Fix tail-merge pass for dead type-unsafe code

2014-11-19  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/62167
	* tree-ssa-tail-merge.c (stmt_local_def): Handle statements with vuse
	conservatively.
	(gimple_equal_p): Don't use vn_valueize to compare for lhs equality of
	assigns.

	* gcc.dg/pr51879-12.c: Add xfails.
	* gcc.dg/pr62167-run.c: New test.
	* gcc.dg/pr62167.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@217761 138bc75d-0d04-0410-961f-82ee72b054a4

6 files changed, 118 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ff9fe1e8b57..9169e354e8e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2014-11-19  Tom de Vries  <tom@codesourcery.com>
+
+	PR tree-optimization/62167
+	* tree-ssa-tail-merge.c (stmt_local_def): Handle statements with vuse
+	conservatively.
+	(gimple_equal_p): Don't use vn_valueize to compare for lhs equality of
+	assigns.
+
 2014-11-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/63915
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 08a6c234acc..35cb09ce4d3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2014-11-19  Tom de Vries  <tom@codesourcery.com>
+
+	PR tree-optimization/62167
+	* gcc.dg/pr51879-12.c: Add xfails.
+	* gcc.dg/pr62167-run.c: New test.
+	* gcc.dg/pr62167.c: New test.
+
 2014-11-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/63915
diff --git a/gcc/testsuite/gcc.dg/pr51879-12.c b/gcc/testsuite/gcc.dg/pr51879-12.c
index 8126505f384..85e2687da17 100644
--- a/gcc/testsuite/gcc.dg/pr51879-12.c
+++ b/gcc/testsuite/gcc.dg/pr51879-12.c
@@ -24,6 +24,6 @@ foo (int y)
   baz (a);
 }
 
-/* { dg-final { scan-tree-dump-times "bar \\(" 1 "pre"} } */
-/* { dg-final { scan-tree-dump-times "bar2 \\(" 1 "pre"} } */
+/* { dg-final { scan-tree-dump-times "bar \\(" 1 "pre" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump-times "bar2 \\(" 1 "pre" { xfail *-*-* } } } */
 /* { dg-final { cleanup-tree-dump "pre" } } */
diff --git a/gcc/testsuite/gcc.dg/pr62167-run.c b/gcc/testsuite/gcc.dg/pr62167-run.c
new file mode 100644
index 00000000000..37214a3ecee
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr62167-run.c
@@ -0,0 +1,47 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -ftree-tail-merge" } */
+
+struct node
+{
+  struct node *next;
+  struct node *prev;
+};
+
+struct node node;
+
+struct head
+{
+  struct node *first;
+};
+
+struct head heads[5];
+
+int k = 2;
+
+struct head *head = &heads[2];
+
+int
+main ()
+{
+  struct node *p;
+
+  node.next = (void*)0;
+
+  node.prev = (void *)head;
+
+  head->first = &node;
+
+  struct node *n = head->first;
+
+  struct head *h = &heads[k];
+
+  heads[2].first = n->next;
+
+  if ((void*)n->prev == (void *)h)
+    p = h->first;
+  else
+    /* Dead tbaa-unsafe load from ((struct node *)&heads[2])->next.  */
+    p = n->prev->next;
+
+  return !(p == (void*)0);
+}
diff --git a/gcc/testsuite/gcc.dg/pr62167.c b/gcc/testsuite/gcc.dg/pr62167.c
new file mode 100644
index 00000000000..f8c31a0792f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr62167.c
@@ -0,0 +1,50 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-tail-merge -fdump-tree-pre" } */
+
+struct node
+{
+  struct node *next;
+  struct node *prev;
+};
+
+struct node node;
+
+struct head
+{
+  struct node *first;
+};
+
+struct head heads[5];
+
+int k = 2;
+
+struct head *head = &heads[2];
+
+int
+main ()
+{
+  struct node *p;
+
+  node.next = (void*)0;
+
+  node.prev = (void *)head;
+
+  head->first = &node;
+
+  struct node *n = head->first;
+
+  struct head *h = &heads[k];
+
+  heads[2].first = n->next;
+
+  if ((void*)n->prev == (void *)h)
+    p = h->first;
+  else
+    /* Dead tbaa-unsafe load from ((struct node *)&heads[2])->next.  */
+    p = n->prev->next;
+
+  return !(p == (void*)0);
+}
+
+/* { dg-final { scan-tree-dump-not "Removing basic block" "pre"} } */
+/* { dg-final { cleanup-tree-dump "pre" } } */
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index 303bd5e4c4a..16519853b0e 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -326,7 +326,8 @@ stmt_local_def (gimple stmt)
 
   if (gimple_vdef (stmt) != NULL_TREE
       || gimple_has_side_effects (stmt)
-      || gimple_could_trap_p_1 (stmt, false, false))
+      || gimple_could_trap_p_1 (stmt, false, false)
+      || gimple_vuse (stmt) != NULL_TREE)
     return false;
 
   def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_DEF);
@@ -1175,7 +1176,8 @@ gimple_equal_p (same_succ same_succ, gimple s1, gimple s2)
 						 gimple_assign_rhs1 (s2)));
       else if (TREE_CODE (lhs1) == SSA_NAME
 	       && TREE_CODE (lhs2) == SSA_NAME)
-	return vn_valueize (lhs1) == vn_valueize (lhs2);
+	return operand_equal_p (gimple_assign_rhs1 (s1),
+				gimple_assign_rhs1 (s2), 0);
       return false;
 
     case GIMPLE_COND: