On Wed, Apr 20, 2016 at 12:02 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
>>
>> That is why I submitted my patches. Since -m32 passes -march=x86-64
>> to cc1 on x86-64, we shouldn't pass -march=i486 to cc1. It is undesirable
>> especially when --with-arch= is used. I noticed the issue when 32-bit
>> libatomic/libgomp/libitm weren't optimized with -march=haswell when GCC
>> was configured with --with-arch=haswell
>
> OK then. IMO, following comment is more informative:
>
> # x86_64 compiler passes -march=x86_64 by default when building 32bit
> target libraries.
>
>>>>>>>> + # Since 64-bit arch > i486, we can use the same -march= to
>>>>>>>> build
>>>>>>>> + # both 32-bit and 64-bit target libraries.
>
> OK with the above change.
>
This is the patch I checked in. I also updated patches for libgomp:
https://gcc.gnu.org/ml/gcc-patches/2016-04/msg01079.html
and libitm:
https://gcc.gnu.org/ml/gcc-patches/2016-04/msg01080.html
Thanks.
--
H.J.
From bafad333cdf4125bf245e05d82df824ffb62c9d5 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.to...@gmail.com>
Date: Wed, 30 Mar 2016 05:51:28 -0700
Subject: [PATCH 1/3] Don't build 32-bit libatomic with -march=i486 on x86-64
Gcc uses the same -march= for both -m32 and -m64 on x86-64 unless
--with-arch-32= is used. There is no need for -march=i486 to compile
32-bit libatomic on x86-64.
PR target/70454
* configure.tgt (XCFLAGS): Don't add -march=i486 to compile
32-bit x86 target library on x86-64.
---
libatomic/configure.tgt | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/libatomic/configure.tgt b/libatomic/configure.tgt
index c5470d7..49233a4 100644
--- a/libatomic/configure.tgt
+++ b/libatomic/configure.tgt
@@ -81,14 +81,8 @@ case "${target_cpu}" in
try_ifunc=yes
;;
x86_64)
- case " ${CC} ${CFLAGS} " in
- *" -m32 "*)
- XCFLAGS="${XCFLAGS} -march=i486 -mtune=generic"
- XCFLAGS="${XCFLAGS} -fomit-frame-pointer"
- ;;
- *)
- ;;
- esac
+ # x86_64 compiler passes -march=x86_64 by default when building
+ # 32bit target libraries.
ARCH=x86
# ??? Detect when -mcx16 is already enabled.
try_ifunc=yes
--
2.5.5
