Re: [commit] mep-tdep.c: prologue analyzer update

Kevin Buettner
2007-07-14T00:17:57Z

> The comment might want to mention why we should only do this for
> forward branches. :)

Thanks for the feedback! I've updated the comment as follows...

* mep-tdep.c (mep_analyze_prologue): Update comment for BRA
instruction case.

Index: mep-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mep-tdep.c,v
retrieving revision 1.6
diff -u -p -r1.6 mep-tdep.c
--- mep-tdep.c 13 Jul 2007 00:00:15 -0000 1.6
+++ mep-tdep.c 14 Jul 2007 00:14:16 -0000
@@ -1812,13 +1812,24 @@ mep_analyze_prologue (CORE_ADDR start_pc
}
else if (IS_BRA (insn) && BRA_DISP (insn) > 0)
{
- /* When a loop appears as the first statement as a function
+ /* When a loop appears as the first statement of a function
body, gcc 4.x will use a BRA instruction to branch to the
loop condition checking code. This BRA instruction is
marked as part of the prologue. We therefore set next_pc
to this branch target and also stop the prologue scan.
The instructions at and beyond the branch target should
- no longer be associated with the prologue. */
+ no longer be associated with the prologue.
+
+ Note that we only consider forward branches here. We
+ presume that a forward branch is being used to skip over
+ a loop body.
+
+ A backwards branch is covered by the default case below.
+ If we were to encounter a backwards branch, that would
+ most likely mean that we've scanned through a loop body.
+ We definitely want to stop the prologue scan when this
+ happens and that is precisely what is done by the default
+ case below. */
next_pc = pc + BRA_DISP (insn);
after_last_frame_setup_insn = next_pc;
break;