Index: gcc/doc/tm.texi
===================================================================
--- gcc/doc/tm.texi	(revision 190493)
+++ gcc/doc/tm.texi	(working copy)
@@ -9894,6 +9894,11 @@ changed via the optimize attribute or pragma, see
 @code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}
 @end deftypefn
 
+@deftypefn {Target Hook} bool TARGET_OPTION_FUNCTION_VERSIONS (tree @var{decl1}, tree @var{decl2})
+This target hook returns @code{true} if @var{FN1} and @var{FN2} are
+versions of the same function.
+@end deftypefn
+
 @deftypefn {Target Hook} bool TARGET_CAN_INLINE_P (tree @var{caller}, tree @var{callee})
 This target hook returns @code{false} if the @var{caller} function
 cannot inline @var{callee}, based on target specific information.  By
@@ -10925,6 +10930,27 @@ The result is another tree containing a simplified
 call's result.  If @var{ignore} is true the value will be ignored.
 @end deftypefn
 
+@deftypefn {Target Hook} int TARGET_COMPARE_VERSION_PRIORITY (tree @var{decl1}, tree @var{decl2})
+This hook is used to compare the target attributes in two functions to
+figure out which function's features get higher priority.  This is used
+during multi-versioning to figure out the order of dispatching. @var{decl1}
+and @var{decl2} are the two function decls that will be compared.
+@end deftypefn
+
+@deftypefn {Target Hook} tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *@var{arglist})
+This hook is used to get the dispatcher function for a set of function
+versions.  The dispatcher function is called to invoke the rignt function
+version at run-time. @var{arglist} is the vector of function versions
+that should be considered for dispatch.
+@end deftypefn
+
+@deftypefn {Target Hook} tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *@var{arg})
+This hook is used to generate the dispatcher logic to invoke the right
+function version at runtime for a given set of function versions.
+@var{arg} points to the callgraph node of the dispatcher function whose
+body must be generated.
+@end deftypefn
+
 @deftypefn {Target Hook} {const char *} TARGET_INVALID_WITHIN_DOLOOP (const_rtx @var{insn})
 
 Take an instruction in @var{insn} and return NULL if it is valid within a
Index: gcc/doc/tm.texi.in
===================================================================
--- gcc/doc/tm.texi.in	(revision 190493)
+++ gcc/doc/tm.texi.in	(working copy)
@@ -9763,6 +9763,11 @@ changed via the optimize attribute or pragma, see
 @code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}
 @end deftypefn
 
+@hook TARGET_OPTION_FUNCTION_VERSIONS
+This target hook returns @code{true} if @var{FN1} and @var{FN2} are
+versions of the same function.
+@end deftypefn
+
 @hook TARGET_CAN_INLINE_P
 This target hook returns @code{false} if the @var{caller} function
 cannot inline @var{callee}, based on target specific information.  By
@@ -10783,6 +10788,27 @@ The result is another tree containing a simplified
 call's result.  If @var{ignore} is true the value will be ignored.
 @end deftypefn
 
+@hook TARGET_COMPARE_VERSION_PRIORITY
+This hook is used to compare the target attributes in two functions to
+figure out which function's features get higher priority.  This is used
+during multi-versioning to figure out the order of dispatching. @var{decl1}
+and @var{decl2} are the two function decls that will be compared.
+@end deftypefn
+
+@hook TARGET_GET_FUNCTION_VERSIONS_DISPATCHER
+This hook is used to get the dispatcher function for a set of function
+versions.  The dispatcher function is called to invoke the rignt function
+version at run-time. @var{arglist} is the vector of function versions
+that should be considered for dispatch.
+@end deftypefn
+
+@hook TARGET_GENERATE_VERSION_DISPATCHER_BODY
+This hook is used to generate the dispatcher logic to invoke the right
+function version at runtime for a given set of function versions.
+@var{arg} points to the callgraph node of the dispatcher function whose
+body must be generated.
+@end deftypefn
+
 @hook TARGET_INVALID_WITHIN_DOLOOP
 
 Take an instruction in @var{insn} and return NULL if it is valid within a
Index: gcc/cgraphbuild.c
===================================================================
--- gcc/cgraphbuild.c	(revision 190493)
+++ gcc/cgraphbuild.c	(working copy)
@@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "ipa-utils.h"
 #include "except.h"
 #include "ipa-inline.h"
+#include "target.h"
 
 /* Context of record_reference.  */
 struct record_reference_ctx
@@ -288,7 +289,6 @@ mark_store (gimple stmt, tree t, void *data)
      }
   return false;
 }
-
 /* Create cgraph edges for function calls.
    Also look for functions and variables having addresses taken.  */
 
@@ -317,8 +317,22 @@ build_cgraph_edges (void)
 							 bb);
 	      decl = gimple_call_fndecl (stmt);
 	      if (decl)
-		cgraph_create_edge (node, cgraph_get_create_node (decl),
-				    stmt, bb->count, freq);
+		{
+		  struct cgraph_node *callee = cgraph_get_create_node (decl);
+	          /* If a call to a multiversioned function dispatcher is
+		     found, generate the body to dispatch the right function
+		     at run-time.  */
+		  if (callee->dispatcher_function)
+		    {
+		      tree resolver_decl;
+		      gcc_assert (callee->next_function_version);
+		      gcc_assert (targetm.generate_version_dispatcher_body);
+		      resolver_decl
+			 = targetm.generate_version_dispatcher_body (callee);
+		      gcc_assert (resolver_decl != NULL_TREE);
+		    }
+		  cgraph_create_edge (node, callee, stmt, bb->count, freq);
+	        }
 	      else
 		cgraph_create_indirect_edge (node, stmt,
 					     gimple_call_flags (stmt),
Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c	(revision 190493)
+++ gcc/c-family/c-common.c	(working copy)
@@ -8502,9 +8502,22 @@ handle_target_attribute (tree *node, tree name, tr
       warning (OPT_Wattributes, "%qE attribute ignored", name);
       *no_add_attrs = true;
     }
-  else if (! targetm.target_option.valid_attribute_p (*node, name, args,
-						      flags))
-    *no_add_attrs = true;
+  else
+    {
+      /* When a target attribute is invalid, it may also be because the
+	 target for the compilation unit and the attribute match.  For
+         instance, target attribute "xxx" is invalid when -mxxx is used.
+         When used with multiversioning, removing the attribute will lead
+         to duplicate definitions if a default version is provided.
+	 So, generate a warning here and remove the attribute.  */
+      if (!targetm.target_option.valid_attribute_p (*node, name, args, flags))
+	{
+	  warning (OPT_Wattributes,
+		   "Invalid target attribute in function %qE, ignored.",
+		   *node);
+	  *no_add_attrs = true;
+	}
+    }
 
   return NULL_TREE;
 }
Index: gcc/target.def
===================================================================
--- gcc/target.def	(revision 190493)
+++ gcc/target.def	(working copy)
@@ -1298,6 +1298,31 @@ DEFHOOK
  tree, (tree fndecl, int n_args, tree *argp, bool ignore),
  hook_tree_tree_int_treep_bool_null)
 
+/* Target hook to compare the priority of target features in function DECL1
+   and DECL2.  It returns positive value if DECL1 is higher priority,
+   negative value if DECL2 is higher priority and 0 if they are the
+   same.  */
+DEFHOOK
+(compare_version_priority,
+ "",
+ int, (tree decl1, tree decl2), NULL)
+
+/* Target hook to generate the dispatcher body for a function version
+   dispatcher ARG, which is a cgraph_node pointer.  */
+
+DEFHOOK
+(generate_version_dispatcher_body,
+ "",
+ tree, (void *arg), NULL) 
+
+/* Target hook to generate a function version dispatcher DECL for the list
+   of function versions in arglist, which is a vector of decls.  */
+
+DEFHOOK
+(get_function_versions_dispatcher,
+ "",
+ tree, (void *arglist), NULL)
+
 /* Returns a code for a target-specific builtin that implements
    reciprocal of the function, or NULL_TREE if not available.  */
 DEFHOOK
@@ -2705,6 +2730,14 @@ DEFHOOK
  void, (void),
  hook_void_void)
 
+/* Returns true if DECL1 and DECL2 are versions of the same function.  */
+
+DEFHOOK
+(function_versions,
+ "",
+ bool, (tree decl1, tree decl2),
+ hook_bool_tree_tree_false)
+
 /* Function to determine if one function can inline another function.  */
 #undef HOOK_PREFIX
 #define HOOK_PREFIX "TARGET_"
Index: gcc/cgraph.c
===================================================================
--- gcc/cgraph.c	(revision 190493)
+++ gcc/cgraph.c	(working copy)
@@ -1281,6 +1281,14 @@ cgraph_mark_address_taken_node (struct cgraph_node
   node->symbol.address_taken = 1;
   node = cgraph_function_or_thunk_node (node, NULL);
   node->symbol.address_taken = 1;
+  /* If the address of a multiversioned function dispatcher is taken,
+     generate the body to dispatch the right function at run-time.  This
+     is needed as the address can be used to do an indirect call.  */
+  if (node->dispatcher_function)
+    {
+      gcc_assert (node->next_function_version);
+      targetm.generate_version_dispatcher_body (node);
+    }
 }
 
