[wasm] Support multi-return WASM function calls from JS

Calling a multi-return WASM function from JS creates an array filled
with the returned values.

See: https://github.com/WebAssembly/multi-value

R=ahaas@chromium.org

Bug: v8:9492
Change-Id: I3151212b6784782c8f89908befab9d26b32e5a8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1739372
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63110}

src/compiler/wasm-compiler.cc

@@ -5606,9 +5606,25 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
     // Clear the ThreadInWasm flag.
     BuildModifyThreadInWasmFlag(false);
 
-    Node* jsval = sig_->return_count() == 0
-                      ? BuildLoadUndefinedValueFromInstance()
-                      : ToJS(rets[0], sig_->GetReturn());
+    Node* jsval;
+    if (sig_->return_count() == 0) {
+      jsval = BuildLoadUndefinedValueFromInstance();
+    } else if (sig_->return_count() == 1) {
+      jsval = ToJS(rets[0], sig_->GetReturn());
+    } else {
+      int32_t return_count = static_cast<int32_t>(sig_->return_count());
+      Node* size = jsgraph()->SmiConstant(return_count);
+      // TODO(thibaudm): Replace runtime calls with TurboFan code.
+      Node* fixed_array =
+          BuildCallToRuntime(Runtime::kWasmNewMultiReturnFixedArray, &size, 1);
+      for (int i = 0; i < return_count; ++i) {
+        Node* value = ToJS(rets[i], sig_->GetReturn(i));
+        STORE_FIXED_ARRAY_SLOT_ANY(fixed_array, i, value);
+      }
+      jsval = BuildCallToRuntimeWithContext(Runtime::kWasmNewMultiReturnJSArray,
+                                            js_context, &fixed_array, 1,
+                                            effect_, Control());
+    }
     Return(jsval);
   }
 

src/runtime/runtime-wasm.cc

@@ -568,5 +568,24 @@ RUNTIME_FUNCTION(Runtime_WasmTableFill) {
   }
   return ReadOnlyRoots(isolate).undefined_value();
 }
+
+RUNTIME_FUNCTION(Runtime_WasmNewMultiReturnFixedArray) {
+  DCHECK_EQ(1, args.length());
+  HandleScope scope(isolate);
+  CONVERT_INT32_ARG_CHECKED(size, 0);
+  Handle<FixedArray> fixed_array = isolate->factory()->NewFixedArray(size);
+  return *fixed_array;
+}
+
+RUNTIME_FUNCTION(Runtime_WasmNewMultiReturnJSArray) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+  DCHECK(!isolate->context().is_null());
+  CONVERT_ARG_CHECKED(FixedArray, fixed_array, 0);
+  Handle<FixedArray> fixed_array_handle(fixed_array, isolate);
+  Handle<JSArray> array = isolate->factory()->NewJSArrayWithElements(
+      fixed_array_handle, PACKED_ELEMENTS);
+  return *array;
+}
 }  // namespace internal
 }  // namespace v8

src/runtime/runtime.h

@@ -529,28 +529,30 @@ namespace internal {
   F(TypedArraySet, 2, 1)                    \
   F(TypedArraySortFast, 1, 1)
 
