/// Like ValueIsPHI but also check if the PHI has no source
/// operands, i.e., it was just added.
static SILPhiArgument *ValueIsNewPHI(SILValue Val, SILSSAUpdater *Updater) {
SILPhiArgument *PHI = ValueIsPHI(Val, Updater);
if (PHI) {
auto *PhiBB = PHI->getParent();
size_t PhiIdx = PHI->getIndex();
// If all predecessor edges are 'not set' this is a new phi.
for (auto *PredBB : PhiBB->getPredecessorBlocks()) {
OperandValueArrayRef Edges =
getEdgeValuesForTerminator(PredBB->getTerminator(), PhiBB);
assert(PhiIdx < Edges.size() && "Not enough edges!");
SILValue V = Edges[PhiIdx];
// Check for the 'not set' sentinel.
if (V != Updater->PHISentinel.get())
return nullptr;
}
return PHI;
}
return nullptr;
}
/// Determine the number of iterations the loop is at most executed. The loop
/// might contain early exits so this is the maximum if no early exits are
/// taken.
static Optional<uint64_t> getMaxLoopTripCount(SILLoop *Loop,
SILBasicBlock *Preheader,
SILBasicBlock *Header,
SILBasicBlock *Latch) {
// Skip a split backedge.
SILBasicBlock *OrigLatch = Latch;
if (!Loop->isLoopExiting(Latch) &&
!(Latch = Latch->getSinglePredecessorBlock()))
return None;
if (!Loop->isLoopExiting(Latch))
return None;
// Get the loop exit condition.
auto *CondBr = dyn_cast<CondBranchInst>(Latch->getTerminator());
if (!CondBr)
return None;
// Match an add 1 recurrence.
auto *Cmp = dyn_cast<BuiltinInst>(CondBr->getCondition());
if (!Cmp)
return None;
unsigned Adjust = 0;
SILBasicBlock *Exit = CondBr->getTrueBB();
switch (Cmp->getBuiltinInfo().ID) {
case BuiltinValueKind::ICMP_EQ:
case BuiltinValueKind::ICMP_SGE:
break;
case BuiltinValueKind::ICMP_SGT:
Adjust = 1;
break;
case BuiltinValueKind::ICMP_SLE:
Exit = CondBr->getFalseBB();
Adjust = 1;
break;
case BuiltinValueKind::ICMP_NE:
case BuiltinValueKind::ICMP_SLT:
Exit = CondBr->getFalseBB();
break;
default:
return None;
}
if (Loop->contains(Exit))
return None;
auto *End = dyn_cast<IntegerLiteralInst>(Cmp->getArguments()[1]);
if (!End)
return None;
SILValue RecNext = Cmp->getArguments()[0];
SILPhiArgument *RecArg;
if (!match(RecNext,
m_TupleExtractInst(m_ApplyInst(BuiltinValueKind::SAddOver,
m_SILPhiArgument(RecArg), m_One()),
0)))
return None;
if (RecArg->getParent() != Header)
return None;
auto *Start = dyn_cast_or_null<IntegerLiteralInst>(
RecArg->getIncomingPhiValue(Preheader));
if (!Start)
return None;
if (RecNext != RecArg->getIncomingPhiValue(OrigLatch))
return None;
auto StartVal = Start->getValue();
auto EndVal = End->getValue();
if (StartVal.sgt(EndVal))
return None;
auto Dist = EndVal - StartVal;
if (Dist.getBitWidth() > 64)
return None;
if (Dist == 0)
return None;
return Dist.getZExtValue() + Adjust;
}
