[wasm] Display wasm globals in the inspector

They are added under the global scope object, as follows:

  {
    "memory": ...,
    "globals": {
      "global#0": ...,
      "global#1": ...,
      "global#2": ...,
    }
  }

We currently don't have any way to name globals in the wasm binary
format, but it is possible to extend the name section with these names
in the future.

Bug: v8:6846
Change-Id: I79fa4ed3d83964bc8e26d66516605d41e92b3d03
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1601829
Commit-Queue: Ben Smith <binji@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61425}

src/wasm/wasm-debug.cc

@@ -60,6 +60,8 @@ Handle<Object> WasmValueToValueObject(Isolate* isolate, WasmValue value) {
       return isolate->factory()->NewNumber(value.to<float>());
     case kWasmF64:
       return isolate->factory()->NewNumber(value.to<double>());
+    case kWasmAnyRef:
+      return value.to_anyref();
     default:
       UNIMPLEMENTED();
       return isolate->factory()->undefined_value();
@@ -359,7 +361,6 @@ class InterpreterHandle {
     Isolate* isolate = isolate_;
     Handle<WasmInstanceObject> instance(debug_info->wasm_instance(), isolate);
 
-    // TODO(clemensh): Add globals to the global scope.
     Handle<JSObject> global_scope_object =
         isolate_->factory()->NewJSObjectWithNullProto();
     if (instance->has_memory_object()) {
@@ -373,6 +374,32 @@ class InterpreterHandle {
                                                uint8_array, NONE)
           .Assert();
     }
+
+    DCHECK_EQ(1, interpreter()->GetThreadCount());
+    WasmInterpreter::Thread* thread = interpreter()->GetThread(0);
+
+    uint32_t global_count = thread->GetGlobalCount();
+    if (global_count > 0) {
+      Handle<JSObject> globals_obj =
+          isolate_->factory()->NewJSObjectWithNullProto();
+      Handle<String> globals_name =
+          isolate_->factory()->InternalizeOneByteString(
+              StaticCharVector("globals"));
+      JSObject::SetOwnPropertyIgnoreAttributes(global_scope_object,
+                                               globals_name, globals_obj, NONE)
+          .Assert();
+
+      for (uint32_t i = 0; i < global_count; ++i) {
+        const char* label = "global#%d";
+        Handle<String> name = PrintFToOneByteString<true>(isolate_, label, i);
+        WasmValue value = thread->GetGlobalValue(i);
+        Handle<Object> value_obj = WasmValueToValueObject(isolate_, value);
+        JSObject::SetOwnPropertyIgnoreAttributes(globals_obj, name, value_obj,
+                                                 NONE)
+            .Assert();
+      }
+    }
+
     return global_scope_object;
   }
 

src/wasm/wasm-interpreter.cc

@@ -1262,6 +1262,37 @@ class ThreadImpl {
     return WasmInterpreter::Thread::HANDLED;
   }
 
