[WebAssembly] WASIP3 and component model threading support#175800
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TartanLlama wants to merge 126 commits intollvm:mainfrom
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[WebAssembly] WASIP3 and component model threading support#175800TartanLlama wants to merge 126 commits intollvm:mainfrom
TartanLlama wants to merge 126 commits intollvm:mainfrom
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alexcrichton
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Two higher-ish level thoughts on this:
- Would it be possible to decouple the selection of how things work internally from the target name and "wasip3" suffix? These options will, I believe, be useful for experimenting on other wasm targets (e.g. even
wasm32-wasip2) and it would be useful to have knobs to turn without faking/forcing a target. My thinking is that the default behavior forwasm32-wasip3is still the same, exactly as-is in this PR, but the knobs could be further refined if so desired for power users. Effectively there'd be per-target defaults for the knobs, but the knobs could be manually overridden if needed. - What happens if objects of one ABI are mixed with objects of another ABI? For example if I were to link code compiled for
wasm32-wasip2with code forwasm32-wasip3, what would happen? Ideally I'd expect a linker-level error to be emitted with some long enough string that could be googled but probably wouldn't be descriptive in its own right. My main worry is less mixing targets and more mixing versions of LLVM by accident and ensuring that things don't silently link and then get weirdly corrupted at runtime.
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@llvm/pr-subscribers-lld-wasm @llvm/pr-subscribers-lld Author: Sy Brand (TartanLlama) Changes(Currently in draft, as this will evolve alongside other toolchain component updates) The WebAssembly Component Model has added support for cooperative multithreading. This has been implemented in the Wasmtime engine and is part of the wider project of WASI preview 3, which is currently tracked here. These changes will require updating the way that Patch is 55.79 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/175800.diff 22 Files Affected:
diff --git a/clang/lib/Basic/Targets/WebAssembly.cpp b/clang/lib/Basic/Targets/WebAssembly.cpp
index daaefd9a1267c..1905b838e52a1 100644
--- a/clang/lib/Basic/Targets/WebAssembly.cpp
+++ b/clang/lib/Basic/Targets/WebAssembly.cpp
@@ -410,7 +410,8 @@ void WebAssemblyTargetInfo::adjust(DiagnosticsEngine &Diags, LangOptions &Opts,
// Turn off POSIXThreads and ThreadModel so that we don't predefine _REENTRANT
// or __STDCPP_THREADS__ if we will eventually end up stripping atomics
// because they are unsupported.
- if (!HasAtomics || !HasBulkMemory) {
+ if (getTriple().getOSName() != "wasip3" &&
+ (!HasAtomics || !HasBulkMemory)) {
Opts.POSIXThreads = false;
Opts.setThreadModel(LangOptions::ThreadModelKind::Single);
Opts.ThreadsafeStatics = false;
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index b5fa5760a46a0..efeadcc6556de 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -30,13 +30,14 @@ using namespace llvm::opt;
std::string WebAssembly::getMultiarchTriple(const Driver &D,
const llvm::Triple &TargetTriple,
StringRef SysRoot) const {
- return (TargetTriple.getArchName() + "-" +
- TargetTriple.getOSAndEnvironmentName()).str();
+ return (TargetTriple.getArchName() + "-" +
+ TargetTriple.getOSAndEnvironmentName())
+ .str();
}
std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {
const ToolChain &ToolChain = getToolChain();
- if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
+ if (const Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
StringRef UseLinker = A->getValue();
if (!UseLinker.empty()) {
if (llvm::sys::path::is_absolute(UseLinker) &&
@@ -79,6 +80,10 @@ static bool WantsPthread(const llvm::Triple &Triple, const ArgList &Args) {
return WantsPthread;
}
+static bool WantsSharedMemory(const llvm::Triple &Triple, const ArgList &Args) {
+ return WantsPthread(Triple, Args) && !TargetBuildsComponents(Triple);
+}
+
void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
const InputInfo &Output,
const InputInfoList &Inputs,
@@ -90,10 +95,14 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
ArgStringList CmdArgs;
CmdArgs.push_back("-m");
+ std::string arch;
if (ToolChain.getTriple().isArch64Bit())
- CmdArgs.push_back("wasm64");
+ arch = "wasm64";
else
- CmdArgs.push_back("wasm32");
+ arch = "wasm32";
+ if (ToolChain.getTriple().getOSName() == "wasip3")
+ arch += "-wasip3";
+ CmdArgs.push_back(Args.MakeArgString(arch));
if (Args.hasArg(options::OPT_s))
CmdArgs.push_back("--strip-all");
@@ -160,7 +169,7 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
- if (WantsPthread(ToolChain.getTriple(), Args))
+ if (WantsSharedMemory(ToolChain.getTriple(), Args))
CmdArgs.push_back("--shared-memory");
if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
@@ -233,9 +242,9 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
/// Given a base library directory, append path components to form the
/// LTO directory.
static std::string AppendLTOLibDir(const std::string &Dir) {
- // The version allows the path to be keyed to the specific version of
- // LLVM in used, as the bitcode format is not stable.
- return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
+ // The version allows the path to be keyed to the specific version of
+ // LLVM in used, as the bitcode format is not stable.
+ return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
}
WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
@@ -508,7 +517,8 @@ void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
if (getTriple().getOS() != llvm::Triple::UnknownOS) {
const std::string MultiarchTriple =
getMultiarchTriple(D, getTriple(), D.SysRoot);
- addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);
+ addSystemInclude(DriverArgs, CC1Args,
+ D.SysRoot + "/include/" + MultiarchTriple);
}
addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
}
@@ -637,5 +647,6 @@ void WebAssembly::addLibStdCXXIncludePaths(
// Second add the generic one.
addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version);
// Third the backward one.
- addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version + "/backward");
+ addSystemInclude(DriverArgs, CC1Args,
+ LibPath + "/c++/" + Version + "/backward");
}
diff --git a/lld/wasm/Config.h b/lld/wasm/Config.h
index 31e08e4e248a4..d291a42da200f 100644
--- a/lld/wasm/Config.h
+++ b/lld/wasm/Config.h
@@ -35,6 +35,7 @@ class Symbol;
class DefinedData;
class GlobalSymbol;
class DefinedFunction;
+class UndefinedFunction;
class DefinedGlobal;
class UndefinedGlobal;
class TableSymbol;
@@ -50,6 +51,8 @@ enum class BuildIdKind { None, Fast, Sha1, Hexstring, Uuid };
// and such fields have the same name as the corresponding options.
// Most fields are initialized by the driver.
struct Config {
+ bool isMultithreaded() const { return sharedMemory || isWasip3; }
+
bool allowMultipleDefinition;
bool bsymbolic;
bool checkFeatures;
@@ -71,6 +74,7 @@ struct Config {
bool importTable;
bool importUndefined;
std::optional<bool> is64;
+ bool isWasip3;
bool mergeDataSegments;
bool noinhibitExec;
bool pie;
@@ -252,6 +256,14 @@ struct Ctx {
// Used as an address space for function pointers, with each function that
// is used as a function pointer being allocated a slot.
TableSymbol *indirectFunctionTable;
+
+ // __wasm_component_model_builtin_context_set_1
+ // Function used to set TLS base in component model modules.
+ UndefinedFunction *contextSet1;
+
+ // __wasm_component_model_builtin_context_get_1
+ // Function used to get TLS base in component model modules.
+ UndefinedFunction *contextGet1;
};
WasmSym sym;
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index b1e36f2ecff74..6eaacd7288f22 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -656,15 +656,16 @@ static void readConfigs(opt::InputArgList &args) {
ctx.arg.exportDynamic =
args.hasFlag(OPT_export_dynamic, OPT_no_export_dynamic, ctx.arg.shared);
- // Parse wasm32/64.
+ // Parse wasm32/64 and maybe -wasip3.
