[wasm] Rename flag to --experimental-liftoff-extern-ref

Rename the flag --liftoff-extern-ref to
--experimental-liftoff-extern-ref to keep the fuzzer from using it.
The implementation is not complete yet, and the next steps may take a
bit.

R=clemensb@chromium.org

Bug: chromium:1137601
Change-Id: I74f1ed8faba44e42f63790d87f4a538dd59ac852
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2465838Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70476}

src/flags/flag-definitions.h

@@ -810,7 +810,7 @@ DEFINE_INT(trace_wasm_ast_start, 0,
 DEFINE_INT(trace_wasm_ast_end, 0, "end function for wasm AST trace (exclusive)")
 DEFINE_BOOL(liftoff, true,
             "enable Liftoff, the baseline compiler for WebAssembly")
-DEFINE_BOOL(liftoff_extern_ref, false,
+DEFINE_BOOL(experimental_liftoff_extern_ref, false,
             "enable support for externref in Liftoff")
 // We can't tier up (from Liftoff to TurboFan) in single-threaded mode, hence
 // disable Liftoff in that configuration for now. The alternative is disabling

src/wasm/baseline/liftoff-compiler.cc

@@ -557,7 +557,7 @@ class LiftoffCompiler {
   void StartFunctionBody(FullDecoder* decoder, Control* block) {
     for (uint32_t i = 0; i < __ num_locals(); ++i) {
       if (!CheckSupportedType(decoder,
-                              FLAG_liftoff_extern_ref
+                              FLAG_experimental_liftoff_extern_ref
                                   ? kSupportedTypes
                                   : kSupportedTypesWithoutRefs,
                               __ local_type(i), "param"))
@@ -621,7 +621,7 @@ class LiftoffCompiler {
       }
     }
 
-    if (FLAG_liftoff_extern_ref) {
+    if (FLAG_experimental_liftoff_extern_ref) {
       // Initialize all reference type locals with ref.null.
       for (uint32_t param_idx = num_params; param_idx < __ num_locals();
            ++param_idx) {
@@ -1633,7 +1633,7 @@ class LiftoffCompiler {
   }
 
   void RefNull(FullDecoder* decoder, ValueType type, Value*) {
-    if (!FLAG_liftoff_extern_ref) {
+    if (!FLAG_experimental_liftoff_extern_ref) {
       unsupported(decoder, kRefTypes, "ref_null");
       return;
     }
@@ -1816,7 +1816,7 @@ class LiftoffCompiler {
                  const GlobalIndexImmediate<validate>& imm) {
     const auto* global = &env_->module->globals[imm.index];
     if (!CheckSupportedType(decoder,
-                            FLAG_liftoff_extern_ref
+                            FLAG_experimental_liftoff_extern_ref
                                 ? kSupportedTypes
                                 : kSupportedTypesWithoutRefs,
                             global->type, "global")) {
@@ -1855,7 +1855,7 @@ class LiftoffCompiler {
                  const GlobalIndexImmediate<validate>& imm) {
     auto* global = &env_->module->globals[imm.index];
     if (!CheckSupportedType(decoder,
-                            FLAG_liftoff_extern_ref
+                            FLAG_experimental_liftoff_extern_ref
                                 ? kSupportedTypes
                                 : kSupportedTypesWithoutRefs,
                             global->type, "global")) {
@@ -3813,7 +3813,7 @@ class LiftoffCompiler {
                   const Value args[], Value returns[], CallKind call_kind) {
     for (ValueType ret : imm.sig->returns()) {
       if (!CheckSupportedType(decoder,
-                              FLAG_liftoff_extern_ref
+                              FLAG_experimental_liftoff_extern_ref
                                   ? kSupportedTypes
                                   : kSupportedTypesWithoutRefs,
                               ret, "return")) {
@@ -3895,7 +3895,7 @@ class LiftoffCompiler {
     }
     for (ValueType ret : imm.sig->returns()) {
       if (!CheckSupportedType(decoder,
-                              FLAG_liftoff_extern_ref
+                              FLAG_experimental_liftoff_extern_ref
                                   ? kSupportedTypes
                                   : kSupportedTypesWithoutRefs,
                               ret, "return")) {

test/mjsunit/wasm/externref-globals-liftoff.js

@@ -3,6 +3,6 @@
 // found in the LICENSE file.
 
 // Flags: --experimental-wasm-reftypes --expose-gc --liftoff
-// Flags: --no-wasm-tier-up --liftoff-extern-ref
+// Flags: --no-wasm-tier-up --experimental-liftoff-extern-ref
 
 load("test/mjsunit/wasm/externref-globals.js");

test/mjsunit/wasm/externref-liftoff.js

@@ -3,6 +3,6 @@
 // found in the LICENSE file.
 
 // Flags: --expose-wasm --experimental-wasm-reftypes --expose-gc --liftoff
-// Flags: --no-wasm-tier-up --liftoff-extern-ref
+// Flags: --no-wasm-tier-up --experimental-liftoff-extern-ref
 
 load("test/mjsunit/wasm/externref.js");