Hello Luis, 

From: Luis Machado <luisgpm at linux dot vnet dot ibm dot com>
Subject: Re: [patch] "single step" atomic instruction sequences as a whole.
Date: Wed, 28 Feb 2007 13:09:00 -0300

> Also, i haven't been able to reproduce the issue related at this post:
> (http://sourceware.org/ml/gdb-patches/2006-09/msg00060.html)

I think one of the reasons why is that you didn't build the target as
Emre did; 'atomic_dec' seemed to be inline expanded in that target.  
I could get it with -O3 option of gcc-4.1.0 on my machine running FC5.  

And I could reproduce the issue with your patch by setting a
breakpoint at where 'printf' preceded by 'atomic_dec' is before
running the target.  

But the fix is fairly easy: 
===================================================================
diff -u rs6000-tdep.c.old rs6000-tdep.c
--- rs6000-tdep.c.old   2007-03-02 19:33:12.000000000 +0900
+++ rs6000-tdep.c       2007-03-02 19:34:07.000000000 +0900
@@ -764,7 +764,7 @@
   if (last_break && breaks[1] == breaks[0])
     last_break = 0;

-  for (i= 0; i < last_break; ++i)
+  for (i= 0; i <= last_break; ++i)
     insert_single_step_breakpoint (breaks[i]);

   printf_unfiltered (_("Stepping over an atomic sequence of instructions beginning at %s\n"),
diff -u ppc-linux-tdep.c.old ppc-linux-tdep.c
--- ppc-linux-tdep.c.old        2007-03-02 19:33:33.000000000 +0900
+++ ppc-linux-tdep.c    2007-03-02 19:33:54.000000000 +0900
@@ -996,7 +996,7 @@
       if (last_break && breaks[1] == breaks[0])
        last_break = 0;

-      for (i= 0; i < last_break; ++i)
+      for (i= 0; i <= last_break; ++i)
        insert_single_step_breakpoint (breaks[i]);

       printf_unfiltered (_("Stepping over an atomic sequence of instructions beginning at %s\n"),
===================================================================

Another thing I want to notice you about Paul's patch is that the
patch for ppc-linux-tdep.c is not needed at all: they do exactly the
same and RS6000 is the superset of PowerPC.  
And I think that the load or store instructions which deal with
doublewords can be appeared as a part of the atomic sequence; Paul's
patch doesn't check it.  But maybe not needed for now.  

BTW, I had another mistake on my patch send last time...
Please replace the attached one.  

My best regards, 
-- 
Emi SUZUKI