[stringrefs] Support stringrefs in DevTools inspection

When a string is in a local or on the value stack at a breakpoint,
DevTools should be able to show its value.

Bug: v8:12868
Change-Id: I79014d74c8ef7b212469382bdedca85568b3bcc7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3834038
Commit-Queue: Philip Pfaffe <pfaffe@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Philip Pfaffe <pfaffe@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82542}

src/debug/debug-wasm-objects.cc

@@ -905,7 +905,6 @@ Handle<WasmValueObject> WasmValueObject::New(
     }
     case wasm::kRefNull:
     case wasm::kRef: {
-      // TODO(12868): Support stringrefs.
       t = GetRefTypeName(isolate, value.type(), module_object->native_module());
       Handle<Object> ref = value.to_ref();
       if (ref->IsWasmStruct()) {
@@ -916,6 +915,7 @@ Handle<WasmValueObject> WasmValueObject::New(
         v = handle(Handle<WasmInternalFunction>::cast(ref)->external(),
                    isolate);
       } else if (ref->IsJSFunction() || ref->IsSmi() || ref->IsNull() ||
+                 ref->IsString() ||
                  value.type().is_reference_to(wasm::HeapType::kExtern)) {
         v = ref;
       } else {

test/inspector/debugger/wasm-gc-breakpoints-expected.txt

@@ -3,18 +3,20 @@ Tests GC object inspection.
 Running test: test
 Instantiating.
 Waiting for wasm script (ignoring first non-wasm script).
-Setting breakpoint at offset 100 on script wasm://wasm/00670fd6
+Setting breakpoint at offset 103 on script wasm://wasm/476d7da6
 Calling main()
 Paused:
-Script wasm://wasm/00670fd6 byte offset 100: Wasm opcode 0x21 (kExprLocalSet)
+Script wasm://wasm/476d7da6 byte offset 103: Wasm opcode 0x1a (kExprDrop)
 Scope:
-at $main (0:100):
+at $main (0:103):
  - scope (wasm-expression-stack):
    0: Array ((ref $ArrC))
+   1: hello world (stringref)
      object details:
    0: Struct ((ref null $StrA))
    length: 1 (number)
  - scope (local):
+   $var0: hello world (stringref)
    $varA: Struct ((ref null $StrA))
    $varB: null ((ref null $ArrC))
      object details:

test/inspector/debugger/wasm-gc-breakpoints.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --experimental-wasm-gc
+// Flags: --experimental-wasm-gc --experimental-wasm-stringref
 
 utils.load('test/inspector/wasm-inspector-test.js');
 
@@ -14,7 +14,7 @@ const module_bytes = [
   0x00, 0x61, 0x73, 0x6d, 1, 0, 0, 0,  // wasm magic
 
   0x01,  // type section
-  0x18,  // section length
+  0x19,  // section length
   0x01,  // number of type section entries
   0x4f,  // recursive type group
   0x04,  // number of types in the recursive group
@@ -33,7 +33,7 @@ const module_bytes = [
   0x6c, 0x00, 0x01,  // mut ref null $StrA
   // type 3: func
   0x60,  // signature
-  0x00,  // number of params
+  0x01, 0x64,  // 1 param: stringref
   0x00,  // number of results
 
   0x03,  // function section
@@ -59,10 +59,10 @@ const module_bytes = [
 
   /////////////////////////// CODE SECTION //////////////////////////
   0x0a,  // code section
-  0x2c,  // section length
+  0x2f,  // section length
   0x01,  // number of functions
 
-  0x2a,  // function 0: size
+  0x2d,  // function 0: size
   0x02,  // number of locals
   0x01, 0x6c, 0x00,  // (local $varA (ref null $StrA))
   0x01, 0x6c, 0x02,  // (local $varC (ref null $ArrC))
@@ -71,16 +71,18 @@ const module_bytes = [
   0x41, 0xFF, 0xFF, 0x01,  // i32.const 32767
   0xfb, 0x08, 0x01,  // struct.new_default $StrB
   0xfb, 0x07, 0x00,  // struct.new $StrA
-  0x22, 0x00,  // local.tee $varA
+  0x22, 0x01,  // local.tee $varA
   // $varA.$pointer.$next = $varA
   0xfb, 0x03, 0x00, 0x02,  // struct.get $StrA $pointer
-  0x20, 0x00,  // local.get $varA
+  0x20, 0x01,  // local.get $varA
   0xfb, 0x06, 0x01, 0x00,  // struct.set $StrB $next
   // $varC := new $ArrC($varA)
-  0x20, 0x00,  // local.get $varA -- value
+  0x20, 0x01,  // local.get $varA -- value
   0x41, 0x01,  // i32.const 1 -- length
   0xfb, 0x1b, 0x02,  // array.new $ArrC
-  0x21, 0x01,  // local.set $varC
+  0x20, 0x00,  // local.get 0
+  0x1a,  // drop
+  0x21, 0x02,  // local.set $varC
   0x0b,  // end
 
   /////////////////////////// NAME SECTION //////////////////////////
@@ -94,10 +96,10 @@ const module_bytes = [
   0x01,  // number of entries
   0x00,  // for function 0
   0x02,  // number of entries for function 0
-  0x00,  // local index
+  0x01,  // local index
   0x04,  // length of "varA"
   0x76, 0x61, 0x72, 0x41,  // "varA"
-  0x01,  // local index
+  0x02,  // local index
   0x04,  // length of "varB"
   0x76, 0x61, 0x72, 0x42,  // "varB"
 
@@ -218,10 +220,11 @@ InspectorTest.runAsyncTestSuite([
     // Ignore javascript and full module wasm script, get scripts for functions.
     const [, {params: wasm_script}] =
         await Protocol.Debugger.onceScriptParsed(2);
-    let offset = 100;  // "local.set $varC" at the end.
+    let offset = 103;  // "drop" before "local.set $varC" at the end.
     await setBreakpoint(offset, wasm_script.scriptId, wasm_script.url);
     InspectorTest.log('Calling main()');
-    await WasmInspectorTest.evalWithUrl('instance.exports.main()', 'runWasm');
+    await WasmInspectorTest.evalWithUrl('instance.exports.main("hello world")',
+                                        'runWasm');
     InspectorTest.log('exports.main returned!');
   }
 ]);