[gcc/devel/c++-modules] tree-optimization/95295 - fix wrong-code with SM

[Nathan Sidwell]

https://gcc.gnu.org/g:4acca1c0635dfa43cd8c4bfe2b22e17909fc23a3

commit 4acca1c0635dfa43cd8c4bfe2b22e17909fc23a3
Author: Richard Biener <rguenther@suse.de>
Date:   Mon May 25 10:09:44 2020 +0200

    tree-optimization/95295 - fix wrong-code with SM
    
    We failed to compare the rematerialized store values when merging
    paths after walking PHIs.
    
    2020-05-25  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/95295
            * tree-ssa-loop-im.c (sm_seq_valid_bb): Compare remat stores
            RHSes and drop to full sm_other if they are not equal.
    
            * gcc.dg/torture/pr95295-1.c: New testcase.
            * gcc.dg/torture/pr95295-2.c: Likewise.
            * gcc.dg/torture/pr95283.c: Likewise.

Diff:
---
 gcc/ChangeLog                            |  6 ++++++
 gcc/testsuite/ChangeLog                  |  7 +++++++
 gcc/testsuite/gcc.dg/torture/pr95283.c   | 19 +++++++++++++++++++
 gcc/testsuite/gcc.dg/torture/pr95295-1.c | 15 +++++++++++++++
 gcc/testsuite/gcc.dg/torture/pr95295-2.c | 14 ++++++++++++++
 gcc/tree-ssa-loop-im.c                   |  8 ++++++++
 6 files changed, 69 insertions(+)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1e037dabe49..150dc096c7a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/95295
+	* tree-ssa-loop-im.c (sm_seq_valid_bb): Compare remat stores
+	RHSes and drop to full sm_other if they are not equal.
+
 2020-05-25  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/95271
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index abe0f32be3e..cba153f166e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2020-05-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/95295
+	* gcc.dg/torture/pr95295-1.c: New testcase.
+	* gcc.dg/torture/pr95295-2.c: Likewise.
+	* gcc.dg/torture/pr95283.c: Likewise.
+
 2020-05-25  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/95271
diff --git a/gcc/testsuite/gcc.dg/torture/pr95283.c b/gcc/testsuite/gcc.dg/torture/pr95283.c
new file mode 100644
index 00000000000..950d3b07ead
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr95283.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+
+short c;
+_Bool d;
+unsigned e, f;
+char g, h;
+extern _Bool i[];
+void j()
+{
+  for (char a = 0; a < 100; a++)
+    for (char b = 0; b < 20; b += 2)
+      {
+	if (e)
+	  d = f = 0;
+	else
+	  g = i[8] = 0;
+	h = c;
+      }
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr95295-1.c b/gcc/testsuite/gcc.dg/torture/pr95295-1.c
new file mode 100644
index 00000000000..76a19f3d17b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr95295-1.c
@@ -0,0 +1,15 @@
+/* { dg-do run } */
+/* { dg-additional-sources "pr95295-2.c" } */
+
+extern int var_4, a;
+extern unsigned var_9;
+extern short arr_272[];
+void test()
+{
+  for (int b = 0; b < 9; b++)
+    for (int c = 0; c < 9; c += 4)
+      {
+	arr_272[c] = var_9 ? var_4 : 0;
+	a = 0;
+      }
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr95295-2.c b/gcc/testsuite/gcc.dg/torture/pr95295-2.c
new file mode 100644
index 00000000000..80caeb8740d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr95295-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+
+int a;
+int var_4 = 1;
+unsigned var_9 = 8;
+short arr_272[20];
+void test();
+int main()
+{
+  test();
+  if (arr_272[4] != 1)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index fcca099355a..b399bd0f729 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -2402,6 +2402,7 @@ sm_seq_valid_bb (class loop *loop, basic_block bb, tree vdef,
 		      if (edge_seq[i].second == sm_ord)
 			bitmap_set_bit (refs_not_supported, edge_seq[i].first);
 		      first_edge_seq[i].second = sm_other;
+		      first_edge_seq[i].from = NULL_TREE;
 		    }
 		  /* sm_other prevails.  */
 		  else if (first_edge_seq[i].second != edge_seq[i].second)
@@ -2410,7 +2411,14 @@ sm_seq_valid_bb (class loop *loop, basic_block bb, tree vdef,
 		      gcc_assert (bitmap_bit_p (refs_not_supported,
 						first_edge_seq[i].first));
 		      first_edge_seq[i].second = sm_other;
+		      first_edge_seq[i].from = NULL_TREE;
 		    }
+		  else if (first_edge_seq[i].second == sm_other
+			   && first_edge_seq[i].from != NULL_TREE
+			   && (edge_seq[i].from == NULL_TREE
+			       || !operand_equal_p (first_edge_seq[i].from,
+						    edge_seq[i].from, 0)))
+		    first_edge_seq[i].from = NULL_TREE;
 		}
 	      /* Any excess elements become sm_other since they are now
 		 coonditionally executed.  */