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GlobalRefining: Do not refine exported globals if their type cannot be public #7973

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Merged
merged 3 commits into from
Oct 15, 2025
Merged

GlobalRefining: Do not refine exported globals if their type cannot be public #7973

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65431e3
fix
kripken Oct 14, 2025
f047e64
fix
kripken Oct 14, 2025
25f9672
fix
kripken Oct 14, 2025
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25 changes: 19 additions & 6 deletions src/passes/GlobalRefining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
#include "ir/find_all.h"
#include "ir/lubs.h"
#include "ir/module-utils.h"
#include "ir/public-type-validator.h"
#include "ir/utils.h"
#include "pass.h"
#include "wasm-type.h"
Expand Down Expand Up @@ -75,13 +76,17 @@ struct GlobalRefining : public Pass {
// fields in subtypes - the types must match exactly, or else a write in
// one place could store a type considered in valid in another place).
std::unordered_set<Name> unoptimizable;
for (auto* global : ExportUtils::getExportedGlobals(*module)) {
auto exportedGlobalsVec = ExportUtils::getExportedGlobals(*module);
std::unordered_set<Global*> exportedGlobals(exportedGlobalsVec.begin(),
exportedGlobalsVec.end());
for (auto* global : exportedGlobalsVec) {
if (getPassOptions().closedWorld || global->mutable_) {
unoptimizable.insert(global->name);
}
}

bool optimized = false;
PublicTypeValidator publicTypeValidator(module->features);

for (auto& global : module->globals) {
if (global->imported() || unoptimizable.count(global->name)) {
Expand All @@ -102,12 +107,20 @@ struct GlobalRefining : public Pass {

auto oldType = global->type;
auto newType = lub.getLUB();
if (newType != oldType) {
// We found an improvement!
assert(Type::isSubType(newType, oldType));
global->type = newType;
optimized = true;
if (newType == oldType) {
continue;
}

// Do not make invalid types public.
if (exportedGlobals.count(global.get()) &&
!publicTypeValidator.isValidPublicType(newType)) {
continue;
}

// We found an improvement!
assert(Type::isSubType(newType, oldType));
global->type = newType;
optimized = true;
}

if (!optimized) {
Expand Down
28 changes: 28 additions & 0 deletions test/lit/passes/global-refining_no-cd.wast
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@@ -0,0 +1,28 @@
;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.

;; RUN: foreach %s %t wasm-opt --global-refining -all --disable-custom-descriptors -S -o - | filecheck %s

;; We cannot refine $global's type, as then it would make the rec group
;; public, and that includes an exact type, which is invalid without custom
;; descriptors.
;;
;; We can refine $unexported, though, as it makes nothing public.
(module
(rec
;; CHECK: (rec
;; CHECK-NEXT: (type $array (array i8))
(type $array (array i8))
;; CHECK: (type $struct (struct (field (ref (exact $array)))))
(type $struct (struct (field (ref (exact $array)))))
)

;; CHECK: (global $global (ref eq) (array.new_fixed $array 0))
(global $global (ref eq) (array.new_fixed $array 0))

;; CHECK: (global $unexported (ref (exact $array)) (array.new_fixed $array 0))
(global $unexported (ref eq) (array.new_fixed $array 0))

;; CHECK: (export "global" (global $global))
(export "global" (global $global))
)

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