From 4acd6b6566df1d91f06c124ead3b4909b342dd3d Mon Sep 17 00:00:00 2001
From: aoliva <aoliva@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Tue, 22 Feb 2005 02:27:37 +0000
Subject: [PATCH] gcc/ChangeLog: PR tree-optimization/19786 * tree-ssa-alias.c
 (compute_flow_insensitive_aliasing): Add one tag to another's may-alias
 bitmap when adding to the other's list. gcc/testsuite/ChangeLog: PR
 tree-optimization/19786 * g++.dg/tree-ssa/pr19786.C: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@95377 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ChangeLog                           |  6 +++++
 gcc/testsuite/ChangeLog                 |  5 ++++
 gcc/testsuite/g++.dg/tree-ssa/pr19786.C | 48 +++++++++++++++++++++++++++++++++
 gcc/tree-ssa-alias.c                    |  1 +
 4 files changed, 60 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/tree-ssa/pr19786.C

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 16cb58b19e5..fa3709688c9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2005-02-21  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR tree-optimization/19786
+	* tree-ssa-alias.c (compute_flow_insensitive_aliasing): Add one
+	tag to another's may-alias bitmap when adding to the other's list.
+
 2005-02-21  DJ Delorie  <dj@redhat.com>
 
 	* tree-ssa-loop-ivopts.c (computation_cost): Start register
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0eae7654672..dd742ed74b9 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2005-02-21  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR tree-optimization/19786
+	* g++.dg/tree-ssa/pr19786.C: New.
+
 2005-02-21  Tobias Schl"uter  <tobias.schlueter@physik.uni-muenchen.de>
 
 	* lib/gfortran-dg.exp (gfortran-dg-test): Split long regexps.
diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr19786.C b/gcc/testsuite/g++.dg/tree-ssa/pr19786.C
new file mode 100644
index 00000000000..faaecdfd971
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/pr19786.C
@@ -0,0 +1,48 @@
+// { dg-do run }
+/* { dg-options "-O2" } */
+
+// We used to get alias grouping wrong on this one, hoisting accesses
+// to the vector's end out of the loop.
+
+#include <vector>
+#include <cassert>
+
+struct A
+{
+  double unused;      // If I remove it => it works.
+  std::vector<int> v;
+
+  A() : v(1) {}
+};
+
+inline // If not inline => it works.
+A g()
+{
+  A r;
+  r.v.resize(2);
+  r.v[0] = 1;
+
+  while (!r.v.empty() && r.v.back() == 0)
+    r.v.pop_back();
+
+  return r;
+}
+
+A f(const A &a)
+{
+  if (a.v.empty())  return a;
+  if (a.v.empty())  return a;
+
+  // A z = g(); return z;  // If I return like this => it works.
+  return g();
+}
+
+int main()
+{
+  A a;
+  A b;
+  A r = f(a);
+  assert(r.v.size() != 0);
+
+  return 0;
+}
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 3e5f8e3dc5f..bfa1685eb9e 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -1116,6 +1116,7 @@ compute_flow_insensitive_aliasing (struct alias_info *ai)
 	      /* Since TAG2 does not have any aliases of its own, add
 		 TAG2 itself to the alias set of TAG1.  */
 	      add_may_alias (tag1, tag2);
+	      SET_BIT (may_aliases1, var_ann (tag2)->uid);
 	    }
 	}
     }
-- 
2.11.4.GIT