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/* Initialize CPU feature data.
This file is part of the GNU C Library.
Copyright (C) 2008-2015 Free Software Foundation, Inc.
Contributed by Ulrich Drepper <drepper@redhat.com>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <atomic.h>
#include <cpuid.h>
#include "init-arch.h"
struct cpu_features __cpu_features attribute_hidden;
static void
get_common_indeces (unsigned int *family, unsigned int *model)
{
__cpuid (1, __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax,
__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ebx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_1].edx);
unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
*family = (eax >> 8) & 0x0f;
*model = (eax >> 4) & 0x0f;
}
void
__init_cpu_features (void)
{
unsigned int ebx;
unsigned int ecx;
unsigned int edx;
unsigned int family = 0;
unsigned int model = 0;
enum cpu_features_kind kind;
__cpuid (0, __cpu_features.max_cpuid, ebx, ecx, edx);
/* This spells out "GenuineIntel". */
if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
{
kind = arch_kind_intel;
get_common_indeces (&family, &model);
unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
unsigned int extended_family = (eax >> 20) & 0xff;
unsigned int extended_model = (eax >> 12) & 0xf0;
if (family == 0x0f)
{
family += extended_family;
model += extended_model;
}
else if (family == 0x06)
{
ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
model += extended_model;
switch (model)
{
case 0x1c:
case 0x26:
/* BSF is slow on Atom. */
__cpu_features.feature[index_Slow_BSF] |= bit_Slow_BSF;
break;
case 0x37:
/* Unaligned load versions are faster than SSSE3
on Silvermont. */
#if index_Fast_Unaligned_Load != index_Prefer_PMINUB_for_stringop
# error index_Fast_Unaligned_Load != index_Prefer_PMINUB_for_stringop
#endif
#if index_Fast_Unaligned_Load != index_Slow_SSE4_2
# error index_Fast_Unaligned_Load != index_Slow_SSE4_2
#endif
__cpu_features.feature[index_Fast_Unaligned_Load]
|= (bit_Fast_Unaligned_Load
| bit_Prefer_PMINUB_for_stringop
| bit_Slow_SSE4_2);
break;
default:
/* Unknown family 0x06 processors. Assuming this is one
of Core i3/i5/i7 processors if AVX is available. */
if ((ecx & bit_AVX) == 0)
break;
case 0x1a:
case 0x1e:
case 0x1f:
case 0x25:
case 0x2c:
case 0x2e:
case 0x2f:
/* Rep string instructions, copy backward, unaligned loads
and pminub are fast on Intel Core i3, i5 and i7. */
#if index_Fast_Rep_String != index_Fast_Copy_Backward
# error index_Fast_Rep_String != index_Fast_Copy_Backward
#endif
#if index_Fast_Rep_String != index_Fast_Unaligned_Load
# error index_Fast_Rep_String != index_Fast_Unaligned_Load
#endif
#if index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
# error index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
#endif
__cpu_features.feature[index_Fast_Rep_String]
|= (bit_Fast_Rep_String
| bit_Fast_Copy_Backward
| bit_Fast_Unaligned_Load
| bit_Prefer_PMINUB_for_stringop);
break;
}
}
}
/* This spells out "AuthenticAMD". */
else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
{
kind = arch_kind_amd;
get_common_indeces (&family, &model);
ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
unsigned int eax;
__cpuid (0x80000000, eax, ebx, ecx, edx);
if (eax >= 0x80000001)
__cpuid (0x80000001,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].eax,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].ebx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].ecx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].edx);
}
else
kind = arch_kind_other;
if (__cpu_features.max_cpuid >= 7)
__cpuid_count (7, 0,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].eax,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].ebx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].ecx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].edx);
/* Can we call xgetbv? */
if (CPUID_OSXSAVE)
{
unsigned int xcrlow;
unsigned int xcrhigh;
asm ("xgetbv" : "=a" (xcrlow), "=d" (xcrhigh) : "c" (0));
/* Is YMM and XMM state usable? */
if ((xcrlow & (bit_YMM_state | bit_XMM_state)) ==
(bit_YMM_state | bit_XMM_state))
{
/* Determine if AVX is usable. */
if (CPUID_AVX)
__cpu_features.feature[index_AVX_Usable] |= bit_AVX_Usable;
/* Determine if AVX2 is usable. */
if (CPUID_AVX2)
__cpu_features.feature[index_AVX2_Usable] |= bit_AVX2_Usable;
/* Determine if FMA is usable. */
if (CPUID_FMA)
__cpu_features.feature[index_FMA_Usable] |= bit_FMA_Usable;
/* Determine if FMA4 is usable. */
if (CPUID_FMA4)
__cpu_features.feature[index_FMA4_Usable] |= bit_FMA4_Usable;
}
}
__cpu_features.family = family;
__cpu_features.model = model;
atomic_write_barrier ();
__cpu_features.kind = kind;
}
#undef __get_cpu_features
const struct cpu_features *
__get_cpu_features (void)
{
if (__cpu_features.kind == arch_kind_unknown)
__init_cpu_features ();
return &__cpu_features;
}
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