|From:||Abhijit Menon-Sen <ams(at)2ndQuadrant(dot)com>|
|Cc:||Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>|
|Subject:||Re: What exactly is our CRC algorithm?|
|Views:||Raw Message | Whole Thread | Download mbox | Resend email|
Here's a proposed patch to use CPUID at startup to determine if the
SSE4.2 CRC instructions are available, to use them instead of the
slice-by-8 implementation (posted earlier).
A few notes:
1. GCC has included cpuid.h since 4.3.0, so I figured it was safe to
use. It can be replaced with some inline assembly otherwise.
2. I've also used the crc32b/crc32q instructions directly rather than
using ".bytes" to encode the instructions; bintuils versions since
2007 or so have supported them.
3. I've included the MSVC implementation mostly as an example of how to
extend this to different compilers/platforms. It's written according
to the documentation for MSVC intrinsics, but I have not tested it.
Suggestions/improvements are welcome.
|Next Message||David Rowley||2014-12-25 10:35:31||Re: Securing "make check" (CVE-2014-0067)|
|Previous Message||Noah Misch||2014-12-25 05:27:06||Re: Securing "make check" (CVE-2014-0067)|