-#define FOR_EACH_INTRINSIC_WASM(F, I) \
-  F(ThrowWasmError, 1, 1)             \
-  F(ThrowWasmStackOverflow, 0, 1)     \
-  F(WasmI32AtomicWait, 4, 1)          \
-  F(WasmI64AtomicWait, 5, 1)          \
-  F(WasmAtomicNotify, 3, 1)           \
-  F(WasmExceptionGetValues, 1, 1)     \
-  F(WasmExceptionGetTag, 1, 1)        \
-  F(WasmMemoryGrow, 2, 1)             \
-  F(WasmRunInterpreter, 2, 1)         \
-  F(WasmStackGuard, 0, 1)             \
-  F(WasmThrowCreate, 2, 1)            \
-  F(WasmThrowTypeError, 0, 1)         \
-  F(WasmRefFunc, 1, 1)                \
-  F(WasmFunctionTableGet, 3, 1)       \
-  F(WasmFunctionTableSet, 4, 1)       \
-  F(WasmTableInit, 5, 1)              \
-  F(WasmTableCopy, 5, 1)              \
-  F(WasmTableGrow, 3, 1)              \
-  F(WasmTableFill, 4, 1)              \
-  F(WasmIsValidFuncRefValue, 1, 1)    \
-  F(WasmCompileLazy, 2, 1)
+#define FOR_EACH_INTRINSIC_WASM(F, I)   \
+  F(ThrowWasmError, 1, 1)               \
+  F(ThrowWasmStackOverflow, 0, 1)       \
+  F(WasmI32AtomicWait, 4, 1)            \
+  F(WasmI64AtomicWait, 5, 1)            \
+  F(WasmAtomicNotify, 3, 1)             \
+  F(WasmExceptionGetValues, 1, 1)       \
+  F(WasmExceptionGetTag, 1, 1)          \
+  F(WasmMemoryGrow, 2, 1)               \
+  F(WasmRunInterpreter, 2, 1)           \
+  F(WasmStackGuard, 0, 1)               \
+  F(WasmThrowCreate, 2, 1)              \
+  F(WasmThrowTypeError, 0, 1)           \
+  F(WasmRefFunc, 1, 1)                  \
+  F(WasmFunctionTableGet, 3, 1)         \
+  F(WasmFunctionTableSet, 4, 1)         \
+  F(WasmTableInit, 5, 1)                \
+  F(WasmTableCopy, 5, 1)                \
+  F(WasmTableGrow, 3, 1)                \
+  F(WasmTableFill, 4, 1)                \
+  F(WasmIsValidFuncRefValue, 1, 1)      \
+  F(WasmCompileLazy, 2, 1)              \
+  F(WasmNewMultiReturnFixedArray, 1, 1) \
+  F(WasmNewMultiReturnJSArray, 1, 1)
 
 #define FOR_EACH_INTRINSIC_RETURN_PAIR_IMPL(F, I) \
   F(DebugBreakOnBytecode, 1, 2)                   \

src/wasm/wasm-opcodes.cc

@@ -447,7 +447,7 @@ std::ostream& operator<<(std::ostream& os, const FunctionSig& sig) {
 }
 
 bool IsJSCompatibleSignature(const FunctionSig* sig, bool has_bigint_feature) {
-  if (sig->return_count() > 1) {
+  if (!FLAG_experimental_wasm_mv && sig->return_count() > 1) {
     return false;
   }
   for (auto type : sig->all()) {

test/mjsunit/wasm/multi-value.js

@@ -319,3 +319,34 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   assertEquals(instance.exports.main(2), 8);
   assertEquals(instance.exports.main(10), 200);
 })();
+
+(function MultiJSReturnTest() {
+  print(arguments.callee.name);
+  let builder = new WasmModuleBuilder();
+  let sig_fi_if = makeSig([kWasmI32, kWasmF32], [kWasmF32, kWasmI32]);
+
+  builder.addFunction("swap", sig_fi_if)
+    .addBody([
+      kExprGetLocal, 1,
+      kExprGetLocal, 0])
+    .exportAs("swap");
+  builder.addFunction("addsubmul", kSig_iii_i)
+      .addBody([
+        kExprGetLocal, 0,
+        kExprGetLocal, 0,
+        kExprI32Add,
+        kExprGetLocal, 0,
+        kExprGetLocal, 0,
+        kExprI32Sub,
+        kExprGetLocal, 0,
+        kExprGetLocal, 0,
+        kExprI32Mul])
+    .exportAs("addsubmul");
+
+  let module = new WebAssembly.Module(builder.toBuffer());
+  let instance = new WebAssembly.Instance(module);
+  assertEquals(instance.exports.swap(0, 1.5), [1.5, 0]);
+  assertEquals(instance.exports.swap(2, 3.75), [3.75, 2]);
+  assertEquals(instance.exports.addsubmul(4), [8, 0, 16]);
+  assertEquals(instance.exports.addsubmul(5), [10, 0, 25]);
+})();