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Re: [PATCH] Support VMX128 Instruction for PowerPC
Segher Boessenkool wrote:
>> The attached patches add support for the VMX128 altivec instructions
>> found on e.g. the Xenon CPU. (These are altivec instructions for a
>> register set of 128 vector registers).
>
> Nice!
>
>> You can find a documentation here:
>> http://wiki.free60.org/Xenon/VMX128
>
> Has this been checked against the official documentation,
> too?
Nope, I don't have access to the official documentation and I guess you
have to sign an NDA or something to get it. I figured this out by
looking at dumpbin outputs some (not to be named) person created for me.
But my opcode list is exhaustive and perfectly matches the output of
dumpbin.
>> The patch is not invasive, but I'm not sure whether there should be an
>> option to enable/disable the extended instruction set. Comments welcome.
>
> Yes there should be such an option, VMX128 isn't part of
> the architecture.
Ok, but I'm a little bit unsure how the configuration stuff works.
Should there an option like "-mxenon" which resembles the xenon cpu or
should there be a modifier like "-mvmx128" which selectively actives the
VMX128 instruction set?
>> +/* Opcode is supported by Altivec Vector128 Unit */
>
> AltiVec (note spelling) is not the right name; it is
> called VMX128. AltiVec is the (trademarked) FreeScale
> name for VMX; not for VMX128.
Ok. So, maybe for consistency reasons we should rename
PPC_OPCODE_ALTIVEC to PPC_OPCODE_VMX? The VMX and VMX128 instructions
are not mutually exclusive, you can mix them (but only the VMX128 give
you access to vr32-vr127).
BTW: I also noticed that I (or my editor) misplaced some tabs. I'll
clean them up in the next version.