------- Comment #19 from michael dot meissner at amd dot com 2005-10-04 20:35 ------- Subject: RE: variable rotate and long long rotate should be better optimized
I almost forgot, kernels should be using -mno-mmx and -mno-sse as a matter of course (or -msoft-float). I first ran into this problem in 1990 when I was supporting the MIPS platform, and the kernel guys were surprised that the compiler would use the double precision registers to do block copies, since it could double the bandwidth of doing 32-bit moves. -----Original Message----- From: ak at muc dot de [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 04, 2005 4:20 PM To: Meissner, Michael Subject: [Bug middle-end/17886] variable rotate and long long rotate should be better optimized ------- Comment #17 from ak at muc dot de 2005-10-04 20:20 ------- The code now looks fine to me thanks I would prefer if it didn't generate SSE2/MMX code because that would be a problem for kernels. Also in many x86 implementations moving things between normal integer registers and SIMD registers is quite slow and would likely eat all advantages -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17886