+  uint32_t GetGlobalCount() {
+    return static_cast<uint32_t>(module()->globals.size());
+  }
+
+  WasmValue GetGlobalValue(uint32_t index) {
+    const WasmGlobal* global = &module()->globals[index];
+    switch (global->type) {
+#define CASE_TYPE(wasm, ctype)                                         \
+  case kWasm##wasm: {                                                  \
+    byte* ptr = GetGlobalPtr(global);                                  \
+    return WasmValue(                                                  \
+        ReadLittleEndianValue<ctype>(reinterpret_cast<Address>(ptr))); \
+    break;                                                             \
+  }
+      WASM_CTYPES(CASE_TYPE)
+#undef CASE_TYPE
+      case kWasmAnyRef:
+      case kWasmAnyFunc:
+      case kWasmExceptRef: {
+        HandleScope handle_scope(isolate_);  // Avoid leaking handles.
+        Handle<FixedArray> global_buffer;    // The buffer of the global.
+        uint32_t global_index = 0;           // The index into the buffer.
+        GetGlobalBufferAndIndex(global, &global_buffer, &global_index);
+        Handle<Object> value(global_buffer->get(global_index), isolate_);
+        return WasmValue(handle_scope.CloseAndEscape(value));
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
  private:
   // Handle a thrown exception. Returns whether the exception was handled inside
   // the current activation. Unwinds the interpreted stack accordingly.
@@ -3055,31 +3086,8 @@ class ThreadImpl {
         case kExprGetGlobal: {
           GlobalIndexImmediate<Decoder::kNoValidate> imm(&decoder,
                                                          code->at(pc));
-          const WasmGlobal* global = &module()->globals[imm.index];
-          switch (global->type) {
-#define CASE_TYPE(wasm, ctype)                                          \
-  case kWasm##wasm: {                                                   \
-    byte* ptr = GetGlobalPtr(global);                                   \
-    Push(WasmValue(                                                     \
-        ReadLittleEndianValue<ctype>(reinterpret_cast<Address>(ptr)))); \
-    break;                                                              \
-  }
-            WASM_CTYPES(CASE_TYPE)
-#undef CASE_TYPE
-            case kWasmAnyRef:
-            case kWasmAnyFunc:
-            case kWasmExceptRef: {
-              HandleScope handle_scope(isolate_);  // Avoid leaking handles.
-              Handle<FixedArray> global_buffer;    // The buffer of the global.
-              uint32_t global_index = 0;           // The index into the buffer.
-              GetGlobalBufferAndIndex(global, &global_buffer, &global_index);
-              Handle<Object> value(global_buffer->get(global_index), isolate_);
-              Push(WasmValue(value));
-              break;
-            }
-            default:
-              UNREACHABLE();
-          }
+          HandleScope handle_scope(isolate_);
+          Push(GetGlobalValue(imm.index));
           len = 1 + imm.length;
           break;
         }
@@ -3821,6 +3829,12 @@ WasmValue WasmInterpreter::Thread::GetReturnValue(int index) {
 TrapReason WasmInterpreter::Thread::GetTrapReason() {
   return ToImpl(this)->GetTrapReason();
 }
+uint32_t WasmInterpreter::Thread::GetGlobalCount() {
+  return ToImpl(this)->GetGlobalCount();
+}
+WasmValue WasmInterpreter::Thread::GetGlobalValue(uint32_t index) {
+  return ToImpl(this)->GetGlobalValue(index);
+}
 bool WasmInterpreter::Thread::PossibleNondeterminism() {
   return ToImpl(this)->PossibleNondeterminism();
 }

src/wasm/wasm-interpreter.h

@@ -138,6 +138,9 @@ class V8_EXPORT_PRIVATE WasmInterpreter {
     WasmValue GetReturnValue(int index = 0);
     TrapReason GetTrapReason();
 
+    uint32_t GetGlobalCount();
+    WasmValue GetGlobalValue(uint32_t index);
+
     // Returns true if the thread executed an instruction which may produce
     // nondeterministic results, e.g. float div, float sqrt, and float mul,
     // where the sign bit of a NaN is nondeterministic.

test/inspector/debugger/wasm-anyref-global-expected.txt

@@ -0,0 +1,7 @@
+Test wasm scope information with anyref globals
+Waiting for wasm script to be parsed.
+Setting breakpoint in wasm.
+Running main.
+Paused in debugger.
+   globals: {"global#0": hello, world}
+Finished.

