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[WebAssembly] Add support for shared tags (#188367)

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Mostly following the structure of other Shared* constructs

Fixes: #188120
This commit is contained in:
Jasmine Tang 2026-04-04 22:53:20 -07:00 committed by GitHub
parent 942e1082ac
commit e3e4b8481d
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
8 changed files with 78 additions and 6 deletions
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5
lld/test/wasm/Inputs/libsearch-dyn.s
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@ -1,4 +1,4 @@
.globl _bar,_dynamic
.globl _bar,_dynamic,_foo_tag
.section .data,"",@
_bar:
@ -6,3 +6,6 @@ _bar:
_dynamic:
.size _dynamic,4
.tagtype _foo_tag i32
_foo_tag:

13
lld/test/wasm/dylink.s
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@ -1,4 +1,4 @@
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten -o %t.o %s
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten -mattr=+exception-handling -o %t.o %s
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %p/Inputs/ret32.s -o %t.ret32.o
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %p/Inputs/libsearch-dyn.s -o %t.dyn.o
# RUN: wasm-ld --experimental-pic -shared %t.ret32.o %t.dyn.o -o %t.lib.so
@ -8,7 +8,7 @@
# Same again for wasm64
# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-emscripten -o %t.o %s
# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-emscripten -mattr=+exception-handling -o %t.o %s
# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-emscripten %p/Inputs/ret32.s -o %t.ret32.o
# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-emscripten %p/Inputs/libsearch-dyn.s -o %t.dyn.o
# RUN: wasm-ld --experimental-pic -mwasm64 -shared %t.ret32.o %t.dyn.o -o %t.lib.so
@ -18,8 +18,9 @@
# ERROR: error: {{.*}}: undefined symbol: ret32
# ERROR: error: {{.*}}: undefined symbol: _bar
# ERROR: error: {{.*}}: undefined symbol: _foo_tag
.functype ret32 (f32) -> (i32)
.tagtype _foo_tag i32
.globl _start
_start:
.functype _start () -> ()
@ -28,6 +29,8 @@ _start:
drop
i32.const _bar@GOT
drop
i32.const 0
throw _foo_tag
end_function
# CHECK: Sections:
@ -39,3 +42,7 @@ _start:
# CHECK-NEXT: TableAlignment: 0
# CHECK-NEXT: Needed:
# CHECK-NEXT: - {{.*}}.lib.so
#
# CHECK: Field: _foo_tag
# CHECK-NEXT: Kind: TAG
# CHECK-NEXT: SigIndex: 1

3
lld/wasm/InputFiles.cpp
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@ -453,6 +453,9 @@ void SharedFile::parse() {
case WASM_SYMBOL_TYPE_DATA:
s = symtab->addSharedData(name, flags, this);
break;
case WASM_SYMBOL_TYPE_TAG:
s = symtab->addSharedTag(name, flags, this, wasmSym.Signature);
break;
default:
continue;
}

38
lld/wasm/SymbolTable.cpp
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@ -352,6 +352,44 @@ static void reportFunctionSignatureMismatch(StringRef symName,
isError);
}
Symbol *SymbolTable::addSharedTag(StringRef name, uint32_t flags,
InputFile *file, const WasmSignature *sig) {
LLVM_DEBUG(dbgs() << "addSharedTag: " << name << " [" << toString(*sig)
<< "]\n");
Symbol *s;
bool wasInserted;
std::tie(s, wasInserted) = insert(name, file);
auto replaceSym = [&](Symbol *sym) {
replaceSymbol<SharedTagSymbol>(sym, name, flags, file, sig);
};
// same as addSharedFunction, but this is in its own function
if (wasInserted || s->isLazy()) {
replaceSym(s);
return s;
}
auto *existingTag = dyn_cast<TagSymbol>(s);
if (!existingTag) {
reportTypeError(s, file, WASM_SYMBOL_TYPE_TAG);
return s;
}
if (s->isDefined()) {
return s;
}
// undefined existing sym
const WasmSignature *oldSig = existingTag->signature;
if (oldSig && sig && *oldSig != *sig)
error("Tag signature mismatch: " + name + "\n>>> defined as " +
toString(*oldSig) + " in " + toString(existingTag->getFile()) +
"\n>>> defined as " + toString(*sig) + " in " + toString(file));
replaceSym(s);
return s;
}
Symbol *SymbolTable::addSharedFunction(StringRef name, uint32_t flags,
InputFile *file,
const WasmSignature *sig) {