 /* Return local info for the compiled function.  */
Index: gcc/cgraph.h
===================================================================
--- gcc/cgraph.h	(revision 190493)
+++ gcc/cgraph.h	(working copy)
@@ -220,6 +220,26 @@ struct GTY(()) cgraph_node {
   struct cgraph_node *prev_sibling_clone;
   struct cgraph_node *clones;
   struct cgraph_node *clone_of;
+
+  /* TODO: Put version_dispatcher_decl, prev_function_version,
+     next_function_version into a struct for readability.
+
+     If this node corresponds to a function version, this points
+     to the dispatcher function decl which is the function that must
+     be called to execute the right function version at run-time.
+
+     If this node is a dispatcher for function versions, this points
+     to resolver function, which holds  the function body for the
+     dispatcher.  */
+  tree version_dispatcher_decl;
+
+  /* Chains all the semantically identical function versions.  The
+     first function in this chain is the default function.  */
+  struct cgraph_node *prev_function_version;
+  /* If this node is a dispatcher for function versions, this also points
+     to the default function version.  */
+  struct cgraph_node *next_function_version;
+
   /* For functions with many calls sites it holds map from call expression
      to the edge to speed up cgraph_edge function.  */
   htab_t GTY((param_is (struct cgraph_edge))) call_site_hash;
@@ -271,6 +291,7 @@ struct GTY(()) cgraph_node {
   /* ?? We should be able to remove this.  We have enough bits in
      cgraph to calculate it.  */
   unsigned tm_clone : 1;
+  unsigned dispatcher_function : 1;
 };
 
 DEF_VEC_P(symtab_node);
@@ -648,6 +669,7 @@ void cgraph_rebuild_references (void);
 int compute_call_stmt_bb_frequency (tree, basic_block bb);
 void record_references_in_initializer (tree, bool);
 
+
 /* In ipa.c  */
 bool symtab_remove_unreachable_nodes (bool, FILE *);
 cgraph_node_set cgraph_node_set_new (void);
Index: gcc/tree.h
===================================================================
--- gcc/tree.h	(revision 190493)
+++ gcc/tree.h	(working copy)
@@ -3436,6 +3436,12 @@ extern VEC(tree, gc) **decl_debug_args_insert (tre
 #define DECL_FUNCTION_SPECIFIC_OPTIMIZATION(NODE) \
    (FUNCTION_DECL_CHECK (NODE)->function_decl.function_specific_optimization)
 
+/* In FUNCTION_DECL, this is set if this function has other versions generated
+   using "target" attributes.  The default version is the one which does not
+   have any "target" attribute set. */
+#define DECL_FUNCTION_VERSIONED(NODE)\
+   (FUNCTION_DECL_CHECK (NODE)->function_decl.versioned_function)
+
 /* FUNCTION_DECL inherits from DECL_NON_COMMON because of the use of the
    arguments/result/saved_tree fields by front ends.   It was either inherit
    FUNCTION_DECL from non_common, or inherit non_common from FUNCTION_DECL,
@@ -3480,8 +3486,8 @@ struct GTY(()) tree_function_decl {
   unsigned looping_const_or_pure_flag : 1;
   unsigned has_debug_args_flag : 1;
   unsigned tm_clone_flag : 1;
-
-  /* 1 bit left */
+  unsigned versioned_function : 1;
+  /* No bits left.  */
 };
 
 /* The source language of the translation-unit.  */
Index: gcc/testsuite/g++.dg/mv2.C
===================================================================
--- gcc/testsuite/g++.dg/mv2.C	(revision 0)
+++ gcc/testsuite/g++.dg/mv2.C	(revision 0)
@@ -0,0 +1,119 @@
+/* Test case to check if Multiversioning chooses the correct
+   dispatching order when versions are for various ISAs.  */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-ifunc "" }  */
+/* { dg-options "-O2 -mno-sse -mno-mmx -mno-popcnt -mno-avx" } */
+
+#include <assert.h>
+
+/* Default version.  */
+int foo ();
+/* The dispatch checks should be in the exact reverse order of the
+   declarations below.  */
+int foo () __attribute__ ((target ("mmx")));
+int foo () __attribute__ ((target ("sse")));
+int foo () __attribute__ ((target ("sse2")));
+int foo () __attribute__ ((target ("sse3")));
+int foo () __attribute__ ((target ("ssse3")));
+int foo () __attribute__ ((target ("sse4.1")));
+int foo () __attribute__ ((target ("sse4.2")));
+int foo () __attribute__ ((target ("popcnt")));
+int foo () __attribute__ ((target ("avx")));
+int foo () __attribute__ ((target ("avx2")));
+
+int main ()
+{
+
+  int val = foo ();
+
+  if (__builtin_cpu_supports ("avx2"))
+    assert (val == 1);
+  else if (__builtin_cpu_supports ("avx"))
+    assert (val == 2);
+  else if (__builtin_cpu_supports ("popcnt"))
+    assert (val == 3);
+  else if (__builtin_cpu_supports ("sse4.2"))
+    assert (val == 4);
+  else if (__builtin_cpu_supports ("sse4.1"))
+    assert (val == 5);
+  else if (__builtin_cpu_supports ("ssse3"))
+    assert (val == 6);
+  else if (__builtin_cpu_supports ("sse3"))
+    assert (val == 7);
+  else if (__builtin_cpu_supports ("sse2"))
+    assert (val == 8);
+  else if (__builtin_cpu_supports ("sse"))
+    assert (val == 9);
+  else if (__builtin_cpu_supports ("mmx"))
+    assert (val == 10);
+  else
+    assert (val == 0);
+
+  return 0;
+}
+
+int
+foo ()
+{
+  return 0;
+}
+
+int __attribute__ ((target("mmx")))
+foo ()
+{
+  return 10;
+}
+
+int __attribute__ ((target("sse")))
+foo ()
+{
+  return 9;
+}
+
+int __attribute__ ((target("sse2")))
+foo ()
+{
+  return 8;
+}
+
+int __attribute__ ((target("sse3")))
+foo ()
+{
+  return 7;
+}
+
+int __attribute__ ((target("ssse3")))
+foo ()
+{
+  return 6;
+}
+
+int __attribute__ ((target("sse4.1")))
+foo ()
+{
+  return 5;
+}
+
+int __attribute__ ((target("sse4.2")))
+foo ()
+{
+  return 4;
+}
+
+int __attribute__ ((target("popcnt")))
+foo ()
+{
+  return 3;
+}
+
+int __attribute__ ((target("avx")))
+foo ()
+{
+  return 2;
+}
+
+int __attribute__ ((target("avx2")))
+foo ()
+{
+  return 1;
+}
Index: gcc/testsuite/g++.dg/mv4.C
===================================================================
--- gcc/testsuite/g++.dg/mv4.C	(revision 0)
+++ gcc/testsuite/g++.dg/mv4.C	(revision 0)
@@ -0,0 +1,23 @@
+/* Test case to check if the compiler generates an error message
+   when the default version of a multiversioned function is absent
+   and its pointer is taken.  */
+
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 -mno-sse -mno-popcnt" } */
+
+int __attribute__ ((target ("sse")))
+foo ()
+{
+  return 1;
+}
+int __attribute__ ((target ("popcnt")))
+foo ()
+{
+  return 0;
+}
+
+int main ()
+{
+  int (*p)() = &foo; /* { dg-error "Pointer to a multiversioned function without a default is not allowed" {} } */
+  return (*p)();
+}
Index: gcc/testsuite/g++.dg/mv1.C
===================================================================
--- gcc/testsuite/g++.dg/mv1.C	(revision 0)
+++ gcc/testsuite/g++.dg/mv1.C	(revision 0)
@@ -0,0 +1,130 @@
+/* Test case to check if Multiversioning works.  */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-ifunc "" }  */
+/* { dg-options "-O2 -fPIC -mno-avx -mno-popcnt" } */
+
+#include <assert.h>
+
+/* Default version.  */
+int foo ();
+/* The other versions of foo.  Mix up the ordering and 
+   check if the dispatching does it in the order of priority. */
+/* Check combination of target attributes.  */
+int foo () __attribute__ ((target("arch=corei7,popcnt")));
+/* The target operands in this declaration and the definition are re-ordered.
+   This should still work.  */
+int foo () __attribute__ ((target("ssse3,avx2")));
+
+/* Check for all target attributes for which dispatchers are available.  */
+/* Check arch= */
+int foo () __attribute__((target("arch=core2")));
+int foo () __attribute__((target("arch=corei7")));
+int foo () __attribute__((target("arch=atom")));
+/* Check ISAs  */
+int foo () __attribute__((target("avx")));
+int foo () __attribute__ ((target("arch=core2,sse4.2")));
+/* Check more arch=.  */
+int foo () __attribute__((target("arch=amdfam10")));
+int foo () __attribute__((target("arch=bdver1")));
+int foo () __attribute__((target("arch=bdver2")));
+
+int (*p)() = &foo;
+int main ()
+{
+  int val = foo ();
+  assert (val ==  (*p)());
+
+  /* Check in the exact same order in which the dispatching
+     is expected to happen.  */
+  if (__builtin_cpu_is ("bdver1"))
+    assert (val == 1);
+  else if (__builtin_cpu_is ("bdver2"))
+    assert (val == 2);
+  else if (__builtin_cpu_supports ("avx2")
+	   && __builtin_cpu_supports ("ssse3"))
+    assert (val == 3);
+  else if (__builtin_cpu_supports ("avx"))
+    assert (val == 4);
+  else if (__builtin_cpu_is ("corei7")
+	   && __builtin_cpu_supports ("popcnt"))
+    assert (val == 5);
+  else if (__builtin_cpu_is ("corei7"))
+    assert (val == 6);
+  else if (__builtin_cpu_is ("amdfam10h"))
+    assert (val == 7);
+  else if (__builtin_cpu_is ("core2")
+	   && __builtin_cpu_supports ("sse4.2"))
+    assert (val == 8);
+  else if (__builtin_cpu_is ("core2"))
+    assert (val == 9);
+  else if (__builtin_cpu_is ("atom"))
+    assert (val == 10);
+  else
+    assert (val == 0);
+  
+  return 0;
+}
+
+int foo ()
+{
+  return 0;
+}
+
+int __attribute__ ((target("arch=corei7,popcnt")))
+foo ()
+{
+  return 5;
+}
+int __attribute__ ((target("avx2,ssse3")))
+foo ()
+{
+  return 3;
+}
+
+int __attribute__ ((target("arch=core2")))
+foo ()
+{
+  return 9;
+}
+
+int __attribute__ ((target("arch=corei7")))
+foo ()
+{
+  return 6;
+}
+
+int __attribute__ ((target("arch=atom")))
+foo ()
+{
+  return 10;
+}
+
+int __attribute__ ((target("avx")))
+foo ()
+{
+  return 4;
+}
+
+int __attribute__ ((target("arch=core2,sse4.2")))
+foo ()
+{
+  return 8;
+}
+
+int __attribute__ ((target("arch=amdfam10")))
+foo ()
+{
+  return 7;
+}
+
+int __attribute__ ((target("arch=bdver1")))
+foo ()
+{
+  return 1;
+}
+
+int __attribute__ ((target("arch=bdver2")))
+foo ()
+{
+  return 2;
+}
Index: gcc/testsuite/g++.dg/mv3.C
===================================================================
--- gcc/testsuite/g++.dg/mv3.C	(revision 0)
+++ gcc/testsuite/g++.dg/mv3.C	(revision 0)
@@ -0,0 +1,37 @@
+/* Test case to check if a call to a multiversioned function
+   is replaced with a direct call to the particular version when
+   the most specialized version's target attributes match the
+   caller.  
+  
+   In this program, foo is multiversioned but there is no default
+   function.  This is an error if the call has to go through a
+   dispatcher.  However, the call to foo in bar can be replaced
+   with a direct call to the popcnt version of foo.  Hence, this
+   test should pass.  */
+
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 -mno-sse -mno-popcnt" } */
+
+
+/* Default version.  */
+int __attribute__ ((target ("sse")))
+foo ()
+{
+  return 1;
+}
+int __attribute__ ((target ("popcnt")))
+foo ()
+{
+  return 0;
+}
+
+int __attribute__ ((target ("popcnt")))
+bar ()
+{
+  return foo ();
+}
+
+int main ()
+{
+  return bar ();
+}
Index: gcc/cp/class.c
===================================================================
--- gcc/cp/class.c	(revision 190493)
+++ gcc/cp/class.c	(working copy)
@@ -1091,7 +1091,32 @@ add_method (tree type, tree method, tree using_dec
 	      || same_type_p (TREE_TYPE (fn_type),
 			      TREE_TYPE (method_type))))
 	{
-	  if (using_decl)
+	  /* For function versions, their parms and types match
+	     but they are not duplicates.  Record function versions
+	     as and when they are found.  */
+	  if (TREE_CODE (fn) == FUNCTION_DECL
+	      && TREE_CODE (method) == FUNCTION_DECL
+	      && (DECL_FUNCTION_SPECIFIC_TARGET (fn)
+		  || DECL_FUNCTION_SPECIFIC_TARGET (method))
+	      && targetm.target_option.function_versions (fn, method))
+ 	    {
+	      /* Mark functions as versions if necessary.  Modify the mangled
+		 decl name if necessary.  */
+	      if (!DECL_FUNCTION_VERSIONED (fn))
+		{
+		  DECL_FUNCTION_VERSIONED (fn) = 1;
+		  if (DECL_ASSEMBLER_NAME_SET_P (fn))
+		    mangle_decl (fn);
+		}
+	      if (!DECL_FUNCTION_VERSIONED (method))
+		{
+		  DECL_FUNCTION_VERSIONED (method) = 1;
+		  if (DECL_ASSEMBLER_NAME_SET_P (method))
+		    mangle_decl (method);
+		}
+	      continue;
+	    }
+	  else if (using_decl)
 	    {
 	      if (DECL_CONTEXT (fn) == type)
 		/* Defer to the local function.  */
@@ -6922,6 +6947,7 @@ resolve_address_of_overloaded_function (tree targe
   tree matches = NULL_TREE;
   tree fn;
   tree target_fn_type;
+  VEC (tree, heap) *fn_ver_vec = NULL;
 
   /* By the time we get here, we should be seeing only real
      pointer-to-member types, not the internal POINTER_TYPE to
@@ -6986,9 +7012,19 @@ resolve_address_of_overloaded_function (tree targe
 	  if (DECL_ANTICIPATED (fn))
 	    continue;
 
-	  /* See if there's a match.  */
+	  /* See if there's a match.   For functions that are multi-versioned,
+	     all the versions match.  */
 	  if (same_type_p (target_fn_type, static_fn_type (fn)))
-	    matches = tree_cons (fn, NULL_TREE, matches);
+	    {
+	      matches = tree_cons (fn, NULL_TREE, matches);
+	      /*If versioned, push all possible versions into a vector.  */
+	      if (DECL_FUNCTION_VERSIONED (fn))
+		{
+		  if (fn_ver_vec == NULL)
+		   fn_ver_vec = VEC_alloc (tree, heap, 2);
+		  VEC_safe_push (tree, heap, fn_ver_vec, fn); 
+		}
+	    }
 	}
     }
 
@@ -7080,13 +7116,26 @@ resolve_address_of_overloaded_function (tree targe
     {
       /* There were too many matches.  First check if they're all
 	 the same function.  */
-      tree match;
+      tree match = NULL_TREE;
 
       fn = TREE_PURPOSE (matches);
-      for (match = TREE_CHAIN (matches); match; match = TREE_CHAIN (match))
-	if (!decls_match (fn, TREE_PURPOSE (match)))
-	  break;
 
+      /* For multi-versioned functions, more than one match is just fine.
+	 Call decls_match to make sure they are different because they are
+	 versioned.  */
+      if (DECL_FUNCTION_VERSIONED (fn))
+	{
+          for (match = TREE_CHAIN (matches); match; match = TREE_CHAIN (match))
+  	    if (decls_match (fn, TREE_PURPOSE (match)))
+	      break;
+	}
+      else
+	{
+          for (match = TREE_CHAIN (matches); match; match = TREE_CHAIN (match))
+  	    if (!decls_match (fn, TREE_PURPOSE (match)))
+	      break;
+	}
+
       if (match)
 	{
 	  if (flags & tf_error)
@@ -7148,6 +7197,28 @@ resolve_address_of_overloaded_function (tree targe
       perform_or_defer_access_check (access_path, fn, fn, flags);
     }
 
+  /* If a pointer to a function that is multi-versioned is requested, the
+     pointer to the dispatcher function is returned instead.  This works
+     well because indirectly calling the function will dispatch the right
+     function version at run-time.  */
+  if (DECL_FUNCTION_VERSIONED (fn))
+    {
+      tree dispatcher_decl = NULL;
+      gcc_assert (fn_ver_vec != NULL);
+      gcc_assert (targetm.get_function_versions_dispatcher);
+      dispatcher_decl = targetm.get_function_versions_dispatcher (fn_ver_vec);
+      if (!dispatcher_decl)
+	{
+	  error_at (input_location, "Pointer to a multiversioned function"
+		    " without a default is not allowed");
+	  return error_mark_node;
+	}
+      retrofit_lang_decl (dispatcher_decl);
+      mark_used (fn);
+      VEC_free (tree, heap, fn_ver_vec);
+      fn = dispatcher_decl;
+    }
+
   if (TYPE_PTRFN_P (target_type) || TYPE_PTRMEMFUNC_P (target_type))
     return cp_build_addr_expr (fn, flags);
   else
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c	(revision 190493)
+++ gcc/cp/decl.c	(working copy)
@@ -53,6 +53,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "pointer-set.h"
 #include "splay-tree.h"
 #include "plugin.h"
+#include "cgraph.h"
 
 /* Possible cases of bad specifiers type used by bad_specifiers. */
 enum bad_spec_place {
@@ -972,6 +973,29 @@ decls_match (tree newdecl, tree olddecl)
       if (t1 != t2)
 	return 0;
 
+      /* The decls dont match if they correspond to two different versions
+	 of the same function.  */
+      if (compparms (p1, p2)
+	  && same_type_p (TREE_TYPE (f1), TREE_TYPE (f2)) 
+	  && targetm.target_option.function_versions (newdecl, olddecl))
+	{
+	  /* Mark functions as versions if necessary.  Modify the mangled decl
+	     name if necessary.  */
+	  if (!DECL_FUNCTION_VERSIONED (newdecl))
+	    {
+	      DECL_FUNCTION_VERSIONED (newdecl) = 1;
+	      if (DECL_ASSEMBLER_NAME_SET_P (newdecl))
+	        mangle_decl (newdecl);
+	    }
+	  if (!DECL_FUNCTION_VERSIONED (olddecl))
+	    {
+	      DECL_FUNCTION_VERSIONED (olddecl) = 1;
+	      if (DECL_ASSEMBLER_NAME_SET_P (olddecl))
+	       mangle_decl (olddecl);
+	    }
+	  return 0;
+	}
+
       if (CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl)
 	  && ! (DECL_EXTERN_C_P (newdecl)
 		&& DECL_EXTERN_C_P (olddecl)))
@@ -1490,7 +1514,11 @@ duplicate_decls (tree newdecl, tree olddecl, bool
 	      error ("previous declaration %q+#D here", olddecl);
 	      return NULL_TREE;
 	    }
-	  else if (compparms (TYPE_ARG_TYPES (TREE_TYPE (newdecl)),
+	  /* For function versions, params and types match, but they
+	     are not ambiguous.  */
+	  else if ((!DECL_FUNCTION_VERSIONED (newdecl)
+		    && !DECL_FUNCTION_VERSIONED (olddecl))
+		   && compparms (TYPE_ARG_TYPES (TREE_TYPE (newdecl)),
 			      TYPE_ARG_TYPES (TREE_TYPE (olddecl))))
 	    {
 	      error ("new declaration %q#D", newdecl);
@@ -2262,6 +2290,11 @@ duplicate_decls (tree newdecl, tree olddecl, bool
   else if (DECL_PRESERVE_P (newdecl))
     DECL_PRESERVE_P (olddecl) = 1;
 
