
WC = &And->getOperandUse(0);
C = &And->getOperandUse(1);
return true;
}
if (match(B, m_Intrinsic<Intrinsic::experimental_widenable_condition>()) &&
B->hasOneUse()) {
WC = &And->getOperandUse(1);
C = &And->getOperandUse(0);
return true;
}
return false;
}
template <typename CallbackType>
static void parseCondition(Value *Condition,
CallbackType RecordCheckOrWidenableCond) {
SmallVector<Value *, 4> Worklist(1, Condition);
SmallPtrSet<Value *, 4> Visited;
Visited.insert(Condition);
do {
Value *Check = Worklist.pop_back_val();
Value *LHS, *RHS;
if (match(Check, m_And(m_Value(LHS), m_Value(RHS)))) {
if (Visited.insert(LHS).second)
Worklist.push_back(LHS);
if (Visited.insert(RHS).second)
Worklist.push_back(RHS);
continue;
}
if (!RecordCheckOrWidenableCond(Check))
break;
} while (!Worklist.empty());
}
void llvm::parseWidenableGuard(const User *U,
llvm::SmallVectorImpl<Value *> &Checks) {
assert((isGuard(U) || isWidenableBranch(U)) && "Should be");
Value *Condition = isGuard(U) ? cast<IntrinsicInst>(U)->getArgOperand(0)
: cast<BranchInst>(U)->getCondition();
parseCondition(Condition, [&](Value *Check) {
if (!isWidenableCondition(Check))
Checks.push_back(Check);
return true;
});
}
Value *llvm::extractWidenableCondition(const User *U) {
auto *BI = dyn_cast<BranchInst>(U);
if (!BI || !BI->isConditional())
return nullptr;
auto Condition = BI->getCondition();
if (!Condition->hasOneUse())
return nullptr;
Value *WidenableCondition = nullptr;
parseCondition(Condition, [&](Value *Check) {
// We require widenable_condition has only one use, otherwise we don't
// consider appropriate branch as widenable.
if (isWidenableCondition(Check) && Check->hasOneUse()) {
WidenableCondition = Check;
return false;
}
return true;
});
return WidenableCondition;
}
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