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Re: PATCH: PR target/59588: Don't check/change generic/i686 tuning
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 26 Dec 2013 08:06:25 -0800
- Subject: Re: PATCH: PR target/59588: Don't check/change generic/i686 tuning
- Authentication-results: sourceware.org; auth=none
- References: <20131224203809 dot GA6048 at intel dot com> <20131226123825 dot GC32027 at atrey dot karlin dot mff dot cuni dot cz> <CAMe9rOpstHX6AeAjFpgiV4iKsa+GkYjAVCFG6kMJFVAZSEib5g at mail dot gmail dot com> <20131226154540 dot GA4236 at kam dot mff dot cuni dot cz>
On Thu, Dec 26, 2013 at 7:45 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> On Thu, Dec 26, 2013 at 4:38 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >> Hi Honza,
>> >>
>> >> We have combined generic32 and generic64 into generic. There is no need
>> >> to check "generic" anymore. Also we shouldn't change -mtune=i686 into
>> >> -mtune=generic. OK to install?
>> >
>> > The i686->generic change was intended to get generic optimized code
>> > for i686-linux configuration rather than pentiumpro. I think it still makes
>> > sense to use this, since it is what most 32bit distros still configure for?
>> >
>>
>> Should -mtune=i686 define __tune_i686__? If not, how can
>> it be defined? Don't we default -mtune to generic for
>> i686-linux?
>
> If i686-linux defaults to -mtune=generic, then I think it is all fine.
We have defaulted
[hjl@gnu-6 gcc]$ ./xgcc -B./ -S /tmp/x.i -v
Reading specs from ./specs
COLLECT_GCC=./xgcc
Target: i686-linux
Configured with: /export/gnu/import/git/gcc/configure
--enable-languages=c,c++ --disable-bootstrap i686-linux
--prefix=/usr/gcc-4.9.0 --with-local-prefix=/usr/local
--enable-targets=all --with-fpmath=sse : (reconfigured)
/export/gnu/import/git/gcc/configure --enable-languages=c,c++
--disable-bootstrap i686-linux --prefix=/usr/gcc-4.9.0
--with-local-prefix=/usr/local --enable-targets=all --with-fpmath=sse
Thread model: posix
gcc version 4.9.0 20131224 (experimental) (GCC)
COLLECT_GCC_OPTIONS='-B' './' '-S' '-v' '-mtune=generic' '-march=pentium4'
./cc1 -fpreprocessed /tmp/x.i -quiet -dumpbase x.i -mtune=generic
-march=pentium4 -auxbase x -version -o x.s
GNU C (GCC) version 4.9.0 20131224 (experimental) (i686-linux)
compiled by GNU C version 4.8.2 20131212 (Red Hat 4.8.2-7), GMP
version 5.1.1, MPFR version 3.1.1, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU C (GCC) version 4.9.0 20131224 (experimental) (i686-linux)
compiled by GNU C version 4.8.2 20131212 (Red Hat 4.8.2-7), GMP
version 5.1.1, MPFR version 3.1.1, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: 8d0a04c49875a54ef44488e5406c52dd
COMPILER_PATH=./
LIBRARY_PATH=./:/lib/../lib/:/usr/lib/../lib/:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-B' './' '-S' '-v' '-mtune=generic' '-march=pentium4'
[hjl@gnu-6 gcc]$
I will check in my patch.
> i686 is bit misbehaved since it was used as both CPU name for PPro (that does not
> make much sense) and for the overall architecture...
>
Thanks.
--
H.J.