Index: builtins.def
===================================================================
--- builtins.def	(revision 125997)
+++ builtins.def	(working copy)
@@ -1,6 +1,6 @@
 /* This file contains the definitions and documentation for the
    builtins used in the GNU compiler.
-   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
+   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -640,6 +640,7 @@ DEF_EXT_LIB_BUILTIN    (BUILT_IN_FFS, "f
 DEF_EXT_LIB_BUILTIN    (BUILT_IN_FFSIMAX, "ffsimax", BT_FN_INT_INTMAX, ATTR_CONST_NOTHROW_LIST)
 DEF_EXT_LIB_BUILTIN    (BUILT_IN_FFSL, "ffsl", BT_FN_INT_LONG, ATTR_CONST_NOTHROW_LIST)
 DEF_EXT_LIB_BUILTIN    (BUILT_IN_FFSLL, "ffsll", BT_FN_INT_LONGLONG, ATTR_CONST_NOTHROW_LIST)
+DEF_GCC_BUILTIN        (BUILT_IN_FLUSH_ICACHE, "flush_icache", BT_FN_VOID_PTR_SIZE, ATTR_NOTHROW_LIST)
 DEF_EXT_LIB_BUILTIN        (BUILT_IN_FORK, "fork", BT_FN_PID, ATTR_NOTHROW_LIST)
 DEF_GCC_BUILTIN        (BUILT_IN_FRAME_ADDRESS, "frame_address", BT_FN_PTR_UINT, ATTR_NULL)
 DEF_LIB_BUILTIN        (BUILT_IN_FREE, "free", BT_FN_VOID_PTR, ATTR_NOTHROW_LIST) 
Index: builtins.c
===================================================================
--- builtins.c	(revision 125997)
+++ builtins.c	(working copy)
@@ -5513,6 +5513,39 @@ expand_builtin_profile_func (bool exitp)
   return const0_rtx;
 }
 
+/* Expand a call to _builtin_flush_icache.  If the target does not
+   support the operation, it is a nop. */
+static rtx
+expand_builtin_flush_icache (tree exp)
+{
+  tree location, len;
+  rtx location_rtx, len_rtx;
+
+  if (!validate_arglist (exp, POINTER_TYPE, INTEGER_TYPE, VOID_TYPE))
+    return NULL_RTX;
+
+  location = CALL_EXPR_ARG (exp, 0);
+  len = CALL_EXPR_ARG (exp, 1);
+
+  /* Evaluate LOCATION in case it has side-effects. */
+  location_rtx = expand_expr (location, NULL_RTX, Pmode, EXPAND_NORMAL);
+  location_rtx = convert_memory_address (Pmode, location_rtx);
+
+  /* If the LEN parameter is zero, return. */
+  if (integer_zerop (len))
+    return const0_rtx;
+
+  len_rtx = expand_normal (len);
+
+#ifdef HAVE_flush_icache
+  if (HAVE_flush_icache)
+    {
+      emit_insn (gen_flush_icache (location_rtx, len_rtx));
+    }
+#endif
+  return const0_rtx;
+}
+
 /* Given a trampoline address, make sure it satisfies TRAMPOLINE_ALIGNMENT.  */
 
 static rtx
@@ -6590,6 +6623,9 @@ expand_builtin (tree exp, rtx target, rt
     case BUILT_IN_PROFILE_FUNC_EXIT:
       return expand_builtin_profile_func (true);
 
+    case BUILT_IN_FLUSH_ICACHE:
+      return expand_builtin_flush_icache (exp);
+
     case BUILT_IN_INIT_TRAMPOLINE:
       return expand_builtin_init_trampoline (exp);
     case BUILT_IN_ADJUST_TRAMPOLINE:
@@ -9558,6 +9594,22 @@ fold_builtin_unordered_cmp (tree fndecl,
 		      fold_build2 (code, type, arg0, arg1));
 }
 
+/* Fold function call to builtin flush_icache.  Return
+   NULL_TREE if no simplification can be made.  */
+
+static tree
+fold_builtin_flush_icache (tree location, tree len)
+{
+  if (! validate_arg (location, POINTER_TYPE)
+      || ! validate_arg (len, INTEGER_TYPE))
+    return NULL_TREE;
+
+  /* If len parameter is zero, do nothing. */
+  if (integer_zerop (len))
+    return omit_one_operand (void_type_node, location, len);
+  return NULL_TREE;
+}
+
 /* Fold a call to built-in function FNDECL with 0 arguments.
    IGNORE is true if the result of the function call is ignored.  This
    function returns NULL_TREE if no simplification was possible.  */
@@ -10068,6 +10120,8 @@ fold_builtin_2 (tree fndecl, tree arg0, 
     case BUILT_IN_VFPRINTF:
       return fold_builtin_fprintf (fndecl, arg0, arg1, NULL_TREE,
 				   ignore, fcode);
+    case BUILT_IN_FLUSH_ICACHE:
+      return fold_builtin_flush_icache (arg0, arg1);
 
     default:
       break;
Index: testsuite/gcc.dg/builtins-64.c
===================================================================
--- testsuite/gcc.dg/builtins-64.c	(revision 0)
+++ testsuite/gcc.dg/builtins-64.c	(revision 0)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+void f()
+{
+  char *memory = __builtin_alloca(40);
+  __builtin_flush_icache(memory, 40);
+}
+
+/* { dg-final { scan-tree-dump "__builtin_flush_icache" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
Index: testsuite/gcc.dg/builtins-65.c
===================================================================
--- testsuite/gcc.dg/builtins-65.c	(revision 0)
+++ testsuite/gcc.dg/builtins-65.c	(revision 0)
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+void f()
+{
+  char *memory = __builtin_alloca(40);
+  /* __builtin_flush_icache should be folded away for size == 0. */
+  __builtin_flush_icache(memory, 0);
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_flush_icache" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
Index: doc/extend.texi
===================================================================
--- doc/extend.texi	(revision 125997)
+++ doc/extend.texi	(working copy)
@@ -6086,6 +6086,19 @@ if (__builtin_expect (ptr != NULL, 1))
 when testing pointer or floating-point values.
 @end deftypefn
 
+@deftypefn {Built-in Function} void __builtin_flush_icache (const void *@var{addr}, size_t @var{len})
+This functions is used to flush the processor's instruction cache for
+the region of memory of length @var{len} at location @var{addr}.  Some
+targets require that the instruction cache be flushed, after modifying
+memory containing code, in order to obtain deterministic behavior.
+
+If the target does not require instruction cache flushes or otherwise
+does not have support for @code{__builtin_flush_icache}, the address
+expression is evaluated if it includes side effects but no other code
+is generated.  Currently MIPS is the only target with support for
+@code{__builtin_flush_icache}.
+@end deftypefn
+
 @deftypefn {Built-in Function} void __builtin_prefetch (const void *@var{addr}, ...)
 This function is used to minimize cache-miss latency by moving data into
 a cache before it is accessed.