From: Robin Dapp <rdapp@ventanamicro.com>
Date: Fri, 10 Nov 2023 07:56:18 +0000 (+0100)
Subject: vect: Look through pattern stmt in fold_left_reduction.
X-Git-Tag: basepoints/gcc-15~4817
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d7b971cf61ae0091dbc777c9aa056e6f1293da2f;p=thirdparty%2Fgcc.git

vect: Look through pattern stmt in fold_left_reduction.

It appears as if we "look through" a statement pattern in
vect_finish_replace_stmt but not before when we replace the newly
created vector statement's lhs.  Then the lhs is the statement pattern's
lhs while in vect_finish_replace_stmt we assert that it's from the
statement the pattern replaced.

This patch uses vect_orig_stmt on the scalar destination's definition so
the replaced statement is used everywhere.

gcc/ChangeLog:

	PR tree-optimization/112464

	* tree-vect-loop.cc (vectorize_fold_left_reduction): Use
	vect_orig_stmt on scalar_dest_def_info.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr112464.c: New test.
---

diff --git a/gcc/testsuite/gcc.target/i386/pr112464.c b/gcc/testsuite/gcc.target/i386/pr112464.c
new file mode 100644
index 000000000000..2290c7149864
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr112464.c
@@ -0,0 +1,10 @@
+/* { dg-do compile }  */
+/* { dg-options "-Ofast -mavx512dq -ftrapv" } */
+
+long *e;
+int n, i, err;
+void fn() {
+  for (; i < n; i++)
+    if (e[i])
+      err++;
+}
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 8abc1937d740..f61adad1ca3d 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -7087,7 +7087,7 @@ vectorize_fold_left_reduction (loop_vec_info loop_vinfo,
 					 opmask, &vec_opmask);
     }
 
-  gimple *sdef = scalar_dest_def_info->stmt;
+  gimple *sdef = vect_orig_stmt (scalar_dest_def_info)->stmt;
   tree scalar_dest = gimple_get_lhs (sdef);
   tree scalar_type = TREE_TYPE (scalar_dest);
   tree reduc_var = gimple_phi_result (reduc_def_stmt);