Reduce size of function restarter frame.

src/ia32/debug-ia32.cc

 // Copyright 2010 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 240 matching lines @@
 
 void Debug::GeneratePlainReturnLiveEdit(MacroAssembler* masm) {
   masm->ret(0);
 }
 
 
 // FrameDropper is a code replacement for a JavaScript frame with possibly
 // several frames above.
 // There is no calling conventions here, because it never actually gets called,
 // it only gets returned to.
 // Frame structure (conforms InternalFrame structure):

[Søren Thygesen Gjesse, 2010/08/12 11:30:48]

Remove "conforms InternalFrame structure"?

[Peter Rybin, 2013/06/26 19:39:23]

I do hope it conforms. I need any stack analyzer (debugger and Top::PrintStack)
to work smoothly with it.

-//   -- JSFunction
 //   -- code
 //   -- SMI maker
-//   -- context
+//   -- function (slot is called "context")
 //   -- frame base
 void Debug::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
   ExternalReference restarter_frame_function_slot =
       ExternalReference(Debug_Address::RestarterFrameFunctionPointer());
   __ mov(Operand::StaticVariable(restarter_frame_function_slot), Immediate(0));
 
   // We do not know our frame height, but set esp based on ebp.
-  __ lea(esp, Operand(ebp, -4 * kPointerSize));
+  __ lea(esp, Operand(ebp, -1 * kPointerSize));
 
-  __ pop(edi);  // function
+  __ pop(edi);  // Function.
+  __ pop(ebp);
 
-  // Skip code self-reference and marker.
-  __ add(Operand(esp), Immediate(2 * kPointerSize));
-
-  __ pop(esi);  // Context.
-  __ pop(ebp);
+  // Load context from the function.
+  __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
 
   // Get function code.
   __ mov(edx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
   __ mov(edx, FieldOperand(edx, SharedFunctionInfo::kCodeOffset));
   __ lea(edx, FieldOperand(edx, Code::kHeaderSize));
 
   // Re-run JSFunction, edi is function, esi is context.
   __ jmp(Operand(edx));
 }
 
 #undef __
 
 
 // TODO(LiveEdit): consider making it platform-independent.
 // TODO(LiveEdit): use more named constants instead of numbers.
 Object** Debug::SetUpFrameDropperFrame(StackFrame* bottom_js_frame,
                                        Handle<Code> code) {
   ASSERT(bottom_js_frame->is_java_script());
 
   Address fp = bottom_js_frame->fp();
-  Memory::Object_at(fp - 4 * kPointerSize) =
-      Memory::Object_at(fp - 2 * kPointerSize);  // Move edi (function).
+
+  // Move function pointer into slot that is called referenced
+  // as StandardFrame::context()
+  Memory::Object_at(fp - 1 * kPointerSize) =
+      Memory::Object_at(fp - 2 * kPointerSize);
 
   Memory::Object_at(fp - 3 * kPointerSize) = *code;
   Memory::Object_at(fp - 2 * kPointerSize) = Smi::FromInt(StackFrame::INTERNAL);
 
-  return reinterpret_cast<Object**>(&Memory::Object_at(fp - 4 * kPointerSize));
+  return reinterpret_cast<Object**>(&Memory::Object_at(fp - 1 * kPointerSize));
 }
 
-const int Debug::kFrameDropperFrameSize = 5;
+const int Debug::kFrameDropperFrameSize = 4;
 
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32