Re: [Openexr-devel] Removing register keyword

[Larry Gritz]

Don't let me bully you into removing it, if it really does something useful for 
performance.

But it will eventually disappear from the language, and it already (even in 
C++11 mode, per current VFX Platform specs) is a deprecation warning, which a 
lot of software build defaults intentionally turns into full-fledged errors.

Sorry about the duplicate PR, I should have scanned the list of pending 
requests before submitting.


> On Sep 30, 2016, at 4:37 PM, Ed Hanway <address@hidden> wrote:
> 
> We have multiple pending pull requests to remove the register keyword from 
> the OpenEXR source.  I've looked at the code generated by gcc 4.8 with and 
> without the register keyword, and, despite the claim that compilers don't 
> care about the register keyword any more, the resulting object code for 
> x86-64 is different, and slightly worse without the keyword.  That choice of 
> compiler and platform isn't arbitrary -- it's consistent with the VFX 
> reference platform.  
> 
> However, since the difference is relatively small, and may not be present at 
> all for other compilers and target architectures, and people will keep 
> submitting bugs and pull requests as long as the register keyword is there, 
> I'm inclined to go ahead and remove the keyword anyway.  If anybody is that 
> concerned about a performance regression on the order of a few percent in the 
> half-from-float constructor, speak now or forever hold your peace.
> 
> -- 
> Ed Hanway
> 

--
Larry Gritz
address@hidden