tree-optimization/95295 - fix sinking after path merging in new SM code

This fixes a missed sinking of remat stores across unrelated stores
after merging from different paths.

2020-05-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/95295
	* tree-ssa-loop-im.c (sm_seq_valid_bb): Fix sinking after
	merging stores from paths.

	* gcc.dg/torture/pr95295-3.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/torture/pr95295-3.c b/gcc/testsuite/gcc.dg/torture/pr95295-3.c
new file mode 100644 (file)
index 0000000..a506af9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr95295-3.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+extern short var_15, var_20;
+extern int var_18, var_21, var_23;
+extern _Bool arr_2[];
+extern long arr_3[];
+void test()
+{
+  var_20 = 1;
+  for (int a = 0; a < 12; a += 2)
+    for (short b = 0; b < 8; b += 2) {
+      arr_2[b] = var_21 = var_18 ? var_15 : 0;
+      arr_3[b] = 8569;
+    }
+  var_23 = -1096835496;
+}

diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index b399bd0..d33f533 100644 (file)
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -2447,12 +2447,16 @@ sm_seq_valid_bb (class loop *loop, basic_block bb, tree vdef,
              unsigned id = first_edge_seq[i].first;
              seq.safe_push (first_edge_seq[i]);
              unsigned new_idx;
-             if (first_edge_seq[i].second == sm_ord
+             if ((first_edge_seq[i].second == sm_ord
+                  || (first_edge_seq[i].second == sm_other
+                      && first_edge_seq[i].from != NULL_TREE))
                  && !sm_seq_push_down (seq, seq.length () - 1, &new_idx))
                {
-                 bitmap_set_bit (refs_not_supported, id);
+                 if (first_edge_seq[i].second == sm_ord)
+                   bitmap_set_bit (refs_not_supported, id);
                  /* Mark it sm_other.  */
                  seq[new_idx].second = sm_other;
+                 seq[new_idx].from = NULL_TREE;
                }
            }
          return 1;