diff mbox series

Update x86: Call ix86_access_stack_p only for larger alignment

Message ID CAMe9rOrzTaLwECORQNLGTN=EG+9OHP_x3RKz5vjRL4iNws=m+g@mail.gmail.com
State New
Headers
Series Update x86: Call ix86_access_stack_p only for larger alignment |

Commit Message

H.J. Lu April 7, 2026, 10:15 a.m. UTC 
  commit f511bf93f947199a9f9099fee87b7052e5515fb9
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Sun Mar 29 14:30:28 2026 -0700

    x86: Call ix86_access_stack_p only for larger alignment

incorrectly uses GET_MODE_ALIGNMENT as memory alignment since memory
alignment can be different from mode alignment as in

(set (reg:OI 20 xmm0 [orig:112 s ] [112])
     (mem/c:OI (plus:DI (reg/f:DI 7 sp)
            (const_int -32 [0xffffffffffffffe0])) [3 s+0 S32 A128]))

MEM_ALIGN should be used instead.

* config/i386/i386.cc (ix86_need_alignment_p_1): Replace
GET_MODE_ALIGNMENT with MEM_ALIGN.

Comments

Richard Biener April 7, 2026, 10:57 a.m. UTC | #1 
On Tue, 7 Apr 2026, H.J. Lu wrote:

> commit f511bf93f947199a9f9099fee87b7052e5515fb9
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date:   Sun Mar 29 14:30:28 2026 -0700
> 
>     x86: Call ix86_access_stack_p only for larger alignment
> 
> incorrectly uses GET_MODE_ALIGNMENT as memory alignment since memory
> alignment can be different from mode alignment as in
> 
> (set (reg:OI 20 xmm0 [orig:112 s ] [112])
>      (mem/c:OI (plus:DI (reg/f:DI 7 sp)
>             (const_int -32 [0xffffffffffffffe0])) [3 s+0 S32 A128]))
> 
> MEM_ALIGN should be used instead.

LGTM if you add the PR reference and the testcase (I assume the
other patch had both).

Thanks,
Richard.

> * config/i386/i386.cc (ix86_need_alignment_p_1): Replace
> GET_MODE_ALIGNMENT with MEM_ALIGN.
> 
> 
>
H.J. Lu April 7, 2026, 11:27 a.m. UTC | #2 
On Tue, Apr 7, 2026 at 6:57 PM Richard Biener <rguenther@suse.de> wrote:
>
> On Tue, 7 Apr 2026, H.J. Lu wrote:
>
> > commit f511bf93f947199a9f9099fee87b7052e5515fb9
> > Author: H.J. Lu <hjl.tools@gmail.com>
> > Date:   Sun Mar 29 14:30:28 2026 -0700
> >
> >     x86: Call ix86_access_stack_p only for larger alignment
> >
> > incorrectly uses GET_MODE_ALIGNMENT as memory alignment since memory
> > alignment can be different from mode alignment as in
> >
> > (set (reg:OI 20 xmm0 [orig:112 s ] [112])
> >      (mem/c:OI (plus:DI (reg/f:DI 7 sp)
> >             (const_int -32 [0xffffffffffffffe0])) [3 s+0 S32 A128]))
> >
> > MEM_ALIGN should be used instead.
>
> LGTM if you add the PR reference and the testcase (I assume the
> other patch had both).

But this alone doesn't fix PR target/124759 and I couldn't find a testcase
which makes a difference.

> Thanks,
> Richard.
>
> > * config/i386/i386.cc (ix86_need_alignment_p_1): Replace
> > GET_MODE_ALIGNMENT with MEM_ALIGN.
> >
> >
> >
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
Richard Biener April 7, 2026, 12:03 p.m. UTC | #3 
On Tue, 7 Apr 2026, H.J. Lu wrote:

> On Tue, Apr 7, 2026 at 6:57 PM Richard Biener <rguenther@suse.de> wrote:
> >
> > On Tue, 7 Apr 2026, H.J. Lu wrote:
> >
> > > commit f511bf93f947199a9f9099fee87b7052e5515fb9
> > > Author: H.J. Lu <hjl.tools@gmail.com>
> > > Date:   Sun Mar 29 14:30:28 2026 -0700
> > >
> > >     x86: Call ix86_access_stack_p only for larger alignment
> > >
> > > incorrectly uses GET_MODE_ALIGNMENT as memory alignment since memory
> > > alignment can be different from mode alignment as in
> > >
> > > (set (reg:OI 20 xmm0 [orig:112 s ] [112])
> > >      (mem/c:OI (plus:DI (reg/f:DI 7 sp)
> > >             (const_int -32 [0xffffffffffffffe0])) [3 s+0 S32 A128]))
> > >
> > > MEM_ALIGN should be used instead.
> >
> > LGTM if you add the PR reference and the testcase (I assume the
> > other patch had both).
> 
> But this alone doesn't fix PR target/124759 and I couldn't find a testcase
> which makes a difference.

Ah, I see.  Still OK then.

Richard.

> > Thanks,
> > Richard.
> >
> > > * config/i386/i386.cc (ix86_need_alignment_p_1): Replace
> > > GET_MODE_ALIGNMENT with MEM_ALIGN.
> > >
> > >
> > >
> >
> > --
> > Richard Biener <rguenther@suse.de>
> > SUSE Software Solutions Germany GmbH,
> > Frankenstrasse 146, 90461 Nuernberg, Germany;
> > GF: Jochen Jaser, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
> 
> 
> 
>
diff mbox series

Patch

From ab0ab385d5feffc62e9b25fda22279f5f1b71748 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 7 Apr 2026 18:12:27 +0800
Subject: [PATCH] Update x86: Call ix86_access_stack_p only for larger
 alignment

commit f511bf93f947199a9f9099fee87b7052e5515fb9
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Sun Mar 29 14:30:28 2026 -0700

    x86: Call ix86_access_stack_p only for larger alignment

incorrectly uses GET_MODE_ALIGNMENT as memory alignment since memory
alignment can be different from mode alignment as in

(set (reg:OI 20 xmm0 [orig:112 s ] [112])
     (mem/c:OI (plus:DI (reg/f:DI 7 sp)
            (const_int -32 [0xffffffffffffffe0])) [3 s+0 S32 A128]))

MEM_ALIGN should be used instead.

	* config/i386/i386.cc (ix86_need_alignment_p_1): Replace
	GET_MODE_ALIGNMENT with MEM_ALIGN.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
 gcc/config/i386/i386.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 39136ce5042..f4d0f623943 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -8789,7 +8789,7 @@  ix86_need_alignment_p_1 (rtx set, unsigned int alignment)
   rtx dest = SET_DEST (set);
 
   if (MEM_P (dest))
-    return GET_MODE_ALIGNMENT (GET_MODE (dest)) > alignment;
+    return MEM_ALIGN (dest) > alignment;
 
   const_rtx src = SET_SRC (set);
 
@@ -8799,7 +8799,7 @@  ix86_need_alignment_p_1 (rtx set, unsigned int alignment)
       auto op = *iter;
 
       if (MEM_P (op))
-	return GET_MODE_ALIGNMENT (GET_MODE (op)) > alignment;
+	return MEM_ALIGN (op) > alignment;
     }
 
   return false;
-- 
2.53.0