Re: [PATCH] Don't build 32-bit libatomic with -march=i486 on x86-64

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Apr 19, 2016 at 11:18 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Tue, Apr 19, 2016 at 8:08 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Tue, Apr 19, 2016 at 8:45 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
>>> On Tue, Apr 19, 2016 at 5:07 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>>>> 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.
>>>>
>>>> Tested on x86-64.  OK for trunk?
>>>>
>>>> H.J.
>>>> ---
>>>>         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..bbb93fc 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
>>>> +       # Since 64-bit arch > i486, we can use the same -march= to build
>>>> +       # both 32-bit and 64-bit target libraries.
>>>>         ARCH=x86
>>>>         # ??? Detect when -mcx16 is already enabled.
>>>>         try_ifunc=yes
>>>> --
>>>> 2.5.5
>>>>
>>>
>>> No, this is wrong. My build with default options defaults to i386. So,
>>> the difference between
>>>
>>
>> How was your GCC configured?  Did you use
>>
>> --with-arch_32=i386
>
> Nope, just:
>
> ~/gcc-svn/trunk/configure
>

$ /ssd/uros/gcc-build/gcc/cc1 -E -dM -m32 hello.c > aaa

I don't think cc1 is supposed to be used directly.  Can you use gcc
driver instead, like

$ /ssd/uros/gcc-build/gcc/xgcc -B/ssd/uros/gcc-build/gcc/  -E -dM -m32 hello.c

-- 
H.J.