Hi,
As PR105940 shown, when rs6000 port tries to assign
m_suggested_unroll_factor by 4 or so, there will be ICE
on below statement:
exact_div (LOOP_VINFO_VECT_FACTOR (loop_vinfo),
loop_vinfo->suggested_unroll_factor);
In function vect_analyze_loop_2, the current place of
suggested_unroll_factor applying can't guarantee it's
applied for all cases. As the case shows, vectorizer
could retry with SLP forced off, the vf is reset by
saved_vectorization_factor which isn't applied with
suggested_unroll_factor before. It means it can end
up with one vf which neglects suggested_unroll_factor.
I think it's off design, we should move the applying
of suggested_unroll_factor after start_over.
Bootstrapped and regtested on x86_64-redhat-linux,
aarch64-linux-gnu and powerpc64{,le}-linux-gnu.
Is it ok for trunk?
BR,
Kewen
-----
PR tree-optimization/105940
gcc/ChangeLog:
* tree-vect-loop.cc (vect_analyze_loop_2): Move the place of
applying suggested_unroll_factor after start_over.
---
gcc/tree-vect-loop.cc | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 896218f23ea..af955d26f8d 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -2393,15 +2393,15 @@ vect_analyze_loop_2 (loop_vec_info loop_vinfo, bool
&fatal,
set of rgroups. */
gcc_assert (LOOP_VINFO_MASKS (loop_vinfo).is_empty ());
+ /* This is the point where we can re-start analysis with SLP forced off. */
+start_over:
+
/* Apply the suggested unrolling factor, this was determined by the backend
during finish_cost the first time we ran the analyzis for this
vector mode. */
if (loop_vinfo->suggested_unroll_factor > 1)
LOOP_VINFO_VECT_FACTOR (loop_vinfo) *= loop_vinfo->suggested_unroll_factor;
- /* This is the point where we can re-start analysis with SLP forced off. */
-start_over:
-
/* Now the vectorization factor is final. */
poly_uint64 vectorization_factor = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
gcc_assert (known_ne (vectorization_factor, 0U));
--
2.27.0
