Add a new API V8::SetJitCodeEventHandler to push code name and location to users such as profilers.

src/code-events.cc

+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "v8.h"
+
+#include "code-events.h"
+
+namespace v8 {
+namespace internal {
+
+static const char* CodeKindToString(Code::Kind kind) {
+  switch (kind) {
+#define DEF_CASE(name) case Code::name: return #name;
+    CODE_KIND_LIST(DEF_CASE)
+#undef DEF_CASE
+    default:
+      return "*UNKNOWN*";
+  }
+}
+
+JitCodeEventHandler CodeEvents::event_handler_ = NULL;
+
+
+void CodeEvents::AddCode(const char* name,
+                         Code* code,
+                         Script* script,
+                         CompilationInfo* info) {
+  JitCodeEvent event = { JitCodeEvent::CODE_ADDED,
+                         code->instruction_start(),
+                         code->instruction_size(),
+                         { NULL } };
+  event.name = name;
+  event_handler_(&event);
+}
+
+
+void CodeEvents::AddCode(Handle<String> name,
+                         Handle<Script> script,
+                         Handle<Code> code,
+                         CompilationInfo* info) {
+  if (!name.is_null()) {
+    SmartArrayPointer<char> name_cstring = name->ToCString(DISALLOW_NULLS);

[mnaganov (inactive), 2012/07/30 11:43:36]

Are you sure this works correctly? SmartArrayPointer is a scoped pointer, it
will delete its contents automatically. You should call Detach to unmanage the
pointer. But after that I'm not actually seeing any code that deletes the
contents of the string.

I think what you need is to add deletion of string contents after calling the
handler (if it wasn't a static string), and specify this behavior in the
documentation.

[mnaganov (inactive), 2012/07/30 13:33:16]

I'm sorry, I haven't realized you are calling the handler inside this code
block.

So the only point here is to specify in the documentation the lifetime of the
string.

[Sigurður Ásgeirsson, 2012/07/30 13:54:43]

I lifted this code pretty much verbatim from GDBJIT, and hadn't considered that
it might be wrong. Thanks for the extra eyeballs!
I've also looked at the StringBuilder/EmbeddedVector code below - and it looks
like it's also correctly discarding the temps on exit.

+    AddCode(*name_cstring, *code, *script, info);
+  } else {
+    AddCode("", *code, *script, info);
+  }
+}
+
+
+void CodeEvents::AddCode(String* name, Code* code) {
+  AddCode(name != NULL ? *name->ToCString(DISALLOW_NULLS) : NULL, code);
+}
+
+
+void CodeEvents::AddCode(const char* name, Code* code) {
+  EmbeddedVector<char, 256> buffer;
+  StringBuilder builder(buffer.start(), buffer.length());
+
+  builder.AddString(CodeKindToString(code->kind()));
+  if ((name != NULL) && (*name != '\0')) {
+    builder.AddString(": ");
+    builder.AddString(name);
+  } else {
+    builder.AddFormatted(": code object %p", static_cast<void*>(code));
+  }
+
+  AddCode(builder.Finalize(), code, NULL, NULL);
+}
+
+
+void CodeEvents::AddCode(Code* code) {
+  AddCode("", code);
+}
+
+void CodeEvents::MoveCode(Address src, Address dst) {
+  Code* src_code = Code::cast(HeapObject::FromAddress(src));
+
+  JitCodeEvent event = { JitCodeEvent::CODE_MOVED,
+                         src_code->instruction_start(),
+                         src_code->instruction_size(),
+                         { NULL } };
+
+  // Calculate the header size.
+  const size_t header_size =
+      src_code->instruction_start() - reinterpret_cast<byte*>(src_code);
+
+  event.new_code_start = dst + header_size;
+
+  event_handler_(&event);
+}
+
+
+void CodeEvents::RemoveCode(Code* code) {
+  JitCodeEvent event = { JitCodeEvent::CODE_REMOVED,
+                         code->instruction_start(),
+                         code->instruction_size(),
+                         { NULL } };
+
+  event_handler_(&event);
+}
+
+
+} }  // namespace v8::internal