+  /* If the olddecl is a version, so is the newdecl.  */
+  if (TREE_CODE (newdecl) == FUNCTION_DECL
+      && DECL_FUNCTION_VERSIONED (olddecl))
+    DECL_FUNCTION_VERSIONED (newdecl) = 1;
+
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
       int function_size;
@@ -14024,7 +14057,11 @@ cxx_comdat_group (tree decl)
 	  else
 	    break;
 	}
-      name = DECL_ASSEMBLER_NAME (decl);
+      if (TREE_CODE (decl) == FUNCTION_DECL
+	  && DECL_FUNCTION_VERSIONED (decl))
+	name = DECL_NAME (decl);
+      else
+        name = DECL_ASSEMBLER_NAME (decl);
     }
 
   return name;
Index: gcc/cp/error.c
===================================================================
--- gcc/cp/error.c	(revision 190493)
+++ gcc/cp/error.c	(working copy)
@@ -1539,8 +1539,15 @@ dump_exception_spec (tree t, int flags)
 static void
 dump_function_name (tree t, int flags)
 {
-  tree name = DECL_NAME (t);
+  tree name;
 
+  /* For function versions, use the assembler name as the decl name is
+     the same for all versions.  */
+  if (DECL_FUNCTION_VERSIONED (t))
+    name = DECL_ASSEMBLER_NAME (t);
+  else
+    name = DECL_NAME (t);
+
   /* We can get here with a decl that was synthesized by language-
      independent machinery (e.g. coverage.c) in which case it won't
      have a lang_specific structure attached and DECL_CONSTRUCTOR_P
Index: gcc/cp/semantics.c
===================================================================
--- gcc/cp/semantics.c	(revision 190493)
+++ gcc/cp/semantics.c	(working copy)
@@ -3775,8 +3775,11 @@ expand_or_defer_fn_1 (tree fn)
       /* If the user wants us to keep all inline functions, then mark
 	 this function as needed so that finish_file will make sure to
 	 output it later.  Similarly, all dllexport'd functions must
-	 be emitted; there may be callers in other DLLs.  */
-      if ((flag_keep_inline_functions
+	 be emitted; there may be callers in other DLLs.
+	 Also, mark this function as needed if it is marked inline but
+	 is a multi-versioned function.  */
+      if (((flag_keep_inline_functions
+	    || DECL_FUNCTION_VERSIONED (fn))
 	   && DECL_DECLARED_INLINE_P (fn)
 	   && !DECL_REALLY_EXTERN (fn))
 	  || (flag_keep_inline_dllexport
Index: gcc/cp/decl2.c
===================================================================
--- gcc/cp/decl2.c	(revision 190493)
+++ gcc/cp/decl2.c	(working copy)
@@ -674,9 +674,13 @@ check_classfn (tree ctype, tree function, tree tem
 	  if (is_template != (TREE_CODE (fndecl) == TEMPLATE_DECL))
 	    continue;
 
+	  /* While finding a match, same types and params are not enough
+	     if the function is versioned.  Also check version ("target")
+	     attributes.  */
 	  if (same_type_p (TREE_TYPE (TREE_TYPE (function)),
 			   TREE_TYPE (TREE_TYPE (fndecl)))
 	      && compparms (p1, p2)
+	      && !targetm.target_option.function_versions (function, fndecl)
 	      && (!is_template
 		  || comp_template_parms (template_parms,
 					  DECL_TEMPLATE_PARMS (fndecl)))
Index: gcc/cp/call.c
===================================================================
--- gcc/cp/call.c	(revision 190493)
+++ gcc/cp/call.c	(working copy)
@@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "langhooks.h"
 #include "c-family/c-objc.h"
 #include "timevar.h"
+#include "cgraph.h"
 
 /* The various kinds of conversion.  */
 
@@ -6407,6 +6408,35 @@ magic_varargs_p (tree fn)
   return false;
 }
 
+/* Returns the decl of the dispatcher function if FN is a function version.  */
+
+static tree
+get_function_version_dispatcher (tree fn)
+{
+  tree dispatcher_decl = NULL;
+  struct cgraph_node *node = NULL;
+
+  gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
+	      && DECL_FUNCTION_VERSIONED (fn));
+
+  node = cgraph_get_node (fn);
+
+  if (node != NULL)
+    dispatcher_decl = node->version_dispatcher_decl;
+  else
+    return NULL;
+
+  if (dispatcher_decl == NULL)
+    {
+      error_at (input_location, "Call to multiversioned function"
+                " without a default is not allowed");
+      return NULL;
+    }
+  retrofit_lang_decl (dispatcher_decl);
+  gcc_assert (dispatcher_decl != NULL);
+  return dispatcher_decl;
+}
+
 /* Subroutine of the various build_*_call functions.  Overload resolution
    has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
    ARGS is a TREE_LIST of the unconverted arguments to the call.  FLAGS is a
@@ -6858,6 +6888,20 @@ build_over_call (struct z_candidate *cand, int fla
   if (!already_used)
     mark_used (fn);
 
+  /* For calls to a multi-versioned function, overload resolution
+     returns the function with the highest target priority, that is,
+     the version that will checked for dispatching first.  If this
+     version is inlinable, a direct call to this version can be made
+     otherwise the call should go through the dispatcher.  */
+
+  if (DECL_FUNCTION_VERSIONED (fn)
+      && !targetm.target_option.can_inline_p (current_function_decl, fn))
+    {
+      fn = get_function_version_dispatcher (fn);
+      if (fn == NULL)
+	return NULL;
+    }
+
   if (DECL_VINDEX (fn) && (flags & LOOKUP_NONVIRTUAL) == 0)
     {
       tree t;
@@ -8136,6 +8180,38 @@ joust (struct z_candidate *cand1, struct z_candida
       && (IS_TYPE_OR_DECL_P (cand1->fn)))
     return 1;
 
+  /* For Candidates of a multi-versioned function,  make the version with
+     the highest priority win.  This version will be checked for dispatching
+     first.  If this version can be inlined into the caller, the front-end
+     will simply make a direct call to this function.  */
+
+  if (TREE_CODE (cand1->fn) == FUNCTION_DECL
+      && DECL_FUNCTION_VERSIONED (cand1->fn)
+      && TREE_CODE (cand2->fn) == FUNCTION_DECL
+      && DECL_FUNCTION_VERSIONED (cand2->fn))
+    {
+      tree f1 = TREE_TYPE (cand1->fn);
+      tree f2 = TREE_TYPE (cand2->fn);
+      tree p1 = TYPE_ARG_TYPES (f1);
+      tree p2 = TYPE_ARG_TYPES (f2);
+     
+      /* Check if cand1->fn and cand2->fn are versions of the same function.  It
+         is possible that cand1->fn and cand2->fn are function versions but of
+         different functions.  Check types to see if they are versions of the same
+         function.  */
+      if (compparms (p1, p2)
+	  && same_type_p (TREE_TYPE (f1), TREE_TYPE (f2)))
+	{
+	  /* Always make the version with the higher priority, more
+	     specialized, win.  */
+	  gcc_assert (targetm.compare_version_priority);
+	  if (targetm.compare_version_priority (cand1->fn, cand2->fn) >= 0)
+	    return 1;
+	  else
+	    return -1;
+	}
+    }
+
   /* a viable function F1
      is defined to be a better function than another viable function F2  if
      for  all arguments i, ICSi(F1) is not a worse conversion sequence than
@@ -8456,6 +8532,37 @@ tweak:
   return 0;
 }
 
+/* Function FN is multi-versioned and CANDIDATES contains the list of all
+   overloaded candidates for FN.  This function extracts all functions from
+   CANDIDATES that are function versions of FN and generates a dispatcher
+   function for this multi-versioned function group.  */
+
+static void
+generate_function_versions_dispatcher (tree fn, struct z_candidate *candidates)
+{
+  tree f1 = TREE_TYPE (fn);
+  tree p1 = TYPE_ARG_TYPES (f1);
+  VEC (tree, heap) *fn_ver_vec = NULL;
+  struct z_candidate *ver = candidates;
+
+  fn_ver_vec = VEC_alloc (tree, heap, 2);
+
+  for (;ver; ver = ver->next)
+    {
+      tree f2 = TREE_TYPE (ver->fn);
+      tree p2 = TYPE_ARG_TYPES (f2);
+      /* If this candidate is a version of FN, types must match.  */
+      if (DECL_FUNCTION_VERSIONED (ver->fn)
+          && compparms (p1, p2)
+	  && same_type_p (TREE_TYPE (f1), TREE_TYPE (f2)))
+        VEC_safe_push (tree, heap, fn_ver_vec, ver->fn);
+    }
+
+  gcc_assert (targetm.get_function_versions_dispatcher);
+  targetm.get_function_versions_dispatcher (fn_ver_vec);
+  VEC_free (tree, heap, fn_ver_vec); 
+}
+
 /* Given a list of candidates for overloading, find the best one, if any.
    This algorithm has a worst case of O(2n) (winner is last), and a best
    case of O(n/2) (totally ambiguous); much better than a sorting
@@ -8508,6 +8615,17 @@ tourney (struct z_candidate *candidates, tsubst_fl
 	return NULL;
     }
 
+  /* For multiversioned functions, aggregate all the versions here for
+     generating the dispatcher body later if necessary.  Check to see if
+     the dispatcher is already generated to avoid doing this more than
+     once.  */
+
+  if (TREE_CODE (champ->fn) == FUNCTION_DECL
+      && DECL_FUNCTION_VERSIONED (champ->fn)
+      && (cgraph_get_node (champ->fn) == NULL
+	  || cgraph_get_node (champ->fn)->version_dispatcher_decl == NULL))
+      generate_function_versions_dispatcher (champ->fn, candidates);
+
   return champ;
 }
 
Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c	(revision 190493)
+++ gcc/config/i386/i386.c	(working copy)
@@ -62,6 +62,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "opts.h"
 #include "diagnostic.h"
 #include "dumpfile.h"
+#include "tree-pass.h"
+#include "tree-flow.h"
 
 enum upper_128bits_state
 {
@@ -28030,6 +28032,984 @@ ix86_init_mmx_sse_builtins (void)
     }
 }
 
+
+/* This adds a condition to the basic_block NEW_BB in function FUNCTION_DECL
+   to return a pointer to VERSION_DECL if the outcome of the expression
+   formed by PREDICATE_CHAIN is true.  This function will be called during
+   version dispatch to decide which function version to execute.  It returns
+   the basic block at the end, to which more conditions can be added.  */
+
+static basic_block
+add_condition_to_bb (tree function_decl, tree version_decl,
+		     tree predicate_chain, basic_block new_bb)
+{
+  gimple return_stmt;
+  tree convert_expr, result_var;
+  gimple convert_stmt;
+  gimple call_cond_stmt;
+  gimple if_else_stmt;
+
+  basic_block bb1, bb2, bb3;
+  edge e12, e23;
+
+  tree cond_var, and_expr_var = NULL_TREE;
+  gimple_seq gseq;
+
+  tree old_current_function_decl;
+  tree predicate_decl, predicate_arg;
+
+  old_current_function_decl = current_function_decl;
+  push_cfun (DECL_STRUCT_FUNCTION (function_decl));
+  current_function_decl = function_decl;
+
+  gcc_assert (new_bb != NULL);
+  gseq = bb_seq (new_bb);
+
+
+  convert_expr = build1 (CONVERT_EXPR, ptr_type_node,
+	     		 build_fold_addr_expr (version_decl));
+  result_var = create_tmp_var (ptr_type_node, NULL);
+  convert_stmt = gimple_build_assign (result_var, convert_expr); 
+  return_stmt = gimple_build_return (result_var);
+
+  if (predicate_chain == NULL_TREE)
+    {
+      gimple_seq_add_stmt (&gseq, convert_stmt);
+      gimple_seq_add_stmt (&gseq, return_stmt);
+      set_bb_seq (new_bb, gseq);
+      gimple_set_bb (convert_stmt, new_bb);
+      gimple_set_bb (return_stmt, new_bb);
+      pop_cfun ();
+      current_function_decl = old_current_function_decl;
+      return new_bb;
+    }
+
+  while (predicate_chain != NULL)
+    {
+      cond_var = create_tmp_var (integer_type_node, NULL);
+      predicate_decl = TREE_PURPOSE (predicate_chain);
+      predicate_arg = TREE_VALUE (predicate_chain);
+      call_cond_stmt = gimple_build_call (predicate_decl, 1, predicate_arg);
+      gimple_call_set_lhs (call_cond_stmt, cond_var);
+
+      gimple_set_block (call_cond_stmt, DECL_INITIAL (function_decl));
+      gimple_set_bb (call_cond_stmt, new_bb);
+      gimple_seq_add_stmt (&gseq, call_cond_stmt);
+
+      predicate_chain = TREE_CHAIN (predicate_chain);
+      
+      if (and_expr_var == NULL)
+        and_expr_var = cond_var;
+      else
+	{
+	  gimple assign_stmt;
+	  /* Use MIN_EXPR to check if any integer is zero?.
+	     and_expr_var = min_expr <cond_var, and_expr_var>  */
+	  assign_stmt = gimple_build_assign (and_expr_var,
+			  build2 (MIN_EXPR, integer_type_node,
+				  cond_var, and_expr_var));
+
+	  gimple_set_block (assign_stmt, DECL_INITIAL (function_decl));
+	  gimple_set_bb (assign_stmt, new_bb);
+	  gimple_seq_add_stmt (&gseq, assign_stmt);
+	}
+    }
+
+  if_else_stmt = gimple_build_cond (GT_EXPR, and_expr_var,
+	  		            integer_zero_node,
+				    NULL_TREE, NULL_TREE);
+  gimple_set_block (if_else_stmt, DECL_INITIAL (function_decl));
+  gimple_set_bb (if_else_stmt, new_bb);
+  gimple_seq_add_stmt (&gseq, if_else_stmt);
+
+  gimple_seq_add_stmt (&gseq, convert_stmt);
+  gimple_seq_add_stmt (&gseq, return_stmt);
+  set_bb_seq (new_bb, gseq);
+
+  bb1 = new_bb;
+  e12 = split_block (bb1, if_else_stmt);
+  bb2 = e12->dest;
+  e12->flags &= ~EDGE_FALLTHRU;
+  e12->flags |= EDGE_TRUE_VALUE;
+
+  e23 = split_block (bb2, return_stmt);
+
+  gimple_set_bb (convert_stmt, bb2);
+  gimple_set_bb (return_stmt, bb2);
+
+  bb3 = e23->dest;
+  make_edge (bb1, bb3, EDGE_FALSE_VALUE); 
+
+  remove_edge (e23);
+  make_edge (bb2, EXIT_BLOCK_PTR, 0);
+
+  pop_cfun ();
+  current_function_decl = old_current_function_decl;
+
+  return bb3;
+}
+
+/* This parses the attribute arguments to target in DECL and determines
+   the right builtin to use to match the platform specification.
+   For now, only one target argument ("arch=" or "<-m>xxx") is allowed.
+   It returns the priority value for this version decl.  If PREDICATE_LIST
+   is not NULL, it stores the list of cpu features that need to be checked
+   before dispatching this function.  */
+
+static unsigned int
+get_builtin_code_for_version (tree decl, tree *predicate_list)
+{
+  tree attrs;
+  struct cl_target_option cur_target;
+  tree target_node;
+  struct cl_target_option *new_target;
+  const char *arg_str = NULL;
+  const char *attrs_str = NULL;
+  char *tok_str = NULL;
+  char *token;
+  unsigned int priority = 0;
+
+  /* Priority of i386 features, greater value is higher priority.   This is
+     used to decide the order in which function dispatch must happen.  For
+     instance, a version specialized for SSE4.2 should be checked for dispatch
+     before a version for SSE3, as SSE4.2 implies SSE3.  */
+  enum feature_priority
+  {
+    P_ZERO = 0,
+    P_MMX,
+    P_SSE,
+    P_SSE2,
+    P_SSE3,
+    P_SSSE3,
+    P_PROC_SSSE3,
+    P_SSE4_a,
+    P_PROC_SSE4_a,
+    P_SSE4_1,
+    P_SSE4_2,
+    P_PROC_SSE4_2,
+    P_POPCNT,
+    P_AVX,
+    P_AVX2,
+    P_FMA,
+    P_PROC_FMA
+  };
+
+  /* These are the target attribute strings for which a dispatcher is
+     available, from fold_builtin_cpu.  */
+
+  static struct _feature_list
+    {
+      const char *const name;
+      const enum feature_priority priority;
+    }
+  const feature_list[] =
+    {
+      {"mmx", P_MMX},
+      {"sse", P_SSE},
+      {"sse2", P_SSE2},
+      {"sse3", P_SSE3},
+      {"ssse3", P_SSSE3},
+      {"sse4.1", P_SSE4_1},
+      {"sse4.2", P_SSE4_2},
+      {"popcnt", P_POPCNT},
+      {"avx", P_AVX},
+      {"avx2", P_AVX2}
+    };
+
+
+  static unsigned int NUM_FEATURES
+    = sizeof (feature_list) / sizeof (struct _feature_list);
+
+  unsigned int i;
+
+  tree predicate_chain = NULL_TREE;
+  tree predicate_decl, predicate_arg;
+
+  attrs = lookup_attribute ("target", DECL_ATTRIBUTES (decl));
+  gcc_assert (attrs != NULL);
+
+  attrs = TREE_VALUE (TREE_VALUE (attrs));
+
+  gcc_assert (TREE_CODE (attrs) == STRING_CST);
+  attrs_str = TREE_STRING_POINTER (attrs);
+
+
+  /* Handle arch= if specified.  For priority, set it to be 1 more than
+     the best instruction set the processor can handle.  For instance, if
+     there is a version for atom and a version for ssse3 (the highest ISA
+     priority for atom), the atom version must be checked for dispatch
+     before the ssse3 version. */
+  if (strstr (attrs_str, "arch=") != NULL)
+    {
+      cl_target_option_save (&cur_target, &global_options);
+      target_node = ix86_valid_target_attribute_tree (attrs);
+    
+      gcc_assert (target_node);
+      new_target = TREE_TARGET_OPTION (target_node);
+      gcc_assert (new_target);
+      
+      if (new_target->arch_specified && new_target->arch > 0)
+	{
+	  switch (new_target->arch)
+	    {
+	    case PROCESSOR_CORE2_32:
+	    case PROCESSOR_CORE2_64:
+	      arg_str = "core2";
+	      priority = P_PROC_SSSE3;
+	      break;
+	    case PROCESSOR_COREI7_32:
+	    case PROCESSOR_COREI7_64:
+	      arg_str = "corei7";
+	      priority = P_PROC_SSE4_2;
+	      break;
+	    case PROCESSOR_ATOM:
+	      arg_str = "atom";
+	      priority = P_PROC_SSSE3;
+	      break;
+	    case PROCESSOR_AMDFAM10:
+	      arg_str = "amdfam10h";
+	      priority = P_PROC_SSE4_a;
+	      break;
+	    case PROCESSOR_BDVER1:
+	      arg_str = "bdver1";
+	      priority = P_PROC_FMA;
+	      break;
+	    case PROCESSOR_BDVER2:
+	      arg_str = "bdver2";
+	      priority = P_PROC_FMA;
+	      break;
+	    }  
+	}    
+    
+      cl_target_option_restore (&global_options, &cur_target);
+	
+      if (predicate_list && arg_str == NULL)
+	{
+	  error_at (DECL_SOURCE_LOCATION (decl),
+	    	"No dispatcher found for the versioning attributes");
+	  return 0;
+	}
+    
+      if (predicate_list)
+	{
+          predicate_decl = ix86_builtins [(int) IX86_BUILTIN_CPU_IS];
+          /* For a C string literal the length includes the trailing NULL.  */
+          predicate_arg = build_string_literal (strlen (arg_str) + 1, arg_str);
+          predicate_chain = tree_cons (predicate_decl, predicate_arg,
+				       predicate_chain);
+	}
+    }
+
+  /* Process feature name.  */
+  tok_str =  (char *) xmalloc (strlen (attrs_str) + 1);
+  strcpy (tok_str, attrs_str);
+  token = strtok (tok_str, ",");
+  predicate_decl = ix86_builtins [(int) IX86_BUILTIN_CPU_SUPPORTS];
+
+  while (token != NULL)
+    {
+      /* Do not process "arch="  */
+      if (strncmp (token, "arch=", 5) == 0)
+	{
+	  token = strtok (NULL, ",");
+	  continue;
+	}
+      for (i = 0; i < NUM_FEATURES; ++i)
+	{
+	  if (strcmp (token, feature_list[i].name) == 0)
+	    {
+	      if (predicate_list)
+		{
+		  predicate_arg = build_string_literal (
+				  strlen (feature_list[i].name) + 1,
+				  feature_list[i].name);
+		  predicate_chain = tree_cons (predicate_decl, predicate_arg,
+					       predicate_chain);
+		}
+	      /* Find the maximum priority feature.  */
+	      if (feature_list[i].priority > priority)
+		priority = feature_list[i].priority;
+
+	      break;
+	    }
+	}
+      if (predicate_list && i == NUM_FEATURES)
+	{
+	  error_at (DECL_SOURCE_LOCATION (decl),
+		    "No dispatcher found for %s", token);
+	  return 0;
+	}
+      token = strtok (NULL, ",");
+    }
+  free (tok_str);
+
+  if (predicate_list && predicate_chain == NULL_TREE)
+    {
+      error_at (DECL_SOURCE_LOCATION (decl),
+	        "No dispatcher found for the versioning attributes : %s",
+	        attrs_str);
+      return 0;
+    }
+  else if (predicate_list)
+    {
+      predicate_chain = nreverse (predicate_chain);
+      *predicate_list = predicate_chain;
+    }
+
+  return priority; 
+}
+
+/* This compares the priority of target features in function DECL1
+   and DECL2.  It returns positive value if DECL1 is higher priority,
+   negative value if DECL2 is higher priority and 0 if they are the
+   same.  */
+
+static int
+ix86_compare_version_priority (tree decl1, tree decl2)
+{
+  unsigned int priority1 = 0;
+  unsigned int priority2 = 0;
+
+  if (lookup_attribute ("target", DECL_ATTRIBUTES (decl1)) != NULL)
+    priority1 = get_builtin_code_for_version (decl1, NULL);
+
+  if (lookup_attribute ("target", DECL_ATTRIBUTES (decl2)) != NULL)
