Add m-esr52 at 52.6.0

1 files changed, 849 insertions, 0 deletions

diff --git a/js/src/wasm/WasmInstance.cpp b/js/src/wasm/WasmInstance.cpp
new file mode 100644
index 000000000..88af4f0db
--- /dev/null
+++ b/js/src/wasm/WasmInstance.cpp
@@ -0,0 +1,849 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ *
+ * Copyright 2016 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "wasm/WasmInstance.h"
+
+#include "jit/BaselineJIT.h"
+#include "jit/JitCommon.h"
+#include "wasm/WasmModule.h"
+
+#include "jsobjinlines.h"
+
+#include "vm/ArrayBufferObject-inl.h"
+
+using namespace js;
+using namespace js::jit;
+using namespace js::wasm;
+using mozilla::BinarySearch;
+using mozilla::BitwiseCast;
+using mozilla::IsNaN;
+using mozilla::Swap;
+
+class SigIdSet
+{
+    typedef HashMap<const Sig*, uint32_t, SigHashPolicy, SystemAllocPolicy> Map;
+    Map map_;
+
+  public:
+    ~SigIdSet() {
+        MOZ_ASSERT_IF(!JSRuntime::hasLiveRuntimes(), !map_.initialized() || map_.empty());
+    }
+
+    bool ensureInitialized(JSContext* cx) {
+        if (!map_.initialized() && !map_.init()) {
+            ReportOutOfMemory(cx);
+            return false;
+        }
+
+        return true;
+    }
+
+    bool allocateSigId(JSContext* cx, const Sig& sig, const void** sigId) {
+        Map::AddPtr p = map_.lookupForAdd(sig);
+        if (p) {
+            MOZ_ASSERT(p->value() > 0);
+            p->value()++;
+            *sigId = p->key();
+            return true;
+        }
+
+        UniquePtr<Sig> clone = MakeUnique<Sig>();
+        if (!clone || !clone->clone(sig) || !map_.add(p, clone.get(), 1)) {
+            ReportOutOfMemory(cx);
+            return false;
+        }
+
+        *sigId = clone.release();
+        MOZ_ASSERT(!(uintptr_t(*sigId) & SigIdDesc::ImmediateBit));
+        return true;
+    }
+
+    void deallocateSigId(const Sig& sig, const void* sigId) {
+        Map::Ptr p = map_.lookup(sig);
+        MOZ_RELEASE_ASSERT(p && p->key() == sigId && p->value() > 0);
+
+        p->value()--;
+        if (!p->value()) {
+            js_delete(p->key());
+            map_.remove(p);
+        }
+    }
+};
+
+ExclusiveData<SigIdSet>* sigIdSet = nullptr;
+
+bool
+js::wasm::InitInstanceStaticData()
+{
+    MOZ_ASSERT(!sigIdSet);
+    sigIdSet = js_new<ExclusiveData<SigIdSet>>(mutexid::WasmSigIdSet);
+    return sigIdSet != nullptr;
+}
+
+void
+js::wasm::ShutDownInstanceStaticData()
+{
+    MOZ_ASSERT(sigIdSet);
+    js_delete(sigIdSet);
+    sigIdSet = nullptr;
+}
+
+const void**
+Instance::addressOfSigId(const SigIdDesc& sigId) const
+{
+    MOZ_ASSERT(sigId.globalDataOffset() >= InitialGlobalDataBytes);
+    return (const void**)(codeSegment().globalData() + sigId.globalDataOffset());
+}
+
+FuncImportTls&
+Instance::funcImportTls(const FuncImport& fi)
+{
+    MOZ_ASSERT(fi.tlsDataOffset() >= InitialGlobalDataBytes);
+    return *(FuncImportTls*)(codeSegment().globalData() + fi.tlsDataOffset());
+}
+
+TableTls&
+Instance::tableTls(const TableDesc& td) const
+{
+    MOZ_ASSERT(td.globalDataOffset >= InitialGlobalDataBytes);
+    return *(TableTls*)(codeSegment().globalData() + td.globalDataOffset);
+}
+
+bool
+Instance::callImport(JSContext* cx, uint32_t funcImportIndex, unsigned argc, const uint64_t* argv,
+                     MutableHandleValue rval)
+{
+    const FuncImport& fi = metadata().funcImports[funcImportIndex];
+
+    InvokeArgs args(cx);
+    if (!args.init(cx, argc))
+        return false;
+
+    bool hasI64Arg = false;
+    MOZ_ASSERT(fi.sig().args().length() == argc);
+    for (size_t i = 0; i < argc; i++) {
+        switch (fi.sig().args()[i]) {
+          case ValType::I32:
+            args[i].set(Int32Value(*(int32_t*)&argv[i]));
+            break;
+          case ValType::F32:
+            args[i].set(JS::CanonicalizedDoubleValue(*(float*)&argv[i]));
+            break;
+          case ValType::F64:
+            args[i].set(JS::CanonicalizedDoubleValue(*(double*)&argv[i]));
