Deoptimizer support for hydrogen stubs that accept a variable number of arguments.

src/frames.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
@@ skipping 1294 matching lines @@
 }
 
 
 Address StubFailureTrampolineFrame::GetCallerStackPointer() const {
   return fp() + StandardFrameConstants::kCallerSPOffset;
 }
 
 
 Code* StubFailureTrampolineFrame::unchecked_code() const {
   int i = 0;
-  for (; i <= StubFailureTrampolineStub::kMaxExtraExpressionStackCount; ++i) {
+  for (; i <= 1; ++i) {
     Code* trampoline;
-    StubFailureTrampolineStub(i).FindCodeInCache(&trampoline, isolate());
+    bool acting_as_js_function = (i == 0) ? false : true;

[danno, 2013/03/20 21:07:33]

Since there is only true/false, I think removing the loop is better and just
testing the two versions linearly makes more sense.

[mvstanton, 2013/03/21 11:47:35]

Thanks, I thought this was awkward too, whew.

+    StubFailureTrampolineStub(acting_as_js_function).FindCodeInCache(
+        &trampoline, isolate());
     ASSERT(trampoline != NULL);
     Address current_pc = pc();
     Address code_start = trampoline->instruction_start();
     Address code_end = code_start + trampoline->instruction_size();
     if (code_start <= current_pc && current_pc < code_end) {
       return trampoline;
     }
   }
   UNREACHABLE();
   return NULL;
@@ skipping 165 matching lines @@
   ZoneList<StackFrame*> list(10, zone);
   for (StackFrameIterator it(isolate); !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame(), zone);
     list.Add(frame, zone);
   }
   return list.ToVector();
 }
 
 
 } }  // namespace v8::internal