[llvm-commits] PATCH: Teach the x86 backend to fold mask & shift patterns into an addressing mode computation

Chandler Carruth chandlerc at gmail.com
Tue Jan 10 16:38:28 PST 2012

On Tue, Jan 10, 2012 at 2:46 PM, Jakob Stoklund Olesen <stoklund at 2pi.dk>wrote:

> On Jan 10, 2012, at 11:14 AM, Chandler Carruth wrote:
> > Anyone else have comments?
> Did you actually see code run faster?
> Simple addressing modes (base+offset) can be faster on Sandy Bridge, for
> example.

Yes, as mentioned in my original message, I'm seeing noticable gains in the
hot loop of Snappy. I can benchmark it and some other software and report
more detailed performance numbers (and I'll do so either before or after
the commit, either way)

It's a bit hard to accurately measure the impact though, as there are more
bugs I've fixed in subsequent patches that prevent this (and other)
transformations from always firing on x86-64 compiles...
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