+            break;
+          case ValType::I64: {
+            if (!JitOptions.wasmTestMode) {
+                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_BAD_I64);
+                return false;
+            }
+            RootedObject obj(cx, CreateI64Object(cx, *(int64_t*)&argv[i]));
+            if (!obj)
+                return false;
+            args[i].set(ObjectValue(*obj));
+            hasI64Arg = true;
+            break;
+          }
+          case ValType::I8x16:
+          case ValType::I16x8:
+          case ValType::I32x4:
+          case ValType::F32x4:
+          case ValType::B8x16:
+          case ValType::B16x8:
+          case ValType::B32x4:
+            MOZ_CRASH("unhandled type in callImport");
+        }
+    }
+
+    FuncImportTls& import = funcImportTls(fi);
+    RootedFunction importFun(cx, &import.obj->as<JSFunction>());
+    RootedValue fval(cx, ObjectValue(*import.obj));
+    RootedValue thisv(cx, UndefinedValue());
+    if (!Call(cx, fval, thisv, args, rval))
+        return false;
+
+    // Throw an error if returning i64 and not in test mode.
+    if (!JitOptions.wasmTestMode && fi.sig().ret() == ExprType::I64) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_BAD_I64);
+        return false;
+    }
+
+    // Don't try to optimize if the function has at least one i64 arg or if
+    // it returns an int64. GenerateJitExit relies on this, as does the
+    // type inference code below in this function.
+    if (hasI64Arg || fi.sig().ret() == ExprType::I64)
+        return true;
+
+    // The import may already have become optimized.
+    void* jitExitCode = codeBase() + fi.jitExitCodeOffset();
+    if (import.code == jitExitCode)
+        return true;
+
+    // Test if the function is JIT compiled.
+    if (!importFun->hasScript())
+        return true;
+
+    JSScript* script = importFun->nonLazyScript();
+    if (!script->hasBaselineScript()) {
+        MOZ_ASSERT(!script->hasIonScript());
+        return true;
+    }
+
+    // Don't enable jit entry when we have a pending ion builder.
+    // Take the interpreter path which will link it and enable
+    // the fast path on the next call.
+    if (script->baselineScript()->hasPendingIonBuilder())
+        return true;
+
+    // Currently we can't rectify arguments. Therefore disable if argc is too low.
+    if (importFun->nargs() > fi.sig().args().length())
+        return true;
+
+    // Ensure the argument types are included in the argument TypeSets stored in
+    // the TypeScript. This is necessary for Ion, because the import will use
+    // the skip-arg-checks entry point.
+    //
+    // Note that the TypeScript is never discarded while the script has a
+    // BaselineScript, so if those checks hold now they must hold at least until
+    // the BaselineScript is discarded and when that happens the import is
+    // patched back.
+    if (!TypeScript::ThisTypes(script)->hasType(TypeSet::UndefinedType()))
+        return true;
+    for (uint32_t i = 0; i < importFun->nargs(); i++) {
+        TypeSet::Type type = TypeSet::UnknownType();
+        switch (fi.sig().args()[i]) {
+          case ValType::I32:   type = TypeSet::Int32Type(); break;
+          case ValType::I64:   MOZ_CRASH("can't happen because of above guard");
+          case ValType::F32:   type = TypeSet::DoubleType(); break;
+          case ValType::F64:   type = TypeSet::DoubleType(); break;
+          case ValType::I8x16: MOZ_CRASH("NYI");
+          case ValType::I16x8: MOZ_CRASH("NYI");
+          case ValType::I32x4: MOZ_CRASH("NYI");
+          case ValType::F32x4: MOZ_CRASH("NYI");
+          case ValType::B8x16: MOZ_CRASH("NYI");
+          case ValType::B16x8: MOZ_CRASH("NYI");
+          case ValType::B32x4: MOZ_CRASH("NYI");
+        }
+        if (!TypeScript::ArgTypes(script, i)->hasType(type))
+            return true;
+    }
+
+    // Let's optimize it!
