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Emit non-defaultable unreachable local.sets #8858

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Merged
tlively merged 1 commit into from
Jun 18, 2026
+80 −2
Merged

Emit non-defaultable unreachable local.sets #8858

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4 changes: 2 additions & 2 deletions src/wasm-stack.h
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Original file line number Diff line number Diff line change
Expand Up @@ -276,7 +276,7 @@ template<typename SubType> void BinaryenIRWriter<SubType>::write() {
template<typename SubType>
void BinaryenIRWriter<SubType>::emitUnreachableLocalSets(Expression* curr) {
for (auto* set : FindAll<LocalSet>(curr).list) {
if (func->getLocalType(set->index).isNonNullable()) {
if (!func->getLocalType(set->index).isDefaultable()) {
emitUnreachableLocalSet(set->index);
}
}
Expand Down Expand Up @@ -340,7 +340,7 @@ void BinaryenIRWriter<SubType>::visit(Expression* curr) {
// `curr` is not reachable, so don't emit it unless it is a
// potentially-necessary local.set itself.
if (auto* set = curr->dynCast<LocalSet>();
set && func->getLocalType(set->index).isNonNullable()) {
set && !func->getLocalType(set->index).isDefaultable()) {
emitUnreachableLocalSet(set->index);
}
return;
Expand Down
78 changes: 78 additions & 0 deletions test/lit/basic/unreachable-local-set.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,46 @@
(local.get $local)
)

;; CHECK: (func $after-unreachable-tuple (type $2) (param $i32 i32) (param $ref (ref struct)) (result i32 (ref struct))
;; CHECK-NEXT: (local $local (tuple i32 (ref struct)))
;; CHECK-NEXT: unreachable
;; CHECK-NEXT: unreachable
;; CHECK-NEXT: local.set $local
;; CHECK-NEXT: drop
;; CHECK-NEXT: local.get $local
;; CHECK-NEXT: )
;; RTRIP: (func $after-unreachable-tuple (type $2) (param $i32 i32) (param $ref (ref struct)) (result i32 (ref struct))
;; RTRIP-NEXT: (local $local i32)
;; RTRIP-NEXT: (local $3 (ref struct))
;; RTRIP-NEXT: (drop
;; RTRIP-NEXT: (local.set $local
;; RTRIP-NEXT: (local.set $3
;; RTRIP-NEXT: (unreachable)
;; RTRIP-NEXT: )
;; RTRIP-NEXT: )
;; RTRIP-NEXT: )
;; RTRIP-NEXT: (tuple.make 2
;; RTRIP-NEXT: (local.get $local)
;; RTRIP-NEXT: (local.get $3)
;; RTRIP-NEXT: )
;; RTRIP-NEXT: )
(func $after-unreachable-tuple (param $i32 i32) (param $ref (ref struct)) (result i32 (ref struct))
(local $local (tuple i32 (ref struct)))
(drop
(block (result i32)
(unreachable)
(local.set $local
(tuple.make 2
(local.get $i32)
(local.get $ref)
)
)
(i32.const 0)
)
)
(local.get $local)
)

;; CHECK: (func $nested-exprs (type $0) (param $ref (ref struct)) (result (ref struct))
;; CHECK-NEXT: (local $local (ref struct))
;; CHECK-NEXT: unreachable
Expand Down Expand Up @@ -226,4 +266,42 @@
(unreachable)
)
)

;; CHECK: (func $tuple (type $1) (result (ref struct))
;; CHECK-NEXT: (local $local (tuple i32 (ref struct)))
;; CHECK-NEXT: unreachable
;; CHECK-NEXT: unreachable
;; CHECK-NEXT: local.set $local
;; CHECK-NEXT: drop
;; CHECK-NEXT: local.get $local
;; CHECK-NEXT: tuple.extract 2 1
;; CHECK-NEXT: )
;; RTRIP: (func $tuple (type $1) (result (ref struct))
;; RTRIP-NEXT: (local $local i32)
;; RTRIP-NEXT: (local $1 (ref struct))
;; RTRIP-NEXT: (drop
;; RTRIP-NEXT: (local.set $local
;; RTRIP-NEXT: (local.set $1
;; RTRIP-NEXT: (unreachable)
;; RTRIP-NEXT: )
;; RTRIP-NEXT: )
;; RTRIP-NEXT: )
;; RTRIP-NEXT: (local.get $1)
;; RTRIP-NEXT: )
(func $tuple (result (ref struct))
;; unreachable sets of tuples containing non-nullable references also need
;; to be kept.
(local $local (tuple i32 (ref struct)))
(drop
(block (result i32)
(local.set $local
(unreachable)
)
(i32.const 0)
)
)
(tuple.extract 2 1
(local.get $local)
)
)
)
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