This patch adds target combine rules to match:
- [AVX] Horizontal add/sub of packed single/double precision floating point
values from 256-bit vectors;
- [AVX2] Horizontal add/sub of packed integer values from 256-bit vectors.
llvm-svn: 210761
This patch moves part of the logic implemented by the target specific
combine rules added at r210477 to a separate helper function.
This should make easier to add more rules for matching AVX/AVX2 horizontal
adds/subs.
This patch also fixes a problem caused by a wrong check performed on indices
of extract_vector_elt dag nodes in input to the scalar adds/subs.
New tests have been added to verify that we correctly check indices of
extract_vector_elt dag nodes when selecting a horizontal operation.
llvm-svn: 210644
This patch slightly changes the algorithm introduced at revision 210477
to fix a problem where the algorithm was producing incorrect code for
the VEX.256 encoded versions of horizontal add/sub.
For these cases, we now try to split the two 256-bit vectors into
128-bit chunks before emitting horizontal add/sub dag nodes.
Added a new test case into haddsub-2.ll.
llvm-svn: 210545
This patch adds new target specific combine rules to identify horizontal
add/sub idioms from BUILD_VECTOR dag nodes.
This patch also teaches the DAGCombiner how to canonicalize sequences of
insert_vector_elt dag nodes according to the following rule:
(insert_vector_elt (insert_vector_elt A, I0), I1) ->
(insert_vecto_elt (insert_vector_elt A, I1), I0)
This new canonicalization rule only triggers if the inner insert_vector
dag node has exactly one use; also, both indices must be known constants,
and I1 < I0.
This last rule made it possible to write a simpler algorithm to identify
horizontal add/sub patterns because now we don't have to worry about the
ordering of insert_vector_elt dag nodes.
llvm-svn: 210477
Sanjay Patel