+    if (!script->baselineScript()->addDependentWasmImport(cx, *this, funcImportIndex))
+        return false;
+
+    import.code = jitExitCode;
+    import.baselineScript = script->baselineScript();
+    return true;
+}
+
+/* static */ int32_t
+Instance::callImport_void(Instance* instance, int32_t funcImportIndex, int32_t argc, uint64_t* argv)
+{
+    JSContext* cx = instance->cx();
+    RootedValue rval(cx);
+    return instance->callImport(cx, funcImportIndex, argc, argv, &rval);
+}
+
+/* static */ int32_t
+Instance::callImport_i32(Instance* instance, int32_t funcImportIndex, int32_t argc, uint64_t* argv)
+{
+    JSContext* cx = instance->cx();
+    RootedValue rval(cx);
+    if (!instance->callImport(cx, funcImportIndex, argc, argv, &rval))
+        return false;
+
+    return ToInt32(cx, rval, (int32_t*)argv);
+}
+
+/* static */ int32_t
+Instance::callImport_i64(Instance* instance, int32_t funcImportIndex, int32_t argc, uint64_t* argv)
+{
+    JSContext* cx = instance->cx();
+    RootedValue rval(cx);
+    if (!instance->callImport(cx, funcImportIndex, argc, argv, &rval))
+        return false;
+
+    return ReadI64Object(cx, rval, (int64_t*)argv);
+}
+
+/* static */ int32_t
+Instance::callImport_f64(Instance* instance, int32_t funcImportIndex, int32_t argc, uint64_t* argv)
+{
+    JSContext* cx = instance->cx();
+    RootedValue rval(cx);
+    if (!instance->callImport(cx, funcImportIndex, argc, argv, &rval))
+        return false;
+
+    return ToNumber(cx, rval, (double*)argv);
+}
+
+/* static */ uint32_t
+Instance::growMemory_i32(Instance* instance, uint32_t delta)
+{
+    MOZ_ASSERT(!instance->isAsmJS());
+
+    JSContext* cx = instance->cx();
+    RootedWasmMemoryObject memory(cx, instance->memory_);
+
+    uint32_t ret = WasmMemoryObject::grow(memory, delta, cx);
+
+    // If there has been a moving grow, this Instance should have been notified.
+    MOZ_RELEASE_ASSERT(instance->tlsData_.memoryBase ==
+                       instance->memory_->buffer().dataPointerEither());
+
+    return ret;
+}
+
+/* static */ uint32_t
+Instance::currentMemory_i32(Instance* instance)
+{
+    uint32_t byteLength = instance->memoryLength();
+    MOZ_ASSERT(byteLength % wasm::PageSize == 0);
+    return byteLength / wasm::PageSize;
+}
+
+Instance::Instance(JSContext* cx,
+                   Handle<WasmInstanceObject*> object,
+                   UniqueCode code,
+                   HandleWasmMemoryObject memory,
+                   SharedTableVector&& tables,
+                   Handle<FunctionVector> funcImports,
+                   const ValVector& globalImports)
+  : compartment_(cx->compartment()),
+    object_(object),
+    code_(Move(code)),
+    memory_(memory),
+    tables_(Move(tables))
+{
+    MOZ_ASSERT(funcImports.length() == metadata().funcImports.length());
+    MOZ_ASSERT(tables_.length() == metadata().tables.length());
+
+    tlsData_.cx = cx;
+    tlsData_.instance = this;
+    tlsData_.globalData = code_->segment().globalData();
+    tlsData_.memoryBase = memory ? memory->buffer().dataPointerEither().unwrap() : nullptr;
+    tlsData_.stackLimit = *(void**)cx->stackLimitAddressForJitCode(StackForUntrustedScript);
+
+    for (size_t i = 0; i < metadata().funcImports.length(); i++) {
+        HandleFunction f = funcImports[i];
+        const FuncImport& fi = metadata().funcImports[i];
+        FuncImportTls& import = funcImportTls(fi);
+        if (!isAsmJS() && IsExportedWasmFunction(f)) {
+            WasmInstanceObject* calleeInstanceObj = ExportedFunctionToInstanceObject(f);
+            const CodeRange& codeRange = calleeInstanceObj->getExportedFunctionCodeRange(f);
+            Instance& calleeInstance = calleeInstanceObj->instance();
+            import.tls = &calleeInstance.tlsData_;
+            import.code = calleeInstance.codeSegment().base() + codeRange.funcNonProfilingEntry();
+            import.baselineScript = nullptr;
+            import.obj = calleeInstanceObj;
+        } else {
