Re: [PATCH 2/2] jump label: disable due to compiler bug

From: Richard Henderson <rth@redhat.com>
To: David Daney <ddaney@caviumnetworks.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Ingo Molnar <mingo@elte.hu>, Jason Baron <jbaron@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	tglx@linutronix.de, andi@firstfloor.org, roland@redhat.com,
	masami.hiramatsu.pt@hitachi.com, fweisbec@gmail.com,
	avi@redhat.com, davem@davemloft.net, vgoyal@redhat.com,
	sam@ravnborg.org, tony@bakeyournoodle.com, dsd@laptop.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] jump label: disable due to compiler bug
Date: Fri, 29 Oct 2010 11:13:52 -0700	[thread overview]
Message-ID: <4CCB0EE0.4000401@redhat.com> (raw)
In-Reply-To: <4CCB08EB.8070004@caviumnetworks.com>

On 10/29/2010 10:48 AM, David Daney wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46226
> 
> Perhaps it could be integrated with the current checks for the presence of 'asm goto'

If you're looking for a cross-compile-able test, you can strip the
testcase down to 

extern void abort(void);
void g(int x, ...);
void f(int x)
{
  if (x == 0)
    g(0);
  g(1, 2, 3, 4, 5, 6, 7);
  asm goto ("XYZZY" : : : : label);
  abort ();
 label:
  return;
}

and use perl to notice the adjustment to esp before or after XYZZY.
It should be fairly obvious looking at the assembly before and after
the patch.

I don't know what sort of embedded processors supported by linux
actually use ACCUMULATE_OUTGOING_ARGS.  Almost all ports don't, so
I'd be pretty comfortable making this a 32-bit x86 only test, and
let other targets just check that the test compiles.

r~