[wasm][debug] Ignore empty local names.

Other WebAssembly tools like wabt and wasmparser ignore empty strings
for local variable and parameter names, and just generate their own
names for it. Update V8 to comply with this convention.

Bug: chromium:1134531
Change-Id: Ic724482d93398feaf6b0797eec5a55f8ca508ca5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2448457Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70305}

src/wasm/wasm-debug.cc

@@ -164,8 +164,8 @@ MaybeHandle<String> GetLocalNameString(Isolate* isolate,
   ModuleWireBytes wire_bytes{native_module->wire_bytes()};
   // Bounds were checked during decoding.
   DCHECK(wire_bytes.BoundsCheck(name_ref));
-  Vector<const char> name = wire_bytes.GetNameOrNull(name_ref);
-  if (name.begin() == nullptr) return {};
+  WasmName name = wire_bytes.GetNameOrNull(name_ref);
+  if (name.size() == 0) return {};
   return isolate->factory()->NewStringFromUtf8(name);
 }
 

test/inspector/debugger/wasm-scope-info-liftoff-expected.txt

@@ -4,14 +4,14 @@ Waiting for wasm script to be parsed.
 Got wasm script!
 Setting breakpoint on line 2 (first instruction) of third function
 {
-    columnNumber : 167
+    columnNumber : 169
     lineNumber : 0
     scriptId : <scriptId>
 }
 Paused:
-Script wasm://wasm/ed01bcee byte offset 167: Wasm opcode 0x20
+Script wasm://wasm/e33badc2 byte offset 169: Wasm opcode 0x20
 Scope:
-at C (interpreted) (0:167):
+at C (interpreted) (0:169):
  - scope (module):
    instance: exports: "exported_global" (Global), "exported_memory" (Memory), "exported_table" (Table), "main" (Function)
    exported_memory: Uint8Array(65536)
@@ -21,6 +21,7 @@ at C (interpreted) (0:167):
  - scope (local):
    i32_arg: 42 (i32)
    i32_local: 0 (i32)
+   var2: 0 (f32)
  - scope (wasm-expression-stack):
 at B (liftoff) (0:158):
  - scope (module):
@@ -54,9 +55,9 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 169: Wasm opcode 0x24
+Script wasm://wasm/e33badc2 byte offset 171: Wasm opcode 0x24
 Scope:
-at C (interpreted) (0:169):
+at C (interpreted) (0:171):
  - scope (module):
    instance: exports: "exported_global" (Global), "exported_memory" (Memory), "exported_table" (Table), "main" (Function)
    exported_memory: Uint8Array(65536)
@@ -66,6 +67,7 @@ at C (interpreted) (0:169):
  - scope (local):
    i32_arg: 42 (i32)
    i32_local: 0 (i32)
+   var2: 0 (f32)
  - scope (wasm-expression-stack):
    0: 42 (i32)
 at B (liftoff) (0:158):
@@ -100,9 +102,9 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 171: Wasm opcode 0x41
+Script wasm://wasm/e33badc2 byte offset 173: Wasm opcode 0x41
 Scope:
-at C (interpreted) (0:171):
+at C (interpreted) (0:173):
  - scope (module):
    instance: exports: "exported_global" (Global), "exported_memory" (Memory), "exported_table" (Table), "main" (Function)
    exported_memory: Uint8Array(65536)
@@ -112,6 +114,7 @@ at C (interpreted) (0:171):
  - scope (local):
    i32_arg: 42 (i32)
    i32_local: 0 (i32)
+   var2: 0 (f32)
  - scope (wasm-expression-stack):
 at B (liftoff) (0:158):
  - scope (module):
@@ -145,9 +148,9 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 173: Wasm opcode 0x21
+Script wasm://wasm/e33badc2 byte offset 175: Wasm opcode 0x21
 Scope:
-at C (interpreted) (0:173):
+at C (interpreted) (0:175):
  - scope (module):
    instance: exports: "exported_global" (Global), "exported_memory" (Memory), "exported_table" (Table), "main" (Function)
    exported_memory: Uint8Array(65536)
@@ -157,6 +160,7 @@ at C (interpreted) (0:173):
  - scope (local):
    i32_arg: 42 (i32)
    i32_local: 0 (i32)
+   var2: 0 (f32)
  - scope (wasm-expression-stack):
    0: 47 (i32)
 at B (liftoff) (0:158):
@@ -191,9 +195,9 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 175: Wasm opcode 0x0b
+Script wasm://wasm/e33badc2 byte offset 177: Wasm opcode 0x0b
 Scope:
-at C (interpreted) (0:175):
+at C (interpreted) (0:177):
  - scope (module):
    instance: exports: "exported_global" (Global), "exported_memory" (Memory), "exported_table" (Table), "main" (Function)
    exported_memory: Uint8Array(65536)
@@ -203,6 +207,7 @@ at C (interpreted) (0:175):
  - scope (local):
    i32_arg: 42 (i32)
    i32_local: 47 (i32)
+   var2: 0 (f32)
  - scope (wasm-expression-stack):
 at B (liftoff) (0:158):
  - scope (module):
@@ -236,7 +241,7 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 160: Wasm opcode 0x1a
+Script wasm://wasm/e33badc2 byte offset 160: Wasm opcode 0x1a
 Scope:
 at B (liftoff) (0:160):
  - scope (module):
@@ -270,7 +275,7 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 161: Wasm opcode 0x1a
+Script wasm://wasm/e33badc2 byte offset 161: Wasm opcode 0x1a
 Scope:
 at B (liftoff) (0:161):
  - scope (module):
@@ -303,7 +308,7 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 162: Wasm opcode 0x0b
+Script wasm://wasm/e33badc2 byte offset 162: Wasm opcode 0x0b
 Scope:
 at B (liftoff) (0:162):
  - scope (module):
@@ -335,7 +340,7 @@ at (anonymous) (0:17):
    -- skipped globals
 
 Paused:
-Script wasm://wasm/ed01bcee byte offset 130: Wasm opcode 0x0b
+Script wasm://wasm/e33badc2 byte offset 130: Wasm opcode 0x0b
 Scope:
 at A (liftoff) (0:130):
  - scope (module):

test/inspector/debugger/wasm-scope-info-liftoff.js

@@ -104,6 +104,7 @@ async function instantiateWasm() {
   // A third function which will be stepped through.
   let func = builder.addFunction('C (interpreted)', kSig_v_i, ['i32_arg'])
       .addLocals(kWasmI32, 1, ['i32_local'])
+      .addLocals(kWasmF32, 1, [''])
       .addBody([
         // Set global 0 to param 0.
         kExprLocalGet, 0, kExprGlobalSet, 0,

test/inspector/debugger/wasm-scope-info.js

@@ -90,6 +90,7 @@ async function instantiateWasm() {
     .addLocals(kWasmI64, 1, ['i64_local'])
     .addLocals(kWasmF64, 3, ['unicode☼f64', '0', '0'])
     .addLocals(kWasmS128, 1)
+    .addLocals(kWasmF32, 1, [''])
     .addBody([
       // Set param 0 to 11.
       kExprI32Const, 11, kExprLocalSet, 0,
@@ -108,6 +109,9 @@ async function instantiateWasm() {
       kExprI32Const, 23,
       kSimdPrefix, kExprI32x4Splat,
       kExprLocalSet, 6,
+      // Set local 7 to 21
+      kExprI32Const, 21, kExprF32UConvertI32,
+      kExprLocalSet, 7,
 
       // Set global 0 to 15
       kExprI32Const, 15, kExprGlobalSet, 0,