if (auto *arg = args.getLastArg(OPT_m)) {
StringRef s = arg->getValue();
- if (s == "wasm32")
+ if (s.starts_with("wasm32"))
ctx.arg.is64 = false;
- else if (s == "wasm64")
+ else if (s.starts_with("wasm64"))
ctx.arg.is64 = true;
else
error("invalid target architecture: " + s);
+ ctx.arg.isWasip3 = s.ends_with("-wasip3");
}
// --threads= takes a positive integer and provides the default value for
@@ -827,6 +828,10 @@ static void checkOptions(opt::InputArgList &args) {
if (ctx.arg.tableBase)
error("--table-base may not be used with -shared/-pie");
}
+
+ if (ctx.arg.sharedMemory && ctx.arg.isWasip3) {
+ error("--shared-memory is incompatible with the wasip3 target");
+ }
}
static const char *getReproduceOption(opt::InputArgList &args) {
@@ -885,7 +890,7 @@ static void writeWhyExtract() {
// Equivalent of demote demoteSharedAndLazySymbols() in the ELF linker
static void demoteLazySymbols() {
for (Symbol *sym : symtab->symbols()) {
- if (auto* s = dyn_cast<LazySymbol>(sym)) {
+ if (auto *s = dyn_cast<LazySymbol>(sym)) {
if (s->signature) {
LLVM_DEBUG(llvm::dbgs()
<< "demoting lazy func: " << s->getName() << "\n");
@@ -906,6 +911,18 @@ createUndefinedGlobal(StringRef name, llvm::wasm::WasmGlobalType *type) {
return sym;
}
+static UndefinedFunction *
+createUndefinedFunction(StringRef name, std::optional<StringRef> importName,
+ std::optional<StringRef> importModule,
+ WasmSignature *signature) {
+ auto *sym = cast<UndefinedFunction>(symtab->addUndefinedFunction(
+ name, importName, importModule, WASM_SYMBOL_UNDEFINED, nullptr, signature,
+ true));
+ ctx.arg.allowUndefinedSymbols.insert(sym->getName());
+ sym->isUsedInRegularObj = true;
+ return sym;
+}
+
static InputGlobal *createGlobal(StringRef name, bool isMutable) {
llvm::wasm::WasmGlobal wasmGlobal;
bool is64 = ctx.arg.is64.value_or(false);
@@ -946,11 +963,13 @@ static void createSyntheticSymbols() {
bool is64 = ctx.arg.is64.value_or(false);
+ auto stack_pointer_name =
+ ctx.arg.isWasip3 ? "__init_stack_pointer" : "__stack_pointer";
if (ctx.isPic) {
ctx.sym.stackPointer =
- createUndefinedGlobal("__stack_pointer", ctx.arg.is64.value_or(false)
- ? &mutableGlobalTypeI64
- : &mutableGlobalTypeI32);
+ createUndefinedGlobal(stack_pointer_name, ctx.arg.is64.value_or(false)
+ ? &mutableGlobalTypeI64
+ : &mutableGlobalTypeI32);
// For PIC code, we import two global variables (__memory_base and
// __table_base) from the environment and use these as the offset at
// which to load our static data and function table.
@@ -963,14 +982,15 @@ static void createSyntheticSymbols() {
ctx.sym.tableBase->markLive();
} else {
// For non-PIC code
- ctx.sym.stackPointer = createGlobalVariable("__stack_pointer", true);
+ ctx.sym.stackPointer = createGlobalVariable(stack_pointer_name, true);
ctx.sym.stackPointer->markLive();
}
- if (ctx.arg.sharedMemory) {
+ if (ctx.arg.isMultithreaded()) {
// TLS symbols are all hidden/dso-local
- ctx.sym.tlsBase =
- createGlobalVariable("__tls_base", true, WASM_SYMBOL_VISIBILITY_HIDDEN);
+ auto tls_base_name = ctx.arg.isWasip3 ? "__init_tls_base" : "__tls_base";
+ ctx.sym.tlsBase = createGlobalVariable(tls_base_name, true,
+ WASM_SYMBOL_VISIBILITY_HIDDEN);
ctx.sym.tlsSize = createGlobalVariable("__tls_size", false,
WASM_SYMBOL_VISIBILITY_HIDDEN);
ctx.sym.tlsAlign = createGlobalVariable("__tls_align", false,
@@ -979,6 +999,21 @@ static void createSyntheticSymbols() {
"__wasm_init_tls", WASM_SYMBOL_VISIBILITY_HIDDEN,
make<SyntheticFunction>(is64 ? i64ArgSignature : i32ArgSignature,
"__wasm_init_tls"));
+ if (ctx.arg.isWasip3) {
+ ctx.sym.tlsBase->markLive();
+ ctx.sym.tlsSize->markLive();
+ ctx.sym.tlsAlign->markLive();
+ static WasmSignature contextSet1Signature{{}, {ValType::I32}};
+ ctx.sym.contextSet1 = createUndefinedFunction(
+ "__wasm_component_model_builtin_context_set_1", "[context-set-1]",
+ "$root", &contextSet1Signature);
+ ctx.sym.contextSet1->markLive();
+ static WasmSignature contextGet1Signature{{ValType::I32}, {}};
+ ctx.sym.contextGet1 = createUndefinedFunction(
+ "__wasm_component_model_builtin_context_get_1", "[context-get-1]",
+ "$root", &contextGet1Signature);
+ ctx.sym.contextGet1->markLive();
+ }
}
}
@@ -1017,7 +1052,7 @@ static void createOptionalSymbols() {
//
// __tls_size and __tls_align are not needed in this case since they are only
// needed for __wasm_init_tls (which we do not create in this case).
- if (!ctx.arg.sharedMemory)
+ if (!ctx.arg.sharedMemory && !ctx.arg.isWasip3)
ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
}
@@ -1026,15 +1061,15 @@ static void processStubLibrariesPreLTO() {
for (auto &stub_file : ctx.stubFiles) {
LLVM_DEBUG(llvm::dbgs()
<< "processing stub file: " << stub_file->getName() << "\n");
- for (auto [name, deps]: stub_file->symbolDependencies) {
- auto* sym = symtab->find(name);
+ for (auto [name, deps] : stub_file->symbolDependencies) {
+ auto *sym = symtab->find(name);
// If the symbol is not present at all (yet), or if it is present but
// undefined, then mark the dependent symbols as used by a regular
// object so they will be preserved and exported by the LTO process.
if (!sym || sym->isUndefined()) {
for (const auto dep : deps) {
- auto* needed = symtab->find(dep);
- if (needed ) {
+ auto *needed = symtab->find(dep);
+ if (needed) {
needed->isUsedInRegularObj = true;
// Like with handleLibcall we have to extract any LTO archive
// members that might need to be exported due to stub library
diff --git a/lld/wasm/Relocations.cpp b/lld/wasm/Relocations.cpp
index a3f87ea3d69c0..cb597fdeffcf3 100644
--- a/lld/wasm/Relocations.cpp
+++ b/lld/wasm/Relocations.cpp
@@ -33,7 +33,7 @@ static bool requiresGOTAccess(const Symbol *sym) {
return true;
}
-static bool allowUndefined(const Symbol* sym) {
+static bool allowUndefined(const Symbol *sym) {
// Symbols that are explicitly imported are always allowed to be undefined at
// link time.
if (sym->isImported())
@@ -125,7 +125,7 @@ void scanRelocations(InputChunk *chunk) {
// In single-threaded builds TLS is lowered away and TLS data can be
// merged with normal data and allowing TLS relocation in non-TLS
// segments.
- if (ctx.arg.sharedMemory) {
+ if (ctx.arg.isMultithreaded()) {
if (!sym->isTLS()) {
error(toString(file) + ": relocation " +
relocTypeToString(reloc.Type) +
diff --git a/lld/wasm/Symbols.cpp b/lld/wasm/Symbols.cpp
index f2040441e6257..97a9871a06308 100644
--- a/lld/wasm/Symbols.cpp
+++ b/lld/wasm/Symbols.cpp
@@ -95,7 +95,7 @@ WasmSymbolType Symbol::getWasmType() const {
}
const WasmSignature *Symbol::getSignature() const {
- if (auto* f = dyn_cast<FunctionSymbol>(this))
+ if (auto *f = dyn_cast<FunctionSymbol>(this))
return f->signature;
if (auto *t = dyn_cast<TagSymbol>(this))
return t->signature;
@@ -223,9 +223,7 @@ bool Symbol::isExportedExplicit() const {
return forceExport || flags & WASM_SYMBOL_EXPORTED;
}
-bool Symbol::isNoStrip() const {
- return flags & WASM_SYMBOL_NO_STRIP;
-}
+bool Symbol::isNoStrip() const { return flags & WASM_SYMBOL_NO_STRIP; }
uint32_t FunctionSymbol::getFunctionIndex() const {
if (const auto *u = dyn_cast<UndefinedFunction>(this))
@@ -413,7 +411,7 @@ void LazySymbol::setWeak() {
flags |= (flags & ~WASM_SYMBOL_BINDING_MASK) | WASM_SYMBOL_BINDING_WEAK;
}
-void printTraceSymbolUndefined(StringRef name, const InputFile* file) {
+void printTraceSymbolUndefined(StringRef name, const InputFile *file) {
message(toString(file) + ": reference to " + name);
}
diff --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index ede6ac4da77b3..023c690c14354 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -466,8 +466,7 @@ void GlobalSection::addInternalGOTEntry(Symbol *sym) {
void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
assert(!ctx.arg.extendedConst);
bool is64 = ctx.arg.is64.value_or(false);
- unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD
- : WASM_OPCODE_I32_ADD;
+ unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD : WASM_OPCODE_I32_ADD;
for (const Symbol *sym : internalGotSymbols) {
if (TLS != sym->isTLS())
@@ -477,7 +476,7 @@ void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
// Get __memory_base
writeU8(os, WASM_OPCODE_GLOBAL_GET, "GLOBAL_GET");
if (sym->isTLS())
- writeUleb128(os, ctx.sym.tlsBase->getGlobalIndex(), "__tls_base");
+ writeGetTLSBase(ctx, os);
else
writeUleb128(os, ctx.sym.memoryBase->getGlobalIndex(), "__memory_base");
@@ -520,9 +519,9 @@ void GlobalSection::writeBody() {
// the correct runtime value during `__wasm_apply_global_relocs`.
if (!ctx.arg.extendedConst && ctx.isPic && !sym->isTLS())
mutable_ = true;
- // With multi-theadeding any TLS globals must be mutable since they get
+ // With multi-threading any TLS globals must be mutable since they get
// set during `__wasm_apply_global_tls_relocs`
- if (ctx.arg.sharedMemory && sym->isTLS())
+ if (ctx.arg.isMultithreaded() && sym->isTLS())
mutable_ = true;
}
WasmGlobalType type{itype, mutable_};
@@ -559,10 +558,11 @@ void GlobalSection::writeBody() {
} else {
WasmInitExpr initExpr;
if (auto *d = dyn_cast<DefinedData>(sym))
- // In the sharedMemory case TLS globals are set during
- // `__wasm_apply_global_tls_relocs`, but in the non-shared case
+ // In the multi-threaded case, TLS globals are set during
+ // `__wasm_apply_global_tls_relocs`, but in the non-multi-threaded case
// we know the absolute value at link time.
