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Avoid PHI - PHI recurrence in vectorization

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The reported regression of libgomp loop-14.C shows that there isn't
generally a good reliable place to insert the permute upfront so
the following simply restricts recurrence vectorization to the cases
where the latch value isn't defined by a PHI.

	* tree-vect-loop.cc (vect_phi_first_order_recurrence_p):
	Disallow latch PHI defs.
	(vectorizable_recurr): Revert previous change.
This commit is contained in:
Richard Biener 2022-10-20 11:04:21 +02:00
parent c7ebee2378
commit 5362b5cc8d
1 changed files with 3 additions and 8 deletions
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11
gcc/tree-vect-loop.cc
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@ -543,6 +543,7 @@ vect_phi_first_order_recurrence_p (loop_vec_info loop_vinfo, class loop *loop,
tree ldef = PHI_ARG_DEF_FROM_EDGE (phi, latch);
if (TREE_CODE (ldef) != SSA_NAME
|| SSA_NAME_IS_DEFAULT_DEF (ldef)
|| is_a <gphi *> (SSA_NAME_DEF_STMT (ldef))
|| !flow_bb_inside_loop_p (loop, gimple_bb (SSA_NAME_DEF_STMT (ldef))))
return false;
@ -8486,14 +8487,8 @@ vectorizable_recurr (loop_vec_info loop_vinfo, stmt_vec_info stmt_info,
vectorized the latch definition. */
edge le = loop_latch_edge (LOOP_VINFO_LOOP (loop_vinfo));
gimple *latch_def = SSA_NAME_DEF_STMT (PHI_ARG_DEF_FROM_EDGE (phi, le));
gimple_stmt_iterator gsi2;
if (is_a <gphi *> (latch_def))
gsi2 = gsi_after_labels (gimple_bb (latch_def));
else
{
gsi2 = gsi_for_stmt (latch_def);
gsi_next (&gsi2);
}
gimple_stmt_iterator gsi2 = gsi_for_stmt (latch_def);
gsi_next (&gsi2);
for (unsigned i = 0; i < ncopies; ++i)
{