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Merge pull request #35198 from gottesmm/pr-0d922ed7f7078d21e2bbfc5273730703a61d7c08

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[sil-combine] Update RefToRawPointer simplifications for ossa.
This commit is contained in:
Michael Gottesman
2020-12-22 21:28:24 -08:00
committed by GitHub
parent 890b202e57 0d2047a359
commit e1a616f1d4
4 changed files with 255 additions and 69 deletions
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72
lib/SILOptimizer/SILCombiner/SILCombinerCastVisitors.cpp
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@@ -30,31 +30,67 @@ using namespace swift;
using namespace swift::PatternMatch;
SILInstruction *
SILCombiner::visitRefToRawPointerInst(RefToRawPointerInst *RRPI) {
if (RRPI->getFunction()->hasOwnership())
return nullptr;
// Ref to raw pointer consumption of other ref casts.
if (auto *URCI = dyn_cast<UncheckedRefCastInst>(RRPI->getOperand())) {
// (ref_to_raw_pointer (unchecked_ref_cast x))
// -> (ref_to_raw_pointer x)
if (URCI->getOperand()->getType().isAnyClassReferenceType()) {
RRPI->setOperand(URCI->getOperand());
return URCI->use_empty() ? eraseInstFromFunction(*URCI) : nullptr;
SILCombiner::visitRefToRawPointerInst(RefToRawPointerInst *rrpi) {
if (auto *urci = dyn_cast<UncheckedRefCastInst>(rrpi->getOperand())) {
// In this optimization, we try to move ref_to_raw_pointer up the def-use
// graph. E.x.:
//
// ```
// %0 = ...
// %1 = unchecked_ref_cast %0
// %2 = ref_to_raw_pointer %1
// ```
//
// to:
//
// ```
// %0 = ...
// %2 = ref_to_raw_pointer %0
// %1 = unchecked_ref_cast %0
// ```
//
// If we find that the unchecked_ref_cast has no uses, we then eliminate
// it.
//
// Naturally, this requires us to always hoist our new instruction (or
// modified instruction) to before the unchecked_ref_cast.
//
// First we handle the case where we have a class type where we do not need
// to insert a new instruction.
if (urci->getOperand()->getType().isAnyClassReferenceType()) {
rrpi->setOperand(urci->getOperand());
rrpi->moveBefore(urci);
return urci->use_empty() ? eraseInstFromFunction(*urci) : nullptr;
}
// Otherwise, we ened to use an unchecked_trivial_bit_cast insert it at
// urci.
//
// (ref_to_raw_pointer (unchecked_ref_cast x))
// -> (unchecked_trivial_bit_cast x)
return Builder.createUncheckedTrivialBitCast(RRPI->getLoc(),
URCI->getOperand(),
RRPI->getType());
auto *utbi = withBuilder(urci, [&](auto &b, auto l) {
return b.createUncheckedTrivialBitCast(l, urci->getOperand(),
rrpi->getType());
});
rrpi->replaceAllUsesWith(utbi);
eraseInstFromFunction(*rrpi);
return urci->use_empty() ? eraseInstFromFunction(*urci) : nullptr;
}
// (ref_to_raw_pointer (open_existential_ref (init_existential_ref x))) ->
// (ref_to_raw_pointer x)
if (auto *OER = dyn_cast<OpenExistentialRefInst>(RRPI->getOperand()))
if (auto *IER = dyn_cast<InitExistentialRefInst>(OER->getOperand()))
return Builder.createRefToRawPointer(RRPI->getLoc(), IER->getOperand(),
RRPI->getType());
//
// In terms of ownership, we need to insert this at the init_existential to
// ensure that x is live if we have an owned value.
if (auto *oeri = dyn_cast<OpenExistentialRefInst>(rrpi->getOperand())) {
if (auto *ieri = dyn_cast<InitExistentialRefInst>(oeri->getOperand())) {
auto *utbi = withBuilder(ieri, [&](auto &b, auto l) {
return b.createRefToRawPointer(l, ieri->getOperand(), rrpi->getType());
});
rrpi->replaceAllUsesWith(utbi);
return eraseInstFromFunction(*rrpi);
}
}
return nullptr;
}