http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50596
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-10-05 07:10:56 UTC --- Until http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=176563 float a[1024], b[1024], c[1024], d[1024]; int j[1024]; void foo (void) { int i; for (i = 0; i < 1024; ++i) { int x = a[i] < b[i]; int y = c[i] < d[i]; j[i] = x & c[i] < y; } } didn't use any bool types, just int and float, still it couldn't vectorize: pr50596-2.c:8: note: not vectorized: relevant stmt not supported: x_5 = D.2699_3 < D.2700_4; I think we could use VECT_COND_EXPR <vect1 < vect2, { 1, 1, ...}, { 0, 0, ... }> for that (and hopefully the backends optimize that well, e.g. into anding the comparison mask with { 1, 1, ... } or doing per-element right shift by element width - 1 on the mask. With bool it would be nice if at least for non-stores we would pick the best suitable wider integer vector type (in this case where the bools are set by comparison operation and feed & that is afterwards cast to int the best is obviously int vector).
