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cpu.c
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1 /*
2  * CPU detection code, extracted from mmx.h
3  * (c)1997-99 by H. Dietz and R. Fisher
4  * Converted to C and improved by Fabrice Bellard.
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <stdlib.h>
24 #include <string.h>
25 
26 #include "libavutil/x86/asm.h"
27 #include "libavutil/x86/cpu.h"
28 #include "libavutil/cpu.h"
29 #include "libavutil/cpu_internal.h"
30 
31 #if HAVE_YASM
32 
33 #define cpuid(index, eax, ebx, ecx, edx) \
34  ff_cpu_cpuid(index, &eax, &ebx, &ecx, &edx)
35 
36 #define xgetbv(index, eax, edx) \
37  ff_cpu_xgetbv(index, &eax, &edx)
38 
39 #elif HAVE_INLINE_ASM
40 
41 /* ebx saving is necessary for PIC. gcc seems unable to see it alone */
42 #define cpuid(index, eax, ebx, ecx, edx) \
43  __asm__ volatile ( \
44  "mov %%"REG_b", %%"REG_S" \n\t" \
45  "cpuid \n\t" \
46  "xchg %%"REG_b", %%"REG_S \
47  : "=a" (eax), "=S" (ebx), "=c" (ecx), "=d" (edx) \
48  : "0" (index), "2"(0))
49 
50 #define xgetbv(index, eax, edx) \
51  __asm__ (".byte 0x0f, 0x01, 0xd0" : "=a"(eax), "=d"(edx) : "c" (index))
52 
53 #define get_eflags(x) \
54  __asm__ volatile ("pushfl \n" \
55  "pop %0 \n" \
56  : "=r"(x))
57 
58 #define set_eflags(x) \
59  __asm__ volatile ("push %0 \n" \
60  "popfl \n" \
61  :: "r"(x))
62 
63 #endif /* HAVE_INLINE_ASM */
64 
65 #if ARCH_X86_64
66 
67 #define cpuid_test() 1
68 
69 #elif HAVE_YASM
70 
71 #define cpuid_test ff_cpu_cpuid_test
72 
73 #elif HAVE_INLINE_ASM
74 
75 static int cpuid_test(void)
76 {
77  x86_reg a, c;
78 
79  /* Check if CPUID is supported by attempting to toggle the ID bit in
80  * the EFLAGS register. */
81  get_eflags(a);
82  set_eflags(a ^ 0x200000);
83  get_eflags(c);
84 
85  return a != c;
86 }
87 #endif
88 
89 /* Function to test if multimedia instructions are supported... */
91 {
92  int rval = 0;
93 
94 #ifdef cpuid
95 
96  int eax, ebx, ecx, edx;
97  int max_std_level, max_ext_level, std_caps = 0, ext_caps = 0;
98  int family = 0, model = 0;
99  union { int i[3]; char c[12]; } vendor;
100 
101  if (!cpuid_test())
102  return 0; /* CPUID not supported */
103 
104  cpuid(0, max_std_level, vendor.i[0], vendor.i[2], vendor.i[1]);
105 
106  if (max_std_level >= 1) {
107  cpuid(1, eax, ebx, ecx, std_caps);
108  family = ((eax >> 8) & 0xf) + ((eax >> 20) & 0xff);
109  model = ((eax >> 4) & 0xf) + ((eax >> 12) & 0xf0);
110  if (std_caps & (1 << 15))
111  rval |= AV_CPU_FLAG_CMOV;
112  if (std_caps & (1 << 23))
113  rval |= AV_CPU_FLAG_MMX;
114  if (std_caps & (1 << 25))
115  rval |= AV_CPU_FLAG_MMXEXT;
116 #if HAVE_SSE
117  if (std_caps & (1 << 25))
118  rval |= AV_CPU_FLAG_SSE;
119  if (std_caps & (1 << 26))
120  rval |= AV_CPU_FLAG_SSE2;
121  if (ecx & 1)
122  rval |= AV_CPU_FLAG_SSE3;
123  if (ecx & 0x00000200 )
124  rval |= AV_CPU_FLAG_SSSE3;
125  if (ecx & 0x00080000 )
126  rval |= AV_CPU_FLAG_SSE4;
127  if (ecx & 0x00100000 )
128  rval |= AV_CPU_FLAG_SSE42;
