PR middle-end/50161
	* simplify-rtx.c (simplify_const_unary_operation): If
	op is CONST_INT, don't look at op_mode, but use instead
	mode.
	* optabs.c (add_equal_note): For FFS, CLZ, CTZ,
	CLRSB, POPCOUNT, PARITY and BSWAP use operand mode for
	operation and TRUNCATE/ZERO_EXTEND if needed.
	* doc/rtl.texi (ffs, clrsb, clz, ctz, popcount, parity, bswap):
	Document that operand mode must be same as operation mode,
	or VOIDmode.
	* config/avr/avr.md (paritysi2, *parityqihi2.libgcc,
	*paritysihi2.libgcc, popcountsi2, *popcountsi2.libgcc,
	*popcountqihi2.libgcc, clzsi2, *clzsihi2.libgcc, ctzsi2,
	*ctzsihi2.libgcc, ffssi2, *ffssihi2.libgcc): For unary ops
	use the mode of operand for the operation and add truncate
	or zero_extend around if needed.
	* config/c6x/c6x.md (ctzdi2): Likewise.
	* config/bfin/bfin.md (clrsbsi2, signbitssi2): Likewise.

	* gcc.dg/pr50161.c: New test.

From-SVN: r177991