On 2012-12-07 02:49, Marc Glisse wrote:
For 2-element vectors, vec_concat does seem more natural than
vec_merge. If we chose vec_merge as the canonical representation, we
should chose it for setting an element in a vector
(ix86_expand_vector_set) everywhere, not just those scalarish
operations.
I'd hate to enshrine vec_merge over vec_concat for the benefit of x86,
and to the detriment of e.g. mips. There are plenty of embedded simd
implementations that are V2xx only.
If we simply pull the various x86 patterns into one common form, set
and extract included, does that buy us most of what we'd get for
playing games in combine?