This patch fixes a bug in the bswap pass.

This patch fixes a bug in the bswap pass.

This patch fixes a bug in the bswap pass.  In big-endian BIT_FIELD_REF uses
big-endian bit numbering so we need to adjust the bit position.
The existing version could potentially generate incorrect code however GCC
doesn't emit a BIT_FIELD_REF to access the low byte in a register, so the
symbolic number never matches in big-endian.

    gcc/
	* tree-ssa-math-opts.c (find_bswap_or_nop_1): Adjust bitnumbering
	for big-endian BIT_FIELD_REF.

From-SVN: r237822