- initExpr = intConst(d->getVA(/*absolute=*/!ctx.arg.sharedMemory), is64);
+ initExpr =
+ intConst(d->getVA(/*absolute=*/!ctx.arg.isMultithreaded()), is64);
else if (auto *f = dyn_cast<FunctionSymbol>(sym))
initExpr = intConst(f->isStub ? 0 : f->getTableIndex(), is64);
else {
@@ -646,7 +646,7 @@ void ElemSection::writeBody() {
uint32_t tableIndex = ctx.arg.tableBase;
for (const FunctionSymbol *sym : indirectFunctions) {
assert(sym->getTableIndex() == tableIndex);
- (void) tableIndex;
+ (void)tableIndex;
writeUleb128(os, sym->getFunctionIndex(), "function index");
++tableIndex;
}
@@ -663,7 +663,7 @@ void DataCountSection::writeBody() {
}
bool DataCountSection::isNeeded() const {
- return numSegments && ctx.arg.sharedMemory;
+ return numSegments && ctx.arg.isMultithreaded();
}
void LinkingSection::writeBody() {
@@ -992,4 +992,4 @@ void BuildIdSection::writeBuildId(llvm::ArrayRef<uint8_t> buf) {
memcpy(hashPlaceholderPtr, buf.data(), hashSize);
}
-} // namespace wasm::lld
+} // namespace lld::wasm
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index dfd856f2faee6..50d6449ca79a9 100644
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -311,7 +311,8 @@ void Writer::writeBuildId() {
}
static void setGlobalPtr(DefinedGlobal *g, uint64_t memoryPtr) {
- LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr << "\n");
+ LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr
+ << "\n");
g->global->setPointerValue(memoryPtr);
}
@@ -358,7 +359,8 @@ void Writer::layoutMemory() {
placeStack();
if (ctx.arg.globalBase) {
if (ctx.arg.globalBase < memoryPtr) {
- error("--global-base cannot be less than stack size when --stack-first is used");
+ error("--global-base cannot be less than stack size when --stack-first "
+ "is used");
return;
}
memoryPtr = ctx.arg.globalBase;
@@ -382,6 +384,7 @@ void Writer::layoutMemory() {
for (OutputSegment *seg : segments) {
out.dylinkSec->memAlign = std::max(out.dylinkSec->memAlign, seg->alignment);
memoryPtr = alignTo(memoryPtr, 1ULL << seg->alignment);
+
seg->startVA = memoryPtr;
log(formatv("mem: {0,-15} offset={1,-8} size={2,-8} align={3}", seg->name,
memoryPtr, seg->size, seg->alignment));
@@ -1029,7 +1032,7 @@ static StringRef getOutputDataSegmentName(const InputChunk &seg) {
OutputSegment *Writer::createOutputSegment(StringRef name) {
LLVM_DEBUG(dbgs() << "new segment: " << name << "\n");
OutputSegment *s = make<OutputSegment>(name);
- if (ctx.arg.sharedMemory)
+ if (ctx.arg.isMultithreaded())
s->initFlags = WASM_DATA_SEGMENT_IS_PASSIVE;
if (!ctx.arg.relocatable && name.starts_with(".bss"))
s->isBss = true;
@@ -1163,14 +1166,14 @@ void Writer::createSyntheticInitFunctions() {
"__wasm_init_memory", WASM_SYMBOL_VISIBILITY_HIDDEN,
make<SyntheticFunction>(nullSignature, "__wasm_init_memory"));
ctx.sym.initMemory->mark...
[truncated]
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Member
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@llvm/pr-subscribers-llvm-mc Author: Sy Brand (TartanLlama) Changes(Currently in draft, as this will evolve alongside other toolchain component updates) The WebAssembly Component Model has added support for cooperative multithreading. This has been implemented in the Wasmtime engine and is part of the wider project of WASI preview 3, which is currently tracked here. These changes will require updating the way that Patch is 55.79 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/175800.diff 22 Files Affected:
diff --git a/clang/lib/Basic/Targets/WebAssembly.cpp b/clang/lib/Basic/Targets/WebAssembly.cpp
index daaefd9a1267c..1905b838e52a1 100644
--- a/clang/lib/Basic/Targets/WebAssembly.cpp
+++ b/clang/lib/Basic/Targets/WebAssembly.cpp
@@ -410,7 +410,8 @@ void WebAssemblyTargetInfo::adjust(DiagnosticsEngine &Diags, LangOptions &Opts,
// Turn off POSIXThreads and ThreadModel so that we don't predefine _REENTRANT
// or __STDCPP_THREADS__ if we will eventually end up stripping atomics
// because they are unsupported.
- if (!HasAtomics || !HasBulkMemory) {
+ if (getTriple().getOSName() != "wasip3" &&
+ (!HasAtomics || !HasBulkMemory)) {
Opts.POSIXThreads = false;
Opts.setThreadModel(LangOptions::ThreadModelKind::Single);
Opts.ThreadsafeStatics = false;
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index b5fa5760a46a0..efeadcc6556de 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -30,13 +30,14 @@ using namespace llvm::opt;
std::string WebAssembly::getMultiarchTriple(const Driver &D,
const llvm::Triple &TargetTriple,
StringRef SysRoot) const {
- return (TargetTriple.getArchName() + "-" +
- TargetTriple.getOSAndEnvironmentName()).str();
+ return (TargetTriple.getArchName() + "-" +
+ TargetTriple.getOSAndEnvironmentName())
+ .str();
}
std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {
const ToolChain &ToolChain = getToolChain();
- if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
+ if (const Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
StringRef UseLinker = A->getValue();
if (!UseLinker.empty()) {
if (llvm::sys::path::is_absolute(UseLinker) &&
@@ -79,6 +80,10 @@ static bool WantsPthread(const llvm::Triple &Triple, const ArgList &Args) {
return WantsPthread;
}
+static bool WantsSharedMemory(const llvm::Triple &Triple, const ArgList &Args) {
+ return WantsPthread(Triple, Args) && !TargetBuildsComponents(Triple);
+}
+
void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
const InputInfo &Output,
const InputInfoList &Inputs,
@@ -90,10 +95,14 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
ArgStringList CmdArgs;
CmdArgs.push_back("-m");
+ std::string arch;
if (ToolChain.getTriple().isArch64Bit())
- CmdArgs.push_back("wasm64");
+ arch = "wasm64";
else
- CmdArgs.push_back("wasm32");
+ arch = "wasm32";
+ if (ToolChain.getTriple().getOSName() == "wasip3")
+ arch += "-wasip3";
+ CmdArgs.push_back(Args.MakeArgString(arch));
if (Args.hasArg(options::OPT_s))
CmdArgs.push_back("--strip-all");
@@ -160,7 +169,7 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
- if (WantsPthread(ToolChain.getTriple(), Args))
+ if (WantsSharedMemory(ToolChain.getTriple(), Args))
CmdArgs.push_back("--shared-memory");
if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
@@ -233,9 +242,9 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
/// Given a base library directory, append path components to form the
/// LTO directory.
static std::string AppendLTOLibDir(const std::string &Dir) {
- // The version allows the path to be keyed to the specific version of
- // LLVM in used, as the bitcode format is not stable.
- return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
+ // The version allows the path to be keyed to the specific version of
+ // LLVM in used, as the bitcode format is not stable.
+ return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
}
WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
@@ -508,7 +517,8 @@ void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
if (getTriple().getOS() != llvm::Triple::UnknownOS) {
const std::string MultiarchTriple =
getMultiarchTriple(D, getTriple(), D.SysRoot);
- addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);
+ addSystemInclude(DriverArgs, CC1Args,
+ D.SysRoot + "/include/" + MultiarchTriple);
}
addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
}
@@ -637,5 +647,6 @@ void WebAssembly::addLibStdCXXIncludePaths(
// Second add the generic one.
addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version);
// Third the backward one.
- addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version + "/backward");
+ addSystemInclude(DriverArgs, CC1Args,
+ LibPath + "/c++/" + Version + "/backward");
}
diff --git a/lld/wasm/Config.h b/lld/wasm/Config.h
index 31e08e4e248a4..d291a42da200f 100644
--- a/lld/wasm/Config.h
+++ b/lld/wasm/Config.h
@@ -35,6 +35,7 @@ class Symbol;
class DefinedData;
class GlobalSymbol;
class DefinedFunction;
+class UndefinedFunction;
class DefinedGlobal;
class UndefinedGlobal;
class TableSymbol;
@@ -50,6 +51,8 @@ enum class BuildIdKind { None, Fast, Sha1, Hexstring, Uuid };
// and such fields have the same name as the corresponding options.
// Most fields are initialized by the driver.
struct Config {
+ bool isMultithreaded() const { return sharedMemory || isWasip3; }
+
bool allowMultipleDefinition;
bool bsymbolic;
bool checkFeatures;
@@ -71,6 +74,7 @@ struct Config {
bool importTable;
bool importUndefined;
std::optional<bool> is64;
+ bool isWasip3;
bool mergeDataSegments;
bool noinhibitExec;
bool pie;
@@ -252,6 +256,14 @@ struct Ctx {
// Used as an address space for function pointers, with each function that
// is used as a function pointer being allocated a slot.
TableSymbol *indirectFunctionTable;
+
+ // __wasm_component_model_builtin_context_set_1
+ // Function used to set TLS base in component model modules.
+ UndefinedFunction *contextSet1;
+
+ // __wasm_component_model_builtin_context_get_1
+ // Function used to get TLS base in component model modules.
+ UndefinedFunction *contextGet1;
};
WasmSym sym;
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index b1e36f2ecff74..6eaacd7288f22 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -656,15 +656,16 @@ static void readConfigs(opt::InputArgList &args) {
ctx.arg.exportDynamic =
args.hasFlag(OPT_export_dynamic, OPT_no_export_dynamic, ctx.arg.shared);
- // Parse wasm32/64.
+ // Parse wasm32/64 and maybe -wasip3.
if (auto *arg = args.getLastArg(OPT_m)) {
StringRef s = arg->getValue();
- if (s == "wasm32")
+ if (s.starts_with("wasm32"))
ctx.arg.is64 = false;
- else if (s == "wasm64")
+ else if (s.starts_with("wasm64"))
ctx.arg.is64 = true;
else
error("invalid target architecture: " + s);
+ ctx.arg.isWasip3 = s.ends_with("-wasip3");
}
// --threads= takes a positive integer and provides the default value for
@@ -827,6 +828,10 @@ static void checkOptions(opt::InputArgList &args) {
if (ctx.arg.tableBase)
error("--table-base may not be used with -shared/-pie");
}
+
+ if (ctx.arg.sharedMemory && ctx.arg.isWasip3) {
+ error("--shared-memory is incompatible with the wasip3 target");
+ }
}
static const char *getReproduceOption(opt::InputArgList &args) {
@@ -885,7 +890,7 @@ static void writeWhyExtract() {
// Equivalent of demote demoteSharedAndLazySymbols() in the ELF linker
static void demoteLazySymbols() {
for (Symbol *sym : symtab->symbols()) {
- if (auto* s = dyn_cast<LazySymbol>(sym)) {
+ if (auto *s = dyn_cast<LazySymbol>(sym)) {
if (s->signature) {
LLVM_DEBUG(llvm::dbgs()
<< "demoting lazy func: " << s->getName() << "\n");
@@ -906,6 +911,18 @@ createUndefinedGlobal(StringRef name, llvm::wasm::WasmGlobalType *type) {
return sym;
}
+static UndefinedFunction *
+createUndefinedFunction(StringRef name, std::optional<StringRef> importName,
+ std::optional<StringRef> importModule,
+ WasmSignature *signature) {
+ auto *sym = cast<UndefinedFunction>(symtab->addUndefinedFunction(
+ name, importName, importModule, WASM_SYMBOL_UNDEFINED, nullptr, signature,
+ true));
+ ctx.arg.allowUndefinedSymbols.insert(sym->getName());
+ sym->isUsedInRegularObj = true;
+ return sym;
+}
+
static InputGlobal *createGlobal(StringRef name, bool isMutable) {
llvm::wasm::WasmGlobal wasmGlobal;
bool is64 = ctx.arg.is64.value_or(false);
@@ -946,11 +963,13 @@ static void createSyntheticSymbols() {
bool is64 = ctx.arg.is64.value_or(false);
+ auto stack_pointer_name =
+ ctx.arg.isWasip3 ? "__init_stack_pointer" : "__stack_pointer";
if (ctx.isPic) {
ctx.sym.stackPointer =
- createUndefinedGlobal("__stack_pointer", ctx.arg.is64.value_or(false)
- ? &mutableGlobalTypeI64
- : &mutableGlobalTypeI32);
+ createUndefinedGlobal(stack_pointer_name, ctx.arg.is64.value_or(false)
+ ? &mutableGlobalTypeI64
+ : &mutableGlobalTypeI32);
// For PIC code, we import two global variables (__memory_base and
// __table_base) from the environment and use these as the offset at
// which to load our static data and function table.
@@ -963,14 +982,15 @@ static void createSyntheticSymbols() {
ctx.sym.tableBase->markLive();
} else {
// For non-PIC code
- ctx.sym.stackPointer = createGlobalVariable("__stack_pointer", true);
+ ctx.sym.stackPointer = createGlobalVariable(stack_pointer_name, true);
ctx.sym.stackPointer->markLive();
}
- if (ctx.arg.sharedMemory) {
+ if (ctx.arg.isMultithreaded()) {
// TLS symbols are all hidden/dso-local
- ctx.sym.tlsBase =
- createGlobalVariable("__tls_base", true, WASM_SYMBOL_VISIBILITY_HIDDEN);
+ auto tls_base_name = ctx.arg.isWasip3 ? "__init_tls_base" : "__tls_base";
+ ctx.sym.tlsBase = createGlobalVariable(tls_base_name, true,
+ WASM_SYMBOL_VISIBILITY_HIDDEN);
ctx.sym.tlsSize = createGlobalVariable("__tls_size", false,
WASM_SYMBOL_VISIBILITY_HIDDEN);
ctx.sym.tlsAlign = createGlobalVariable("__tls_align", false,
@@ -979,6 +999,21 @@ static void createSyntheticSymbols() {
"__wasm_init_tls", WASM_SYMBOL_VISIBILITY_HIDDEN,
make<SyntheticFunction>(is64 ? i64ArgSignature : i32ArgSignature,
"__wasm_init_tls"));
+ if (ctx.arg.isWasip3) {
+ ctx.sym.tlsBase->markLive();
+ ctx.sym.tlsSize->markLive();
+ ctx.sym.tlsAlign->markLive();
+ static WasmSignature contextSet1Signature{{}, {ValType::I32}};
+ ctx.sym.contextSet1 = createUndefinedFunction(
+ "__wasm_component_model_builtin_context_set_1", "[context-set-1]",
+ "$root", &contextSet1Signature);
+ ctx.sym.contextSet1->markLive();
+ static WasmSignature contextGet1Signature{{ValType::I32}, {}};
+ ctx.sym.contextGet1 = createUndefinedFunction(
+ "__wasm_component_model_builtin_context_get_1", "[context-get-1]",
+ "$root", &contextGet1Signature);
+ ctx.sym.contextGet1->markLive();
+ }
}
}
@@ -1017,7 +1052,7 @@ static void createOptionalSymbols() {
//
// __tls_size and __tls_align are not needed in this case since they are only
// needed for __wasm_init_tls (which we do not create in this case).
- if (!ctx.arg.sharedMemory)
+ if (!ctx.arg.sharedMemory && !ctx.arg.isWasip3)
ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
}
@@ -1026,15 +1061,15 @@ static void processStubLibrariesPreLTO() {
for (auto &stub_file : ctx.stubFiles) {
LLVM_DEBUG(llvm::dbgs()
<< "processing stub file: " << stub_file->getName() << "\n");
- for (auto [name, deps]: stub_file->symbolDependencies) {
- auto* sym = symtab->find(name);
+ for (auto [name, deps] : stub_file->symbolDependencies) {
+ auto *sym = symtab->find(name);
// If the symbol is not present at all (yet), or if it is present but
// undefined, then mark the dependent symbols as used by a regular
// object so they will be preserved and exported by the LTO process.
if (!sym || sym->isUndefined()) {
for (const auto dep : deps) {
- auto* needed = symtab->find(dep);
- if (needed ) {
+ auto *needed = symtab->find(dep);
+ if (needed) {
needed->isUsedInRegularObj = true;
// Like with handleLibcall we have to extract any LTO archive
// members that might need to be exported due to stub library
diff --git a/lld/wasm/Relocations.cpp b/lld/wasm/Relocations.cpp
index a3f87ea3d69c0..cb597fdeffcf3 100644
--- a/lld/wasm/Relocations.cpp
+++ b/lld/wasm/Relocations.cpp
@@ -33,7 +33,7 @@ static bool requiresGOTAccess(const Symbol *sym) {
return true;
}
-static bool allowUndefined(const Symbol* sym) {
+static bool allowUndefined(const Symbol *sym) {
// Symbols that are explicitly imported are always allowed to be undefined at
// link time.
if (sym->isImported())
@@ -125,7 +125,7 @@ void scanRelocations(InputChunk *chunk) {
// In single-threaded builds TLS is lowered away and TLS data can be
// merged with normal data and allowing TLS relocation in non-TLS
// segments.
