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[NFC] Introduce function getIVStep for further reuse

This commit is contained in:
Max Kazantsev 2021-03-01 13:04:17 +07:00
parent fdbad5e5ac
commit 8d835f42a5
1 changed files with 23 additions and 10 deletions
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33
llvm/lib/CodeGen/CodeGenPrepare.cpp
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@ -1276,20 +1276,33 @@ static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
return SinkCast(CI);
}
/// If given \p PN is an inductive variable with value IVInc coming from the
/// backedge, and on each iteration it gets increased by Step, return pair
/// <IVInc, Step>. Otherwise, return None.
static Optional<std::pair<Instruction *, Constant *> >
getIVIncrement(const PHINode *PN, const LoopInfo *LI) {
const Loop *L = LI->getLoopFor(PN->getParent());
if (!L || L->getHeader() != PN->getParent() || !L->getLoopLatch())
return None;
auto *IVInc =
dyn_cast<Instruction>(PN->getIncomingValueForBlock(L->getLoopLatch()));
if (!IVInc)
return None;
Constant *Step = nullptr;
if (match(IVInc, m_Sub(m_Specific(PN), m_Constant(Step))))
return std::make_pair(IVInc, ConstantExpr::getNeg(Step));
if (match(IVInc, m_Add(m_Specific(PN), m_Constant(Step))))
return std::make_pair(IVInc, Step);
return None;
}
static bool isIVIncrement(const BinaryOperator *BO, const LoopInfo *LI) {
auto *PN = dyn_cast<PHINode>(BO->getOperand(0));
if (!PN)
return false;
const Loop *L = LI->getLoopFor(BO->getParent());
if (!L || L->getHeader() != PN->getParent() || !L->getLoopLatch())
return false;
const BasicBlock *Latch = L->getLoopLatch();
if (PN->getIncomingValueForBlock(Latch) != BO)
return false;
if (!L->isLoopInvariant(BO->getOperand(1)))
// Avoid complexities w/loop varying steps.
return false;
return true;
if (auto IVInc = getIVIncrement(PN, LI))
return IVInc->first == BO;
return false;
}
bool CodeGenPrepare::replaceMathCmpWithIntrinsic(BinaryOperator *BO,