[PATCH] Don't check for optab for 16bit bswap

[Thomas Preud'homme]

> From: Richard Henderson [mailto:rth@redhat.com]
> Sent: Friday, January 23, 2015 2:43 AM
> On 01/21/2015 11:52 PM, Richard Biener wrote:
> >
> > I was asking for the generic expander to consider bswapHI.  Rotates are
> > certainly more likely to get combined with sth else.
> 
> Maybe.  Alternately, don't we canonicalize byte-swapping memory ops
> as
> 
>  (set (reg:HI) (bswap:HI (mem:HI)))
> 
>  (set (mem:HI) (bswap:HI (reg:HI)))

Given the expmed.c bit I pasted, I'd say that's how it would be canonicalized
in RTL form yes. I think Richard was referring to combination at GIMPLE level
but that expander should expand to bswapHI to not break expectations.

Best regards,

Thomas