| Message ID | 20170216131149.7028-3-jdarnley@obe.tv |
|---|---|
| State | Accepted |
| Headers | show |
On 2/16/17, James Darnley <jdarnley@obe.tv> wrote: > Originally committed to x264 in 1637239a by Henrik Gramner who has > agreed to re-license it as LGPL. Original commit message follows. > > x86: Avoid some bypass delays and false dependencies > > A bypass delay of 1-3 clock cycles may occur on some CPUs when > transitioning > between int and float domains, so try to avoid that if possible. > --- > libavutil/x86/x86util.asm | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/libavutil/x86/x86util.asm b/libavutil/x86/x86util.asm > index c063436..1408f0a 100644 > --- a/libavutil/x86/x86util.asm > +++ b/libavutil/x86/x86util.asm > @@ -876,3 +876,15 @@ > psrlq %1, 8*(%2) > %endif > %endmacro > + > +%macro MOVHL 2 ; dst, src > +%ifidn %1, %2 > + punpckhqdq %1, %2 > +%elif cpuflag(avx) > + punpckhqdq %1, %2, %2 > +%elif cpuflag(sse4) > + pshufd %1, %2, q3232 ; pshufd is slow on some older CPUs, so only > use it on more modern ones > +%else > + movhlps %1, %2 ; may cause an int/float domain transition and > has a dependency on dst > +%endif > +%endmacro lgtm
diff --git a/libavutil/x86/x86util.asm b/libavutil/x86/x86util.asm index c063436..1408f0a 100644 --- a/libavutil/x86/x86util.asm +++ b/libavutil/x86/x86util.asm @@ -876,3 +876,15 @@ psrlq %1, 8*(%2) %endif %endmacro + +%macro MOVHL 2 ; dst, src +%ifidn %1, %2 + punpckhqdq %1, %2 +%elif cpuflag(avx) + punpckhqdq %1, %2, %2 +%elif cpuflag(sse4) + pshufd %1, %2, q3232 ; pshufd is slow on some older CPUs, so only use it on more modern ones +%else + movhlps %1, %2 ; may cause an int/float domain transition and has a dependency on dst +%endif +%endmacro
Originally committed to x264 in 1637239a by Henrik Gramner who has agreed to re-license it as LGPL. Original commit message follows. x86: Avoid some bypass delays and false dependencies A bypass delay of 1-3 clock cycles may occur on some CPUs when transitioning between int and float domains, so try to avoid that if possible. --- libavutil/x86/x86util.asm | 12 ++++++++++++ 1 file changed, 12 insertions(+)