+            import.tls = &tlsData_;
+            import.code = codeBase() + fi.interpExitCodeOffset();
+            import.baselineScript = nullptr;
+            import.obj = f;
+        }
+    }
+
+    for (size_t i = 0; i < tables_.length(); i++) {
+        const TableDesc& td = metadata().tables[i];
+        TableTls& table = tableTls(td);
+        table.length = tables_[i]->length();
+        table.base = tables_[i]->base();
+    }
+
+    uint8_t* globalData = code_->segment().globalData();
+
+    for (size_t i = 0; i < metadata().globals.length(); i++) {
+        const GlobalDesc& global = metadata().globals[i];
+        if (global.isConstant())
+            continue;
+
+        uint8_t* globalAddr = globalData + global.offset();
+        switch (global.kind()) {
+          case GlobalKind::Import: {
+            globalImports[global.importIndex()].writePayload(globalAddr);
+            break;
+          }
+          case GlobalKind::Variable: {
+            const InitExpr& init = global.initExpr();
+            switch (init.kind()) {
+              case InitExpr::Kind::Constant: {
+                init.val().writePayload(globalAddr);
+                break;
+              }
+              case InitExpr::Kind::GetGlobal: {
+                const GlobalDesc& imported = metadata().globals[init.globalIndex()];
+                globalImports[imported.importIndex()].writePayload(globalAddr);
+                break;
+              }
+            }
+            break;
+          }
+          case GlobalKind::Constant: {
+            MOZ_CRASH("skipped at the top");
+          }
+        }
+    }
+}
+
+bool
+Instance::init(JSContext* cx)
+{
+    if (memory_ && memory_->movingGrowable() && !memory_->addMovingGrowObserver(cx, object_))
+        return false;
+
+    for (const SharedTable& table : tables_) {
+        if (table->movingGrowable() && !table->addMovingGrowObserver(cx, object_))
+            return false;
+    }
+
+    if (!metadata().sigIds.empty()) {
+        ExclusiveData<SigIdSet>::Guard lockedSigIdSet = sigIdSet->lock();
+
+        if (!lockedSigIdSet->ensureInitialized(cx))
+            return false;
+
+        for (const SigWithId& sig : metadata().sigIds) {
+            const void* sigId;
+            if (!lockedSigIdSet->allocateSigId(cx, sig, &sigId))
+                return false;
+
+            *addressOfSigId(sig.id) = sigId;
+        }
+    }
+
+    return true;
+}
+
+Instance::~Instance()
+{
+    compartment_->wasm.unregisterInstance(*this);
+
+    for (unsigned i = 0; i < metadata().funcImports.length(); i++) {
+        FuncImportTls& import = funcImportTls(metadata().funcImports[i]);
+        if (import.baselineScript)
+            import.baselineScript->removeDependentWasmImport(*this, i);
+    }
+
+    if (!metadata().sigIds.empty()) {
+        ExclusiveData<SigIdSet>::Guard lockedSigIdSet = sigIdSet->lock();
+
+        for (const SigWithId& sig : metadata().sigIds) {
+            if (const void* sigId = *addressOfSigId(sig.id))
+                lockedSigIdSet->deallocateSigId(sig, sigId);
+        }
+    }
+}
+
+size_t
+Instance::memoryMappedSize() const
+{
+    return memory_->buffer().wasmMappedSize();
+}
+
+bool
+Instance::memoryAccessInGuardRegion(uint8_t* addr, unsigned numBytes) const
+{
+    MOZ_ASSERT(numBytes > 0);
+
+    if (!metadata().usesMemory())
+        return false;
+
+    uint8_t* base = memoryBase().unwrap(/* comparison */);
+    if (addr < base)
+        return false;
+
+    size_t lastByteOffset = addr - base + (numBytes - 1);
+    return lastByteOffset >= memoryLength() && lastByteOffset < memoryMappedSize();
+}
+
+void
+Instance::tracePrivate(JSTracer* trc)
+{
+    // This method is only called from WasmInstanceObject so the only reason why
+    // TraceEdge is called is so that the pointer can be updated during a moving
+    // GC. TraceWeakEdge may sound better, but it is less efficient given that
+    // we know object_ is already marked.
+    MOZ_ASSERT(!gc::IsAboutToBeFinalized(&object_));
+    TraceEdge(trc, &object_, "wasm instance object");
+
+    for (const FuncImport& fi : metadata().funcImports)
+        TraceNullableEdge(trc, &funcImportTls(fi).obj, "wasm import");
+
+    for (const SharedTable& table : tables_)
+        table->trace(trc);
+
+    TraceNullableEdge(trc, &memory_, "wasm buffer");
+}
+
+void
+Instance::trace(JSTracer* trc)
+{
+    // Technically, instead of having this method, the caller could use
+    // Instance::object() to get the owning WasmInstanceObject to mark,
+    // but this method is simpler and more efficient. The trace hook of
+    // WasmInstanceObject will call Instance::tracePrivate at which point we
+    // can mark the rest of the children.
+    TraceEdge(trc, &object_, "wasm instance object");
+}
+
+SharedMem<uint8_t*>
+Instance::memoryBase() const
+{
+    MOZ_ASSERT(metadata().usesMemory());
+    MOZ_ASSERT(tlsData_.memoryBase == memory_->buffer().dataPointerEither());
+    return memory_->buffer().dataPointerEither();
+}
+
+size_t
+Instance::memoryLength() const
+{
+    return memory_->buffer().byteLength();
+}
+
+WasmInstanceObject*
+Instance::objectUnbarriered() const
+{
+    return object_.unbarrieredGet();
+}
+
+WasmInstanceObject*
+Instance::object() const
+{
+    return object_;
+}
+
+bool
+Instance::callExport(JSContext* cx, uint32_t funcIndex, CallArgs args)
+{
+    // If there has been a moving grow, this Instance should have been notified.
+    MOZ_RELEASE_ASSERT(!memory_ || tlsData_.memoryBase == memory_->buffer().dataPointerEither());
+
+    if (!cx->compartment()->wasm.ensureProfilingState(cx))
+        return false;
+
+    const FuncExport& func = metadata().lookupFuncExport(funcIndex);
+
+    // The calling convention for an external call into wasm is to pass an
+    // array of 16-byte values where each value contains either a coerced int32
+    // (in the low word), a double value (in the low dword) or a SIMD vector
+    // value, with the coercions specified by the wasm signature. The external
+    // entry point unpacks this array into the system-ABI-specified registers
+    // and stack memory and then calls into the internal entry point. The return
+    // value is stored in the first element of the array (which, therefore, must
+    // have length >= 1).
+    Vector<ExportArg, 8> exportArgs(cx);
+    if (!exportArgs.resize(Max<size_t>(1, func.sig().args().length())))
+        return false;
+
+    RootedValue v(cx);
+    for (unsigned i = 0; i < func.sig().args().length(); ++i) {
+        v = i < args.length() ? args[i] : UndefinedValue();
+        switch (func.sig().arg(i)) {
+          case ValType::I32:
+            if (!ToInt32(cx, v, (int32_t*)&exportArgs[i]))
+                return false;
+            break;
+          case ValType::I64:
+            if (!JitOptions.wasmTestMode) {
+                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_BAD_I64);
+                return false;
+            }
+            if (!ReadI64Object(cx, v, (int64_t*)&exportArgs[i]))
+                return false;
+            break;
+          case ValType::F32:
+            if (JitOptions.wasmTestMode && v.isObject()) {
+                if (!ReadCustomFloat32NaNObject(cx, v, (uint32_t*)&exportArgs[i]))
+                    return false;
+                break;
+            }
+            if (!RoundFloat32(cx, v, (float*)&exportArgs[i]))
+                return false;
+            break;
+          case ValType::F64:
+            if (JitOptions.wasmTestMode && v.isObject()) {
+                if (!ReadCustomDoubleNaNObject(cx, v, (uint64_t*)&exportArgs[i]))
+                    return false;
+                break;
+            }
+            if (!ToNumber(cx, v, (double*)&exportArgs[i]))
+                return false;
+            break;
+          case ValType::I8x16: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Int8x16>(cx, v, &simd))
+                return false;
+            memcpy(&exportArgs[i], simd.asInt8x16(), Simd128DataSize);
+            break;
+          }
+          case ValType::I16x8: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Int16x8>(cx, v, &simd))
+                return false;
+            memcpy(&exportArgs[i], simd.asInt16x8(), Simd128DataSize);
+            break;
+          }
+          case ValType::I32x4: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Int32x4>(cx, v, &simd))
+                return false;
+            memcpy(&exportArgs[i], simd.asInt32x4(), Simd128DataSize);
+            break;
+          }
+          case ValType::F32x4: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Float32x4>(cx, v, &simd))
+                return false;
+            memcpy(&exportArgs[i], simd.asFloat32x4(), Simd128DataSize);
+            break;
+          }
+          case ValType::B8x16: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Bool8x16>(cx, v, &simd))
+                return false;
+            // Bool8x16 uses the same representation as Int8x16.
