[wasm] Fix stack-switching import wrapper return

The JS import returns a tagged value, not a value of the machine
representation that corresponds to the signature's return type, since it
hasn't been converted yet.

R=ahaas@chromium.org

Bug: v8:12191
Change-Id: I0783af85eed9c5d25347200540e3e4eee48edfd4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3464036Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80213}

src/compiler/wasm-compiler.cc

@@ -7065,11 +7065,10 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
                         global_proxy);
   }
 
-  Node* BuildSuspend(Node* value, Node* api_function_ref,
-                     MachineRepresentation rep) {
+  Node* BuildSuspend(Node* value, Node* api_function_ref) {
     // If value is a promise, suspend to the js-to-wasm prompt, and resume later
     // with the promise's resolved value.
-    auto resume = gasm_->MakeLabel(rep);
+    auto resume = gasm_->MakeLabel(MachineRepresentation::kTagged);
     gasm_->GotoIf(IsSmi(value), &resume, value);
     gasm_->GotoIfNot(gasm_->HasInstanceType(value, JS_PROMISE_TYPE), &resume,
                      BranchHint::kTrue, value);
@@ -7158,11 +7157,7 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
         DCHECK_EQ(pos, args.size());
         call = gasm_->Call(call_descriptor, pos, args.begin());
         if (suspend == wasm::kSuspend) {
-          MachineRepresentation rep =
-              sig_->return_count() >= 1
-                  ? sig_->GetReturn(0).machine_representation()
-                  : MachineRepresentation::kNone;
-          call = BuildSuspend(call, Param(0), rep);
+          call = BuildSuspend(call, Param(0));
         }
         break;
       }

test/mjsunit/wasm/stack-switching.js

@@ -226,3 +226,26 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
       wrapped_export.apply(null, args);
   combined_promise.then(v => assertEquals(reduce(args), v));
 })();
+
+(function TestStackSwitchReturnFloat() {
+  print(arguments.callee.name);
+  let builder = new WasmModuleBuilder();
+  import_index = builder.addImport('m', 'import', kSig_f_v);
+  builder.addFunction("test", kSig_f_v)
+      .addBody([
+          kExprCallFunction, import_index, // suspend
+      ]).exportFunc();
+  let suspender = new WebAssembly.Suspender();
+  function js_import() {
+    return Promise.resolve(0.5);
+  };
+  let wasm_js_import = new WebAssembly.Function(
+      {parameters: [], results: ['externref']}, js_import);
+  let suspending_wasm_js_import =
+      suspender.suspendOnReturnedPromise(wasm_js_import);
+
+  let instance = builder.instantiate({m: {import: suspending_wasm_js_import}});
+  let wrapped_export = suspender.returnPromiseOnSuspend(instance.exports.test);
+  let combined_promise = wrapped_export();
+  combined_promise.then(v => assertEquals(0.5, v));
+})();