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[Custom Descriptors] AbstractTypeRefining: Fix up ref.get_desc #7922

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Merged
merged 4 commits into from
Sep 25, 2025
Merged

[Custom Descriptors] AbstractTypeRefining: Fix up ref.get_desc #7922

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Update src/passes/AbstractTypeRefining.cpp
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15 changes: 15 additions & 0 deletions src/passes/AbstractTypeRefining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -394,6 +394,21 @@ struct AbstractTypeRefining : public Pass {
}
}

// If we optimize away a descriptor type, then we must fix up any
// ref.get_desc of it, as ReFinalize would fix us up to return it. This
// can only happen when no such descriptor is created, which means the
// instruction will trap (no struct with such a descriptor was created).
void visitRefGetDesc(RefGetDesc* curr) {
auto optimized = getOptimized(curr->type);
if (!optimized) {
return;
}

Builder builder(*getModule());
replaceCurrent(builder.makeSequence(builder.makeDrop(curr->ref),
builder.makeUnreachable()));
}

void visitBrOn(BrOn* curr) {
if (curr->op == BrOnNull || curr->op == BrOnNonNull) {
return;
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45 changes: 45 additions & 0 deletions test/lit/passes/abstract-type-refining-desc.wast
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Expand Up @@ -1020,3 +1020,48 @@
)
)
)

(module
;; $B is never created. When removing it from the result of the function, we
;; must remove the ref.get_desc too (otherwise it would return a non-
;; validating type for the new result; and it traps anyhow).
(rec
;; YESTNH: (rec
;; YESTNH-NEXT: (type $A (sub (descriptor $B (struct))))
;; NO_TNH: (rec
;; NO_TNH-NEXT: (type $A (sub (descriptor $B (struct))))
(type $A (sub (descriptor $B (struct))))
;; YESTNH: (type $B (describes $A (struct)))
;; NO_TNH: (type $B (describes $A (struct)))
(type $B (describes $A (struct)))
)

;; YESTNH: (type $2 (func (result (ref none))))

;; YESTNH: (func $test (type $2) (result (ref none))
;; YESTNH-NEXT: (drop
;; YESTNH-NEXT: (struct.new_default $A
;; YESTNH-NEXT: (ref.null none)
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: (unreachable)
;; YESTNH-NEXT: )
;; NO_TNH: (type $2 (func (result (ref none))))

;; NO_TNH: (func $test (type $2) (result (ref none))
;; NO_TNH-NEXT: (drop
;; NO_TNH-NEXT: (struct.new_default $A
;; NO_TNH-NEXT: (ref.null none)
;; NO_TNH-NEXT: )
;; NO_TNH-NEXT: )
;; NO_TNH-NEXT: (unreachable)
;; NO_TNH-NEXT: )
(func $test (result (ref (exact $B)))
(ref.get_desc $A
(struct.new_default $A
(ref.null none)
)
)
)
)

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