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Handle new block-nested pops in Unsubtyping #9130

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Merged
tlively merged 1 commit into from
Sep 21, 2026
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Handle new block-nested pops in Unsubtyping #9130

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9 changes: 9 additions & 0 deletions src/passes/Unsubtyping.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
#include <memory>

#include "ir/effects.h"
#include "ir/eh-utils.h"
#include "ir/js-utils.h"
#include "ir/localize.h"
#include "ir/module-utils.h"
Expand Down Expand Up @@ -1073,6 +1074,7 @@ struct Unsubtyping : Pass, Noter<Unsubtyping> {
// collecting and iterating over all the types, though.
struct Rewriter : WalkerPass<PostWalker<Rewriter>> {
const TypeTree& types;
bool needEHFixups = false;

// Allocations that might trap that have been removed from module-level
// initializers. These need to be placed in new globals to preserve any
Expand Down Expand Up @@ -1114,6 +1116,7 @@ struct Unsubtyping : Pass, Noter<Unsubtyping> {
block->list.push_back(curr);
block->type = curr->type;
replaceCurrent(block);
needEHFixups = true;
} else {
// We are dropping this descriptor, but it might have a potential trap
// nested inside it. In that case we need to preserve the trap by
Expand All @@ -1125,6 +1128,12 @@ struct Unsubtyping : Pass, Noter<Unsubtyping> {
}
curr->desc = nullptr;
}

void visitFunction(Function* curr) {
if (needEHFixups) {
EHUtils::handleBlockNestedPops(curr, *getModule());
}
}
};

Rewriter rewriter(types);
Expand Down
52 changes: 52 additions & 0 deletions test/lit/passes/unsubtyping-desc.wast
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Expand Up @@ -1240,3 +1240,55 @@
)
)
)

;; Removing a descriptor from a struct.new_desc uses ChildLocalizer, which wraps
;; the allocation in a block. Ensure any nested `pop` inside a catch block is
;; hoisted out of the new block so the IR remains valid.
(module
(rec
;; CHECK: (rec
;; CHECK-NEXT: (type $A (struct))
(type $A (descriptor $A.desc) (struct))
;; CHECK: (type $A.desc (struct))
(type $A.desc (describes $A) (struct))
)
;; CHECK: (type $2 (func (param (ref (exact $A.desc)))))

;; CHECK: (type $3 (func))

;; CHECK: (tag $e (type $2) (param (ref (exact $A.desc))))
(tag $e (param (ref (exact $A.desc))))
;; CHECK: (func $pop-in-struct-new-desc (type $3)
;; CHECK-NEXT: (local $0 (ref (exact $A.desc)))
;; CHECK-NEXT: (local $1 (ref (exact $A.desc)))
;; CHECK-NEXT: (try
;; CHECK-NEXT: (do
;; CHECK-NEXT: )
;; CHECK-NEXT: (catch $e
;; CHECK-NEXT: (local.set $1
;; CHECK-NEXT: (pop (ref (exact $A.desc)))
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result (ref (exact $A)))
;; CHECK-NEXT: (local.set $0
;; CHECK-NEXT: (local.get $1)
;; CHECK-NEXT: )
;; CHECK-NEXT: (struct.new_default $A)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $pop-in-struct-new-desc
(try
(do)
(catch $e
(drop
(struct.new_desc $A
(pop (ref (exact $A.desc)))
)
)
)
)
)
)
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