[PATCH] x86: Remove brand ID check for Intel processors

[Uros Bizjak]

On Wed, Jun 24, 2020 at 5:01 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Brand ID was a feature that briefly existed in some Pentium III and
> Pentium 4 CPUs.  The CPUs that had non-zero brand ID still have had
> valid family/model.  Brand ID just gives a marketing name for the CPU.
> Remove the extra code for brand ID check.
>
> gcc/
>
>         PR target/95660
>         * common/config/i386/cpuinfo.h (get_intel_cpu): Remove brand_id.
>         (cpu_indicator_init): Likewise.
>         * config/i386/driver-i386.c (host_detect_local_cpu): Updated.
>
> gcc/testsuite/
>
>         PR target/95660
>         * gcc.target/i386/builtin_target.c (check_detailed): Updated.

LGTM.

Thanks,
Uros.

> ---
>  gcc/common/config/i386/cpuinfo.h               | 12 +++++-------
>  gcc/config/i386/driver-i386.c                  |  2 +-
>  gcc/testsuite/gcc.target/i386/builtin_target.c |  2 +-
>  3 files changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/gcc/common/config/i386/cpuinfo.h b/gcc/common/config/i386/cpuinfo.h
> index 27b7b4d8581..3eda53240f6 100644
> --- a/gcc/common/config/i386/cpuinfo.h
> +++ b/gcc/common/config/i386/cpuinfo.h
> @@ -254,13 +254,12 @@ get_amd_cpu (struct __processor_model *cpu_model,
>  static inline const char *
>  get_intel_cpu (struct __processor_model *cpu_model,
>                struct __processor_model2 *cpu_model2,
> -              unsigned int *cpu_features2,
> -              unsigned int brand_id)
> +              unsigned int *cpu_features2)
>  {
>    const char *cpu = NULL;
>
> -  /* Parse family and model only for brand ID 0 and model 6. */
> -  if (brand_id != 0 || cpu_model2->__cpu_family != 0x6)
> +  /* Parse family and model only for model 6. */
> +  if (cpu_model2->__cpu_family != 0x6)
>      return cpu;
>
>    switch (cpu_model2->__cpu_model)
> @@ -758,7 +757,7 @@ cpu_indicator_init (struct __processor_model *cpu_model,
>
>    int max_level;
>    unsigned int vendor;
> -  unsigned int model, family, brand_id;
> +  unsigned int model, family;
>    unsigned int extended_model, extended_family;
>
>    /* This function needs to run just once.  */
> @@ -791,7 +790,6 @@ cpu_indicator_init (struct __processor_model *cpu_model,
>
>    model = (eax >> 4) & 0x0f;
>    family = (eax >> 8) & 0x0f;
> -  brand_id = ebx & 0xff;
>    extended_model = (eax >> 12) & 0xf0;
>    extended_family = (eax >> 20) & 0xff;
>
> @@ -813,7 +811,7 @@ cpu_indicator_init (struct __processor_model *cpu_model,
>        get_available_features (cpu_model, cpu_model2, cpu_features2,
>                               ecx, edx);
>        /* Get CPU type.  */
> -      get_intel_cpu (cpu_model, cpu_model2, cpu_features2, brand_id);
> +      get_intel_cpu (cpu_model, cpu_model2, cpu_features2);
>        cpu_model->__cpu_vendor = VENDOR_INTEL;
>      }
>    else if (vendor == signature_AMD_ebx)
> diff --git a/gcc/config/i386/driver-i386.c b/gcc/config/i386/driver-i386.c
> index e9e4d6ed023..6da2a15c1b0 100644
> --- a/gcc/config/i386/driver-i386.c
> +++ b/gcc/config/i386/driver-i386.c
> @@ -555,7 +555,7 @@ const char *host_detect_local_cpu (int argc, const char **argv)
>         cpu = "pentium";
>        break;
>      case PROCESSOR_PENTIUMPRO:
> -      cpu = get_intel_cpu (&cpu_model, &cpu_model2, cpu_features2, 0);
> +      cpu = get_intel_cpu (&cpu_model, &cpu_model2, cpu_features2);
>        if (cpu == NULL)
>         {
>           if (arch)
> diff --git a/gcc/testsuite/gcc.target/i386/builtin_target.c b/gcc/testsuite/gcc.target/i386/builtin_target.c
> index e87f262a775..aa9680544d8 100644
> --- a/gcc/testsuite/gcc.target/i386/builtin_target.c
> +++ b/gcc/testsuite/gcc.target/i386/builtin_target.c
> @@ -46,7 +46,7 @@ check_detailed ()
>      {
>      case VENDOR_INTEL:
>        assert (__builtin_cpu_is ("intel"));
> -      get_intel_cpu (&cpu_model, &cpu_model2, cpu_features2, 0);
> +      get_intel_cpu (&cpu_model, &cpu_model2, cpu_features2);
>        break;
>      case VENDOR_AMD:
>        assert (__builtin_cpu_is ("amd"));
> --
> 2.26.2
>