- if (ctx.arg.sharedMemory) {
+ if (ctx.arg.isMultithreaded()) {
if (!sym->isTLS()) {
error(toString(file) + ": relocation " +
relocTypeToString(reloc.Type) +
diff --git a/lld/wasm/Symbols.cpp b/lld/wasm/Symbols.cpp
index f2040441e6257..97a9871a06308 100644
--- a/lld/wasm/Symbols.cpp
+++ b/lld/wasm/Symbols.cpp
@@ -95,7 +95,7 @@ WasmSymbolType Symbol::getWasmType() const {
}
const WasmSignature *Symbol::getSignature() const {
- if (auto* f = dyn_cast<FunctionSymbol>(this))
+ if (auto *f = dyn_cast<FunctionSymbol>(this))
return f->signature;
if (auto *t = dyn_cast<TagSymbol>(this))
return t->signature;
@@ -223,9 +223,7 @@ bool Symbol::isExportedExplicit() const {
return forceExport || flags & WASM_SYMBOL_EXPORTED;
}
-bool Symbol::isNoStrip() const {
- return flags & WASM_SYMBOL_NO_STRIP;
-}
+bool Symbol::isNoStrip() const { return flags & WASM_SYMBOL_NO_STRIP; }
uint32_t FunctionSymbol::getFunctionIndex() const {
if (const auto *u = dyn_cast<UndefinedFunction>(this))
@@ -413,7 +411,7 @@ void LazySymbol::setWeak() {
flags |= (flags & ~WASM_SYMBOL_BINDING_MASK) | WASM_SYMBOL_BINDING_WEAK;
}
-void printTraceSymbolUndefined(StringRef name, const InputFile* file) {
+void printTraceSymbolUndefined(StringRef name, const InputFile *file) {
message(toString(file) + ": reference to " + name);
}
diff --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index ede6ac4da77b3..023c690c14354 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -466,8 +466,7 @@ void GlobalSection::addInternalGOTEntry(Symbol *sym) {
void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
assert(!ctx.arg.extendedConst);
bool is64 = ctx.arg.is64.value_or(false);
- unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD
- : WASM_OPCODE_I32_ADD;
+ unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD : WASM_OPCODE_I32_ADD;
for (const Symbol *sym : internalGotSymbols) {
if (TLS != sym->isTLS())
@@ -477,7 +476,7 @@ void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
// Get __memory_base
writeU8(os, WASM_OPCODE_GLOBAL_GET, "GLOBAL_GET");
if (sym->isTLS())
- writeUleb128(os, ctx.sym.tlsBase->getGlobalIndex(), "__tls_base");
+ writeGetTLSBase(ctx, os);
else
writeUleb128(os, ctx.sym.memoryBase->getGlobalIndex(), "__memory_base");
@@ -520,9 +519,9 @@ void GlobalSection::writeBody() {
// the correct runtime value during `__wasm_apply_global_relocs`.
if (!ctx.arg.extendedConst && ctx.isPic && !sym->isTLS())
mutable_ = true;
- // With multi-theadeding any TLS globals must be mutable since they get
+ // With multi-threading any TLS globals must be mutable since they get
// set during `__wasm_apply_global_tls_relocs`
- if (ctx.arg.sharedMemory && sym->isTLS())
+ if (ctx.arg.isMultithreaded() && sym->isTLS())
mutable_ = true;
}
WasmGlobalType type{itype, mutable_};
@@ -559,10 +558,11 @@ void GlobalSection::writeBody() {
} else {
WasmInitExpr initExpr;
if (auto *d = dyn_cast<DefinedData>(sym))
- // In the sharedMemory case TLS globals are set during
- // `__wasm_apply_global_tls_relocs`, but in the non-shared case
+ // In the multi-threaded case, TLS globals are set during
+ // `__wasm_apply_global_tls_relocs`, but in the non-multi-threaded case
// we know the absolute value at link time.
- initExpr = intConst(d->getVA(/*absolute=*/!ctx.arg.sharedMemory), is64);
+ initExpr =
+ intConst(d->getVA(/*absolute=*/!ctx.arg.isMultithreaded()), is64);
else if (auto *f = dyn_cast<FunctionSymbol>(sym))
initExpr = intConst(f->isStub ? 0 : f->getTableIndex(), is64);
else {
@@ -646,7 +646,7 @@ void ElemSection::writeBody() {
uint32_t tableIndex = ctx.arg.tableBase;
for (const FunctionSymbol *sym : indirectFunctions) {
assert(sym->getTableIndex() == tableIndex);
- (void) tableIndex;
+ (void)tableIndex;
writeUleb128(os, sym->getFunctionIndex(), "function index");
++tableIndex;
}
@@ -663,7 +663,7 @@ void DataCountSection::writeBody() {
}
bool DataCountSection::isNeeded() const {
- return numSegments && ctx.arg.sharedMemory;
+ return numSegments && ctx.arg.isMultithreaded();
}
void LinkingSection::writeBody() {
@@ -992,4 +992,4 @@ void BuildIdSection::writeBuildId(llvm::ArrayRef<uint8_t> buf) {
memcpy(hashPlaceholderPtr, buf.data(), hashSize);
}
-} // namespace wasm::lld
+} // namespace lld::wasm
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index dfd856f2faee6..50d6449ca79a9 100644
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -311,7 +311,8 @@ void Writer::writeBuildId() {
}
static void setGlobalPtr(DefinedGlobal *g, uint64_t memoryPtr) {
- LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr << "\n");
+ LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr
+ << "\n");
g->global->setPointerValue(memoryPtr);
}
@@ -358,7 +359,8 @@ void Writer::layoutMemory() {
placeStack();
if (ctx.arg.globalBase) {
if (ctx.arg.globalBase < memoryPtr) {
- error("--global-base cannot be less than stack size when --stack-first is used");
+ error("--global-base cannot be less than stack size when --stack-first "
+ "is used");
return;
}
memoryPtr = ctx.arg.globalBase;
@@ -382,6 +384,7 @@ void Writer::layoutMemory() {
for (OutputSegment *seg : segments) {
out.dylinkSec->memAlign = std::max(out.dylinkSec->memAlign, seg->alignment);
memoryPtr = alignTo(memoryPtr, 1ULL << seg->alignment);
+
seg->startVA = memoryPtr;
log(formatv("mem: {0,-15} offset={1,-8} size={2,-8} align={3}", seg->name,
memoryPtr, seg->size, seg->alignment));
@@ -1029,7 +1032,7 @@ static StringRef getOutputDataSegmentName(const InputChunk &seg) {
OutputSegment *Writer::createOutputSegment(StringRef name) {
LLVM_DEBUG(dbgs() << "new segment: " << name << "\n");
OutputSegment *s = make<OutputSegment>(name);
- if (ctx.arg.sharedMemory)
+ if (ctx.arg.isMultithreaded())
s->initFlags = WASM_DATA_SEGMENT_IS_PASSIVE;
if (!ctx.arg.relocatable && name.starts_with(".bss"))
s->isBss = true;
@@ -1163,14 +1166,14 @@ void Writer::createSyntheticInitFunctions() {
"__wasm_init_memory", WASM_SYMBOL_VISIBILITY_HIDDEN,
make<SyntheticFunction>(nullSignature, "__wasm_init_memory"));
ctx.sym.initMemory->mark...
[truncated]
|
Member
|
@llvm/pr-subscribers-backend-webassembly Author: Sy Brand (TartanLlama) Changes(Currently in draft, as this will evolve alongside other toolchain component updates) The WebAssembly Component Model has added support for cooperative multithreading. This has been implemented in the Wasmtime engine and is part of the wider project of WASI preview 3, which is currently tracked here. These changes will require updating the way that Patch is 55.79 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/175800.diff 22 Files Affected:
diff --git a/clang/lib/Basic/Targets/WebAssembly.cpp b/clang/lib/Basic/Targets/WebAssembly.cpp
index daaefd9a1267c..1905b838e52a1 100644
--- a/clang/lib/Basic/Targets/WebAssembly.cpp
+++ b/clang/lib/Basic/Targets/WebAssembly.cpp
@@ -410,7 +410,8 @@ void WebAssemblyTargetInfo::adjust(DiagnosticsEngine &Diags, LangOptions &Opts,
// Turn off POSIXThreads and ThreadModel so that we don't predefine _REENTRANT
// or __STDCPP_THREADS__ if we will eventually end up stripping atomics
// because they are unsupported.
