[MPlayer-dev-eng] [PATCH] fast_cmov should be set on x86_64
Reimar.Doeffinger at stud.uni-karlsruhe.de
Wed Dec 24 10:55:37 CET 2008
On Wed, Dec 24, 2008 at 05:47:54PM +0800, Zuxy Meng wrote:
> 2008/12/23 Reimar Döffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de>:
> > Index: configure
> > ===================================================================
> > --- configure (revision 28181)
> > +++ configure (working copy)
> > @@ -1935,6 +1938,7 @@
> > else
> > cpuopt=-mcpu
> > fi
> > + test $_fast_cmov = "auto" && _fast_cmov=yes
> > if test "$_runtime_cpudetection" = no ; then
> > case "$pvendor" in
> > AuthenticAMD)
> > @@ -1946,7 +1950,6 @@
> > # 64-bit prescotts exist, but as far as GCC is concerned they
> > # have the same capabilities as a nocona.
> > proc=nocona
> > - test $_fast_cmov = "auto" && _fast_cmov=no
> > ;;
> > esac
> > ;;
> Hmmm so we don't care for those who bought a 64-bit P4.
At the expense of everyone else who made sane buying decisions?
Also even Intel recommends to use cmov if in doubt, so if even Intel
thinks it best :-P.
If you know how and have the motivation to extend the check to disable
fast_cmov on P4 _and only_ on P4, I'm happy.
Something like this might work, but I doubt it catches all (and I
suspect that some of those cases are missing from the 32 bit case as
--- configure (revision 28186)
+++ configure (working copy)
@@ -1937,7 +1938,6 @@
- test $_fast_cmov = "auto" && _fast_cmov=yes
if test "$_runtime_cpudetection" = no ; then
case "$pvendor" in
@@ -1945,6 +1945,9 @@
case "$pfamily" in
+ 15) proc=nocona
+ test $_fast_cmov = "auto" && _fast_cmov=no
# 64-bit prescotts exist, but as far as GCC is concerned they
# have the same capabilities as a nocona.
@@ -1956,6 +1959,7 @@
fi # test "$_runtime_cpudetection" = no
+ test $_fast_cmov = "auto" && _fast_cmov=yes
echocheck "GCC & CPU optimization abilities"
cat > $TMPC << EOF
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