[PATCH] Fix PR92252

[Richard Biener]

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2019-10-28  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/92252
        * tree-vect-slp.c (vect_get_and_check_slp_defs): Adjust
        STMT_VINFO_REDUC_IDX when swapping operands.

        * gcc.dg/torture/pr92252.c: New testcase.

Index: gcc/tree-vect-slp.c
===================================================================
--- gcc/tree-vect-slp.c (revision 277504)
+++ gcc/tree-vect-slp.c (working copy)
@@ -563,6 +563,10 @@ again:
            {
              swap_ssa_operands (stmt, gimple_assign_rhs2_ptr (stmt),
                                 gimple_assign_rhs3_ptr (stmt));
+             if (STMT_VINFO_REDUC_IDX (stmt_info) == 1)
+               STMT_VINFO_REDUC_IDX (stmt_info) = 2;
+             else if (STMT_VINFO_REDUC_IDX (stmt_info) == 2)
+               STMT_VINFO_REDUC_IDX (stmt_info) = 1;
              bool honor_nans = HONOR_NANS (TREE_OPERAND (cond, 0));
              code = invert_tree_comparison (TREE_CODE (cond), honor_nans);
              gcc_assert (code != ERROR_MARK);
Index: gcc/testsuite/gcc.dg/torture/pr92252.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr92252.c      (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr92252.c      (working copy)
@@ -0,0 +1,23 @@
+/* { do-do compile } */
+/* { dg-additional-options "-ftree-vectorize" } */
+
+long int ar;
+int dt;
+
+long int
+pc (unsigned long int q3, int zw)
+{
+  long int em = 0;
+
+  while (zw < 1)
+    {
+      q3 = zw * 2ul;
+      if (q3 != 0)
+        for (ar = 0; ar < 2; ++ar)
+          em = dt;
+
+      ++zw;
+    }
+
+  return em;
+}