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[sil-cse] Fix a bug in the CSE of open_existential_ref instructions #4606

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Merged
merged 1 commit into from
Sep 3, 2016
Merged

[sil-cse] Fix a bug in the CSE of open_existential_ref instructions #4606

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37 changes: 36 additions & 1 deletion lib/SILOptimizer/Transforms/CSE.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -681,13 +681,48 @@ bool CSE::processOpenExistentialRef(SILInstruction *Inst, ValueBase *V,
auto &Builder = Cloner.getBuilder();
Builder.setOpenedArchetypesTracker(&OpenedArchetypesTracker);

llvm::SmallPtrSet<SILInstruction *, 16> Processed;
// Now clone each candidate and replace the opened archetype
// by a dominating one.
for (auto Candidate : Candidates) {
while (!Candidates.empty()) {
auto Candidate = Candidates.pop_back_val();
if (Processed.count(Candidate))
continue;
// True if a candidate depends on the old opened archetype.
bool DependsOnOldOpenedArchetype = !Candidate->getTypeDependentOperands().empty();
if (!Candidate->use_empty() &&
Candidate->getType().getSwiftRValueType()->hasOpenedExistential()) {
// Check if the result type of the candidate depends on the opened
// existential in question.
auto ResultDependsOnOldOpenedArchetype =
Candidate->getType().getSwiftRValueType().findIf(
[&OldOpenedArchetype](Type t) -> bool {
if (t.getCanonicalTypeOrNull() == OldOpenedArchetype)
return true;
return false;
});
if (ResultDependsOnOldOpenedArchetype) {
DependsOnOldOpenedArchetype |= ResultDependsOnOldOpenedArchetype;
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cosmetic: would be simpler to write
DependsOnOldOpenedArchetype = true

// We need to update uses of this candidate, because their types
// may be affected.
for (auto Use : Candidate->getUses()) {
Candidates.insert(Use->getUser());
}
}
}
// Remember that this candidate was processed already.
Processed.insert(Candidate);

// No need to clone if there is no dependency on the old opened archetype.
if (!DependsOnOldOpenedArchetype)
continue;

Builder.getOpenedArchetypes().addOpenedArchetypeOperands(
Candidate->getTypeDependentOperands());
Builder.setInsertionPoint(Candidate);
auto NewI = Cloner.clone(Candidate);
// Result types of candidate's uses instructions may be using this archetype.
// Thus, we need to try to replace it there.
Candidate->replaceAllUsesWith(NewI);
if (I == Candidate->getIterator())
I = NewI->getIterator();
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18 changes: 14 additions & 4 deletions test/SILOptimizer/cse.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -1325,6 +1325,8 @@ protocol Proto : class {
}

// Check that all open_existential_ref instructions are CSEd
// Any reference to the $@opened("1B685052-4796-11E6-B7DF-B8E856428C60") Proto should be replaced by
// references to $@opened("1B68354A-4796-11E6-B7DF-B8E856428C60") Proto.
// CHECK-LABEL: sil @cse_open_existential : $@convention(thin) (@guaranteed Proto, Bool) -> ()
// CHECK: bb0
// CHECK: %[[OPENED_EXISTENTIAL:[0-9]+]] = open_existential_ref %{{[0-9]+}} : $Proto to $@opened("1B68354A-4796-11E6-B7DF-B8E856428C60") Proto
Expand All @@ -1334,10 +1336,12 @@ protocol Proto : class {
// CHECK: bb1:
// CHECK-NEXT: %[[WM2:[0-9]+]] = witness_method $@opened("1B68354A-4796-11E6-B7DF-B8E856428C60") Proto, #Proto.doThat!1
// CHECK-NEXT: apply %[[WM2]]{{.*}}(%[[OPENED_EXISTENTIAL]])
// CHECK-NEXT: br bb
// CHECK-NOT: 1B6851A6-4796-11E6-B7DF-B8E856428C60
// CHECK: br bb
// CHECK: bb2:
// CHECK-NEXT: apply %[[WM1]]{{.*}}(%[[OPENED_EXISTENTIAL]])
// CHECK-NEXT: br bb
// CHECK-NOT: 1B6851A6-4796-11E6-B7DF-B8E856428C60
// CHECK: br bb
// CHECK: bb3:
// CHECK-NEXT: tuple
// CHECK-NEXT: return
Expand All @@ -1359,10 +1363,16 @@ bb2: // Preds: bb0
%13 = open_existential_ref %0 : $Proto to $@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto
%14 = witness_method $@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto, #Proto.doThis!1, %13 : $@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto : $@convention(witness_method) <τ_0_0 where τ_0_0 : Proto> (@guaranteed τ_0_0) -> ()
%15 = apply %14<@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto>(%13) : $@convention(witness_method) <τ_0_0 where τ_0_0 : Proto> (@guaranteed τ_0_0) -> ()
%16 = alloc_stack $@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto
store %13 to %16 : $*@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto
// This is to check that result types of instructions are updated by CSE as well.
%17 = load %16 : $*@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto
strong_release %17 : $@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto
dealloc_stack %16 : $*@opened("1B6851A6-4796-11E6-B7DF-B8E856428C60") Proto
br bb3

bb3:
%17 = tuple ()
return %17 : $()
%20 = tuple ()
return %20 : $()
}