- if (!HasAtomics || !HasBulkMemory) {
+ if (getTriple().getOSName() != "wasip3" &&
+ (!HasAtomics || !HasBulkMemory)) {
Opts.POSIXThreads = false;
Opts.setThreadModel(LangOptions::ThreadModelKind::Single);
Opts.ThreadsafeStatics = false;
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index b5fa5760a46a0..efeadcc6556de 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -30,13 +30,14 @@ using namespace llvm::opt;
std::string WebAssembly::getMultiarchTriple(const Driver &D,
const llvm::Triple &TargetTriple,
StringRef SysRoot) const {
- return (TargetTriple.getArchName() + "-" +
- TargetTriple.getOSAndEnvironmentName()).str();
+ return (TargetTriple.getArchName() + "-" +
+ TargetTriple.getOSAndEnvironmentName())
+ .str();
}
std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {
const ToolChain &ToolChain = getToolChain();
- if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
+ if (const Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
StringRef UseLinker = A->getValue();
if (!UseLinker.empty()) {
if (llvm::sys::path::is_absolute(UseLinker) &&
@@ -79,6 +80,10 @@ static bool WantsPthread(const llvm::Triple &Triple, const ArgList &Args) {
return WantsPthread;
}
+static bool WantsSharedMemory(const llvm::Triple &Triple, const ArgList &Args) {
+ return WantsPthread(Triple, Args) && !TargetBuildsComponents(Triple);
+}
+
void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
const InputInfo &Output,
const InputInfoList &Inputs,
@@ -90,10 +95,14 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
ArgStringList CmdArgs;
CmdArgs.push_back("-m");
+ std::string arch;
if (ToolChain.getTriple().isArch64Bit())
- CmdArgs.push_back("wasm64");
+ arch = "wasm64";
else
- CmdArgs.push_back("wasm32");
+ arch = "wasm32";
+ if (ToolChain.getTriple().getOSName() == "wasip3")
+ arch += "-wasip3";
+ CmdArgs.push_back(Args.MakeArgString(arch));
if (Args.hasArg(options::OPT_s))
CmdArgs.push_back("--strip-all");
@@ -160,7 +169,7 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
- if (WantsPthread(ToolChain.getTriple(), Args))
+ if (WantsSharedMemory(ToolChain.getTriple(), Args))
CmdArgs.push_back("--shared-memory");
if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
@@ -233,9 +242,9 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
/// Given a base library directory, append path components to form the
/// LTO directory.
static std::string AppendLTOLibDir(const std::string &Dir) {
- // The version allows the path to be keyed to the specific version of
- // LLVM in used, as the bitcode format is not stable.
- return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
+ // The version allows the path to be keyed to the specific version of
+ // LLVM in used, as the bitcode format is not stable.
+ return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
}
WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
@@ -508,7 +517,8 @@ void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
if (getTriple().getOS() != llvm::Triple::UnknownOS) {
const std::string MultiarchTriple =
getMultiarchTriple(D, getTriple(), D.SysRoot);
- addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);
+ addSystemInclude(DriverArgs, CC1Args,
+ D.SysRoot + "/include/" + MultiarchTriple);
}
addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
}
@@ -637,5 +647,6 @@ void WebAssembly::addLibStdCXXIncludePaths(
// Second add the generic one.
addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version);
// Third the backward one.
- addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version + "/backward");
+ addSystemInclude(DriverArgs, CC1Args,
+ LibPath + "/c++/" + Version + "/backward");
}
diff --git a/lld/wasm/Config.h b/lld/wasm/Config.h
index 31e08e4e248a4..d291a42da200f 100644
--- a/lld/wasm/Config.h
+++ b/lld/wasm/Config.h
@@ -35,6 +35,7 @@ class Symbol;
class DefinedData;
class GlobalSymbol;
class DefinedFunction;
+class UndefinedFunction;
class DefinedGlobal;
class UndefinedGlobal;
class TableSymbol;
@@ -50,6 +51,8 @@ enum class BuildIdKind { None, Fast, Sha1, Hexstring, Uuid };
// and such fields have the same name as the corresponding options.
// Most fields are initialized by the driver.
struct Config {
+ bool isMultithreaded() const { return sharedMemory || isWasip3; }
+
bool allowMultipleDefinition;
bool bsymbolic;
bool checkFeatures;
@@ -71,6 +74,7 @@ struct Config {
bool importTable;
bool importUndefined;
std::optional<bool> is64;
+ bool isWasip3;
bool mergeDataSegments;
bool noinhibitExec;
bool pie;
@@ -252,6 +256,14 @@ struct Ctx {
// Used as an address space for function pointers, with each function that
// is used as a function pointer being allocated a slot.
TableSymbol *indirectFunctionTable;
+
+ // __wasm_component_model_builtin_context_set_1
+ // Function used to set TLS base in component model modules.
+ UndefinedFunction *contextSet1;
+
+ // __wasm_component_model_builtin_context_get_1
+ // Function used to get TLS base in component model modules.
+ UndefinedFunction *contextGet1;
};
WasmSym sym;
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index b1e36f2ecff74..6eaacd7288f22 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -656,15 +656,16 @@ static void readConfigs(opt::InputArgList &args) {
ctx.arg.exportDynamic =
args.hasFlag(OPT_export_dynamic, OPT_no_export_dynamic, ctx.arg.shared);
- // Parse wasm32/64.
+ // Parse wasm32/64 and maybe -wasip3.
if (auto *arg = args.getLastArg(OPT_m)) {
StringRef s = arg->getValue();
- if (s == "wasm32")
+ if (s.starts_with("wasm32"))
ctx.arg.is64 = false;
- else if (s == "wasm64")
+ else if (s.starts_with("wasm64"))
ctx.arg.is64 = true;
else
error("invalid target architecture: " + s);
+ ctx.arg.isWasip3 = s.ends_with("-wasip3");
}
// --threads= takes a positive integer and provides the default value for
@@ -827,6 +828,10 @@ static void checkOptions(opt::InputArgList &args) {
if (ctx.arg.tableBase)
error("--table-base may not be used with -shared/-pie");
}
+
+ if (ctx.arg.sharedMemory && ctx.arg.isWasip3) {
+ error("--shared-memory is incompatible with the wasip3 target");
+ }
}
static const char *getReproduceOption(opt::InputArgList &args) {
@@ -885,7 +890,7 @@ static void writeWhyExtract() {
// Equivalent of demote demoteSharedAndLazySymbols() in the ELF linker
static void demoteLazySymbols() {
for (Symbol *sym : symtab->symbols()) {
- if (auto* s = dyn_cast<LazySymbol>(sym)) {
+ if (auto *s = dyn_cast<LazySymbol>(sym)) {
if (s->signature) {
LLVM_DEBUG(llvm::dbgs()
<< "demoting lazy func: " << s->getName() << "\n");
@@ -906,6 +911,18 @@ createUndefinedGlobal(StringRef name, llvm::wasm::WasmGlobalType *type) {
return sym;
}
+static UndefinedFunction *
+createUndefinedFunction(StringRef name, std::optional<StringRef> importName,
+ std::optional<StringRef> importModule,
+ WasmSignature *signature) {
+ auto *sym = cast<UndefinedFunction>(symtab->addUndefinedFunction(
+ name, importName, importModule, WASM_SYMBOL_UNDEFINED, nullptr, signature,
+ true));
+ ctx.arg.allowUndefinedSymbols.insert(sym->getName());
+ sym->isUsedInRegularObj = true;
+ return sym;
+}
+
static InputGlobal *createGlobal(StringRef name, bool isMutable) {
llvm::wasm::WasmGlobal wasmGlobal;
bool is64 = ctx.arg.is64.value_or(false);
@@ -946,11 +963,13 @@ static void createSyntheticSymbols() {
bool is64 = ctx.arg.is64.value_or(false);
+ auto stack_pointer_name =
+ ctx.arg.isWasip3 ? "__init_stack_pointer" : "__stack_pointer";
if (ctx.isPic) {
ctx.sym.stackPointer =
- createUndefinedGlobal("__stack_pointer", ctx.arg.is64.value_or(false)
- ? &mutableGlobalTypeI64
- : &mutableGlobalTypeI32);
+ createUndefinedGlobal(stack_pointer_name, ctx.arg.is64.value_or(false)
+ ? &mutableGlobalTypeI64
+ : &mutableGlobalTypeI32);
// For PIC code, we import two global variables (__memory_base and
// __table_base) from the environment and use these as the offset at
// which to load our static data and function table.
@@ -963,14 +982,15 @@ static void createSyntheticSymbols() {
ctx.sym.tableBase->markLive();
} else {
// For non-PIC code
- ctx.sym.stackPointer = createGlobalVariable("__stack_pointer", true);
+ ctx.sym.stackPointer = createGlobalVariable(stack_pointer_name, true);
ctx.sym.stackPointer->markLive();
}
- if (ctx.arg.sharedMemory) {
+ if (ctx.arg.isMultithreaded()) {
// TLS symbols are all hidden/dso-local
- ctx.sym.tlsBase =
- createGlobalVariable("__tls_base", true, WASM_SYMBOL_VISIBILITY_HIDDEN);
+ auto tls_base_name = ctx.arg.isWasip3 ? "__init_tls_base" : "__tls_base";
+ ctx.sym.tlsBase = createGlobalVariable(tls_base_name, true,
+ WASM_SYMBOL_VISIBILITY_HIDDEN);
ctx.sym.tlsSize = createGlobalVariable("__tls_size", false,
WASM_SYMBOL_VISIBILITY_HIDDEN);
ctx.sym.tlsAlign = createGlobalVariable("__tls_align", false,
@@ -979,6 +999,21 @@ static void createSyntheticSymbols() {
"__wasm_init_tls", WASM_SYMBOL_VISIBILITY_HIDDEN,
make<SyntheticFunction>(is64 ? i64ArgSignature : i32ArgSignature,
"__wasm_init_tls"));
+ if (ctx.arg.isWasip3) {
+ ctx.sym.tlsBase->markLive();
+ ctx.sym.tlsSize->markLive();
+ ctx.sym.tlsAlign->markLive();
+ static WasmSignature contextSet1Signature{{}, {ValType::I32}};
+ ctx.sym.contextSet1 = createUndefinedFunction(
+ "__wasm_component_model_builtin_context_set_1", "[context-set-1]",
+ "$root", &contextSet1Signature);
+ ctx.sym.contextSet1->markLive();
+ static WasmSignature contextGet1Signature{{ValType::I32}, {}};
+ ctx.sym.contextGet1 = createUndefinedFunction(
+ "__wasm_component_model_builtin_context_get_1", "[context-get-1]",
+ "$root", &contextGet1Signature);
+ ctx.sym.contextGet1->markLive();
+ }
}
}
@@ -1017,7 +1052,7 @@ static void createOptionalSymbols() {
//
// __tls_size and __tls_align are not needed in this case since they are only
// needed for __wasm_init_tls (which we do not create in this case).
