On Thu, Dec 25, 2014 at 11:57:29AM +0530, Abhijit Menon-Sen wrote: > Hi. > > 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.
Uh, what happens if the system is compiled on a different CPU that it is run on? Seems we would need a run-time CPU test. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers