obtained gcc-4.6.4.tar.bz2 from upstream website;upstream

verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.

downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.

if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.

16 files changed, 816 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/plugin/finish_unit-test-1.c b/gcc/testsuite/gcc.dg/plugin/finish_unit-test-1.c
new file mode 100644
index 000000000..4cd8a40f4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/finish_unit-test-1.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+int main (int argc, char **argv) 
+{ 
+  return 0;  
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/finish_unit_plugin.c b/gcc/testsuite/gcc.dg/plugin/finish_unit_plugin.c
new file mode 100644
index 000000000..26496a2e6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/finish_unit_plugin.c
@@ -0,0 +1,29 @@
+/* This plugin creates a fake function in the FINISH_UNIT callback, in
+ * other words right after compilation of the translation unit. 
+*/
+#include "gcc-plugin.h"
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+#include "basic-block.h"
+#include "gimple.h"
+#include "tree.h"
+#include "tree-pass.h"
+#include "intl.h"
+#include "cgraph.h"
+
+int plugin_is_GPL_compatible;
+
+static void finish_unit_callback (void *gcc_data, void *user_data)
+{
+  cgraph_build_static_cdtor ('I', NULL, DEFAULT_INIT_PRIORITY);
+}
+
+int plugin_init (struct plugin_name_args *plugin_info,
+                 struct plugin_gcc_version *version)
+{
+  register_callback ("finish_unit", PLUGIN_FINISH_UNIT, &finish_unit_callback, NULL);
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/ggcplug-test-1.c b/gcc/testsuite/gcc.dg/plugin/ggcplug-test-1.c
new file mode 100644
index 000000000..74e68bb82
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/ggcplug-test-1.c
@@ -0,0 +1,12 @@
+/* Test the ggcplug plugin.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+int main()
+{
+  int i=0, j=0;
+  for (i= 0; i<1000; i++)
+    if (i%8 == 0)
+      j++;
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/ggcplug.c b/gcc/testsuite/gcc.dg/plugin/ggcplug.c
new file mode 100644
index 000000000..3094b2ebb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/ggcplug.c
@@ -0,0 +1,114 @@
+/* This plugin tests the GGC related plugin events.  */
+/* { dg-options "-O" } */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+#include "basic-block.h"
+#include "gimple.h"
+#include "tree.h"
+#include "tree-pass.h"
+#include "intl.h"
+#include "gcc-plugin.h"
+#include "plugin-version.h"
+#include "diagnostic.h"
+
+int plugin_is_GPL_compatible;
+
+/* our callback is the same for all PLUGIN_GGC_START,
+   PLUGIN_GGC_MARKING, PLUGIN_GGC_END events; it just increments the
+   user_data which is an int */
+static void increment_callback (void *gcc_data, void *user_data);
+
+/* our counters are user_data */
+static int our_ggc_start_counter;
+static int our_ggc_end_counter;
+static int our_ggc_marking_counter;
+
+/* our empty GGC extra root table */
+static const struct ggc_root_tab our_xtratab[] = {
+  LAST_GGC_ROOT_TAB
+};
+
+
+/* The initialization routine exposed to and called by GCC. The spec of this
+   function is defined in gcc/gcc-plugin.h.
+
+   Note that this function needs to be named exactly "plugin_init".  */
+int
+plugin_init (struct plugin_name_args *plugin_info,
+	      struct plugin_gcc_version *version)
+{
+  const char *plugin_name = plugin_info->base_name;
+  int argc = plugin_info->argc;
+  int i = 0;
+  struct plugin_argument *argv = plugin_info->argv;
+  if (!plugin_default_version_check (version, &gcc_version))
+    return 1;
+  /* Process the plugin arguments. This plugin takes the following arguments:
+     count-ggc-start count-ggc-end count-ggc-mark */
+  for (i = 0; i < argc; ++i)
+    {
+      if (!strcmp (argv[i].key, "count-ggc-start"))
+	{
+	  if (argv[i].value)
+	    warning (0, G_ ("option '-fplugin-arg-%s-count-ggc-start=%s'"
+			    " ignored (superfluous '=%s')"),
+		     plugin_name, argv[i].value, argv[i].value);
+	  else
+	    register_callback ("ggcplug",
+			       PLUGIN_GGC_START,
+			       increment_callback,
+			       (void *) &our_ggc_start_counter);
+	}
+      else if (!strcmp (argv[i].key, "count-ggc-end"))
+	{
+	  if (argv[i].value)
+	    warning (0, G_ ("option '-fplugin-arg-%s-count-ggc-end=%s'"
+			    " ignored (superfluous '=%s')"),
+		     plugin_name, argv[i].value, argv[i].value);
+	  else
+	    register_callback ("ggcplug",
+			       PLUGIN_GGC_END,
+			       increment_callback,
+			       (void *) &our_ggc_end_counter);
+	}
+      else if (!strcmp (argv[i].key, "count-ggc-mark"))
+	{
+	  if (argv[i].value)
+	    warning (0, G_ ("option '-fplugin-arg-%s-count-ggc-mark=%s'"
+			    " ignored (superfluous '=%s')"),
+		     plugin_name, argv[i].value, argv[i].value);
+	  else
+	    register_callback ("ggcplug",
+			       PLUGIN_GGC_MARKING,
+			       increment_callback,
+			       (void *) &our_ggc_marking_counter);
+	}
+      else if (!strcmp (argv[i].key, "test-extra-root"))
+	{
+	  if (argv[i].value)
+	    warning (0, G_ ("option '-fplugin-arg-%s-test-extra-root=%s'"
+			    " ignored (superfluous '=%s')"),
+		     plugin_name, argv[i].value, argv[i].value);
+	  else
+	    register_callback ("ggcplug",
+			       PLUGIN_REGISTER_GGC_ROOTS,
+			       NULL,
+			       (void *) our_xtratab);
+	}
+    }
+  /* plugin initialization succeeded */
+  return 0;
+ }
+
+static void
+increment_callback (void *gcc_data, void *user_data)
+{
+  int *usercountptr = (int *) user_data;
+  gcc_assert (!gcc_data);
+  gcc_assert (user_data);
+  (*usercountptr)++;
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/one_time-test-1.c b/gcc/testsuite/gcc.dg/plugin/one_time-test-1.c
new file mode 100644
index 000000000..a49ecb4af
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/one_time-test-1.c
@@ -0,0 +1,8 @@
+/* Test that pass is inserted and invoked once. */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+int main (int argc, char **argv) 
+{ 
+  return 0;  
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/one_time_plugin.c b/gcc/testsuite/gcc.dg/plugin/one_time_plugin.c
new file mode 100644
index 000000000..2c4cd4971
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/one_time_plugin.c
@@ -0,0 +1,63 @@
+/* Plugin that prints message if it inserted (and invoked) more than once. */
+#include "config.h"
+#include "gcc-plugin.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+#include "gimple.h"
+#include "tree-pass.h"
+#include "intl.h"
+
+int plugin_is_GPL_compatible;
+
+static bool one_pass_gate (void)
+{
+  return true;
+}
+
+static unsigned int one_pass_exec (void)
+{
+  static int counter = 0;
+
+  if (counter > 0) {
+    printf ("Executed more than once \n");
+ }
+ counter++;
+ return 0;
+}
+
+struct gimple_opt_pass one_pass = 
+{
+  {
+  GIMPLE_PASS,
+  "cfg",                           /* name */
+  one_pass_gate,                         /* gate */
+  one_pass_exec,       /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  TV_NONE,                              /* tv_id */
+  PROP_gimple_any,                      /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  TODO_dump_func                        /* todo_flags_finish */
+  }
+};
+
+
+int plugin_init (struct plugin_name_args *plugin_info,
+                 struct plugin_gcc_version *version)
+{
+  struct register_pass_info p;
+
+  p.pass = &one_pass.pass;
+  p.reference_pass_name = "cfg";
+  p.ref_pass_instance_number = 1;
+  p.pos_op = PASS_POS_INSERT_AFTER;
+
+  register_callback ("one_pass", PLUGIN_PASS_MANAGER_SETUP, NULL, &p);
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/plugin.exp b/gcc/testsuite/gcc.dg/plugin/plugin.exp
new file mode 100644
index 000000000..444bd1bb6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/plugin.exp
@@ -0,0 +1,82 @@
+#   Copyright (C) 2009, 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# Test the functionality of the GCC plugin support
+
+load_lib target-supports.exp
+load_lib gcc-dg.exp
+
+global TESTING_IN_BUILD_TREE
+global ENABLE_PLUGIN
+
+# The plugin testcases currently only work when the build tree is available.
+# Also check whether the host supports plugins.
+if { ![info exists TESTING_IN_BUILD_TREE] || ![info exists ENABLE_PLUGIN] } {
+    return
+}
+
+# If a testcase doesn't have special options, use these.
+global DEFAULT_CFLAGS
+if ![info exists DEFAULT_CFLAGS] then {
+    set DEFAULT_CFLAGS " -ansi -pedantic-errors"
+}
+
+# The procedures in plugin-support.exp need these parameters.
+set default_flags $DEFAULT_CFLAGS
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+# Load support procs.
+load_lib plugin-support.exp
+
+# Specify the plugin source file and the associated test files in a list.
+# plugin_test_list={ {plugin1 test1 test2 ...} {plugin2 test1 ...} ... }
+set plugin_test_list [list \
+    { selfassign.c self-assign-test-1.c self-assign-test-2.c } \
+    { ggcplug.c ggcplug-test-1.c } \
+    { one_time_plugin.c one_time-test-1.c } \
+    { start_unit_plugin.c start_unit-test-1.c } \
+    { finish_unit_plugin.c finish_unit-test-1.c } \
+]
+
+foreach plugin_test $plugin_test_list {
+    # Replace each source file with its full-path name
+    for {set i 0} {$i < [llength $plugin_test]} {incr i} {
+	set basename [lindex $plugin_test $i]
+	set plugin_test [lreplace $plugin_test $i $i $srcdir/$subdir/$basename]
+    }
+    set plugin_src [lindex $plugin_test 0]
+    # If we're only testing specific files and this isn't one of them, skip it.
+    if ![runtest_file_p $runtests $plugin_src] then {
+        continue
+    }
+    set plugin_input_tests [lreplace $plugin_test 0 0]
+    plugin-test-execute $plugin_src $plugin_input_tests
+}
+
+# run the plugindir tests
+
+# Initialize `dg'.
+dg-init
+
+# Main loop.
+dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/plugindir*.\[cSi\]]] \
+	"" $DEFAULT_CFLAGS
+
+# All done.
+dg-finish
diff --git a/gcc/testsuite/gcc.dg/plugin/plugindir1.c b/gcc/testsuite/gcc.dg/plugin/plugindir1.c
new file mode 100644
index 000000000..a973ec0c5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/plugindir1.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "-c -fplugin=foo" } */
+
+/* { dg-prune-output ".*inacessible plugin file.*foo\.so expanded from short plugin name.*" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/plugindir2.c b/gcc/testsuite/gcc.dg/plugin/plugindir2.c
new file mode 100644
index 000000000..58c150550
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/plugindir2.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "-save-temps -c -fplugin=foo" } */
+
+/* { dg-prune-output ".*inacessible plugin file.*foo\.so expanded from short plugin name.*" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/plugindir3.c b/gcc/testsuite/gcc.dg/plugin/plugindir3.c
new file mode 100644
index 000000000..41037534a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/plugindir3.c
@@ -0,0 +1,4 @@
+/* { dg-do preprocess } */
+/* { dg-options "-fplugin=foo" } */
+
+/* { dg-prune-output ".*inacessible plugin file.*foo\.so expanded from short plugin name.*" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/plugindir4.c b/gcc/testsuite/gcc.dg/plugin/plugindir4.c
new file mode 100644
index 000000000..27b2f24aa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/plugindir4.c
@@ -0,0 +1,4 @@
+/* { dg-do preprocess } */
+/* { dg-options "-iplugindir=my-plugindir -fplugin=foo" } */
+
+/* { dg-prune-output ".*inacessible plugin file.*my-plugindir/foo\.so expanded from short plugin name.*" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/self-assign-test-1.c b/gcc/testsuite/gcc.dg/plugin/self-assign-test-1.c
new file mode 100644
index 000000000..f6dc5240f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/self-assign-test-1.c
@@ -0,0 +1,23 @@
+/* Test the self-assignemnt detection plugin.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct Bar {
+  int b_;
+  int c_;
+};
+
+int g;
+
+int main()
+{
+  struct Bar *bar;
+  int x = x; /* { dg-warning "assigned to itself" } */
+  static int y;
+  struct Bar b_array[5];
+
+  b_array[x+g].b_ = b_array[x+g].b_; /* { dg-warning "self-assignment detected" } */
+  g = g; /* { dg-warning "assigned to itself" } */
+  y = y; /* { dg-warning "assigned to itself" } */
+  bar->b_ = bar->b_; /* { dg-warning "assigned to itself" } */
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/self-assign-test-2.c b/gcc/testsuite/gcc.dg/plugin/self-assign-test-2.c
new file mode 100644
index 000000000..2ede371a6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/self-assign-test-2.c
@@ -0,0 +1,23 @@
+/* Test the self-assignemnt detection plugin with the 'disable' argument.  */
+/* { dg-do compile } */
+/* { dg-options "-O -fplugin-arg-selfassign-disable" } */
+
+struct Bar {
+  int b_;
+  int c_;
+};
+
+int g;
+
+int main()
+{
+  struct Bar *bar;
+  int x = x; /* { dg-bogus "assigned to itself" } */
+  static int y;
+  struct Bar b_array[5];
+
+  b_array[x+g].b_ = b_array[x+g].b_; /* { dg-bogus "self-assignment detected" } */
+  g = g; /* { dg-bogus "assigned to itself" } */
+  y = y; /* { dg-bogus "assigned to itself" } */
+  bar->b_ = bar->b_; /* { dg-bogus "assigned to itself" } */
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/selfassign.c b/gcc/testsuite/gcc.dg/plugin/selfassign.c
new file mode 100644
index 000000000..84d2801d2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/selfassign.c
@@ -0,0 +1,366 @@
+/* This plugin contains an analysis pass that detects and warns about
+   self-assignment statements.  */
+/* { dg-options "-O" } */
+
+#include "gcc-plugin.h"
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+#include "basic-block.h"
+#include "gimple.h"
+#include "tree.h"
+#include "tree-pass.h"
+#include "intl.h"
+#include "plugin-version.h"
+#include "diagnostic.h"
+
+int plugin_is_GPL_compatible;
+
+/* Indicate whether to check overloaded operator '=', which is performed by
+   default. To disable it, use -fplugin-arg-NAME-no-check-operator-eq.  */
+bool check_operator_eq = true;
+
+/* Given a rhs EXPR of a gimple assign statement, if it is
+   - SSA_NAME : returns its var decl, or, if it is a temp variable,
+                returns the rhs of its SSA def statement.
+   - VAR_DECL, PARM_DECL, FIELD_DECL, or a reference expression :
+                returns EXPR itself.
+   - any other expression : returns NULL_TREE.  */
+
+static tree
+get_real_ref_rhs (tree expr)
+{
+  switch (TREE_CODE (expr))
+    {
+      case SSA_NAME:
+        {
+          /* Given a self-assign statement, say foo.x = foo.x,
+             the IR (after SSA) looks like:
+
+             D.1797_14 = foo.x;
+             foo.x ={v} D.1797_14;
+
+             So if the rhs EXPR is an SSA_NAME of a temp variable,
+             e.g. D.1797_14, we need to grab the rhs of its SSA def
+             statement (i.e. foo.x).  */
+          tree vdecl = SSA_NAME_VAR (expr);
+          if (DECL_ARTIFICIAL (vdecl)
+              && !gimple_nop_p (SSA_NAME_DEF_STMT (expr)))
+            {
+              gimple def_stmt = SSA_NAME_DEF_STMT (expr);
+              /* We are only interested in an assignment with a single
+                 rhs operand because if it is not, the original assignment
+                 will not possibly be a self-assignment.  */
+              if (gimple_assign_single_p (def_stmt))
+                return get_real_ref_rhs (gimple_assign_rhs1 (def_stmt));
+              else
+                return NULL_TREE;
+            }
+          else
+            return vdecl;
+        }
+      case VAR_DECL:
+      case PARM_DECL:
+      case FIELD_DECL:
+      case COMPONENT_REF:
+      case MEM_REF:
+      case ARRAY_REF:
+        return expr;
+      default:
+        return NULL_TREE;
+    }
+}
+
+/* Given an expression tree, EXPR, that may contains SSA names, returns an
+   equivalent tree with the SSA names converted to var/parm/field decls
+   so that it can be used with '%E' format modifier when emitting warning
+   messages.
+
+   This function currently only supports VAR/PARM/FIELD_DECL, reference
+   expressions (COMPONENT_REF, INDIRECT_REF, ARRAY_REF), integer constant,
+   and SSA_NAME. If EXPR contains any other tree nodes (e.g. an arithmetic
+   expression appears in array index), NULL_TREE is returned.  */
+
+static tree
+get_non_ssa_expr (tree expr)
+{
+  switch (TREE_CODE (expr))
+    {
+      case VAR_DECL:
+      case PARM_DECL:
+      case FIELD_DECL:
+        {
+          if (DECL_NAME (expr))
+            return expr;
+          else
+            return NULL_TREE;
+        }
+      case COMPONENT_REF:
+        {
+          tree base, orig_base = TREE_OPERAND (expr, 0);
+          tree component, orig_component = TREE_OPERAND (expr, 1);
+          base = get_non_ssa_expr (orig_base);
+          if (!base)
+            return NULL_TREE;
+          component = get_non_ssa_expr (orig_component);
+          if (!component)
+            return NULL_TREE;
+          /* If either BASE or COMPONENT is converted, build a new
+             component reference tree.  */
+          if (base != orig_base || component != orig_component)
+            return build3 (COMPONENT_REF, TREE_TYPE (component),
+                           base, component, NULL_TREE);
+          else
+            return expr;
+        }
+      case MEM_REF:
+        {
+          tree orig_base = TREE_OPERAND (expr, 0);
+	  if (TREE_CODE (orig_base) == SSA_NAME)
+	    {
+	      tree base = get_non_ssa_expr (orig_base);
+	      if (!base)
+		return NULL_TREE;
+	      return fold_build2 (MEM_REF, TREE_TYPE (expr),
+				  base, TREE_OPERAND (expr, 1));
+	    }
+	  return expr;
+        }
+      case ARRAY_REF:
+        {
+          tree array, orig_array = TREE_OPERAND (expr, 0);
+          tree index, orig_index = TREE_OPERAND (expr, 1);
+          array = get_non_ssa_expr (orig_array);
+          if (!array)
+            return NULL_TREE;
+          index = get_non_ssa_expr (orig_index);
+          if (!index)
+            return NULL_TREE;
+          /* If either ARRAY or INDEX is converted, build a new array
+             reference tree.  */
+          if (array != orig_array || index != orig_index)
+            return build4 (ARRAY_REF, TREE_TYPE (expr), array, index,
+                           TREE_OPERAND (expr, 2), TREE_OPERAND (expr, 3));
+          else
+            return expr;
+        }
+      case SSA_NAME:
+        {
+          tree vdecl = SSA_NAME_VAR (expr);
+          if (DECL_ARTIFICIAL (vdecl)
+              && !gimple_nop_p (SSA_NAME_DEF_STMT (expr)))
+            {
+              gimple def_stmt = SSA_NAME_DEF_STMT (expr);
+              if (gimple_assign_single_p (def_stmt))
+                vdecl = gimple_assign_rhs1 (def_stmt);
+            }
+          return get_non_ssa_expr (vdecl);
+        }
+      case INTEGER_CST:
+        return expr;
+      default:
+        /* Return NULL_TREE for any other kind of tree nodes.  */
+        return NULL_TREE;
+    }
+}
+
+/* Given the LHS and (real) RHS of a gimple assign statement, STMT, check if
+   they are the same. If so, print a warning message about self-assignment.  */
+
+static void
+compare_and_warn (gimple stmt, tree lhs, tree rhs)
+{
+  if (operand_equal_p (lhs, rhs, OEP_PURE_SAME))
+    {
+      location_t location;
+      location = (gimple_has_location (stmt)
+                  ? gimple_location (stmt)
+                  : (DECL_P (lhs)
+                     ? DECL_SOURCE_LOCATION (lhs)
+                     : input_location));
+      /* If LHS contains any tree node not currently supported by
+         get_non_ssa_expr, simply emit a generic warning without
+         specifying LHS in the message.  */
+      lhs = get_non_ssa_expr (lhs);
+      if (lhs)
+        warning_at (location, 0, G_("%qE is assigned to itself"), lhs);
+      else
+        warning_at (location, 0, G_("self-assignment detected"));
+    }
+}
+
+/* Check and warn if STMT is a self-assign statement.  */
+
+static void
+warn_self_assign (gimple stmt)
+{
+  tree rhs, lhs;
+
+  /* Check assigment statement.  */
+  if (gimple_assign_single_p (stmt))
+    {
+      rhs = get_real_ref_rhs (gimple_assign_rhs1 (stmt));
+      if (!rhs)
+        return;
+
+      lhs = gimple_assign_lhs (stmt);
+      if (TREE_CODE (lhs) == SSA_NAME)
+        {
+          lhs = SSA_NAME_VAR (lhs);
+          if (DECL_ARTIFICIAL (lhs))
+            return;
+        }
+
+      compare_and_warn (stmt, lhs, rhs);
+    }
+  /* Check overloaded operator '=' (if enabled).  */
+  else if (check_operator_eq && is_gimple_call (stmt))
+    {
+      tree fdecl = gimple_call_fndecl (stmt);
+      if (fdecl && (DECL_NAME (fdecl) == maybe_get_identifier ("operator=")))
+        {
+          /* If 'operator=' takes reference operands, the arguments will be 
+             ADDR_EXPR trees. In this case, just remove the address-taken
+             operator before we compare the lhs and rhs.  */
+          lhs = gimple_call_arg (stmt, 0);
+          if (TREE_CODE (lhs) == ADDR_EXPR)
+            lhs = TREE_OPERAND (lhs, 0);
+          rhs = gimple_call_arg (stmt, 1);
+          if (TREE_CODE (rhs) == ADDR_EXPR)
+            rhs = TREE_OPERAND (rhs, 0);
+
+          compare_and_warn (stmt, lhs, rhs);
+        }
+    }
+}
+
+/* Entry point for the self-assignment detection pass.  */
+
+static unsigned int
+execute_warn_self_assign (void)
+{
+  gimple_stmt_iterator gsi;
+  basic_block bb;
+
+  FOR_EACH_BB (bb)
+    {
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+        warn_self_assign (gsi_stmt (gsi));
+    }
+
+  return 0;
+}
+
+/* Pass gate function. Currently always returns true.  */
+
+static bool
+gate_warn_self_assign (void)
+{
+  return true;
+}
+
+static struct gimple_opt_pass pass_warn_self_assign =
+{
+  {
+    GIMPLE_PASS,
+    "warn_self_assign",                   /* name */
+    gate_warn_self_assign,                /* gate */
+    execute_warn_self_assign,             /* execute */
+    NULL,                                 /* sub */
+    NULL,                                 /* next */
+    0,                                    /* static_pass_number */
+    TV_NONE,                              /* tv_id */
+    PROP_ssa,                             /* properties_required */
+    0,                                    /* properties_provided */
+    0,                                    /* properties_destroyed */
+    0,                                    /* todo_flags_start */
+    TODO_dump_func                        /* todo_flags_finish */
+  }
+};
+
+/* The initialization routine exposed to and called by GCC. The spec of this
+   function is defined in gcc/gcc-plugin.h.
+
+   PLUGIN_NAME - name of the plugin (useful for error reporting)
+   ARGC        - the size of the ARGV array
+   ARGV        - an array of key-value argument pair
+
+   Returns 0 if initialization finishes successfully.
+
+   Note that this function needs to be named exactly "plugin_init".  */
+
+int
+plugin_init (struct plugin_name_args *plugin_info,
+             struct plugin_gcc_version *version)
+{
+  struct register_pass_info pass_info;
+  const char *plugin_name = plugin_info->base_name;
+  int argc = plugin_info->argc;
+  struct plugin_argument *argv = plugin_info->argv;
+  bool enabled = true;
+  int i;
+
+  if (!plugin_default_version_check (version, &gcc_version))
+    return 1;
+
+  /* Self-assign detection should happen after SSA is constructed.  */
+  pass_info.pass = &pass_warn_self_assign.pass;
+  pass_info.reference_pass_name = "ssa";
+  pass_info.ref_pass_instance_number = 1;
+  pass_info.pos_op = PASS_POS_INSERT_AFTER;
+
+  /* Process the plugin arguments. This plugin takes the following arguments:
+     check-operator-eq, no-check-operator-eq, enable, and disable.
