This improves code generation with SSE2 for the testcase by
making sure to only generate a single IV when the group size
is a multiple of the vector size. It also adjusts the testcase
which was passing before.
Bootstrapped / tested on x86_64-unknown-linux-gnu, pushed.
2020-05-20 Richard Biener <rguent...@suse.de>
PR tree-optimization/95219
* tree-vect-loop.c (vectorizable_induction): Reduce
group_size before computing the number of required IVs.
* gcc.dg/vect/costmodel/x86_64/costmodel-pr30843.c: Adjust.
---
.../gcc.dg/vect/costmodel/x86_64/costmodel-pr30843.c | 4 +++-
gcc/tree-vect-loop.c | 14 +++++++++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-pr30843.c
b/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-pr30843.c
index 257d098cf8b..9a75b987d6d 100644
--- a/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-pr30843.c
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-pr30843.c
@@ -20,4 +20,6 @@ void dacP98FillRGBMap (unsigned char *pBuffer)
}
}
-/* { dg-final { scan-tree-dump-times "vectorization not profitable" 1 "vect" {
target vect_interleave } } } */
+/* Even with SSE2 we should only generate one IV for the induction. */
+/* { dg-final { scan-tree-dump-times "# vect_vec_iv" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index f065acc12f5..ecce348b39c 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -7528,7 +7528,13 @@ vectorizable_induction (loop_vec_info loop_vinfo,
unsigned group_size = SLP_TREE_SCALAR_STMTS (slp_node).length ();
unsigned nvects = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
unsigned elts = const_nunits * nvects;
- unsigned nivs = least_common_multiple (group_size,
+ /* Compute the number of distinct IVs we need. First reduce
+ group_size if it is a multiple of const_nunits so we get
+ one IV for a group_size of 4 but const_nunits 2. */
+ unsigned group_sizep = group_size;
+ if (group_sizep % const_nunits == 0)
+ group_sizep = group_sizep / const_nunits;
+ unsigned nivs = least_common_multiple (group_sizep,
const_nunits) / const_nunits;
gcc_assert (elts % group_size == 0);
tree elt = init_expr;
@@ -7576,6 +7582,12 @@ vectorizable_induction (loop_vec_info loop_vinfo,
SLP_TREE_VEC_STMTS (slp_node).quick_push (induction_phi_info);
}
+ /* Fill up to the number of vectors we need for the whole group. */
+ nivs = least_common_multiple (group_size,
+ const_nunits) / const_nunits;
+ for (; ivn < nivs; ++ivn)
+ SLP_TREE_VEC_STMTS (slp_node)
+ .quick_push (SLP_TREE_VEC_STMTS (slp_node)[0]);
/* Re-use IVs when we can. */
if (ivn < nvects)
--
2.12.3
