Hi Distinguish based on stepping number is not recommended for some reasons: 1) Intel doesn't officially disclose stepping information in SDM. 2) Stepping can be changing in the future.
We still prefer the conventional distinguish approach based on feature bits.
I have refined the patch as attached according to all your suggestions.
Wei
gcc/
* common/config/i386/i386-common.c (processor_names): Add cascadelake.
(processor_alias_table): Add cascadelake.
* config.gcc: Add -march=cascadelake.
* config/i386/driver-i386.c
(host_detect_local_cpu): Detect cascadelake.
* config/i386/i386-c.c (ix86_target_macros_internal): Handle
cascadelake.
* config/i386/i386.c (ix86_cost): Add m_CASCADELAKE.
(processor_cost_table): Add cascadelake.
(get_builtin_code_for_version): Handle cascadelake.
(fold_builtin_cpu): Ditto.
* config/i386/i386.h (TARGET_CASCADELAKE, PROCESSOR_CASCADELAKE): New.
(PTA_CASCADELAKE): Ditto.
* doc/extend.texi: Add cascadelake.
* doc/invoke.texi: Add -march=cascadelake.
gcc/testsuite/
* g++.target/i386/mv16.C: Handle new march.
* gcc.target/i386/builtin_target.c: Ditto.
* gcc.target/i386/funcspec-56.inc: Ditto.
libgcc/
* config/i386/cpuinfo.c (get_intel_cpu): Handle cascadelake.
* config/i386/cpuinfo.h: Add INTEL_COREI7_CASCADELAKE.
Wei Xiao <wei.william.x...@gmail.com> 于2018年11月27日周二 下午6:40写道：
>
> Thanks for the helpful information!
> But I'm still checking with hardware team about the
> family/model/stepping numbers for Cascadelake which are not officially
> disclosed by Intel (to my best knowledge).
>
> Wei
> Martin Liška <mli...@suse.cz> 于2018年11月26日周一 下午10:00写道：
> >
> > On 11/26/18 12:18 PM, Jakub Jelinek wrote:
> > > On Mon, Nov 26, 2018 at 12:03:53PM +0100, Martin Liška wrote:
> > >>> For Cascade Lake the model number is the same as Skylake Server,
> > >>> it can only be distinguished based on the stepping (5 vs 4)
> > >>
> > >> Very interesting, probably the first time a distinguish is based on
> > >> stepping number?
> > >
> > > Wouldn't it be better to distinguish it based on availability of VNNI,
> > > like
> > > we do for unknown family/model?
> > >
> > >>> Like gcc -mcpu=native needs to learn about this.
> > >>
> > >> I'm attaching patch that does that. Note that it's completely untested
> > >> as I don't have
> > >> access to any of the new machines (Skylake server).
> >
> > Would be possible, the only ugly place would be in
> > libgcc/config/i386/cpuinfo.c where we
> > call:
> >
> > get_intel_cpu (family, model, stepping, brand_id);
> > /* Find available features. */
> > get_available_features (ecx, edx, max_level, &avx512_vnni);
> >
> > one would need a feature to distinguish CPU model. Do we really want that?
> >
> > Martin
> >
> > >
> > > Jakub
> > >
> >
cascadelake-v3.diff
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