+    priority2 = get_builtin_code_for_version (decl2, NULL);
+
+  return (int)priority1 - (int)priority2;
+}
+
+/* V1 and V2 point to function versions with different priorities
+   based on the target ISA.  This function compares their priorities.  */
+ 
+static int
+feature_compare (const void *v1, const void *v2)
+{
+  typedef struct _function_version_info
+    {
+      tree version_decl;
+      tree predicate_chain;
+      unsigned int dispatch_priority;
+    } function_version_info;
+
+  const function_version_info c1 = *(const function_version_info *)v1;
+  const function_version_info c2 = *(const function_version_info *)v2;
+  return (c2.dispatch_priority - c1.dispatch_priority);
+}
+
+/* This function generates the dispatch function for
+   multi-versioned functions.  DISPATCH_DECL is the function which will
+   contain the dispatch logic.  FNDECLS are the function choices for
+   dispatch, and is a tree chain.  EMPTY_BB is the basic block pointer
+   in DISPATCH_DECL in which the dispatch code is generated.  */
+
+static int
+dispatch_function_versions (tree dispatch_decl,
+			    void *fndecls_p,
+			    basic_block *empty_bb)
+{
+  tree default_decl;
+  gimple ifunc_cpu_init_stmt;
+  gimple_seq gseq;
+  tree old_current_function_decl;
+  int ix;
+  tree ele;
+  VEC (tree, heap) *fndecls;
+  unsigned int num_versions = 0;
+  unsigned int actual_versions = 0;
+  unsigned int i;
+
+  struct _function_version_info
+    {
+      tree version_decl;
+      tree predicate_chain;
+      unsigned int dispatch_priority;
+    }*function_version_info;
+
+  gcc_assert (dispatch_decl != NULL
+	      && fndecls_p != NULL
+	      && empty_bb != NULL);
+
+  /*fndecls_p is actually a vector.  */
+  fndecls = (VEC (tree, heap) *)fndecls_p;
+
+  /* Atleast one more version other than the default.  */
+  num_versions = VEC_length (tree, fndecls);
+  gcc_assert (num_versions >= 2);
+
+  function_version_info = (struct _function_version_info *)
+    xmalloc ((num_versions - 1) * sizeof (struct _function_version_info));
+
+  /* The first version in the vector is the default decl.  */
+  default_decl = VEC_index (tree, fndecls, 0);
+
+  old_current_function_decl = current_function_decl;
+  push_cfun (DECL_STRUCT_FUNCTION (dispatch_decl));
+  current_function_decl = dispatch_decl;
+
+  gseq = bb_seq (*empty_bb);
+  /* Function version dispatch is via IFUNC.  IFUNC resolvers fire before
+     constructors, so explicity call __builtin_cpu_init here.  */
+  ifunc_cpu_init_stmt = gimple_build_call_vec (
+                     ix86_builtins [(int) IX86_BUILTIN_CPU_INIT], NULL);
+  gimple_seq_add_stmt (&gseq, ifunc_cpu_init_stmt);
+  gimple_set_bb (ifunc_cpu_init_stmt, *empty_bb);
+  set_bb_seq (*empty_bb, gseq);
+
+  pop_cfun ();
+  current_function_decl = old_current_function_decl;
+
+
+  for (ix = 1; VEC_iterate (tree, fndecls, ix, ele); ++ix)
+    {
+      tree version_decl = ele;
+      tree predicate_chain = NULL_TREE;
+      unsigned int priority;
+      /* Get attribute string, parse it and find the right predicate decl.
+         The predicate function could be a lengthy combination of many
+	 features, like arch-type and various isa-variants.  */
+      priority = get_builtin_code_for_version (version_decl,
+	 			               &predicate_chain);
+
+      if (predicate_chain == NULL_TREE)
+	continue;
+
+      actual_versions++;
+      function_version_info [ix - 1].version_decl = version_decl;
+      function_version_info [ix - 1].predicate_chain = predicate_chain;
+      function_version_info [ix - 1].dispatch_priority = priority;
+    }
+
+  /* Sort the versions according to descending order of dispatch priority.  The
+     priority is based on the ISA.  This is not a perfect solution.  There
+     could still be ambiguity.  If more than one function version is suitable
+     to execute,  which one should be dispatched?  In future, allow the user
+     to specify a dispatch  priority next to the version.  */
+  qsort (function_version_info, actual_versions,
+         sizeof (struct _function_version_info), feature_compare);
+
+  for  (i = 0; i < actual_versions; ++i)
+    *empty_bb = add_condition_to_bb (dispatch_decl,
+				     function_version_info[i].version_decl,
+				     function_version_info[i].predicate_chain,
+				     *empty_bb);
+
+  /* dispatch default version at the end.  */
+  *empty_bb = add_condition_to_bb (dispatch_decl, default_decl,
+				   NULL, *empty_bb);
+
+  free (function_version_info);
+  return 0;
+}
+
+/* This function returns true if fn1 and fn2 are versions of the same function.
+   Returns false if only one of the function decls has the target attribute
+   set or if the targets of the function decls are different.  This assumes
+   the fn1 and fn2 have the same signature.  */
+
+static bool
+ix86_function_versions (tree fn1, tree fn2)
+{
+  tree attr1, attr2;
+  struct cl_target_option *target1, *target2;
+
+  if (TREE_CODE (fn1) != FUNCTION_DECL
+      || TREE_CODE (fn2) != FUNCTION_DECL)
+    return false;
+
+  attr1 = DECL_FUNCTION_SPECIFIC_TARGET (fn1);
+  attr2 = DECL_FUNCTION_SPECIFIC_TARGET (fn2);
+
+  if (attr1 == NULL_TREE && attr2 == NULL_TREE)
+    return false;
+
+  if ((attr1 == NULL_TREE && attr2 != NULL_TREE)
+      || (attr1 != NULL_TREE && attr2 == NULL_TREE))
+    return true;
+
+  target1 = TREE_TARGET_OPTION (attr1);
+  target2 = TREE_TARGET_OPTION (attr2);
+
+  if (target1->x_ix86_isa_flags == target2->x_ix86_isa_flags
+      && target1->x_target_flags == target2->x_target_flags
+      && target1->arch == target2->arch
+      && target1->tune == target2->tune
+      && target1->x_ix86_fpmath == target2->x_ix86_fpmath
+      && target1->branch_cost == target2->branch_cost)
+    return false;
+
+  return true;
+}
+
+/* Comparator function to be used in qsort routine to sort attribute
+   specification strings to "target".  */
+
+static int
+attr_strcmp (const void *v1, const void *v2)
+{
+  const char *c1 = *(char *const*)v1;
+  const char *c2 = *(char *const*)v2;
+  return strcmp (c1, c2);
+}
+
+/* STR is the argument to target attribute.  This function tokenizes
+   the comma separated arguments, sorts them and returns a string which
+   is a unique identifier for the comma separated arguments.   It also
+   replaces non-identifier characters "=,-" with "_".  */
+
+static char *
+sorted_attr_string (const char *str)
+{
+  char **args = NULL;
+  char *attr_str, *ret_str;
+  char *attr = NULL;
+  unsigned int argnum = 1;
+  unsigned int i;
+
+  for (i = 0; i < strlen (str); i++)
+    if (str[i] == ',')
+      argnum++;
+
+  attr_str = (char *)xmalloc (strlen (str) + 1);
+  strcpy (attr_str, str);
+
+  /* Replace "=,-" with "_".  */
+  for (i = 0; i < strlen (attr_str); i++)
+    if (attr_str[i] == '=' || attr_str[i]== '-')
+      attr_str[i] = '_';
+
+  if (argnum == 1)
+    return attr_str;
+
+  args = (char **)xmalloc (argnum * sizeof (char *));
+
+  i = 0;
+  attr = strtok (attr_str, ",");
+  while (attr != NULL)
+    {
+      args[i] = attr;
+      i++;
+      attr = strtok (NULL, ",");
+    }
+
+  qsort (args, argnum, sizeof (char*), attr_strcmp);
+
+  ret_str = (char *)xmalloc (strlen (str) + 1);
+  strcpy (ret_str, args[0]);
+  for (i = 1; i < argnum; i++)
+    {
+      strcat (ret_str, "_");
+      strcat (ret_str, args[i]);
+    }
+
+  free (args);
+  free (attr_str);
+  return ret_str;
+}
+
+/* This function changes the assembler name for functions that are
+   versions.  If DECL is a function version and has a "target"
+   attribute, it appends the attribute string to its assembler name.  */
+
+static tree
+ix86_mangle_function_version_assembler_name (tree decl, tree id)
+{
+  tree version_attr;
+  const char *orig_name, *version_string, *attr_str;
+  char *assembler_name;
+
+  if (DECL_DECLARED_INLINE_P (decl)
+      && lookup_attribute ("gnu_inline",
+			   DECL_ATTRIBUTES (decl)))
+    error_at (DECL_SOURCE_LOCATION (decl),
+	      "Function versions cannot be marked as gnu_inline,"
+	      " bodies have to be generated\n");
+
+  if (DECL_VIRTUAL_P (decl)
+      || DECL_VINDEX (decl))
+    error_at (DECL_SOURCE_LOCATION (decl),
+	      "Virtual function versioning not supported\n");
+
+  version_attr = lookup_attribute ("target", DECL_ATTRIBUTES (decl));
+
+  /* target attribute string is NULL for default functions.  */
+  if (version_attr == NULL_TREE)
+    return id;
+
+  orig_name = IDENTIFIER_POINTER (id);
+  version_string
+    = TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (version_attr)));
+
+  attr_str = sorted_attr_string (version_string);
+  assembler_name = (char *) xmalloc (strlen (orig_name)
+				     + strlen (attr_str) + 2);
+
+  sprintf (assembler_name, "%s.%s", orig_name, attr_str);
+  if (dump_file)
+    fprintf (stderr, "Assembler name set to %s for function version %s\n",
+	     assembler_name, IDENTIFIER_POINTER (id));
+
+  /* Allow assembler name to be modified if already set.  */
+  if (DECL_ASSEMBLER_NAME_SET_P (decl))
+    SET_DECL_RTL (decl, NULL);
+
+  return get_identifier (assembler_name);
+}
+
+static tree 
+ix86_mangle_decl_assembler_name (tree decl, tree id)
+{
+  /* For function version, add the target suffix to the assembler name.  */
+  if (TREE_CODE (decl) == FUNCTION_DECL
+      && DECL_FUNCTION_VERSIONED (decl))
+    return ix86_mangle_function_version_assembler_name (decl, id);
+
+  return id;
+}
+
+/* Return a new name by appending SUFFIX to the DECL name.  If
+   make_unique is true, append the full path name.  */
+
+static char *
+make_name (tree decl, const char *suffix, bool make_unique)
+{
+  char *global_var_name;
+  int name_len;
+  const char *name;
+  const char *unique_name = NULL;
+
+  name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
+
+  /* Get a unique name that can be used globally without any chances
+     of collision at link time.  */
+  if (make_unique)
+    unique_name = IDENTIFIER_POINTER (get_file_function_name ("\0"));
+
+  name_len = strlen (name) + strlen (suffix) + 2;
+
+  if (make_unique)
+    name_len += strlen (unique_name) + 1;
+  global_var_name = (char *) xmalloc (name_len);
+
+  /* Use '.' to concatenate names as it is demangler friendly.  */
+  if (make_unique)
+      snprintf (global_var_name, name_len, "%s.%s.%s", name,
+		unique_name, suffix);
+  else
+      snprintf (global_var_name, name_len, "%s.%s", name, suffix);
+
+  return global_var_name;
+}
+
+/* Make a dispatcher declaration for the multi-versioned function DECL.
+   Calls to DECL function will be replaced with calls to the dispatcher
