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Fix MemoryLifetimeVerifier for enums with empty/non-uniform element types #39173

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Fix MemoryLifetimeVerifier for enums with empty/non-uniform element types #39173

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16 changes: 15 additions & 1 deletion lib/SIL/Utils/MemoryLocations.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -366,7 +366,21 @@ bool MemoryLocations::analyzeLocationUsesRecursively(SILValue V, unsigned locIdx
if (cast<DebugValueInst>(user)->hasAddrVal())
break;
return false;
case SILInstructionKind::InjectEnumAddrInst:
case SILInstructionKind::InjectEnumAddrInst: {
auto *ieai = cast<InjectEnumAddrInst>(user);
if (ieai->getElement()->hasAssociatedValues()) {
auto eleType = ieai->getOperand()->getType().getEnumElementType(
ieai->getElement(), ieai->getFunction());
if (isEmptyType(eleType, ieai->getFunction()))
return false;
auto key = std::make_pair(locIdx, /* fieldNr*/ 0);
unsigned subLocIdx = subLocationMap[key];
if (subLocIdx > 0 &&
getLocation(subLocIdx)->representativeValue->getType() != eleType)
return false;
}
break;
}
case SILInstructionKind::SelectEnumAddrInst:
case SILInstructionKind::ExistentialMetatypeInst:
case SILInstructionKind::ValueMetatypeInst:
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57 changes: 57 additions & 0 deletions test/SIL/memory_lifetime.sil
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Expand Up @@ -650,3 +650,60 @@ bb0(%0 : $Int, %1 : @guaranteed $@callee_guaranteed (@in_guaranteed (Int, ((), (
dealloc_stack %2 : $*(Int, ((), ()))
return %5 : $Int
}

enum Result<T1, T2>{
case success(T1)
case failure(T2)
}

sil @try_get_error : $@convention(thin) () -> @error Error

sil [ossa] @test_init_enum_empty_case : $@convention(thin) () -> @error Error {
bb0:
%0 = alloc_stack $Result<(), Error>
%1 = function_ref @try_get_error : $@convention(thin) () -> @error Error
try_apply %1() : $@convention(thin) () -> @error Error, normal bb1, error bb2

bb1(%3 : $()):
inject_enum_addr %0 : $*Result<(), Error>, #Result.success!enumelt
br bb3

bb2(%6 : @owned $Error):
%7 = init_enum_data_addr %0 : $*Result<(), Error>, #Result.failure!enumelt
store %6 to [init] %7 : $*Error
inject_enum_addr %0 : $*Result<(), Error>, #Result.failure!enumelt
br bb3

bb3:
%11 = load [take] %0 : $*Result<(), Error>
destroy_value %11 : $Result<(), Error>
dealloc_stack %0 : $*Result<(), Error>
%14 = tuple ()
return %14 : $()
}

sil [ossa] @test_init_enum_trivial_case : $@convention(thin) () -> @error Error {
bb0:
%0 = alloc_stack $Result<Int, Error>
%1 = function_ref @try_get_error : $@convention(thin) () -> @error Error
try_apply %1() : $@convention(thin) () -> @error Error, normal bb1, error bb2

bb1(%3 : $()):
inject_enum_addr %0 : $*Result<Int, Error>, #Result.success!enumelt
br bb3


bb2(%7 : @owned $Error):
%8 = init_enum_data_addr %0 : $*Result<Int, Error>, #Result.failure!enumelt
store %7 to [init] %8 : $*Error
inject_enum_addr %0 : $*Result<Int, Error>, #Result.failure!enumelt
br bb3

bb3:
%12 = load [take] %0 : $*Result<Int, Error>
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@eeckstein eeckstein Sep 8, 2021 •
edited
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I think this should be considered as illegal SIL. This load [take] is loading an uninitialized value (the Int-case coming from bb1). It will not crash, because the only thing which is done is to destroy the value. But still, loading an uninitialized value is not something we should be allowing in SIL.

In my PR (#39200) I have put this test case into memory_lifetime_failures.sil

destroy_value %12 : $Result<Int, Error>
dealloc_stack %0 : $*Result<Int, Error>
%15 = tuple ()
return %15 : $()
}