Re: [PATCH] optimize bitmap_bit_p + bitmap_{clear,set}_bit

[Nathan Froyd <froydnj at codesourcery dot com>]

On Thu, Aug 19, 2010 at 12:51:54PM -0700, Mark Mitchell wrote:
> >> This patch does the same thing for (nearly) all other relevant calls to
> >> bitmap_bit_p.  I might have missed a couple and I think there were one
> >> or two that looked particularly tricky to untangle, so I left them
> >> as-is.
> 
> I like this patch just for the fact that it simplifies use of the API,
> in addition to the fact that it should theoretically be a bit faster.
> Out of curiosity, did you measure any speedup?

I didn't try; I figured Honza would have caught any hotspots with his
earlier patch.  This was more of a fit-and-finish sort of patch.

Since you asked, though...

Eyeballing a callgrind profile taken while compiling a reasonably large
C++ file indicates that all of the callsites modified are in the noise.
The biggest callers of bitmap_bit_p are in the DF code and SSA updating.
None of them are amenable to the transformation used in the patch.

-Nathan