1 /* Initialize CPU feature data.
2 This file is part of the GNU C Library.
3 Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4 Contributed by Ulrich Drepper <drepper@redhat.com>.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
23 #include "init-arch.h"
26 struct cpu_features __cpu_features attribute_hidden;
30 get_common_indeces (unsigned int *family, unsigned int *model)
32 __cpuid (1, __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax,
33 __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ebx,
34 __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx,
35 __cpu_features.cpuid[COMMON_CPUID_INDEX_1].edx);
37 unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
38 *family = (eax >> 8) & 0x0f;
39 *model = (eax >> 4) & 0x0f;
44 __init_cpu_features (void)
49 unsigned int family = 0;
50 unsigned int model = 0;
51 enum cpu_features_kind kind;
53 __cpuid (0, __cpu_features.max_cpuid, ebx, ecx, edx);
55 /* This spells out "GenuineIntel". */
56 if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
58 kind = arch_kind_intel;
60 get_common_indeces (&family, &model);
62 /* Intel processors prefer SSE instruction for memory/string
63 routines if they are available. */
64 __cpu_features.feature[index_Prefer_SSE_for_memop]
65 |= bit_Prefer_SSE_for_memop;
67 unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
68 unsigned int extended_family = (eax >> 20) & 0xff;
69 unsigned int extended_model = (eax >> 12) & 0xf0;
72 family += extended_family;
73 model += extended_model;
75 else if (family == 0x06)
77 ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
78 model += extended_model;
83 /* BSF is slow on Atom. */
84 __cpu_features.feature[index_Slow_BSF] |= bit_Slow_BSF;
88 /* Unknown family 0x06 processors. Assuming this is one
89 of Core i3/i5/i7 processors if AVX is available. */
90 if ((ecx & bit_AVX) == 0)
100 /* Rep string instructions, copy backward, unaligned loads
101 and pminub are fast on Intel Core i3, i5 and i7. */
102 #if index_Fast_Rep_String != index_Fast_Copy_Backward
103 # error index_Fast_Rep_String != index_Fast_Copy_Backward
105 #if index_Fast_Rep_String != index_Fast_Unaligned_Load
106 # error index_Fast_Rep_String != index_Fast_Unaligned_Load
108 #if index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
109 # error index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
111 __cpu_features.feature[index_Fast_Rep_String]
112 |= (bit_Fast_Rep_String
113 | bit_Fast_Copy_Backward
114 | bit_Fast_Unaligned_Load
115 | bit_Prefer_PMINUB_for_stringop);
120 /* This spells out "AuthenticAMD". */
121 else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
123 kind = arch_kind_amd;
125 get_common_indeces (&family, &model);
127 unsigned int ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
129 /* AMD processors prefer SSE instructions for memory/string routines
130 if they are available, otherwise they prefer integer instructions. */
132 __cpu_features.feature[index_Prefer_SSE_for_memop]
133 |= bit_Prefer_SSE_for_memop;
136 kind = arch_kind_other;
138 __cpu_features.family = family;
139 __cpu_features.model = model;
140 atomic_write_barrier ();
141 __cpu_features.kind = kind;
144 #undef __get_cpu_features
146 const struct cpu_features *
147 __get_cpu_features (void)
149 if (__cpu_features.kind == arch_kind_unknown)
150 __init_cpu_features ();
152 return &__cpu_features;