Tom Lane wrote:
> Alan Stange <stange@rentec.com> writes:
>
>> Check out the comment and implementation for cas32() in this .il
>> template file for libc from OpenSolaris:
>>
>
>
>> http://cvs.opensolaris.org/source/xref/on/usr/src/lib/libc/sparc/threads/sparc.il
>>
>
> If you mean
>
> * When compiling with -xarch=v8, the compiler refuses to
> * accept the 'cas' instruction, so we encode it in hex below.
>
> I can't say that that impresses me. It still will fail on v8 chips no?
> What's the point of fooling the compiler if you can't fool the hardware?
I believe the trick here is that Solaris 10 will only run on v9 hardware
(or the sun4u systems), which all have the instruction. But the v8 ABI
"model" doesn't have it. So, in some sense the ABI doesn't "allow"
this instruction, but the hardware does, so they can just slam it in
knowing that it'll work.
-- Alan