[Bug tree-optimization/53726] [4.8 Regression] aes test performance drop for eembc_2_0_peak_32

rguenth at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Wed Jun 20 15:10:00 GMT 2012


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53726

--- Comment #16 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-20 15:09:46 UTC ---
What we could do for the case in question is look at the maximum possible
value of c, derived from number-of-iteration analysis which should tell
us 8 because of the size of the tem array.

But I am not sure if a good library implementation shouldn't be always
preferable to a byte-wise copy.  We could, at least try to envision a way
to retain and use the knowledge that the size is at most 8 when expanding
the memcpy (with AVX we could use a masked store for example - quite fancy).



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