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Merge pull request #68110 from atrick/fix-silcombine-moveonly

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Fix SILCombine miscompile for discard on non-copyable types
This commit is contained in:
Andrew Trick
2023-08-24 08:48:55 -07:00
committed by GitHub
parent 3687ddfac6 a946922798
commit 5dd2cf706a
2 changed files with 35 additions and 0 deletions
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12
lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
View File

@@ -371,6 +371,18 @@ public:
// anything other than the init_existential_addr/open_existential_addr
// container.
// There is no interesting scenario where a non-copyable type should have
// its allocation eliminated. A destroy_addr cannot be removed because it
// may run the struct-deinit, and the lifetime cannot be shortened. A
// copy_addr [take] [init] cannot be replaced by a destroy_addr because the
// destination may hold a 'discard'ed value, which is never destroyed. This
// analysis assumes memory is deinitialized on all paths, which is not the
// case for discarded values. Eventually copyable types may also be
// discarded; to support that, we will leave a drop_deinit_addr in place.
if (ASI->getType().isPureMoveOnly()) {
LegalUsers = false;
return;
}
for (auto *Op : getNonDebugUses(ASI)) {
visit(Op->getUser());

23
test/SILOptimizer/sil_combine_moveonly.sil
View File

@@ -24,6 +24,12 @@ enum MaybeFileDescriptor: ~Copyable {
deinit
}
struct Wrapper<T>: ~Copyable {
var t: T
}
sil @getWrappedValue : $@convention(thin) <T> (@in_guaranteed Wrapper<T>) -> @out T
// Test that a release_value is not removed for a struct-with-deinit.
// Doing so would forget the deinit.
//
@@ -71,3 +77,20 @@ bb0:
%9 = tuple ()
return %9 : $()
}
// Test that a move into a discarded value does not result in a destroy_addr
//
// CHECK-LABEL: sil @testNoDeinit : $@convention(method) <T> (@in Wrapper<T>) -> @out T {
// CHECK-NOT: destroy_addr
// CHECK-LABEL: } // end sil function 'testNoDeinit'
sil @testNoDeinit : $@convention(method) <T> (@in Wrapper<T>) -> @out T {
bb0(%0 : $*T, %1 : $*Wrapper<T>):
%2 = function_ref @getWrappedValue : $@convention(thin) <T> (@in_guaranteed Wrapper<T>) -> @out T
%3 = apply %2<T>(%0, %1) : $@convention(thin) <τ_0_0> (@in_guaranteed Wrapper<τ_0_0>) -> @out τ_0_0
%4 = alloc_stack $Wrapper<T>
copy_addr [take] %1 to [init] %4 : $*Wrapper<T>
// discard
dealloc_stack %4 : $*Wrapper<T>
%9 = tuple ()
return %9 : $()
}