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[Mem2Reg] Complete single-block trivial enum cases

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Add `end_lifetime` for values of non-trivial enum type which aren't
destroyed in non-dead-end blocks.
This commit is contained in:
Nate Chandler
2025-08-29 15:43:18 -07:00
parent 4b3588c9b9
commit 1c52364d28
2 changed files with 59 additions and 1 deletions
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21
lib/SILOptimizer/Transforms/SILMem2Reg.cpp
View File

@@ -2097,7 +2097,10 @@ void MemoryToRegisters::removeSingleBlockAllocation(AllocStackInst *asi) {
}
}
if (!runningVals || !runningVals->isStorageValid) {
auto *function = asi->getFunction();
if (!function->hasOwnership() || !runningVals ||
!runningVals->isStorageValid ||
asi->getElementType().isTrivial(function)) {
return;
}
// There is still valid storage after visiting all instructions in this
@@ -2105,6 +2108,22 @@ void MemoryToRegisters::removeSingleBlockAllocation(AllocStackInst *asi) {
// That can happen if:
// (1) this block is a dead-end. TODO: OSSACompleteLifetime: Complete such
// lifetimes.
// (2) a trivial case of a non-trivial enum was stored to the address
auto *deadEndBlocks = deadEndBlocksAnalysis->get(function);
if (!deadEndBlocks->isDeadEnd(parentBlock)) {
// We may have incomplete lifetimes for enum locations on trivial paths.
// After promoting them, complete lifetime here.
ASSERT(asi->getElementType().isOrHasEnum());
OSSACompleteLifetime completion(function, domInfo, *deadEndBlocks,
OSSACompleteLifetime::IgnoreTrivialVariable,
/*forceLivenessVerification=*/false,
/*nonDestroyingEnd=*/true);
completion.completeOSSALifetime(
runningVals->value.replacement(asi, nullptr),
OSSACompleteLifetime::Boundary::Liveness);
}
}
void MemoryToRegisters::collectStoredValues(AllocStackInst *asi,

39
test/SILOptimizer/mem2reg_ossa_nontrivial.sil
View File

@@ -1669,6 +1669,45 @@ x(%13 : @guaranteed $X):
exit:
destroy_addr %main_addr
dealloc_stack %temp
dealloc_stack %main_addr
%retval = tuple ()
return %retval
}
// CHECK-LABEL: sil [ossa] @end_lifetime_at_trivial_case_dealloc_stack_3 : {{.*}} {
// CHECK: bb0([[IN_ADDR:%[^,]+]] :
// CHECK: [[IN_BORROW:%[^,]+]] = load_borrow [[IN_ADDR]]
// CHECK: switch_enum [[IN_BORROW]]
// CHECK: case #Result.success!enumelt: [[INT:bb[0-9]+]]
// CHECK: [[INT]]
// CHECK: end_borrow [[IN_BORROW]]
// CHECK: [[IN_COPY:%[^,]+]] = load [copy] [[IN_ADDR]]
// CHECK: end_lifetime [[IN_COPY]]
// CHECK-LABEL: } // end sil function 'end_lifetime_at_trivial_case_dealloc_stack_3'
sil [ossa] @end_lifetime_at_trivial_case_dealloc_stack_3 : $@convention(thin) (@in_guaranteed Result<Int, X>) -> () {
entry(%in_addr : $*Result<Int, X>):
%in_borrow = load_borrow %in_addr
switch_enum %in_borrow,
case #Result.success!enumelt: int,
case #Result.failure!enumelt: x
int(%int : $Int):
end_borrow %in_borrow
%temp = alloc_stack $Result<Int, X>
%in_copy = load [copy] %in_addr
store %in_copy to [init] %temp
dealloc_stack %temp
br int2
int2:
br exit
x(%13 : @guaranteed $X):
end_borrow %in_borrow
br exit
exit:
%retval = tuple ()
return %retval
}