+     By default, the analysis is enabled with 'operator=' checked.  */
+  for (i = 0; i < argc; ++i)
+    {
+      if (!strcmp (argv[i].key, "check-operator-eq"))
+        {
+          if (argv[i].value)
+            warning (0, G_("option '-fplugin-arg-%s-check-operator-eq=%s'"
+                           " ignored (superfluous '=%s')"),
+                     plugin_name, argv[i].value, argv[i].value);
+          else
+            check_operator_eq = true;
+        }
+      else if (!strcmp (argv[i].key, "no-check-operator-eq"))
+        {
+          if (argv[i].value)
+            warning (0, G_("option '-fplugin-arg-%s-no-check-operator-eq=%s'"
+                           " ignored (superfluous '=%s')"),
+                     plugin_name, argv[i].value, argv[i].value);
+          else
+            check_operator_eq = false;
+        }
+      else if (!strcmp (argv[i].key, "enable"))
+        {
+          if (argv[i].value)
+            warning (0, G_("option '-fplugin-arg-%s-enable=%s' ignored"
+                           " (superfluous '=%s')"),
+                     plugin_name, argv[i].value, argv[i].value);
+          else
+            enabled = true;
+        }
+      else if (!strcmp (argv[i].key, "disable"))
+        {
+          if (argv[i].value)
+            warning (0, G_("option '-fplugin-arg-%s-disable=%s' ignored"
+                           " (superfluous '=%s')"),
+                     plugin_name, argv[i].value, argv[i].value);
+          else
+            enabled = false;
+        }
+      else
+        warning (0, G_("plugin %qs: unrecognized argument %qs ignored"),
+                 plugin_name, argv[i].key);
+    }
+
+  /* Register this new pass with GCC if the analysis is enabled.  */
+  if (enabled)
+    register_callback (plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL,
+                       &pass_info);
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/start_unit-test-1.c b/gcc/testsuite/gcc.dg/plugin/start_unit-test-1.c
new file mode 100644
index 000000000..4cd8a40f4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/start_unit-test-1.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+int main (int argc, char **argv) 
+{ 
+  return 0;  
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/start_unit_plugin.c b/gcc/testsuite/gcc.dg/plugin/start_unit_plugin.c
new file mode 100644
index 000000000..5b16e84a4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/start_unit_plugin.c
@@ -0,0 +1,66 @@
+/* This plugin tests the correct operation of a PLUGIN_START_UNIT callback.
+ * By the time a PLUGIN_START_UNIT callback is invoked, the frontend 
+ * initialization should have completed. At least the different *_type_nodes
+ * should have been created. This plugin creates an artifical global 
+ * interger variable.
+ * 
+*/
+#include "gcc-plugin.h"
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+#include "basic-block.h"
+#include "gimple.h"
+#include "tree.h"
+#include "tree-pass.h"
+#include "intl.h"
+
+int plugin_is_GPL_compatible;
+static tree fake_var = NULL;
+
+static bool
+gate_start_unit (void)
+{
+  return true;
+}
+
+static void start_unit_callback (void *gcc_data, void *user_data)
+{
+  if (integer_type_node) {
+    fake_var = build_decl (UNKNOWN_LOCATION, VAR_DECL, 
+                           get_identifier ("_fake_var_"),
+                           integer_type_node);
+    TREE_PUBLIC (fake_var) = 1;
+    DECL_ARTIFICIAL (fake_var) = 1;
+  }
+}
+
+static void finish_unit_callback (void *gcc_data, void *user_data)
+{
+  if (fake_var == NULL) {
+    printf ("fake_var not created \n");
+    return;
+  }
+  if (TREE_CODE (fake_var) != VAR_DECL) {
+    printf ("fake_var not a VAR_DECL \n");
+    return;
+  }
+  if (TREE_CODE (TREE_TYPE (fake_var)) != INTEGER_TYPE) {
+    printf ("fake_var not INTEGER_TYPE \n");
+    return;
+  }
+  if (DECL_ARTIFICIAL (fake_var) == 0) {
+    printf ("fake_var not ARTIFICIAL \n");
+    return;
+  }
+}
+
+int plugin_init (struct plugin_name_args *plugin_info,
+                 struct plugin_gcc_version *version)
+{
+  register_callback ("start_unit", PLUGIN_START_UNIT, &start_unit_callback, NULL);
+  register_callback ("finish_unit", PLUGIN_FINISH_UNIT, &finish_unit_callback, NULL);
+  return 0;
+}