re PR middle-end/61762 (failure to optimize memcpy from constant string)

re PR middle-end/61762 (failure to optimize memcpy from constant string)

2014-07-25  Richard Biener  <rguenther@suse.de>

	PR middle-end/61762
	PR middle-end/61894
	* fold-const.c (native_encode_int): Add and handle offset
	parameter to do partial encodings of expr.
	(native_encode_fixed): Likewise.
	(native_encode_real): Likewise.
	(native_encode_complex): Likewise.
	(native_encode_vector): Likewise.
	(native_encode_string): Likewise.
	(native_encode_expr): Likewise.
	* fold-const.c (native_encode_expr): Add offset parameter
	defaulting to -1.
	* gimple-fold.c (fold_string_cst_ctor_reference): Remove.
	(fold_ctor_reference): Handle all reads from tcc_constant
	ctors.

	* gcc.dg/pr61762.c: New testcase.
	* gcc.dg/fold-cstring.c: Likewise.
	* gcc.dg/fold-cvect.c: Likewise.

From-SVN: r213045