/hg/icedtea6: S7032388, PR682: Make HotSpot work on machines wit...

[Pavel Tisnovsky]

Matthias Klose wrote:
> On 31.03.2011 16:34, andrew at icedtea.classpath.org wrote:
>> changeset 64437a39a9c8 in /hg/icedtea6
>> details: http://icedtea.classpath.org/hg/icedtea6?cmd=changeset;node=64437a39a9c8
>> author: Andrew John Hughes <ahughes at redhat.com>
>> date: Thu Mar 31 15:34:49 2011 +0100
>>
>> 	S7032388, PR682: Make HotSpot work on machines without cmov
>> 	instruction again
>>
>> 	2011-03-31 Andrew John Hughes <ahughes at redhat.com>
>>
>> 	 S7032388, PR682: Make HotSpot work on machines without
>> 	cmov instruction again
>> 		* Makefile.am: Add new patch.
>> 		* NEWS: Mention patch.
>> 		* patches/hotspot/hs20/7032388-work_without_cmov_instruction.patch,
>> 		* patches/hotspot/original/7032388-work_without_cmov_instruction.patch
>> 	: Versions of patch for each HotSpot version.
> 
> does this have a performance impact?

It depends ;-) If this patch only replaces CMOV instruction by a
conditional jump (over regular MOV), it could be faster on some
processors and faster on older ones:

http://ondioline.org/mail/cmov-a-bad-idea-on-out-of-order-cpus