4 ms·

GCC vectorizes the sum fine if the input is unsigned bytes, cf [1]. My guess is some odd interaction between integer promotions and the backend. [1] http://goo

by pbsd 12y ago

GCC vectorizes the sum fine if the input is unsigned bytes, cf [1]. My guess is some odd interaction between integer promotions and the backend. [1] http://goo.gl/B7KX1V http://goo.gl/B7KX1V

deleted 12y ago
[deleted]
detrino 12y ago
I think it's just the type of the accumulator[1] that influences this, GCC seems to vectorize it fine for any type other than signed char/signed short. [1] s in your code, result in the author's Edit: The reason for the failure appears to be this: test.c:7:2: note: reduction: not commutative/associative: s_11 = (int8_t) _10; Edit: GCC vectorizes this fine when compiling with -fwrapv, which gives you the semantics the author probably expected.
jxf 12y ago
This link seems to be breaking the HN comments for this page. :)
- dbaupp 12y ago
  It's a shortened link (because the true link is so long, as you discovered), maybe you have a browser extension that expands them?
  - jxf 12y ago
    Ah, you're right, I do (Tactical URL Expander for Chrome)! That'd sure explain it.