builtin-types.def (BT_FN_PTR_CONST_PTR_SIZE_VAR): New.

	* builtin-types.def (BT_FN_PTR_CONST_PTR_SIZE_VAR): New.
	* builtins.def (BUILT_IN_ASSUME_ALIGNED): New builtin.
	* tree-ssa-structalias.c (find_func_aliases_for_builtin_call,
	find_func_clobbers): Handle BUILT_IN_ASSUME_ALIGNED.
	* tree-ssa-ccp.c (bit_value_assume_aligned): New function.
	(evaluate_stmt, execute_fold_all_builtins): Handle
	BUILT_IN_ASSUME_ALIGNED.
	* tree-ssa-dce.c (propagate_necessity): Likewise.
	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1,
	call_may_clobber_ref_p_1): Likewise.
	* builtins.c (is_simple_builtin, expand_builtin): Likewise.
	(expand_builtin_assume_aligned): New function.
	* doc/extend.texi (__builtin_assume_aligned): Document.

	* c-common.c (check_builtin_function_arguments): Handle
	BUILT_IN_ASSUME_ALIGNED.

	* gcc.dg/builtin-assume-aligned-1.c: New test.
	* gcc.dg/builtin-assume-aligned-2.c: New test.
	* gcc.target/i386/builtin-assume-aligned-1.c: New test.

From-SVN: r175541

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 2d9c689..0e80590 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -7646,6 +7646,28 @@ int g (int c)
 
 @end deftypefn
 
+@deftypefn {Built-in Function} void *__builtin_assume_aligned (const void *@var{exp}, size_t @var{align}, ...)
+This function returns its first argument, and allows the compiler
+to assume that the returned pointer is at least @var{align} bytes
+aligned.  This built-in can have either two or three arguments,
+if it has three, the third argument should have integer type, and
+if it is non-zero means misalignment offset.  For example:
+
+@smallexample
+void *x = __builtin_assume_aligned (arg, 16);
+@end smallexample
+
+means that the compiler can assume x, set to arg, is at least
+16 byte aligned, while:
+
+@smallexample
+void *x = __builtin_assume_aligned (arg, 32, 8);
+@end smallexample
+
+means that the compiler can assume for x, set to arg, that
+(char *) x - 8 is 32 byte aligned.
+@end deftypefn
+
 @deftypefn {Built-in Function} void __builtin___clear_cache (char *@var{begin}, char *@var{end})
 This function is used to flush the processor's instruction cache for
 the region of memory between @var{begin} inclusive and @var{end}