http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51074
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-10 13:47:47 UTC --- Created attachment 25784 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25784 gcc47-pr51074.patch Folding patch. For __builtin_shuffle it works well. For the interleaved stores of addresses like: char *a[1024]; extern char b[]; void foo () { int i; for (i = 0; i < 1024; i += 16) { a[i] = b + 1; a[i + 15] = b + 2; a[i + 1] = b + 3; a[i + 14] = b + 4; a[i + 2] = b + 5; a[i + 13] = b + 6; a[i + 3] = b + 7; a[i + 12] = b + 8; a[i + 4] = b + 9; a[i + 11] = b + 10; a[i + 5] = b + 11; a[i + 10] = b + 12; a[i + 6] = b + 13; a[i + 9] = b + 14; a[i + 7] = b + 15; a[i + 8] = b + 16; } } it doesn't help, I'd need to do something like: --- tree-ssa-propagate.c.jj 2011-09-29 14:25:46.000000000 +0200 +++ tree-ssa-propagate.c 2011-11-10 14:33:55.923268422 +0100 @@ -610,6 +610,8 @@ valid_gimple_rhs_p (tree expr) return false; case tcc_exceptional: + if (code == CONSTRUCTOR && TREE_CODE (TREE_TYPE (expr)) == VECTOR_TYPE) + break; if (code != SSA_NAME) return false; break; but that isn't helpful either (because it puts the vector CONSTRUCTOR inside of loop and thus prevents vectorization - is expanded piecewise).