[LLVMdev] TableGen !eq() Operator Patch

[Chris Lattner]

On Jan 5, 2010, at 9:59 AM, David Greene wrote:

> Attached is a patch to implement an !eq() operator in TableGen.  We  
> use this
> for the AVX specification to allow the user to control what kind of  
> pattern
> should be used for a particular instruction def.  For example, we  
> use it for
> reg-mem instructions to let the user choose between a built-in  
> generic reg-mem
> pattern, the same pattern that was used for the reg-reg variant of the
> instruction or a custom pattern provided by the user.
>
> It only operates on strings.
>
> An alternative to this would be to implement named parameters in  
> TableGen but
> that seems like overkill for this case.  Named parameters could be  
> useful in
> other areas to reduce template complexity but implementing it is non- 
> trivial
> given the widespread assumption in the TableGen sources that template
> parameters exactly match up with template arguments.

I can't say if this is really the best answer for AVX, but  
independently of that the patch looks great, please commit.

-Chris