Subject: Re: BUG: GCC-4.4.x changes the function frame on some functions
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: Andrew Haley <aph@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
       "H. Peter Anvin" <hpa@zytor.com>, LKML <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Heiko Carstens <heiko.carstens@de.ibm.com>, feng.tang@intel.com,
       Fr??d??ric Weisbecker <fweisbec@gmail.com>,
       Peter Zijlstra <peterz@infradead.org>, jakub@redhat.com,
       gcc@gcc.gnu.org
In-Reply-To: <4B058C76.9090609@redhat.com>
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Organization: Kihon Technologies Inc.
Date: Thu, 19 Nov 2009 13:33:05 -0500
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On Thu, 2009-11-19 at 18:20 +0000, Andrew Haley wrote:

> OK, I found it.  There is a struct defined as
> 
> struct entry {
>  ...
> } __attribute__((__aligned__((1 << (4)))));
> 
> and then in timer_stats_update_stats you have a local variable of type
> struct entry:
> 
> void timer_stats_update_stats()
> {
>  spinlock_t *lock;
>  struct entry *entry, input;
> 
> So, gcc has to 16-align the stack pointer to satisfy the alignment
> for struct entry.

It has to align the entire stack? Why not just the variable within the
stack?

-- Steve


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