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From: "Kris Warkentin" <kewarken@qnx.com>
To: <Richard.Earnshaw@arm.com>
Cc: <gdb@sources.redhat.com>
References: <200211201618.gAKGITW18622@pc960.cambridge.arm.com>
Subject: Re: ARM stack alignment on hand called functions 
Date: Wed, 20 Nov 2002 08:26:00 -0000
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The problem arises only with functions which return structures whose size is
not evenly divisible by 4.  Below is what I did to solve it.

Index: arm-tdep.c
===================================================================
RCS file: /product/tools/gdb/gdb/arm-tdep.c,v
retrieving revision 1.9
retrieving revision 1.10
diff -c -r1.9 -r1.10
*** arm-tdep.c  20 Sep 2002 17:11:31 -0000      1.9
--- arm-tdep.c  19 Nov 2002 18:33:37 -0000      1.10
***************
*** 1480,1485 ****
--- 1480,1486 ----
        }
      }

+   sp = (sp + 3) & ~3;
    /* Return adjusted stack pointer.  */
    return sp;
  }

The code in valops.c : hand_function_call() that was causing the problem was
this:

  /* Reserve space for the return structure to be written on the
     stack, if necessary */
  if (struct_return)
    {
      int len = TYPE_LENGTH (value_type);
      if (STACK_ALIGN_P ())
 /* MVS 11/22/96: I think at least some of this stack_align
    code is really broken.  Better to let PUSH_ARGUMENTS adjust
    the stack in a target-defined manner.  */
 len = STACK_ALIGN (len);
      if (INNER_THAN (1, 2))
 {
   /* stack grows downward */
   sp -= len;
   struct_addr = sp;
 }

So what I did was to make sure that arm_push_arguments would always return
an aligned stack pointer.  I think we can safely agree that
arm_push_arguments should NEVER return an unaligned stack pointer right?

cheers,

Kris