Reland "[wasm-gc] Liftoff support part 4: subtyping"

This is a reland of dc369749
Changes: relaxed --liftoff-only mode to still allow bailing
out due to missing CPU support.

Original change's description:
> [wasm-gc] Liftoff support part 4: subtyping
>
> This adds support for the following instructions:
> struct.new_default, rtt.sub, ref.test, ref.cast
>
> Bug: v8:7748
> Change-Id: I7423ddd7a83c80cb1e82c620780c27bec59ec762
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2593341
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#71805}

Bug: v8:7748
Change-Id: If31fcee5e7e173d7c2a6e1c624f4ff04cec7fe9c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2596338
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71823}

src/builtins/wasm.tq

@@ -231,9 +231,9 @@ builtin WasmAllocateJSArray(implicit context: Context)(size: Smi): JSArray {
   return AllocateJSArray(ElementsKind::PACKED_ELEMENTS, map, size, size);
 }
 
-builtin WasmAllocateRtt(implicit context: Context)(
-    typeIndex: Smi, parent: Map): Map {
-  tail runtime::WasmAllocateRtt(context, typeIndex, parent);
+builtin WasmAllocateRtt(typeIndex: intptr, parent: Map): Map {
+  tail runtime::WasmAllocateRtt(
+      LoadContextFromFrame(), SmiTag(typeIndex), parent);
 }
 
 builtin WasmAllocateStructWithRtt(rtt: Map): HeapObject {

src/compiler/wasm-compiler.cc

@@ -5701,12 +5701,10 @@ Node* WasmGraphBuilder::RttCanon(wasm::HeapType type) {
 }
 
 Node* WasmGraphBuilder::RttSub(wasm::HeapType type, Node* parent_rtt) {
-  return CALL_BUILTIN(
-      WasmAllocateRtt,
-      graph()->NewNode(
-          mcgraph()->common()->NumberConstant(type.representation())),
-      parent_rtt,
-      LOAD_INSTANCE_FIELD(NativeContext, MachineType::TaggedPointer()));
+  return CALL_BUILTIN(WasmAllocateRtt,
+                      graph()->NewNode(mcgraph()->common()->Int32Constant(
+                          type.representation())),
+                      parent_rtt);
 }
 
 void AssertFalse(MachineGraph* mcgraph, GraphAssembler* gasm, Node* condition) {

src/wasm/function-compiler.cc

@@ -196,9 +196,6 @@ WasmCompilationResult WasmCompilationUnit::ExecuteFunctionCompilation(
                                            func_body, func_index_,
                                            for_debugging_, counters, detected);
         if (result.succeeded()) break;
-        // In --liftoff-only mode, we should have aborted the process
-        // on bailout, i.e. before getting here.
-        DCHECK(!FLAG_liftoff_only);
       }
 
       // If Liftoff failed, fall back to turbofan.

src/wasm/wasm-code-manager.h

@@ -86,6 +86,7 @@ struct WasmModule;
   V(RecordWrite)                         \
   V(ToNumber)                            \
   V(WasmAllocateArrayWithRtt)            \
+  V(WasmAllocateRtt)                     \
   V(WasmAllocateStructWithRtt)
 
 // Sorted, disjoint and non-overlapping memory regions. A region is of the

test/cctest/wasm/test-gc.cc

@@ -745,8 +745,9 @@ WASM_COMPILED_EXEC_TEST(WasmPackedArrayS) {
   tester.CheckResult(kF, static_cast<int16_t>(expected_outputs[3]), 3);
 }
 
-TEST(NewDefault) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(NewDefault) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   const byte struct_type = tester.DefineStruct(
       {F(wasm::kWasmI32, true), F(wasm::kWasmF64, true), F(optref(0), true)});
   const byte array_type = tester.DefineArray(wasm::kWasmI32, true);
@@ -873,8 +874,9 @@ TEST(BasicRTT) {
   tester.CheckResult(kRefCast, 43);
 }
 
-TEST(AnyRefRtt) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(AnyRefRtt) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
 
   ValueType any_rtt_0_type = ValueType::Rtt(HeapType::kAny, 0);
   FunctionSig sig_any_canon(1, 0, &any_rtt_0_type);
@@ -947,8 +949,10 @@ TEST(AnyRefRtt) {
   tester.CheckResult(kCheckAnyAgainstAny, 1);
 }
 
-TEST(ArrayNewMap) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(ArrayNewMap) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
+
   const byte type_index = tester.DefineArray(kWasmI32, true);
 
   ValueType array_type = ValueType::Ref(type_index, kNonNullable);
@@ -1065,8 +1069,9 @@ TEST(CallRef) {
   tester.CheckResult(caller, 47, 5);
 }
 
-TEST(RefTestCastNull) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(RefTestCastNull) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   byte type_index = tester.DefineStruct({F(wasm::kWasmI32, true)});
 
   const byte kRefTestNull = tester.DefineFunction(
@@ -1266,8 +1271,9 @@ TEST(CastsBenchmark) {
   tester.CheckResult(Main, (kListLength * (kListLength - 1) / 2) * kLoops);
 }
 
-TEST(GlobalInitReferencingGlobal) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(GlobalInitReferencingGlobal) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   const byte from = tester.AddGlobal(kWasmI32, false, WasmInitExpr(42));
   const byte to =
       tester.AddGlobal(kWasmI32, false, WasmInitExpr::GlobalGet(from));
@@ -1280,8 +1286,9 @@ TEST(GlobalInitReferencingGlobal) {
   tester.CheckResult(func, 42);
 }
 
-TEST(IndirectNullSetManually) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(IndirectNullSetManually) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   byte sig_index = tester.DefineSignature(tester.sigs.i_i());
   tester.DefineTable(ValueType::Ref(sig_index, kNullable), 1, 1);
   byte func_index = tester.DefineFunction(