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

[Sriraman Tallam <tmsriram at google dot com>]

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,
-Sri.


>
> Otherwise, it looks good to me.
>
> Thanks.
>
>
> --
> H.J.