linux-kernel - Re: BUG: GCC-4.4.x changes the function frame on some functions

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Message-ID: <84fc9c000911190757w42186dav1d3b0141bb6cf79b@mail.gmail.com>
Date:	Thu, 19 Nov 2009 16:57:53 +0100
From:	Richard Guenther <richard.guenther@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andrew Haley <aph@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	feng.tang@...el.com, "Fr??d??ric Weisbecker" <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>, jakub@...hat.com,
	gcc@....gnu.org, "H.J. Lu" <hjl.tools@...il.com>
Subject: Re: BUG: GCC-4.4.x changes the function frame on some functions

On Thu, Nov 19, 2009 at 4:54 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 11/19/2009 07:44 AM, Andrew Haley wrote:
>>
>> We're aligning the stack properly, as per the ABI requirements.  Can't
>> you just fix the tracer?
>>
>
> "Per the ABI requirements?"  We're talking 32 bits, here.

Hm, even with

void bar (int *);
void foo (void)
{
  int x;
  bar (&x);
}

gcc -S -O2 -m32 -mincoming-stack-boundary=2 t.c

we re-align the stack.  That looks indeed bogus.

HJ, you invented all this code, what's the reason for the above?

Richard.
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