+   by the front-end.  Return the decl created.  */
+
+static tree
+make_dispatcher_decl (const tree decl)
+{
+  tree func_decl;
+  char *func_name, *resolver_name;
+  tree fn_type, func_type;
+  bool is_uniq = false;
+
+  if (TREE_PUBLIC (decl) == 0)
+    is_uniq = true;
+
+  func_name = make_name (decl, "ifunc", is_uniq);
+  resolver_name = make_name (decl, "resolver", is_uniq);
+  gcc_assert (resolver_name);
+
+  fn_type = TREE_TYPE (decl);
+  func_type = build_function_type (TREE_TYPE (fn_type),
+				   TYPE_ARG_TYPES (fn_type));
+  
+  func_decl = build_fn_decl (func_name, func_type);
+  TREE_USED (func_decl) = 1;
+  DECL_CONTEXT (func_decl) = NULL_TREE;
+  DECL_INITIAL (func_decl) = error_mark_node;
+  DECL_ARTIFICIAL (func_decl) = 1;
+  /* Mark this func as external, the resolver will flip it again if
+     it gets generated.  */
+  DECL_EXTERNAL (func_decl) = 1;
+  /* This will be of type IFUNCs have to be externally visible.  */
+  TREE_PUBLIC (func_decl) = 1;
+
+  return func_decl;  
+}
+
+/* Returns true if decl is multi-versioned and DECL is the default function,
+   that is it is not tagged with target specific optimization.  */
+
+static bool
+is_function_default_version (const tree decl)
+{
+  return (TREE_CODE (decl) == FUNCTION_DECL
+	  && DECL_FUNCTION_VERSIONED (decl)
+	  && DECL_FUNCTION_SPECIFIC_TARGET (decl) == NULL_TREE);
+}
+
+/* Make a dispatcher declaration for the multi-versioned function DECL.
+   Calls to DECL function will be replaced with calls to the dispatcher
+   by the front-end.  It also chains the cgraph nodes of all the
+   semantically identical versions in vector FN_VER_VEC_P.  Returns the
+   decl of the dispatcher function.  */
+
+static tree
+ix86_get_function_versions_dispatcher (void *fn_ver_vec_p)
+{
+  struct cgraph_node *node = NULL;
+  struct cgraph_node *default_node = NULL;
+  struct cgraph_node *curr_node = NULL;
+  int ix;
+  tree ele;
+  tree dispatch_decl = NULL;
+  VEC (tree, heap) *fn_ver_vec = NULL;
+
+  fn_ver_vec = (VEC (tree,heap) *) fn_ver_vec_p;
+  gcc_assert (fn_ver_vec != NULL);
+
+  /* Find the default version.  */
+  for (ix = 0; VEC_iterate (tree, fn_ver_vec, ix, ele); ++ix)
+    {
+      if (is_function_default_version (ele))
+	{
+	  default_node = cgraph_get_create_node (ele);
+	  break;
+	}
+    }
+
+  /* If there is no default node, just return NULL.  */
+  if (!default_node)
+    return NULL;
+
+  if (default_node->version_dispatcher_decl)
+    return default_node->version_dispatcher_decl;
+
+#if defined (ASM_OUTPUT_TYPE_DIRECTIVE) && HAVE_GNU_INDIRECT_FUNCTION
+  /* Right now, the dispatching is done via ifunc.  */
+  dispatch_decl = make_dispatcher_decl (default_node->symbol.decl); 
+#else
+  error_at (DECL_SOURCE_LOCATION (default_node->symbol.decl),
+	    "Multiversioning needs ifunc which is not supported "
+	    "in this configuration");
+#endif
+  default_node->version_dispatcher_decl = dispatch_decl;
+  curr_node = cgraph_get_create_node (dispatch_decl);
+  gcc_assert (curr_node);
+  curr_node->dispatcher_function = 1;
+  cgraph_mark_address_taken_node (default_node);
+
+  for (ix = 0; VEC_iterate (tree, fn_ver_vec, ix, ele); ++ix)
+    {
+      node = cgraph_get_create_node (ele);
+      gcc_assert (node != NULL && DECL_FUNCTION_VERSIONED (ele));
+      if (node == default_node)
+	continue;
+      gcc_assert (DECL_FUNCTION_SPECIFIC_TARGET (ele) != NULL_TREE);
+
+      if (curr_node->next_function_version)
+ 	{
+	  node->next_function_version = curr_node->next_function_version;
+	  curr_node->next_function_version->prev_function_version = node;
+	}
+      curr_node->next_function_version = node;
+      node->prev_function_version = curr_node;
+      node->version_dispatcher_decl = dispatch_decl;
+    }
+
+  /* The default version should be the first node.  */
+  default_node->next_function_version = curr_node->next_function_version;
+  curr_node->next_function_version->prev_function_version = default_node;
+  curr_node->next_function_version = default_node;
+  
+  return dispatch_decl;
+}
+
+/* Makes a function attribute of the form NAME(ARG_NAME) and chains
+   it to CHAIN.  */
+
+static tree
+make_attribute (const char *name, const char *arg_name, tree chain)
+{
+  tree attr_name;
+  tree attr_arg_name;
+  tree attr_args;
+  tree attr;
+
+  attr_name = get_identifier (name);
+  attr_arg_name = build_string (strlen (arg_name), arg_name);
+  attr_args = tree_cons (NULL_TREE, attr_arg_name, NULL_TREE);
+  attr = tree_cons (attr_name, attr_args, chain);
+  return attr;
+}
+
+/* Make the resolver function decl to dispatch the versions of
+   a multi-versioned function,  DEFAULT_DECL.  Create an
+   empty basic block in the resolver and store the pointer in
+   EMPTY_BB.  Return the decl of the resolver function.  */
+
+static tree
+make_resolver_func (const tree default_decl,
+		    const tree dispatch_decl,
+		    basic_block *empty_bb)
+{
+  char *resolver_name;
+  tree decl, type, decl_name, t;
+  basic_block new_bb;
+  tree old_current_function_decl;
+  bool is_uniq = false;
+
+  /* IFUNC's have to be globally visible.  So, if the default_decl is
+     not, then the name of the IFUNC should be made unique.  */
+  if (TREE_PUBLIC (default_decl) == 0)
+    is_uniq = true;
+
+  /* Append the filename to the resolver function if the versions are
+     not externally visible.  This is because the resolver function has
+     to be externally visible for the loader to find it.  So, appending
+     the filename will prevent conflicts with a resolver function from
+     another module which is based on the same version name.  */
+  resolver_name = make_name (default_decl, "resolver", is_uniq);
+
+  /* The resolver function should return a (void *). */
+  type = build_function_type_list (ptr_type_node, NULL_TREE);
+
+  decl = build_fn_decl (resolver_name, type);
+  decl_name = get_identifier (resolver_name);
+  SET_DECL_ASSEMBLER_NAME (decl, decl_name);
+
+  DECL_NAME (decl) = decl_name;
+  TREE_USED (decl) = 1;
+  DECL_ARTIFICIAL (decl) = 1;
+  DECL_IGNORED_P (decl) = 0;
+  /* IFUNC resolvers have to be externally visible.  */
+  TREE_PUBLIC (decl) = 1;
+  DECL_UNINLINABLE (decl) = 1;
+
+  DECL_EXTERNAL (decl) = 0;
+  DECL_EXTERNAL (dispatch_decl) = 0;
+
+  DECL_CONTEXT (decl) = NULL_TREE;
+  DECL_INITIAL (decl) = make_node (BLOCK);
+  DECL_STATIC_CONSTRUCTOR (decl) = 0;
+  TREE_READONLY (decl) = 0;
+  DECL_PURE_P (decl) = 0;
+
+  if (DECL_COMDAT_GROUP (default_decl))
+    {
+      DECL_COMDAT (decl) = DECL_COMDAT (default_decl);
+      make_decl_one_only (decl, DECL_COMDAT_GROUP (default_decl));
+    }
+  else if (TREE_PUBLIC (default_decl))
+    {
+      /* In this case, each translation unit with a call to this
+	 versioned function will put out a resolver.  Ensure it
+	 is comdat to keep just one copy.  */
+      DECL_COMDAT (decl) = 1;
+      make_decl_one_only (decl, DECL_ASSEMBLER_NAME (decl));
+    }
+  /* Build result decl and add to function_decl. */
+  t = build_decl (UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE, ptr_type_node);
+  DECL_ARTIFICIAL (t) = 1;
+  DECL_IGNORED_P (t) = 1;
+  DECL_RESULT (decl) = t;
+
+  gimplify_function_tree (decl);
+  old_current_function_decl = current_function_decl;
+  push_cfun (DECL_STRUCT_FUNCTION (decl));
+  current_function_decl = decl;
+  gimple_register_cfg_hooks ();
+  init_empty_tree_cfg_for_function (DECL_STRUCT_FUNCTION (decl));
+  cfun->curr_properties |=
+    (PROP_gimple_lcf | PROP_gimple_leh | PROP_cfg | PROP_ssa
+     | PROP_gimple_any);
+  cfun->curr_properties = 15;
+  new_bb = create_empty_bb (ENTRY_BLOCK_PTR);
+  make_edge (ENTRY_BLOCK_PTR, new_bb, EDGE_FALLTHRU);
+  make_edge (new_bb, EXIT_BLOCK_PTR, 0);
+  *empty_bb = new_bb;
+
+  cgraph_add_new_function (decl, true);
+  cgraph_call_function_insertion_hooks (cgraph_get_create_node (decl));
+
+  if (DECL_COMDAT_GROUP (default_decl))
+    {
+      gcc_assert (cgraph_get_node (default_decl));
+      symtab_add_to_same_comdat_group (
+	(symtab_node) cgraph_get_node (decl),
+	(symtab_node) cgraph_get_node (default_decl));
+    }
+
+  pop_cfun ();
+  current_function_decl = old_current_function_decl;
+
+  gcc_assert (dispatch_decl != NULL);
+  /* Mark dispatch_decl as "ifunc" with resolver as resolver_name.  */
+  DECL_ATTRIBUTES (dispatch_decl) 
+    = make_attribute ("ifunc", resolver_name, DECL_ATTRIBUTES (dispatch_decl));
+
+  /* Create the alias for dispatch to resolver here.  */
+  cgraph_create_function_alias (dispatch_decl, decl);
+  return decl;
+}
+
+/* Generate the dispatching code body to dispatch multi-versioned function
+   DECL.  The target hook is called to process the "target" attributes and
+   provide the code to dispatch the right function at run-time.  NODE points
+   to the dispatcher decl whose body will be created.  */
+
+static tree 
+ix86_generate_version_dispatcher_body (void *node_p)
+{
+  tree resolver_decl;
+  basic_block empty_bb;
+  VEC (tree, heap) *fn_ver_vec = NULL;
+  tree old_current_function_decl;
+  tree default_ver_decl;
+  struct cgraph_node *versn;
+  struct cgraph_node *node;
+
+  node = (cgraph_node *)node_p;
+
+  gcc_assert (node->dispatcher_function);
+
+  if (node->version_dispatcher_decl)
+    return node->version_dispatcher_decl;
+
+  default_ver_decl = node->next_function_version->symbol.decl;
+  resolver_decl = make_resolver_func (default_ver_decl,
+				      node->symbol.decl, &empty_bb);
+  node->version_dispatcher_decl = resolver_decl;
+
+  old_current_function_decl = current_function_decl;
+  push_cfun (DECL_STRUCT_FUNCTION (resolver_decl));
+  current_function_decl = resolver_decl;
+
+  fn_ver_vec = VEC_alloc (tree, heap, 2);
+
+  for (versn = node->next_function_version; versn;
+       versn = versn->next_function_version)
+    {
+      /* Check for virtual functions here again, as by this time it should
+	 have been determined if this function needs a vtable index or
+	 not.  This happens for methods in derived classes that override
+	 virtual methods in base classes but are not explicitly marked as
+	 virtual.  */
+      if (DECL_VINDEX (versn->symbol.decl))
+        error_at (DECL_SOURCE_LOCATION (versn->symbol.decl),
+		  "Virtual function multiversioning not supported");
+      VEC_safe_push (tree, heap, fn_ver_vec, versn->symbol.decl);
+    }
+
+  dispatch_function_versions(resolver_decl, fn_ver_vec, &empty_bb);
+
+  rebuild_cgraph_edges (); 
+  pop_cfun ();
+  current_function_decl = old_current_function_decl;
+  return resolver_decl;
+}
+
 /* This builds the processor_model struct type defined in
    libgcc/config/i386/cpuinfo.c  */
 
