Use a reserved stack local variable to store the Code object so that it can be looked up easily whe…

vm/assembler_macros_ia32.h

Index: vm/assembler_macros_ia32.h
===================================================================
--- vm/assembler_macros_ia32.h	(revision 7576)
+++ vm/assembler_macros_ia32.h	(working copy)
@@ -33,6 +33,49 @@
                           Register class_reg,
                           Label* failure,
                           Register instance_reg);
+
+  // Set up a dart frame on entry with a frame pointer and PC information to
+  // enable easy access to the RawInstruction object of code corresponding
+  // to this frame.
+  // The dart frame layout is as follows:
+  //   ....
+  //   ret PC
+  //   saved EBP     <=== EBP
+  //   pc (used to derive the RawInstruction Object of the dart code)
+  //   locals space  <=== ESP
+  //   .....
+  // This code sets this up with the sequence:
+  //   pushl ebp
+  //   movl ebp, esp
+  //   call L
+  //   L: <code to adjust saved pc if there is any intrinsification code>
+  //   .....
+  static void EnterDartFrame(Assembler* assembler, intptr_t frame_space);

[srdjan, 2012/05/14 20:00:17]

what is 'frame_space' ? frame_size? From EBP-1 to ESP?

[siva, 2012/05/15 23:52:39]

Sorry that should be frame_size not frame_space, i.e number
of slots on the frame.

On 2012/05/14 20:00:17, srdjan wrote:

+
+  // Set up a stub frame so that the stack traversal code can easily identify
+  // a stub frame.
+  // The stub frame layout is as follows:
+  //   ....
+  //   ret PC
+  //   saved EBP
+  //   0 (used to indicate frame is a stub frame)
+  //   .....
+  // This code sets this up with the sequence:
+  //   pushl ebp
+  //   movl ebp, esp
+  //   pushl immediate(0)
+  //   .....
+  static void EnterStubFrame(Assembler* assembler);
+
+  // Instruction pattern from entrypoint is used in dart frame prologs
+  // to set up the frame and save a PC which can be used to figure out the
+  // RawInstruction object corresponding to the code running in the frame.
+  // entrypoint:
+  //   pushl ebp          (size is 1 byte)
+  //   movl ebp, esp      (size is 2 bytes)
+  //   call L             (size is 5 bytes)

[srdjan, 2012/05/14 20:00:17]

Can we have a Call near added to the assembler (3 instead of 5 bytes) .. maybe
in next CL.

[siva, 2012/05/15 23:52:39]

I have added an issue (3069) for this as I did not want to clutter this CL too
much.

On 2012/05/14 20:00:17, srdjan wrote:

+  //   L:
+  static const intptr_t kOffsetOfSavedPCfromEntrypoint = 8;
 };
 
 }  // namespace dart.