129 #if HAVE_AVX
130  /* Check OXSAVE and AVX bits */
131  if ((ecx & 0x18000000) == 0x18000000) {
132  /* Check for OS support */
133  xgetbv(0, eax, edx);
134  if ((eax & 0x6) == 0x6) {
135  rval |= AV_CPU_FLAG_AVX;
136  if (ecx & 0x00001000)
137  rval |= AV_CPU_FLAG_FMA3;
138  }
139  }
140 #endif /* HAVE_AVX */
141 #endif /* HAVE_SSE */
142  }
143  if (max_std_level >= 7) {
144  cpuid(7, eax, ebx, ecx, edx);
145 #if HAVE_AVX2
146  if ((rval & AV_CPU_FLAG_AVX) && (ebx & 0x00000020))
147  rval |= AV_CPU_FLAG_AVX2;
148 #endif /* HAVE_AVX2 */
149  /* BMI1/2 don't need OS support */
150  if (ebx & 0x00000008) {
151  rval |= AV_CPU_FLAG_BMI1;
152  if (ebx & 0x00000100)
153  rval |= AV_CPU_FLAG_BMI2;
154  }
155  }
156 
157  cpuid(0x80000000, max_ext_level, ebx, ecx, edx);
158 
159  if (max_ext_level >= 0x80000001) {
160  cpuid(0x80000001, eax, ebx, ecx, ext_caps);
161  if (ext_caps & (1U << 31))
162  rval |= AV_CPU_FLAG_3DNOW;
163  if (ext_caps & (1 << 30))
164  rval |= AV_CPU_FLAG_3DNOWEXT;
165  if (ext_caps & (1 << 23))
166  rval |= AV_CPU_FLAG_MMX;
167  if (ext_caps & (1 << 22))
168  rval |= AV_CPU_FLAG_MMXEXT;
169 
170  if (!strncmp(vendor.c, "AuthenticAMD", 12)) {
171  /* Allow for selectively disabling SSE2 functions on AMD processors
172  with SSE2 support but not SSE4a. This includes Athlon64, some
173  Opteron, and some Sempron processors. MMX, SSE, or 3DNow! are faster
174  than SSE2 often enough to utilize this special-case flag.
175  AV_CPU_FLAG_SSE2 and AV_CPU_FLAG_SSE2SLOW are both set in this case
176  so that SSE2 is used unless explicitly disabled by checking
177  AV_CPU_FLAG_SSE2SLOW. */
178  if (rval & AV_CPU_FLAG_SSE2 && !(ecx & 0x00000040))
179  rval |= AV_CPU_FLAG_SSE2SLOW;
180 
181  /* Similar to the above but for AVX functions on AMD processors.
182  This is necessary only for functions using YMM registers on Bulldozer
183  based CPUs as they lack 256-bits execution units. SSE/AVX functions
184  using XMM registers are always faster on them.
185  AV_CPU_FLAG_AVX and AV_CPU_FLAG_AVXSLOW are both set so that AVX is
186  used unless explicitly disabled by checking AV_CPU_FLAG_AVXSLOW.
187  TODO: Confirm if Excavator is affected or not by this once it's
188  released, and update the check if necessary. Same for btver2. */
189  if (family == 0x15 && (rval & AV_CPU_FLAG_AVX))
190  rval |= AV_CPU_FLAG_AVXSLOW;
191  }
192 
193  /* XOP and FMA4 use the AVX instruction coding scheme, so they can't be
194  * used unless the OS has AVX support. */
195  if (rval & AV_CPU_FLAG_AVX) {
196  if (ecx & 0x00000800)
197  rval |= AV_CPU_FLAG_XOP;
198  if (ecx & 0x00010000)
199  rval |= AV_CPU_FLAG_FMA4;
200  }
201  }
202 
203  if (!strncmp(vendor.c, "GenuineIntel", 12)) {
204  if (family == 6 && (model == 9 || model == 13 || model == 14)) {
205  /* 6/9 (pentium-m "banias"), 6/13 (pentium-m "dothan"), and
206  * 6/14 (core1 "yonah") theoretically support sse2, but it's
207  * usually slower than mmx, so let's just pretend they don't.