test/inspector/debugger/wasm-anyref-global.js

@@ -0,0 +1,83 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --experimental-wasm-anyref
+
+let {session, contextGroup, Protocol} =
+    InspectorTest.start('Test wasm scope information with anyref globals');
+
+(async function() {
+  try {
+    utils.load('test/mjsunit/wasm/wasm-module-builder.js');
+
+    let builder = new WasmModuleBuilder();
+    builder.addImportedGlobal('m', 'global', kWasmAnyRef, false);
+    builder.addFunction('func', kSig_v_v)
+        .addBody([
+          kExprGetGlobal, 0,  //
+          kExprDrop,          //
+        ])
+        .exportAs('main');
+    let moduleBytes = JSON.stringify(builder.toArray());
+
+    function test(moduleBytes) {
+      let module = new WebAssembly.Module((new Uint8Array(moduleBytes)).buffer);
+      let global = 'hello, world';
+      instance = new WebAssembly.Instance(module, {m: {global}});
+    }
+
+    Protocol.Debugger.enable();
+    Protocol.Runtime.evaluate({
+      expression: `
+      let instance;
+      ${test.toString()}
+      test(${moduleBytes});`
+    });
+
+    InspectorTest.log('Waiting for wasm script to be parsed.');
+    let scriptId;
+    while (true) {
+      let msg = await Protocol.Debugger.onceScriptParsed();
+      if (msg.params.url.startsWith('wasm://')) {
+        scriptId = msg.params.scriptId;
+        break;
+      }
+    }
+
+    InspectorTest.log('Setting breakpoint in wasm.');
+    await Protocol.Debugger.setBreakpoint(
+        {location: {scriptId, lineNumber: 2}});
+
+    InspectorTest.log('Running main.');
+    Protocol.Runtime.evaluate({expression: 'instance.exports.main()'});
+
+    let msg = await Protocol.Debugger.oncePaused();
+    let callFrames = msg.params.callFrames;
+    InspectorTest.log('Paused in debugger.');
+    let scopeChain = callFrames[0].scopeChain;
+    for (let scope of scopeChain) {
+      if (scope.type != 'global') continue;
+
+      let globalObjectProps = (await Protocol.Runtime.getProperties({
+                              'objectId': scope.object.objectId
+                            })).result.result;
+
+      for (let prop of globalObjectProps) {
+        let subProps = (await Protocol.Runtime.getProperties({
+                              objectId: prop.value.objectId
+                            })).result.result;
+        let values =
+            subProps.map((value) => `"${value.name}": ${value.value.value}`)
+                .join(', ');
+        InspectorTest.log(`   ${prop.name}: {${values}}`);
+      }
+    }
+
+    InspectorTest.log('Finished.');
+  } catch (exc) {
+    InspectorTest.log(`Failed with exception: ${exc}.`);
+  } finally {
+    InspectorTest.completeTest();
+  }
+})();

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

@@ -17,7 +17,7 @@ Paused:
 Scope:
 at func (2:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 4 (number), "local#1": 0 (number), "i64_local": 0 (number), "unicode☼f64": 0 (number)
    stack: 
@@ -33,7 +33,7 @@ Paused:
 Scope:
 at func (3:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 4 (number), "local#1": 0 (number), "i64_local": 0 (number), "unicode☼f64": 0 (number)
    stack: "0": 11 (number)
@@ -49,7 +49,7 @@ Paused:
 Scope:
 at func (4:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 0 (number), "i64_local": 0 (number), "unicode☼f64": 0 (number)
    stack: 
@@ -65,7 +65,7 @@ Paused:
 Scope:
 at func (5:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 0 (number), "i64_local": 0 (number), "unicode☼f64": 0 (number)
    stack: "0": 47 (number)
@@ -81,7 +81,7 @@ Paused:
 Scope:
 at func (6:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": 0 (number), "unicode☼f64": 0 (number)
    stack: 
@@ -97,7 +97,7 @@ Paused:
 Scope:
 at func (7:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": 0 (number), "unicode☼f64": 0 (number)
    stack: "0": 9223372036854775807 (string)
@@ -113,7 +113,7 @@ Paused:
 Scope:
 at func (8:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": 9223372036854775807 (string), "unicode☼f64": 0 (number)
    stack: 
@@ -129,7 +129,7 @@ Paused:
 Scope:
 at func (9:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": 9223372036854775807 (string), "unicode☼f64": 0 (number)
    stack: "0": -9223372036854775808 (string)
@@ -145,7 +145,7 @@ Paused:
 Scope:
 at func (10:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0 (number)
    stack: 
@@ -161,7 +161,7 @@ Paused:
 Scope:
 at func (11:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0 (number)
    stack: "0": 1 (number)
@@ -177,7 +177,7 @@ Paused:
 Scope:
 at func (12:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0 (number)
    stack: "0": 1 (number)
@@ -193,7 +193,7 @@ Paused:
 Scope:
 at func (13:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0 (number)
    stack: "0": 1 (number), "1": 7 (number)
@@ -209,7 +209,7 @@ Paused:
 Scope:
 at func (14:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0 (number)
    stack: "0": 1 (number), "1": 7 (number)
@@ -220,12 +220,12 @@ at (anonymous) (0:17):
 Paused:
   f64.div
   #set_local 3
-end
+  i32.const 15
 
