Reimplement stack manipulations for LiveEdit

src/ia32/debug-ia32.cc

Index: src/ia32/debug-ia32.cc
diff --git a/src/ia32/debug-ia32.cc b/src/ia32/debug-ia32.cc
index 9b558bd90b5af27d8a97cbe085199916fad486a1..1dce441d8c618ee4e865094a3efc1da0765d2b40 100644
--- a/src/ia32/debug-ia32.cc
+++ b/src/ia32/debug-ia32.cc
@@ -254,25 +254,30 @@ void Debug::GeneratePlainReturnLiveEdit(MacroAssembler* masm) {
 }
 
 
-// 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):
-//   -- JSFunction
-//   -- code
-//   -- SMI maker
-//   -- context
-//   -- frame base
-void Debug::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
-  // We do not know our frame height, but set esp based on ebp.
-  __ lea(esp, Operand(ebp, -4 * kPointerSize));
+// See documentation in debug.h.
+void Debug::GenerateRestarterPatchLiveEdit(MacroAssembler* masm) {
+#ifdef DEBUG
+  int offset1 = masm->pc_offset();
+  __ nop();
+  int offset2 = masm->pc_offset();
+  ASSERT_EQ(offset2 - offset1, kFrameRestarterEntryOffset);
+#else
+  __ nop();
+#endif
 
-  __ pop(edi);  // function
+  ExternalReference restarted_frame_id =
+      ExternalReference(Debug_Address::RestartedFrameFp());
+
+  // Reset restarted_frame_id variable. It means that frame has
+  // actually restarted and has become a regular frame.
+  __ mov(Operand::StaticVariable(restarted_frame_id), Immediate(0));
 
-  // Skip code self-reference and marker.
-  __ add(Operand(esp), Immediate(2 * kPointerSize));
+  // Whatever the height the frame was, reset the stack pointer
+  // according to the base pointer.
+  __ lea(esp, Operand(ebp, -2 * kPointerSize));
 
+  // Read back registers value.
+  __ pop(edi);  // function
   __ pop(esi);  // Context.
   __ pop(ebp);
 
@@ -288,18 +293,9 @@ void Debug::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
 #undef __
 
 
-void 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).
+const int Debug::kFrameRestarterEntryOffset = 1;
+const int Debug::kRestartedFrameHeight = 3;
 
-  Memory::Object_at(fp - 3 * kPointerSize) = *code;
-  Memory::Object_at(fp - 2 * kPointerSize) = Smi::FromInt(StackFrame::INTERNAL);
-}
-const int Debug::kFrameDropperFrameSize = 5;
 
 
 #endif  // ENABLE_DEBUGGER_SUPPORT