208  * AV_CPU_FLAG_SSE2 is disabled and AV_CPU_FLAG_SSE2SLOW is
209  * enabled so that SSE2 is not used unless explicitly enabled
210  * by checking AV_CPU_FLAG_SSE2SLOW. The same situation
211  * applies for AV_CPU_FLAG_SSE3 and AV_CPU_FLAG_SSE3SLOW. */
212  if (rval & AV_CPU_FLAG_SSE2)
214  if (rval & AV_CPU_FLAG_SSE3)
216  }
217  /* The Atom processor has SSSE3 support, which is useful in many cases,
218  * but sometimes the SSSE3 version is slower than the SSE2 equivalent
219  * on the Atom, but is generally faster on other processors supporting
220  * SSSE3. This flag allows for selectively disabling certain SSSE3
221  * functions on the Atom. */
222  if (family == 6 && model == 28)
223  rval |= AV_CPU_FLAG_ATOM;
224  }
225 
226 #endif /* cpuid */
227 
228  return rval;
229 }
#define AV_CPU_FLAG_AVX
AVX functions: requires OS support even if YMM registers aren't used.
Definition: cpu.h:45
#define AV_CPU_FLAG_SSE
SSE functions.
Definition: cpu.h:33
#define AV_CPU_FLAG_CMOV
supports cmov instruction
Definition: cpu.h:50
#define AV_CPU_FLAG_FMA3
Haswell FMA3 functions.
Definition: cpu.h:55
#define AV_CPU_FLAG_MMXEXT
SSE integer functions or AMD MMX ext.
Definition: cpu.h:30
#define AV_CPU_FLAG_ATOM
Atom processor, some SSSE3 instructions are slower.
Definition: cpu.h:42
#define AV_CPU_FLAG_AVX2
AVX2 functions: requires OS support even if YMM registers aren't used.
Definition: cpu.h:54
#define AV_CPU_FLAG_SSE2SLOW
SSE2 supported, but usually not faster.
Definition: cpu.h:35
#define AV_CPU_FLAG_XOP
Bulldozer XOP functions.
Definition: cpu.h:47
#define U(x)
Definition: vp56_arith.h:37
#define AV_CPU_FLAG_SSE42
Nehalem SSE4.2 functions.
Definition: cpu.h:44
#define AV_CPU_FLAG_SSSE3
Conroe SSSE3 functions.
Definition: cpu.h:41
#define AV_CPU_FLAG_SSE3
Prescott SSE3 functions.
Definition: cpu.h:38
int ff_get_cpu_flags_x86(void)
Definition: cpu.c:90
#define AV_CPU_FLAG_BMI2
Bit Manipulation Instruction Set 2.
Definition: cpu.h:57
#define AV_CPU_FLAG_3DNOW
AMD 3DNOW.
Definition: cpu.h:32
#define AV_CPU_FLAG_SSE3SLOW
SSE3 supported, but usually not faster.
Definition: cpu.h:39
#define AV_CPU_FLAG_AVXSLOW
AVX supported, but slow when using YMM registers (e.g. Bulldozer)
Definition: cpu.h:46
#define AV_CPU_FLAG_BMI1
Bit Manipulation Instruction Set 1.
Definition: cpu.h:56
#define AV_CPU_FLAG_MMX
standard MMX
Definition: cpu.h:29
#define AV_CPU_FLAG_FMA4
Bulldozer FMA4 functions.
Definition: cpu.h:48
#define AV_CPU_FLAG_SSE4
Penryn SSE4.1 functions.
Definition: cpu.h:43
#define AV_CPU_FLAG_3DNOWEXT
AMD 3DNowExt.
Definition: cpu.h:37
static double c[64]
int x86_reg
Definition: asm.h:72
#define AV_CPU_FLAG_SSE2
PIV SSE2 functions.
Definition: cpu.h:34