+            memcpy(&exportArgs[i], simd.asInt8x16(), Simd128DataSize);
+            break;
+          }
+          case ValType::B16x8: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Bool16x8>(cx, v, &simd))
+                return false;
+            // Bool16x8 uses the same representation as Int16x8.
+            memcpy(&exportArgs[i], simd.asInt16x8(), Simd128DataSize);
+            break;
+          }
+          case ValType::B32x4: {
+            SimdConstant simd;
+            if (!ToSimdConstant<Bool32x4>(cx, v, &simd))
+                return false;
+            // Bool32x4 uses the same representation as Int32x4.
+            memcpy(&exportArgs[i], simd.asInt32x4(), Simd128DataSize);
+            break;
+          }
+        }
+    }
+
+    {
+        // Push a WasmActivation to describe the wasm frames we're about to push
+        // when running this module. Additionally, push a JitActivation so that
+        // the optimized wasm-to-Ion FFI call path (which we want to be very
+        // fast) can avoid doing so. The JitActivation is marked as inactive so
+        // stack iteration will skip over it.
+        WasmActivation activation(cx);
+        JitActivation jitActivation(cx, /* active */ false);
+
+        // Call the per-exported-function trampoline created by GenerateEntry.
+        auto funcPtr = JS_DATA_TO_FUNC_PTR(ExportFuncPtr, codeBase() + func.entryOffset());
+        if (!CALL_GENERATED_2(funcPtr, exportArgs.begin(), &tlsData_))
+            return false;
+    }
+
+    if (isAsmJS() && args.isConstructing()) {
+        // By spec, when a JS function is called as a constructor and this
+        // function returns a primary type, which is the case for all asm.js
+        // exported functions, the returned value is discarded and an empty
+        // object is returned instead.
+        PlainObject* obj = NewBuiltinClassInstance<PlainObject>(cx);
+        if (!obj)
+            return false;
+        args.rval().set(ObjectValue(*obj));
+        return true;
+    }
+
+    void* retAddr = &exportArgs[0];
+    JSObject* retObj = nullptr;
+    switch (func.sig().ret()) {
+      case ExprType::Void:
+        args.rval().set(UndefinedValue());
+        break;
+      case ExprType::I32:
+        args.rval().set(Int32Value(*(int32_t*)retAddr));
+        break;
+      case ExprType::I64:
+        if (!JitOptions.wasmTestMode) {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_BAD_I64);
+            return false;
+        }
+        retObj = CreateI64Object(cx, *(int64_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::F32:
+        if (JitOptions.wasmTestMode && IsNaN(*(float*)retAddr)) {
+            retObj = CreateCustomNaNObject(cx, (float*)retAddr);
+            if (!retObj)
+                return false;
+            break;
+        }
+        args.rval().set(NumberValue(*(float*)retAddr));
+        break;
+      case ExprType::F64:
+        if (JitOptions.wasmTestMode && IsNaN(*(double*)retAddr)) {
+            retObj = CreateCustomNaNObject(cx, (double*)retAddr);
+            if (!retObj)
+                return false;
+            break;
+        }
+        args.rval().set(NumberValue(*(double*)retAddr));
+        break;
+      case ExprType::I8x16:
+        retObj = CreateSimd<Int8x16>(cx, (int8_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::I16x8:
+        retObj = CreateSimd<Int16x8>(cx, (int16_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::I32x4:
+        retObj = CreateSimd<Int32x4>(cx, (int32_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::F32x4:
+        retObj = CreateSimd<Float32x4>(cx, (float*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::B8x16:
+        retObj = CreateSimd<Bool8x16>(cx, (int8_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::B16x8:
+        retObj = CreateSimd<Bool16x8>(cx, (int16_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::B32x4:
+        retObj = CreateSimd<Bool32x4>(cx, (int32_t*)retAddr);
+        if (!retObj)
+            return false;
+        break;
+      case ExprType::Limit:
+        MOZ_CRASH("Limit");
+    }
+
+    if (retObj)
+        args.rval().set(ObjectValue(*retObj));
+
+    return true;
+}
+
+void
+Instance::onMovingGrowMemory(uint8_t* prevMemoryBase)
+{
+    MOZ_ASSERT(!isAsmJS());
+    ArrayBufferObject& buffer = memory_->buffer().as<ArrayBufferObject>();
+    tlsData_.memoryBase = buffer.dataPointer();
+    code_->segment().onMovingGrow(prevMemoryBase, metadata(), buffer);
+}
+
+void
+Instance::onMovingGrowTable()
+{
+    MOZ_ASSERT(!isAsmJS());
+    MOZ_ASSERT(tables_.length() == 1);
+    TableTls& table = tableTls(metadata().tables[0]);
+    table.length = tables_[0]->length();
+    table.base = tables_[0]->base();
+}
+
+void
+Instance::deoptimizeImportExit(uint32_t funcImportIndex)
+{
+    const FuncImport& fi = metadata().funcImports[funcImportIndex];
+    FuncImportTls& import = funcImportTls(fi);
+    import.code = codeBase() + fi.interpExitCodeOffset();
+    import.baselineScript = nullptr;
+}
+
+static void
+UpdateEntry(const Code& code, bool profilingEnabled, void** entry)
+{
+    const CodeRange& codeRange = *code.lookupRange(*entry);
+    void* from = code.segment().base() + codeRange.funcNonProfilingEntry();
+    void* to = code.segment().base() + codeRange.funcProfilingEntry();
+
+    if (!profilingEnabled)
+        Swap(from, to);
+
+    MOZ_ASSERT(*entry == from);
+    *entry = to;
+}
+
+bool
+Instance::ensureProfilingState(JSContext* cx, bool newProfilingEnabled)
+{
+    if (code_->profilingEnabled() == newProfilingEnabled)
+        return true;
+
+    if (!code_->ensureProfilingState(cx, newProfilingEnabled))
+        return false;
+
+    // Imported wasm functions and typed function tables point directly to
+    // either the profiling or non-profiling prologue and must therefore be
+    // updated when the profiling mode is toggled.
+
+    for (const FuncImport& fi : metadata().funcImports) {
+        FuncImportTls& import = funcImportTls(fi);
+        if (import.obj && import.obj->is<WasmInstanceObject>()) {
+            Code& code = import.obj->as<WasmInstanceObject>().instance().code();
+            UpdateEntry(code, newProfilingEnabled, &import.code);
+        }
+    }
+
+    for (const SharedTable& table : tables_) {
+        if (!table->isTypedFunction())
+            continue;
+
+        // This logic will have to be generalized to match the import logic
+        // above if wasm can create typed function tables since a single table
+        // can contain elements from multiple instances.
+        MOZ_ASSERT(metadata().kind == ModuleKind::AsmJS);
+
+        void** array = table->internalArray();
+        uint32_t length = table->length();
+        for (size_t i = 0; i < length; i++) {
+            if (array[i])
+                UpdateEntry(*code_, newProfilingEnabled, &array[i]);
+        }
+    }
+
+    return true;
+}
+
+void
+Instance::addSizeOfMisc(MallocSizeOf mallocSizeOf,
+                        Metadata::SeenSet* seenMetadata,
+                        ShareableBytes::SeenSet* seenBytes,
+                        Table::SeenSet* seenTables,
+                        size_t* code,
+                        size_t* data) const
+{
+    *data += mallocSizeOf(this);
+
+    code_->addSizeOfMisc(mallocSizeOf, seenMetadata, seenBytes, code, data);
+
+    for (const SharedTable& table : tables_)
+         *data += table->sizeOfIncludingThisIfNotSeen(mallocSizeOf, seenTables);
+}