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Properly hash and compare internalized strings #8081

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Merged
kripken merged 1 commit into from
Dec 1, 2025
Merged

Properly hash and compare internalized strings #8081

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14 changes: 12 additions & 2 deletions src/literal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -828,10 +828,19 @@ template<> struct hash<wasm::Literal> {
wasm::rehash(digest, a.getFunc());
return digest;
}
if (a.type.getHeapType().isMaybeShared(wasm::HeapType::i31)) {
auto type = a.type.getHeapType();
if (type.isMaybeShared(wasm::HeapType::i31)) {
wasm::rehash(digest, a.geti31(true));
return digest;
}
if (type.isMaybeShared(wasm::HeapType::any)) {
// This may be an extern string that was internalized to |any|. Undo
// that to get the actual value. (Rehash here with the existing digest,
// which contains the |any| type, so that the final hash takes into
// account the fact that it was internalized.)
wasm::rehash(digest, (*this)(a.externalize()));
return digest;
}
if (a.type.isString()) {
auto& values = a.getGCData()->values;
wasm::rehash(digest, values.size());
Expand All @@ -841,7 +850,8 @@ template<> struct hash<wasm::Literal> {
return digest;
}
// other non-null reference type literals cannot represent concrete
// values, i.e. there is no concrete anyref or eqref other than null.
// values, i.e. there is no concrete anyref or eqref other than null and
// internalized strings.
WASM_UNREACHABLE("unexpected type");
}
WASM_UNREACHABLE("unexpected type");
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10 changes: 7 additions & 3 deletions src/wasm/literal.cpp
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Expand Up @@ -493,13 +493,17 @@ bool Literal::operator==(const Literal& other) const {
if (type.isData()) {
return gcData == other.gcData;
}
assert(type.getHeapType().isBasic());
if (type.getHeapType().isMaybeShared(HeapType::i31)) {
auto heapType = type.getHeapType();
assert(heapType.isBasic());
if (heapType.isMaybeShared(HeapType::i31)) {
return i32 == other.i32;
}
if (type.getHeapType().isMaybeShared(HeapType::ext)) {
if (heapType.isMaybeShared(HeapType::ext)) {
return internalize() == other.internalize();
}
if (heapType.isMaybeShared(HeapType::any)) {
return externalize() == other.externalize();
}
WASM_UNREACHABLE("unexpected type");
}
WASM_UNREACHABLE("unexpected type");
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40 changes: 40 additions & 0 deletions test/lit/passes/rse-gc.wast
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Expand Up @@ -303,4 +303,44 @@
(local.get $s)
)
)

;; CHECK: (func $any-extern (type $3)
;; CHECK-NEXT: (local $any anyref)
;; CHECK-NEXT: (local.set $any
;; CHECK-NEXT: (any.convert_extern
;; CHECK-NEXT: (string.const "hello")
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (any.convert_extern
;; CHECK-NEXT: (string.const "hello")
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $any
;; CHECK-NEXT: (any.convert_extern
;; CHECK-NEXT: (string.const "world")
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $any-extern
;; Test internalized strings.
(local $any anyref)
(local.set $any
(any.convert_extern
(string.const "hello")
)
)
;; This set can turn into a drop, as the value is already in the local.
(local.set $any
(any.convert_extern
(string.const "hello")
)
)
;; This is a different string.
(local.set $any
(any.convert_extern
(string.const "world")
)
)
)
)
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