- if (!ctx.arg.sharedMemory)
+ if (!ctx.arg.sharedMemory && !ctx.arg.isWasip3)
ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
}
@@ -1026,15 +1061,15 @@ static void processStubLibrariesPreLTO() {
for (auto &stub_file : ctx.stubFiles) {
LLVM_DEBUG(llvm::dbgs()
<< "processing stub file: " << stub_file->getName() << "\n");
- for (auto [name, deps]: stub_file->symbolDependencies) {
- auto* sym = symtab->find(name);
+ for (auto [name, deps] : stub_file->symbolDependencies) {
+ auto *sym = symtab->find(name);
// If the symbol is not present at all (yet), or if it is present but
// undefined, then mark the dependent symbols as used by a regular
// object so they will be preserved and exported by the LTO process.
if (!sym || sym->isUndefined()) {
for (const auto dep : deps) {
- auto* needed = symtab->find(dep);
- if (needed ) {
+ auto *needed = symtab->find(dep);
+ if (needed) {
needed->isUsedInRegularObj = true;
// Like with handleLibcall we have to extract any LTO archive
// members that might need to be exported due to stub library
diff --git a/lld/wasm/Relocations.cpp b/lld/wasm/Relocations.cpp
index a3f87ea3d69c0..cb597fdeffcf3 100644
--- a/lld/wasm/Relocations.cpp
+++ b/lld/wasm/Relocations.cpp
@@ -33,7 +33,7 @@ static bool requiresGOTAccess(const Symbol *sym) {
return true;
}
-static bool allowUndefined(const Symbol* sym) {
+static bool allowUndefined(const Symbol *sym) {
// Symbols that are explicitly imported are always allowed to be undefined at
// link time.
if (sym->isImported())
@@ -125,7 +125,7 @@ void scanRelocations(InputChunk *chunk) {
// In single-threaded builds TLS is lowered away and TLS data can be
// merged with normal data and allowing TLS relocation in non-TLS
// segments.
- if (ctx.arg.sharedMemory) {
+ if (ctx.arg.isMultithreaded()) {
if (!sym->isTLS()) {
error(toString(file) + ": relocation " +
relocTypeToString(reloc.Type) +
diff --git a/lld/wasm/Symbols.cpp b/lld/wasm/Symbols.cpp
index f2040441e6257..97a9871a06308 100644
--- a/lld/wasm/Symbols.cpp
+++ b/lld/wasm/Symbols.cpp
@@ -95,7 +95,7 @@ WasmSymbolType Symbol::getWasmType() const {
}
const WasmSignature *Symbol::getSignature() const {
- if (auto* f = dyn_cast<FunctionSymbol>(this))
+ if (auto *f = dyn_cast<FunctionSymbol>(this))
return f->signature;
if (auto *t = dyn_cast<TagSymbol>(this))
return t->signature;
@@ -223,9 +223,7 @@ bool Symbol::isExportedExplicit() const {
return forceExport || flags & WASM_SYMBOL_EXPORTED;
}
-bool Symbol::isNoStrip() const {
- return flags & WASM_SYMBOL_NO_STRIP;
-}
+bool Symbol::isNoStrip() const { return flags & WASM_SYMBOL_NO_STRIP; }
uint32_t FunctionSymbol::getFunctionIndex() const {
if (const auto *u = dyn_cast<UndefinedFunction>(this))
@@ -413,7 +411,7 @@ void LazySymbol::setWeak() {
flags |= (flags & ~WASM_SYMBOL_BINDING_MASK) | WASM_SYMBOL_BINDING_WEAK;
}
-void printTraceSymbolUndefined(StringRef name, const InputFile* file) {
+void printTraceSymbolUndefined(StringRef name, const InputFile *file) {
message(toString(file) + ": reference to " + name);
}
diff --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index ede6ac4da77b3..023c690c14354 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -466,8 +466,7 @@ void GlobalSection::addInternalGOTEntry(Symbol *sym) {
void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
assert(!ctx.arg.extendedConst);
bool is64 = ctx.arg.is64.value_or(false);
- unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD
- : WASM_OPCODE_I32_ADD;
+ unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD : WASM_OPCODE_I32_ADD;
for (const Symbol *sym : internalGotSymbols) {
if (TLS != sym->isTLS())
@@ -477,7 +476,7 @@ void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
// Get __memory_base
writeU8(os, WASM_OPCODE_GLOBAL_GET, "GLOBAL_GET");
if (sym->isTLS())
- writeUleb128(os, ctx.sym.tlsBase->getGlobalIndex(), "__tls_base");
+ writeGetTLSBase(ctx, os);
else
writeUleb128(os, ctx.sym.memoryBase->getGlobalIndex(), "__memory_base");
@@ -520,9 +519,9 @@ void GlobalSection::writeBody() {
// the correct runtime value during `__wasm_apply_global_relocs`.
if (!ctx.arg.extendedConst && ctx.isPic && !sym->isTLS())
mutable_ = true;
- // With multi-theadeding any TLS globals must be mutable since they get
+ // With multi-threading any TLS globals must be mutable since they get
// set during `__wasm_apply_global_tls_relocs`
- if (ctx.arg.sharedMemory && sym->isTLS())
+ if (ctx.arg.isMultithreaded() && sym->isTLS())
mutable_ = true;
}
WasmGlobalType type{itype, mutable_};
@@ -559,10 +558,11 @@ void GlobalSection::writeBody() {
} else {
WasmInitExpr initExpr;
if (auto *d = dyn_cast<DefinedData>(sym))
- // In the sharedMemory case TLS globals are set during
- // `__wasm_apply_global_tls_relocs`, but in the non-shared case
+ // In the multi-threaded case, TLS globals are set during
+ // `__wasm_apply_global_tls_relocs`, but in the non-multi-threaded case
// we know the absolute value at link time.
- initExpr = intConst(d->getVA(/*absolute=*/!ctx.arg.sharedMemory), is64);
+ initExpr =
+ intConst(d->getVA(/*absolute=*/!ctx.arg.isMultithreaded()), is64);
else if (auto *f = dyn_cast<FunctionSymbol>(sym))
initExpr = intConst(f->isStub ? 0 : f->getTableIndex(), is64);
else {
@@ -646,7 +646,7 @@ void ElemSection::writeBody() {
uint32_t tableIndex = ctx.arg.tableBase;
for (const FunctionSymbol *sym : indirectFunctions) {
assert(sym->getTableIndex() == tableIndex);
- (void) tableIndex;
+ (void)tableIndex;
writeUleb128(os, sym->getFunctionIndex(), "function index");
++tableIndex;
}
@@ -663,7 +663,7 @@ void DataCountSection::writeBody() {
}
bool DataCountSection::isNeeded() const {
- return numSegments && ctx.arg.sharedMemory;
+ return numSegments && ctx.arg.isMultithreaded();
}
void LinkingSection::writeBody() {
@@ -992,4 +992,4 @@ void BuildIdSection::writeBuildId(llvm::ArrayRef<uint8_t> buf) {
memcpy(hashPlaceholderPtr, buf.data(), hashSize);
}
-} // namespace wasm::lld
+} // namespace lld::wasm
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index dfd856f2faee6..50d6449ca79a9 100644
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -311,7 +311,8 @@ void Writer::writeBuildId() {
}
static void setGlobalPtr(DefinedGlobal *g, uint64_t memoryPtr) {
- LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr << "\n");
+ LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr
+ << "\n");
g->global->setPointerValue(memoryPtr);
}
@@ -358,7 +359,8 @@ void Writer::layoutMemory() {
placeStack();
if (ctx.arg.globalBase) {
if (ctx.arg.globalBase < memoryPtr) {
- error("--global-base cannot be less than stack size when --stack-first is used");
+ error("--global-base cannot be less than stack size when --stack-first "
+ "is used");
return;
}
memoryPtr = ctx.arg.globalBase;
@@ -382,6 +384,7 @@ void Writer::layoutMemory() {
for (OutputSegment *seg : segments) {
out.dylinkSec->memAlign = std::max(out.dylinkSec->memAlign, seg->alignment);
memoryPtr = alignTo(memoryPtr, 1ULL << seg->alignment);
+
seg->startVA = memoryPtr;
log(formatv("mem: {0,-15} offset={1,-8} size={2,-8} align={3}", seg->name,
memoryPtr, seg->size, seg->alignment));
@@ -1029,7 +1032,7 @@ static StringRef getOutputDataSegmentName(const InputChunk &seg) {
OutputSegment *Writer::createOutputSegment(StringRef name) {
LLVM_DEBUG(dbgs() << "new segment: " << name << "\n");
OutputSegment *s = make<OutputSegment>(name);
- if (ctx.arg.sharedMemory)
+ if (ctx.arg.isMultithreaded())
s->initFlags = WASM_DATA_SEGMENT_IS_PASSIVE;
if (!ctx.arg.relocatable && name.starts_with(".bss"))
s->isBss = true;
@@ -1163,14 +1166,14 @@ void Writer::createSyntheticInitFunctions() {
"__wasm_init_memory", WASM_SYMBOL_VISIBILITY_HIDDEN,
make<SyntheticFunction>(nullSignature, "__wasm_init_memory"));
ctx.sym.initMemory->mark...
