1 Dec
2011
1 Dec
'11
4:55 p.m.
Le 2011-12-01 à 07:00:00, Jonathan Wilkes a écrit :
After looking at d_arithmetic.c, I'm curiouswhy there is scalartimes_perform and scalartimes_perf8?
One is made for blocksizes at least 8, and the other for blocksizes 1,2,4.
Perf8 is a kind of explicit loop-unrolling, coded to greatly reduce the number of conditional jumps when looping a lot on tight loops. Conditional jumps are extremely slow on modern CPUs, and this affects if/else/for/do/while/switch as well as function pointers and virtual function calls.
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