[PATCH] Fix invalid tree sharing caused by the inliner (PR tree-optimization/59386)

[Jakub Jelinek]

Hi!

If id->retvar isn't a decl (can happen for DECL_BY_REFERENCE returns),
then we can end up with invalid tree sharing because we reuse it more than
once (on the following testcase id->retvar is a COMPONENT_REF).

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2013-12-11  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/59386
        * tree-inline.c (remap_gimple_stmt): If not id->do_not_unshare,
        unshare_expr (id->retval) before passing it to gimple_build_assign.

        * gcc.c-torture/compile/pr59386.c: New test.

--- gcc/tree-inline.c.jj        2013-12-10 08:52:13.000000000 +0100
+++ gcc/tree-inline.c   2013-12-10 17:04:09.022069945 +0100
@@ -1273,7 +1273,9 @@ remap_gimple_stmt (gimple stmt, copy_bod
                  || ! SSA_NAME_VAR (retval)
                  || TREE_CODE (SSA_NAME_VAR (retval)) != RESULT_DECL)))
         {
-         copy = gimple_build_assign (id->retvar, retval);
+         copy = gimple_build_assign (id->do_not_unshare
+                                     ? id->retvar : unshare_expr (id->retvar),
+                                     retval);
          /* id->retvar is already substituted.  Skip it on later remapping.  */
          skip_first = true;
        }
--- gcc/testsuite/gcc.c-torture/compile/pr59386.c.jj    2013-12-10 
17:06:39.389291052 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr59386.c       2013-12-10 
17:05:37.000000000 +0100
@@ -0,0 +1,24 @@
+/* PR tree-optimization/59386 */
+
+struct S { int s; };
+struct T { int t; struct S u; } c;
+int b;
+
+struct S
+foo ()
+{
+  struct T d;
+  if (b)
+    while (c.t)
+      ;
+  else
+    return d.u;
+}
+
+struct S
+bar ()
+{
+  struct T a;
+  a.u = foo ();
+  return a.u;
+}

        Jakub