[truncated]
|
Contributor
Author
|
@alexcrichton I've factored out the WASIP3 changes into feature flags and linker options like |
Contributor
Author
|
@alexcrichton I've made it so that if you try to link an object file compiled with/without the |
Contributor
Author
|
I'll progressively add tests to this, but the core functionality is ready for review |
Contributor
Author
|
@sbc100 any more thoughts on this? Maybe we can set some time to chat about this synchronously? |
Collaborator
Yes I think it would be great if you could join the Wasm Tools char we have with @sunfishcode on Mondays. @dschuff can invite you I think? |
sbc100
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Mar 23, 2026
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I love that the wasm-ld patch is now smaller.
I'm still not totally sure about the new --component-model-thread-context command line flag or the internal componentModelThreadContext naming, especially now that we don't have compontent model in the names of the new functions we are using.
lld/wasm/Driver.cpp
Outdated
| } | ||
|
|
||
| // Create synthetic symbols that rely on information that is only available | ||
| // after LTO, e.g. __stack_pointer, __tls_base. |
Collaborator
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What is this need split needed now but not before?
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Because the thread context ABI must have been determined prior to creating these symbols so that we know which ones to create, and we could have a case where every object file is an LTO bitcode file, in which case we'd need to wait until after LTO to determine the ABI. However, the __wasm_create_ctors function is needed earlier in the process, so I split that out
sbc100
reviewed
Mar 23, 2026
| } | ||
|
|
||
| static bool WantsSharedMemory(const llvm::Triple &Triple, const ArgList &Args) { | ||
| return WantsPthread(Triple, Args) && |
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Does this means the the component model green threads is passing -pthread? I would hope that in this mode we could make WantsPthread return false?
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The WASIP3 green threads for wasi-libc is implemented as pthreads
sbc100
reviewed
Mar 23, 2026
| "\"[context-set-1]\"\n" | ||
| "local.get 0\n" | ||
| "call __wasm_component_model_builtin_context_set_1"); | ||
| } |
Collaborator
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Given this whole file is just asm perhaps it would be more readable if you just make it into a .S file? (i.e. assembly with pre-processor enabled).
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Yeah, I did that originally but hit the issue that the build system for compiler-rt doesn't set --target for .S files, which means the #ifdef doesn't fire. There's a comment above here that tries to explain.
It may be that the changes required for the build system would be minimal, but there's a lot of CMake that deals with setting the CFLAGS correctly, so I figured I'd take the simpler path for now to minimise changes (especially since this could affect other targets). We could address it in a follow-up PR.
sbc100
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Mar 23, 2026
sbc100
reviewed
Mar 23, 2026
lld/wasm/Driver.cpp
Outdated
| continue; | ||
| } | ||
| // Treat this as using the globals ABI | ||
| usesComponentModelThreadContext = false; |
Collaborator
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Can we just assume that all objects files without the component-model-thread-context feature don't use this API?
i.e. why do we need to check for the __stack_pointer import here?
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We can assume that all object files without that feature don't use this ABI, but we can't assume that they are compatible.
The categories I see are:
- Files that do not use a guest stack at all, and will not disallow
component-model-thread-context. These will work with either ABI. - Files that use a guest stack and disallow
component-model-thread-context. These are incompatible with the new ABI and will be diagnosed based on the feature mismatch. - Files that use a guest stack but do not disallow
component-model-thread-context(e.g.-mcpu mvp, files produced forwasm32-wasip3with an older toolchain). These are incompatible with the new ABI, but will not be diagnosed based on features, but we really want a linker error with a message that can be searched if, for example, a user tries to link object files produced by a version of rustc using an older LLVM with ones produced by a newerwasi-sdk. This is the case for which we do this check: the presence of__stack_pointeris used as a proxy for "this object file is using the global ABI".
sbc100
reviewed
Mar 23, 2026
lld/wasm/Driver.cpp
Outdated
| ThreadContextABI threadContextABI = ThreadContextABI::Undetermined; | ||
|
|
||
| for (ObjFile *obj : files) { | ||
| auto targetFeatures = obj->getWasmObj()->getTargetFeatures(); |
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In general we process target features of the input object in Writer::populateTargetFeatures. We also generate errors about incompatible object files here.
is there some way to integrate this code in to that existing location? (or maybe have it called from there?) Or is it too late the game?
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Yeah, that's where I originally put this, but it's too late unfortunately, as we need this code to decide which symbols to create.
Contributor
Author
To clarify, do you mean this just for For the linker changes, I think there are two separate types of modification:
Since the changes in How does this proposal sound:
This way, everything becomes more generic, the It would also be possible to remove all component-model-specificity from the linker by changing the WASM feature name to I think some of this is complicated by the |
Contributor
Author
|
@sbc100 I've stripped out all of the changes related to cooperative threading from this PR and left only the parts related to making library calls for thread context, which I've put under a new Having a linker flag actually simplifies the implementation, because it no longer has to look thread the object files to determine which synthetic symbols to create. This lets me do the feature checks in the usual place in With these refactors, there is no longer anything component-model specific in this PR. I haven't quite got my |
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Nice! This PR seems far less invasive now, especially the wasm-ld parts.
lld/wasm/SymbolTable.cpp
Outdated
| InputFunction *function) { | ||
| LLVM_DEBUG(dbgs() << "addSyntheticFunction: " << name << "\n"); | ||
| assert(!find(name)); | ||
| assert(!find(name) || find(name)->isUndefined()); |
Collaborator
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I guess this is needed because we now have calls to addSynthetixXXX later in the linker process?
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Ah, it was, but since I've now removed the need for that, I can also revert this change
| writeU8(os, WASM_OPCODE_GLOBAL_GET, "GLOBAL_SET"); | ||
| writeUleb128(os, ctx.sym.tlsBase->getGlobalIndex(), "__tls_base"); | ||
| } | ||
| } |
| sym->kind() == Symbol::UndefinedGlobalKind && | ||
| sym->importModule && sym->importModule == "env"; | ||
| })) { | ||
| disallowed.insert({"libcall-thread-context", std::string(fileName)}); |
Collaborator
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Nice, I like this. This way the error message about the incompatibility will still like to the offending file.
| } else { | ||
| writeU8(os, WASM_OPCODE_GLOBAL_SET, "global.set"); | ||
| writeUleb128(os, ctx.sym.tlsBase->getGlobalIndex(), "global index"); | ||
| } |
Collaborator
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Can this just be writeSetTLSBase?
| } | ||
| writeU8(os, WASM_OPCODE_GLOBAL_SET, "GLOBAL_SET"); | ||
| writeUleb128(os, ctx.sym.tlsBase->getGlobalIndex(), "__tls_base"); | ||
| writeSetTLSBase(ctx, os); |
Collaborator
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I'm a little confused about that is the point of the __init_tls_base global if we are calling out to the libcall here?
| HelpText<"Initial size of the linear memory">; | ||
|
|
||
| def libcall_thread_context: FF<"libcall-thread-context">, | ||
| HelpText<"Use library calls for thread context access instead of globals.">; |
Collaborator
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Why do we still need this flag if the object files feature section contains this flag?
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The WebAssembly Component Model has added support for cooperative multithreading. This has been implemented in the Wasmtime engine and is part of the wider project of WASI preview 3, which is currently tracked here.
These changes will require updating the way that
__stack_pointerand__tls_basework purely for a newwasm32-wasip3target; other targets will not be touched. Specifically, rather than using a Wasm global for tracking the stack pointer and TLS base, the newcontext.get/setcomponent model builtin functions will be used (the intention being that runtimes will need to aggressively optimize these calls into single load/stores). For justification on this choice rather than switching out the global at context-switch boundaries, see this comment and this comment.I guard the new behaviour behind a new
component-model-thread-contextfeature, which is automatically enabled for WASIP3 targets. The linker determines what thread context ABI to use based on the presence of this feature.Includes #182896