There are MMX processors that don't support CMOV (pentium-mmx, amd-k6, cyrix
6x86). Therefore, we must not use cmov in in MMX code.
All processors supporing mmx2 also support cmov, so if a test for mmx2 succeeds,
we can use cmov.
---
libavcodec/x86/h264_idct.asm | 6 ++++++
1 file changed, 6 insertions(+)
Index: ffmpeg/libavcodec/x86/h264_idct.asm
===================================================================
--- ffmpeg.orig/libavcodec/x86/h264_idct.asm 2014-08-25 03:59:06.376569389
+0200
+++ ffmpeg/libavcodec/x86/h264_idct.asm 2014-08-25 18:47:46.988574579 +0200
@@ -1063,7 +1063,13 @@ cglobal h264_luma_dc_dequant_idct, 3, 4,
add t3d, 128 << 16
mov t1d, 7
cmp t0d, t1d
+%if cpuflag(mmx2)
cmovg t0d, t1d
+%else
+ jng .skip_mov
+ mov t0d, t1d
+.skip_mov:
+%endif
inc t1d
shr t3d, t0b
sub t1d, t0d
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