[FFmpeg-devel] [PATCH] x86/cpu: set avxslow cpuflag on bdver4 and btver2 CPUs

James Almer jamrial at gmail.com
Sun Feb 7 04:05:43 CET 2016


They are also slow when using 256 bit wide registers

Signed-off-by: James Almer <jamrial at gmail.com>
---
See https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=3a33f4ce8ea1efdebec7f7138d00e9be9a12d630
 libavutil/x86/cpu.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/libavutil/x86/cpu.c b/libavutil/x86/cpu.c
index f57d72d..bb63daa 100644
--- a/libavutil/x86/cpu.c
+++ b/libavutil/x86/cpu.c
@@ -182,13 +182,11 @@ int ff_get_cpu_flags_x86(void)
 
         /* Similar to the above but for AVX functions on AMD processors.
            This is necessary only for functions using YMM registers on Bulldozer
-           based CPUs as they lack 256-bits execution units. SSE/AVX functions
-           using XMM registers are always faster on them.
+           and Jaguar based CPUs as they lack 256-bits execution units. SSE/AVX
+           functions using XMM registers are always faster on them.
            AV_CPU_FLAG_AVX and AV_CPU_FLAG_AVXSLOW are both set so that AVX is
-           used unless explicitly disabled by checking AV_CPU_FLAG_AVXSLOW.
-           TODO: Confirm if Excavator is affected or not by this once it's
-                 released, and update the check if necessary. Same for btver2. */
-            if (family == 0x15 && (rval & AV_CPU_FLAG_AVX))
+           used unless explicitly disabled by checking AV_CPU_FLAG_AVXSLOW. */
+            if ((family == 0x15 || family == 0x16) && (rval & AV_CPU_FLAG_AVX))
                 rval |= AV_CPU_FLAG_AVXSLOW;
         }
 
-- 
2.7.0



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