On Sun, 9 Sep 2012, Marc Glisse wrote:
Hello,
this patch lets the compiler try to rewrite:
(vec_concat (vec_select x [a]) (vec_select x [b]))
as:
vec_select x [a b]
or even just "x" if appropriate.
In a first iteration I was restricting it to b-a==1, but it seemed better not
to: it helps for {v[1],v[0]} and doesn't change anything for unknown
patterns.
Note that I am planning to do a similar optimization at tree level, but it
shouldn't make this one useless because such patterns can be created during
rtl passes. The testcase may need an additional -fno-tree-xxx to still be
useful at that point though.
Since the tree-ssa patch was reviewed faster, assume there is a
-fno-tree-forwprop in dg-options for the testcase.
bootstrap+testsuite on x86_64-linux-gnu.
2012-09-09 Marc Glisse <marc.gli...@inria.fr>
gcc/
* simplify-rtx.c (simplify_binary_operation_1): Handle vec_concat
of vec_selects from the same vector.
gcc/testsuite/
* gcc.target/i386/vect-rebuild.c: New testcase.
http://gcc.gnu.org/ml/gcc-patches/2012-09/msg00540.html
--
Marc Glisse
