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Re: Support for Runtime CPU type detection via builtins (issue5754058)


On Tue, Apr 24, 2012 at 7:06 PM, Sriraman Tallam <tmsriram@google.com> wrote:
> On Tue, Apr 24, 2012 at 5:24 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Tue, Apr 24, 2012 at 5:10 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>>> Hi,
>>>
>>> ? Thanks for all the comments. I have made all the changes as
>>> mentioned and submiited the patch. Summary of changes made:
>>>
>>> * Add support for AVX
>>> * Fix documentation in extend.texi
>>> * Make it thread-safe according to H.J.'s comments.
>>>
>>> I have attached the patch. Boot-strapped and checked for test parity
>>> with pristine build.
>>>
>>> ? ? ? * config/i386/i386.c (build_processor_model_struct): New function.
>>> ? ? ? ?(make_var_decl): New function.
>>> ? ? ? ?(fold_builtin_cpu): New function.
>>> ? ? ? ?(ix86_fold_builtin): New function.
>>> ? ? ? ?(make_cpu_type_builtin): New function.
>>> ? ? ? ?(ix86_init_platform_type_builtins): New function.
>>> ? ? ? ?(ix86_expand_builtin): Expand new builtins by folding them.
>>> ? ? ? ?(ix86_init_builtins): Make new builtins to detect CPU type.
>>> ? ? ? ?(TARGET_FOLD_BUILTIN): New macro.
>>> ? ? ? ?(IX86_BUILTIN_CPU_INIT): New enum value.
>>> ? ? ? ?(IX86_BUILTIN_CPU_IS): New enum value.
>>> ? ? ? ?(IX86_BUILTIN_CPU_SUPPORTS): New enum value.
>>> ? ? ? ?* config/i386/i386-builtin-types.def: New function type.
>>> ? ? ? ?* testsuite/gcc.target/builtin_target.c: New testcase.
>>> ? ? ? ?* doc/extend.texi: Document builtins.
>>>
>>> ? ? ? ?* libgcc/config/i386/i386-cpuinfo.c: New file.
>>> ? ? ? ?* libgcc/config/i386/t-cpuinfo: New file.
>>> ? ? ? ?* libgcc/config.host: Include t-cpuinfo.
>>> ? ? ? ?* libgcc/config/i386/libgcc-glibc.ver: Version symbol __cpu_model.
>>>
>>>
>>
>> + ?/* This function needs to run just once. ?*/
>> + ?if (__cpu_model.__cpu_vendor)
>> + ? ?return 0;
>> +
>> + ?/* Assume cpuid insn present. Run in level 0 to get vendor id. */
>> + ?if (!__get_cpuid_output (0, &eax, &ebx, &ecx, &edx))
>> + ? ?return -1;
>>
>> If __get_cpuid_output returns non-zero, it will be called
>> repeatedly. ?I think you should set __cpu_model.__cpu_vendor
>> to non-zero in this case.
>
> Done now.
>
> 2012-04-24 ?Sriraman Tallam ?<tmsriram@google.com>
>
> ? ? ? ?* libgcc/config/i386/i386-cpuinfo.c: Set __cpu_vendor always.
>
>
> Index: libgcc/config/i386/i386-cpuinfo.c
> ===================================================================
> --- libgcc/config/i386/i386-cpuinfo.c ? (revision 186789)
> +++ libgcc/config/i386/i386-cpuinfo.c ? (working copy)
> @@ -256,16 +256,25 @@ __cpu_indicator_init (void)
>
> ? /* Assume cpuid insn present. Run in level 0 to get vendor id. */
> ? if (!__get_cpuid_output (0, &eax, &ebx, &ecx, &edx))
> - ? ?return -1;
> + ? ?{
> + ? ? ?__cpu_model.__cpu_vendor = VENDOR_OTHER;
> + ? ? ?return -1;
> + ? ?}
>
> ? vendor = ebx;
> ? max_level = eax;
>
> ? if (max_level < 1)
> - ? ?return -1;
> + ? ?{
> + ? ? ?__cpu_model.__cpu_vendor = VENDOR_OTHER;
> + ? ? ?return -1;
> + ? ?}
>
> ? if (!__get_cpuid_output (1, &eax, &ebx, &ecx, &edx))
> - ? ?return -1;
> + ? ?{
> + ? ? ?__cpu_model.__cpu_vendor = VENDOR_OTHER;
> + ? ? ?return -1;
> + ? ?}
>
> ? model = (eax >> 4) & 0x0f;
> ? family = (eax >> 8) & 0x0f;
>
>
> Thanks,

Should you also handle AVX2?


-- 
H.J.


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