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[6.3] SILCombine: don't sink forwarding instructions with address operands #86040

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Merged
eeckstein merged 1 commit into from
Dec 16, 2025
+37 −0
Merged

[6.3] SILCombine: don't sink forwarding instructions with address operands #86040

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17 changes: 17 additions & 0 deletions lib/SILOptimizer/SILCombiner/SILCombine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -429,6 +429,14 @@ bool SILCombiner::doOneIteration(SILFunction &F, unsigned Iteration) {
return MadeChange;
}

static bool hasAddressOperands(SILInstruction *inst) {
for (Operand *op : inst->getRealOperands()) {
if (op->get()->getType().isAddress())
return true;
}
return false;
}

void SILCombiner::processInstruction(SILInstruction *I,
SILCombineCanonicalize &scCanonicalize,
bool &MadeChange) {
Expand Down Expand Up @@ -467,6 +475,15 @@ void SILCombiner::processInstruction(SILInstruction *I,
if (auto *svi = dyn_cast<SingleValueInstruction>(I)) {
if (auto fwdOp = ForwardingOperation(svi)) {
if (fwdOp.getSingleForwardingOperand() &&

// Don't risk sinking instructions with address operands out of the
// addressed memory's lifetime. E.g:
// ```
// %3 = mark_dependence %2 on %1 : $*T // must not be moved after the destroy_addr
// destroy_addr %1
// ```
!hasAddressOperands(svi) &&

SILValue(svi)->getOwnershipKind() == OwnershipKind::Owned) {
// Try to sink the value. If we sank the value and deleted it,
// return. If we didn't optimize or sank but we are still able to
Expand Down
20 changes: 20 additions & 0 deletions test/SILOptimizer/sil_combine_ossa.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -5577,4 +5577,24 @@ bb0(%0 : @guaranteed $String):
return %1
}

// CHECK-LABEL: sil [ossa] @dont_sink_mark_dependence_out_of_memory_lifetime :
// CHECK: mark_dependence
// CHECK: bb1:
// CHECK: } // end sil function 'dont_sink_mark_dependence_out_of_memory_lifetime'
sil [ossa] @dont_sink_mark_dependence_out_of_memory_lifetime : $@convention(thin) (@owned Klass, @owned Klass) -> () {
bb0(%0 : @owned $Klass, %1 : @owned $Klass):
%2 = alloc_stack $Klass
store %1 to [init] %2
%4 = mark_dependence %0 on %2
destroy_addr %2
br bb1

bb1:
destroy_value %4
dealloc_stack %2
%9 = tuple ()
return %9
}