[bug #30821] Support new SSE 4.2 string searching instructions?

[Nick Welch]

URL:
  <http://savannah.gnu.org/bugs/?30821>

                 Summary: Support new SSE 4.2 string searching instructions?
                 Project: grep
            Submitted by: mackstann
            Submitted on: Thu 19 Aug 2010 05:17:51 PM GMT
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

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Details:

Here is an implementation of strstr using these new instructions:
<http://www.strchr.com/strcmp_and_strlen_using_sse_4.2> (you actually might
not actually want to read the code if you plan on implementing this, as it
does not appear to be made available under a free license)

It could possibly provide a performance boost in i3/i5/i7 and subsequent
CPUs.  Right now that might limit its usefulness, but after a few years I'm
sure SSE 4.2 support should be a lot more widespread.

The Boyer-Moore and other algorithms(?) grep uses might end up being faster
anyway, so this would definitely be an experiment.  I also don't know if GNU
or the grep maintainers have philosophical problems with implementing
CPU-specific assembly code like these, but I figured it was at least worth
mentioning.




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