This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
[PATCH] Fix PR91896
- From: Richard Biener <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Wed, 25 Sep 2019 12:48:09 +0200 (CEST)
- Subject: [PATCH] Fix PR91896
Removing operand swapping for reduction vectorization has enabled
more pattern recognition which in turn triggers a latent bug
in reduction vectorization.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
Richard.
2019-09-25 Richard Biener <rguenther@suse.de>
PR tree-optimization/91896
* tree-vect-loop.c (vectorizable_reduction): The single
def-use cycle optimization cannot apply when there's more
than one pattern stmt involved.
* gcc.dg/torture/pr91896.c: New testcase.
Index: gcc/testsuite/gcc.dg/torture/pr91896.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr91896.c (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr91896.c (working copy)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-ftree-vectorize" } */
+
+unsigned int
+zj (unsigned int et)
+{
+ signed char jr = 0;
+
+ do {
+ et *= 3;
+ jr += 2;
+ } while (jr >= 0);
+
+ if (et == (unsigned int) jr)
+ et = 0;
+
+ return et;
+}
Index: gcc/tree-vect-loop.c
===================================================================
--- gcc/tree-vect-loop.c (revision 276120)
+++ gcc/tree-vect-loop.c (working copy)
@@ -6101,6 +6101,8 @@ vectorizable_reduction (stmt_vec_info st
if (ncopies > 1
&& STMT_VINFO_RELEVANT (reduc_stmt_info) <= vect_used_only_live
&& (use_stmt_info = loop_vinfo->lookup_single_use (phi_result))
+ && (!STMT_VINFO_IN_PATTERN_P (use_stmt_info)
+ || !STMT_VINFO_PATTERN_DEF_SEQ (use_stmt_info))
&& vect_stmt_to_vectorize (use_stmt_info) == reduc_stmt_info)
single_defuse_cycle = true;
@@ -6868,6 +6870,8 @@ vectorizable_reduction (stmt_vec_info st
if (ncopies > 1
&& (STMT_VINFO_RELEVANT (stmt_info) <= vect_used_only_live)
&& (use_stmt_info = loop_vinfo->lookup_single_use (reduc_phi_result))
+ && (!STMT_VINFO_IN_PATTERN_P (use_stmt_info)
+ || !STMT_VINFO_PATTERN_DEF_SEQ (use_stmt_info))
&& vect_stmt_to_vectorize (use_stmt_info) == stmt_info)
{
single_defuse_cycle = true;