 Scope:
 at func (15:2):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 0 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0 (number)
    stack: "0": 0.14285714285714285 (number)
@@ -235,13 +235,45 @@ at (anonymous) (0:17):
 
 Paused:
   set_local 3
+  #i32.const 15
+  set_global 0
+
+Scope:
+at func (16:2):
+ - scope (global):
+   globals: "global#0": 0 (number)
+ - scope (local):
+   locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0.14285714285714285 (number)
+   stack: 
+at (anonymous) (0:17):
+ - scope (global):
+   -- skipped globals
+
+Paused:
+  i32.const 15
+  #set_global 0
+end
+
+Scope:
+at func (17:2):
+ - scope (global):
+   globals: "global#0": 0 (number)
+ - scope (local):
+   locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0.14285714285714285 (number)
+   stack: "0": 15 (number)
+at (anonymous) (0:17):
+ - scope (global):
+   -- skipped globals
+
+Paused:
+  set_global 0
 #end
 
 
 Scope:
-at func (16:0):
+at func (18:0):
  - scope (global):
-   -- skipped globals
+   globals: "global#0": 15 (number)
  - scope (local):
    locals: "i32Arg": 11 (number), "local#1": 47 (number), "i64_local": -9223372036854775808 (string), "unicode☼f64": 0.14285714285714285 (number)
    stack: 

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

@@ -33,6 +33,7 @@ async function instantiateWasm() {
   utils.load('test/mjsunit/wasm/wasm-module-builder.js');
 
   var builder = new WasmModuleBuilder();
+  builder.addGlobal(kWasmI32, true);
 
   builder.addFunction('func', kSig_v_i)
       .addLocals(
@@ -51,7 +52,10 @@ async function instantiateWasm() {
         kExprSetLocal, 2,
         // Set local 3 to 1/7.
         kExprI32Const, 1, kExprF64UConvertI32, kExprI32Const, 7,
-        kExprF64UConvertI32, kExprF64Div, kExprSetLocal, 3
+        kExprF64UConvertI32, kExprF64Div, kExprSetLocal, 3,
+
+        // Set global 0 to 15
+        kExprI32Const, 15, kExprSetGlobal, 0,
       ])
       .exportAs('main');
 
@@ -129,13 +133,15 @@ async function dumpScopeProperties(message) {
 async function dumpScopeChainsOnPause(message) {
   InspectorTest.log(`Scope:`);
   for (var frame of message.params.callFrames) {
+    var isWasmFrame = /^wasm/.test(frame.url);
     var functionName = frame.functionName || '(anonymous)';
     var lineNumber = frame.location ? frame.location.lineNumber : frame.lineNumber;
     var columnNumber = frame.location ? frame.location.columnNumber : frame.columnNumber;
     InspectorTest.log(`at ${functionName} (${lineNumber}:${columnNumber}):`);
     for (var scope of frame.scopeChain) {
       InspectorTest.logObject(' - scope (' + scope.type + '):');
-      if (scope.type == 'global') {
+      if (!isWasmFrame && scope.type == 'global') {
+        // Skip global scope for non wasm-functions.
         InspectorTest.logObject('   -- skipped globals');
         continue;
       }