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[CopyPropagation] Canonicalize moved-from values. #64495

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Merged
merged 1 commit into from
Mar 21, 2023
Merged

[CopyPropagation] Canonicalize moved-from values. #64495

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11 changes: 7 additions & 4 deletions lib/SILOptimizer/Transforms/CopyPropagation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -282,13 +282,16 @@ static bool convertExtractsToDestructures(CanonicalDefWorklist &copiedDefs,
/// the lifetime at it), replace its uses with uses of the moved-from value and
/// delete it.
static bool eliminateRedundantMove(MoveValueInst *mvi,
InstructionDeleter &deleter) {
InstructionDeleter &deleter,
CanonicalDefWorklist &defWorklist) {
if (!isRedundantMoveValue(mvi))
return false;
mvi->replaceAllUsesWith(mvi->getOperand());
auto original = mvi->getOperand();
mvi->replaceAllUsesWith(original);
// Call InstructionDeleter::forceDeleteWithUsers to avoid "fixing up"
// ownership of the moved-from value, i.e. inserting a destroy_value.
deleter.forceDeleteWithUsers(mvi);
defWorklist.updateForCopy(original);
return true;
}

Expand Down Expand Up @@ -512,12 +515,12 @@ void CopyPropagation::run() {
hoistDestroysOfOwnedLexicalValue(folded, *f, deleter, calleeAnalysis);
// Keep running even if the new move's destroys can't be hoisted.
(void)hoisted;
eliminateRedundantMove(folded, deleter);
eliminateRedundantMove(folded, deleter, defWorklist);
firstRun = false;
}
}
for (auto *mvi : moveValues) {
eliminateRedundantMove(mvi, deleter);
eliminateRedundantMove(mvi, deleter, defWorklist);
}
for (auto *argument : f->getArguments()) {
if (argument->getOwnershipKind() == OwnershipKind::Owned) {
Expand Down
20 changes: 20 additions & 0 deletions test/SILOptimizer/copy_propagation.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -874,6 +874,26 @@ entry:
return %retval : $()
}

// Canonicalize the moved-from value when a move_value is deemed redundant and
// eliminated.
// CHECK-LABEL: sil [ossa] @canonicalize_source_of_redundant_move_value : {{.*}} {
// CHECK: [[GET_OWNED_C:%[^,]+]] = function_ref @getOwnedC
// CHECK: [[TAKE_OWNED_C:%[^,]+]] = function_ref @takeOwnedC
// CHECK: [[C:%[^,]+]] = apply [[GET_OWNED_C]]() : $@convention(thin) () -> @owned C
// CHECK: apply [[TAKE_OWNED_C]]([[C]]) : $@convention(thin) (@owned C) -> ()
// CHECK-LABEL: } // end sil function 'canonicalize_source_of_redundant_move_value'
sil [ossa] @canonicalize_source_of_redundant_move_value : $@convention(thin) () -> () {
%getOwnedC = function_ref @getOwnedC : $@convention(thin) () -> (@owned C)
%takeOwnedC = function_ref @takeOwnedC : $@convention(thin) (@owned C) -> ()
%c = apply %getOwnedC() : $@convention(thin) () -> (@owned C)
%c2 = move_value %c : $C
%c3 = copy_value %c2 : $C
apply %takeOwnedC(%c3) : $@convention(thin) (@owned C) -> ()
destroy_value %c2 : $C
%retval = tuple ()
return %retval : $()
}

// Verify that a dead copy_value is deleted.
// CHECK-LABEL: sil [ossa] @delete_dead_reborrow_copy : {{.*}} {
// CHECK-NOT: copy_value
Expand Down