@@ -40559,6 +41539,9 @@ ix86_memmodel_check (unsigned HOST_WIDE_INT val)
 #undef TARGET_PROFILE_BEFORE_PROLOGUE
 #define TARGET_PROFILE_BEFORE_PROLOGUE ix86_profile_before_prologue
 
+#undef TARGET_MANGLE_DECL_ASSEMBLER_NAME
+#define TARGET_MANGLE_DECL_ASSEMBLER_NAME ix86_mangle_decl_assembler_name
+
 #undef TARGET_ASM_UNALIGNED_HI_OP
 #define TARGET_ASM_UNALIGNED_HI_OP TARGET_ASM_ALIGNED_HI_OP
 #undef TARGET_ASM_UNALIGNED_SI_OP
@@ -40652,6 +41635,17 @@ ix86_memmodel_check (unsigned HOST_WIDE_INT val)
 #undef TARGET_FOLD_BUILTIN
 #define TARGET_FOLD_BUILTIN ix86_fold_builtin
 
+#undef TARGET_COMPARE_VERSION_PRIORITY
+#define TARGET_COMPARE_VERSION_PRIORITY ix86_compare_version_priority
+
+#undef TARGET_GENERATE_VERSION_DISPATCHER_BODY
+#define TARGET_GENERATE_VERSION_DISPATCHER_BODY \
+  ix86_generate_version_dispatcher_body
+
+#undef TARGET_GET_FUNCTION_VERSIONS_DISPATCHER
+#define TARGET_GET_FUNCTION_VERSIONS_DISPATCHER \
+  ix86_get_function_versions_dispatcher
+
 #undef TARGET_ENUM_VA_LIST_P
 #define TARGET_ENUM_VA_LIST_P ix86_enum_va_list
 
@@ -40789,6 +41783,9 @@ ix86_memmodel_check (unsigned HOST_WIDE_INT val)
 #undef TARGET_OPTION_PRINT
 #define TARGET_OPTION_PRINT ix86_function_specific_print
 
+#undef TARGET_OPTION_FUNCTION_VERSIONS
+#define TARGET_OPTION_FUNCTION_VERSIONS ix86_function_versions
+
 #undef TARGET_CAN_INLINE_P
 #define TARGET_CAN_INLINE_P ix86_can_inline_p
 
