[refactor] Introduce dedicated WasmScript::SetBreakPointOnEntry().

Previously we had passed kOnEntryBreakpointPosition as a marker through
the regular SetBreakPointForScript() logic and handled that specially in
WasmScript, however this instrumentation breakpoint is special and gets
in the way of returning more information about a regular breakpoint in
case of crbug.com/700516, so I decided to just isolate that into it's
own method, especially since the only user already special-cases Wasm
anyways.

Bug: chromium:1162229, chromium:700516
Change-Id: Ie7966c1701365a4b03710d6dc32cc8278577ee3a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3026711
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75724}

src/debug/debug-interface.cc

@@ -545,9 +545,8 @@ bool Script::SetBreakpointOnScriptEntry(BreakpointId* id) const {
   i::Isolate* isolate = script->GetIsolate();
 #if V8_ENABLE_WEBASSEMBLY
   if (script->type() == i::Script::TYPE_WASM) {
-    int position = i::WasmScript::kOnEntryBreakpointPosition;
-    return isolate->debug()->SetBreakPointForScript(
-        script, isolate->factory()->empty_string(), &position, id);
+    isolate->debug()->SetOnEntryBreakpointForWasmScript(script, id);
+    return true;
   }
 #endif  // V8_ENABLE_WEBASSEMBLY
   i::SharedFunctionInfo::ScriptIterator it(isolate, *script);

src/debug/debug.cc

@@ -805,6 +805,16 @@ void Debug::RemoveBreakpoint(int id) {
 }
 
 #if V8_ENABLE_WEBASSEMBLY
+void Debug::SetOnEntryBreakpointForWasmScript(Handle<Script> script, int* id) {
+  RCS_SCOPE(isolate_, RuntimeCallCounterId::kDebugger);
+  DCHECK_EQ(Script::TYPE_WASM, script->type());
+  *id = ++thread_local_.last_breakpoint_id_;
+  Handle<BreakPoint> break_point = isolate_->factory()->NewBreakPoint(
+      *id, isolate_->factory()->empty_string());
+  RecordWasmScriptWithBreakpoints(script);
+  WasmScript::SetBreakPointOnEntry(script, break_point);
+}
+
 void Debug::RemoveBreakpointForWasmScript(Handle<Script> script, int id) {
   RCS_SCOPE(isolate_, RuntimeCallCounterId::kDebugger);
   if (script->type() == Script::TYPE_WASM) {

src/debug/debug.h

@@ -252,6 +252,7 @@ class V8_EXPORT_PRIVATE Debug {
                                 Handle<String> condition, int* id);
   void RemoveBreakpoint(int id);
 #if V8_ENABLE_WEBASSEMBLY
+  void SetOnEntryBreakpointForWasmScript(Handle<Script> script, int* id);
   void RemoveBreakpointForWasmScript(Handle<Script> script, int id);
 
   void RecordWasmScriptWithBreakpoints(Handle<Script> script);

src/wasm/wasm-debug.cc

@@ -902,21 +902,7 @@ int FindNextBreakablePosition(wasm::NativeModule* native_module, int func_index,
 // static
 bool WasmScript::SetBreakPoint(Handle<Script> script, int* position,
                                Handle<BreakPoint> break_point) {
-  // Special handling for on-entry breakpoints.
-  if (*position == kOnEntryBreakpointPosition) {
-    AddBreakpointToInfo(script, *position, break_point);
-    script->set_break_on_entry(true);
-
-    // Update the "break_on_entry" flag on all live instances.
-    i::WeakArrayList weak_instance_list = script->wasm_weak_instance_list();
-    for (int i = 0; i < weak_instance_list.length(); ++i) {
-      if (weak_instance_list.Get(i)->IsCleared()) continue;
-      i::WasmInstanceObject instance = i::WasmInstanceObject::cast(
-          weak_instance_list.Get(i)->GetHeapObject());
-      instance.set_break_on_entry(true);
-    }
-    return true;
-  }
+  DCHECK_NE(kOnEntryBreakpointPosition, *position);
 
   // Find the function for this breakpoint.
   const wasm::WasmModule* module = script->wasm_native_module()->module();
@@ -934,6 +920,23 @@ bool WasmScript::SetBreakPoint(Handle<Script> script, int* position,
                                               breakable_offset, break_point);
 }
 
+// static
+void WasmScript::SetBreakPointOnEntry(Handle<Script> script,
+                                      Handle<BreakPoint> break_point) {
+  // Special handling for on-entry breakpoints.
+  AddBreakpointToInfo(script, kOnEntryBreakpointPosition, break_point);
+  script->set_break_on_entry(true);
+
+  // Update the "break_on_entry" flag on all live instances.
+  i::WeakArrayList weak_instance_list = script->wasm_weak_instance_list();
+  for (int i = 0; i < weak_instance_list.length(); ++i) {
+    if (weak_instance_list.Get(i)->IsCleared()) continue;
+    i::WasmInstanceObject instance =
+        i::WasmInstanceObject::cast(weak_instance_list.Get(i)->GetHeapObject());
+    instance.set_break_on_entry(true);
+  }
+}
+
 // static
 bool WasmScript::SetBreakPointOnFirstBreakableForFunction(
     Handle<Script> script, int func_index, Handle<BreakPoint> break_point) {

src/wasm/wasm-objects.h

@@ -754,6 +754,12 @@ class WasmScript : public AllStatic {
   V8_EXPORT_PRIVATE static bool SetBreakPoint(Handle<Script>, int* position,
                                               Handle<BreakPoint> break_point);
 
+  // Set an "on entry" breakpoint (a.k.a. instrumentation breakpoint) inside
+  // the given module. This will affect all live and future instances of the
+  // module.
+  V8_EXPORT_PRIVATE static void SetBreakPointOnEntry(
+      Handle<Script>, Handle<BreakPoint> break_point);
+
   // Set a breakpoint on first breakable position of the given function index
   // inside the given module. This will affect all live and future instances of
   // the module.