From: Richard Biener <rguenther@suse.de>
Date: Wed, 16 Jun 2021 07:49:18 +0000 (+0200)
Subject: tree-optimization/101088 - fix SM invalidation issue
X-Git-Tag: releases/gcc-11.2.0~106
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=91fc9610464281bb28e3c6529399fdcfb57fa812;p=thirdparty%2Fgcc.git

tree-optimization/101088 - fix SM invalidation issue

When we face a sm_ord vs sm_unord for the same ref during
store sequence merging we assert that the ref is already marked
unsupported.  But it can be that it will only be marked so
during the ongoing merging so instead of asserting mark it here.

Also apply some optimization to not waste resources to search
for already unsupported refs.

2021-06-16  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/101088
	* tree-ssa-loop-im.c (sm_seq_valid_bb): Only look for
	supported refs on edges.  Do not assert same ref but
	different kind stores are unsuported but mark them so.
	(hoist_memory_references): Only look for supported refs
	on exits.

	* gcc.dg/torture/pr101088.c: New testcase.

(cherry picked from commit 43fc4234ad3d9302d3460385b6fdb5e3f59b6986)
---

diff --git a/gcc/testsuite/gcc.dg/torture/pr101088.c b/gcc/testsuite/gcc.dg/torture/pr101088.c
new file mode 100644
index 000000000000..00fce39d2f4f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr101088.c
@@ -0,0 +1,45 @@
+/* { dg-do compile } */
+
+int bh, on, h0;
+
+void
+qw (int n2)
+{
+  int *e5;
+
+  if (n2 == 0)
+    {
+      n2 = 1;
+      while (n2 != 0)
+	for (n2 = 0; n2 < 1; ++n2)
+	  {
+	  }
+
+      e5 = &n2;
+    }
+  else
+    e5 = &on;
+
+  while (h0 < 1)
+    {
+      if (on == 0)
+	{
+	  ++*e5;
+	  bh = 0;
+	}
+      else
+	{
+	  bh = 0;
+	  ++on;
+	  *e5 = on;
+	  h0 = *e5;
+	  if (h0 == 0)
+	    {
+	      *e5 = 0;
+	      ++h0;
+	    }
+	}
+
+      ++h0;
+    }
+}
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index 1c865b28fd65..7de47edbcb30 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -2340,7 +2340,13 @@ sm_seq_valid_bb (class loop *loop, basic_block bb, tree vdef,
 	      tree vuse = gimple_phi_arg_def (phi, i);
 	      edge e = gimple_phi_arg_edge (phi, i);
 	      auto_vec<seq_entry> edge_seq;
-	      bitmap_copy (tem_refs_not_in_seq, refs_not_in_seq);
+	      bitmap_and_compl (tem_refs_not_in_seq,
+				refs_not_in_seq, refs_not_supported);
+	      /* If we've marked all refs we search for as unsupported
+		 we can stop processing and use the sequence as before
+		 the PHI.  */
+	      if (bitmap_empty_p (tem_refs_not_in_seq))
+		return 1;
 	      eret = sm_seq_valid_bb (loop, e->src, vuse, edge_seq,
 				      tem_refs_not_in_seq, refs_not_supported,
 				      true, fully_visited);
@@ -2379,9 +2385,9 @@ sm_seq_valid_bb (class loop *loop, basic_block bb, tree vdef,
 		  /* sm_other prevails.  */
 		  else if (first_edge_seq[i].second != edge_seq[i].second)
 		    {
-		      /* This is just an optimization.  */
-		      gcc_assert (bitmap_bit_p (refs_not_supported,
-						first_edge_seq[i].first));
+		      /* Make sure the ref is marked as not supported.  */
+		      bitmap_set_bit (refs_not_supported,
+				      first_edge_seq[i].first);
 		      first_edge_seq[i].second = sm_other;
 		      first_edge_seq[i].from = NULL_TREE;
 		    }
@@ -2533,7 +2539,12 @@ hoist_memory_references (class loop *loop, bitmap mem_refs,
       vec<seq_entry> seq;
       seq.create (4);
       auto_bitmap refs_not_in_seq (&lim_bitmap_obstack);
-      bitmap_copy (refs_not_in_seq, mem_refs);
+      bitmap_and_compl (refs_not_in_seq, mem_refs, refs_not_supported);
+      if (bitmap_empty_p (refs_not_in_seq))
+	{
+	  seq.release ();
+	  break;
+	}
       auto_bitmap fully_visited;
       int res = sm_seq_valid_bb (loop, e->src, NULL_TREE,
 				 seq, refs_not_in_seq,