[llvm-commits] [PATCH] Rework bit/bits value resolving in tblgen

[Michael Liao]

On Thu, 2012-08-30 at 09:45 -0700, Jakob Stoklund Olesen wrote:
> On Aug 30, 2012, at 9:16 AM, Michael Liao <michael.liao at intel.com> wrote:
> 
> > It makes tblgen runs slower. Here my test script
> > 
> >  time llvm-tblgen -I include -I lib/Target/X86 lib/Target/X86/X86.td
> > -o /dev/null (or ARM)
> > 
> > for release build
> >     w/o patch    with patch
> > X86  0.584s        0.665s
> > ARM  0.514s        0.623s
> > 
> > time is measured by selecting the middle one from 3 consecutive runs.
> 
> That's quite significant.
> 
> > VarBitInit reference may contributes the most as the way they are formed
> > in the patch is 'getBit(Init, Bit)' and will result in more duplicated
> > value resolving.
> 
> We already have way too much redundant resolving going on, and I think there is an opportunity to make TableGen a lot faster by fixing it.
> 
> Could I ask you to look at that? I'd rather not make it worse.

Sure, I will look into it to get better performance.

Yours
- Michael

> 
> /jakob
>