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Add check for Athlon64 and similar AMD processors with slow SSE2.

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Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
(cherry picked from commit 74b1f96859)
This commit is contained in:
Justin Ruggles 2011-02-11 15:17:32 -05:00 committed by Michael Niedermayer
parent 3ae4484cdf
commit b7195837cd
1 changed files with 16 additions and 1 deletions
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17
libavutil/x86/cpu.c
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@ -109,13 +109,28 @@ int ff_get_cpu_flags_x86(void)
rval |= AV_CPU_FLAG_MMX;
if (ext_caps & (1<<22))
rval |= AV_CPU_FLAG_MMX2;
/* Allow for selectively disabling SSE2 functions on AMD processors
with SSE2 support but not SSE4a. This includes Athlon64, some
Opteron, and some Sempron processors. MMX, SSE, or 3DNow! are faster
than SSE2 often enough to utilize this special-case flag.
AV_CPU_FLAG_SSE2 and AV_CPU_FLAG_SSE2SLOW are both set in this case
so that SSE2 is used unless explicitly disabled by checking
AV_CPU_FLAG_SSE2SLOW. */
if (!strncmp(vendor.c, "AuthenticAMD", 12) &&
rval & AV_CPU_FLAG_SSE2 && !(ecx & 0x00000040)) {
rval |= AV_CPU_FLAG_SSE2SLOW;
}
}
if (!strncmp(vendor.c, "GenuineIntel", 12) &&
family == 6 && (model == 9 || model == 13 || model == 14)) {
/* 6/9 (pentium-m "banias"), 6/13 (pentium-m "dothan"), and 6/14 (core1 "yonah")
* theoretically support sse2, but it's usually slower than mmx,
* so let's just pretend they don't. */
* so let's just pretend they don't. AV_CPU_FLAG_SSE2 is disabled and
* AV_CPU_FLAG_SSE2SLOW is enabled so that SSE2 is not used unless
* explicitly enabled by checking AV_CPU_FLAG_SSE2SLOW. The same
* situation applies for AV_CPU_FLAG_SSE3 and AV_CPU_FLAG_SSE3SLOW. */
if (rval & AV_CPU_FLAG_SSE2) rval ^= AV_CPU_FLAG_SSE2SLOW|AV_CPU_FLAG_SSE2;
if (rval & AV_CPU_FLAG_SSE3) rval ^= AV_CPU_FLAG_SSE3SLOW|AV_CPU_FLAG_SSE3;
}