2
lld/wasm/SymbolTable.h
View File

@ -53,6 +53,8 @@ public:
Symbol *addSharedFunction(StringRef name, uint32_t flags, InputFile *file,
const WasmSignature *sig);
Symbol *addSharedData(StringRef name, uint32_t flags, InputFile *file);
Symbol *addSharedTag(StringRef name, uint32_t flags, InputFile *file,
const WasmSignature *sig);
Symbol *addDefinedFunction(StringRef name, uint32_t flags, InputFile *file,
InputFunction *function);
Symbol *addDefinedData(StringRef name, uint32_t flags, InputFile *file,

2
lld/wasm/Symbols.cpp
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@ -72,6 +72,8 @@ std::string toString(wasm::Symbol::Kind kind) {
return "SharedFunctionKind";
case wasm::Symbol::SharedDataKind:
return "SharedDataKind";
case wasm::Symbol::SharedTagKind:
return "SharedTagSymbol";
}
llvm_unreachable("invalid symbol kind");
}

17
lld/wasm/Symbols.h
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@ -62,6 +62,7 @@ public:
LazyKind,
SharedFunctionKind,
SharedDataKind,
SharedTagKind,
};
Kind kind() const { return symbolKind; }
@ -77,7 +78,8 @@ public:
bool isLazy() const { return symbolKind == LazyKind; }
bool isShared() const {
return symbolKind == SharedFunctionKind || symbolKind == SharedDataKind;
return symbolKind == SharedFunctionKind || symbolKind == SharedDataKind ||
symbolKind == SharedTagKind;
}
bool isLocal() const;
@ -461,7 +463,8 @@ public:
class TagSymbol : public Symbol {
public:
static bool classof(const Symbol *s) {
return s->kind() == DefinedTagKind || s->kind() == UndefinedTagKind;
return s->kind() == DefinedTagKind || s->kind() == UndefinedTagKind ||
s->kind() == SharedTagKind;
}
// Get/set the tag index
@ -501,6 +504,15 @@ public:
static bool classof(const Symbol *s) { return s->kind() == UndefinedTagKind; }
};
class SharedTagSymbol : public TagSymbol {
public:
SharedTagSymbol(StringRef name, uint32_t flags, InputFile *f,
const WasmSignature *sig)
: TagSymbol(name, SharedTagKind, flags, f, sig) {}
static bool classof(const Symbol *s) { return s->kind() == SharedTagKind; }
};
class SharedFunctionSymbol : public FunctionSymbol {
public:
SharedFunctionSymbol(StringRef name, uint32_t flags, InputFile *file,
@ -553,6 +565,7 @@ union SymbolUnion {
alignas(UndefinedTable) char j[sizeof(UndefinedTable)];
alignas(SectionSymbol) char k[sizeof(SectionSymbol)];
alignas(SharedFunctionSymbol) char l[sizeof(SharedFunctionSymbol)];
alignas(SharedTagSymbol) char m[sizeof(SharedTagSymbol)];
};
// It is important to keep the size of SymbolUnion small for performance and

4
llvm/lib/Object/WasmObjectFile.cpp
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@ -1547,6 +1547,10 @@ Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
object_error::parse_failed);
Info.Kind = wasm::WASM_SYMBOL_TYPE_TAG;
Info.ElementIndex = Ex.Index;
if (isDefinedTagIndex(Ex.Index)) {
unsigned TagIndex = Ex.Index - NumImportedTags;
Signature = &Signatures[Tags[TagIndex].SigIndex];
}
break;
case wasm::WASM_EXTERNAL_MEMORY:
break;