Use TImode for piecewise move in 64-bit mode

Use TImode for piecewise move in 64-bit mode

Use TImode for piecewise move in 64-bit mode.  We should use TImode in
32-bit mode and use OImode or XImode if they are available.  But since
by_pieces_ninsns determines the widest mode with MAX_FIXED_MODE_SIZE,
we can only use TImode in 64-bit mode.

gcc/

	* config/i386/i386.h (MOVE_MAX_PIECES): Use TImode in 64-bit
	mode if unaligned SSE load and store are optimal.

gcc/testsuite/

	* gcc.target/i386/pieces-memcpy-1.c: New test.
	* gcc.target/i386/pieces-memcpy-2.c: Likewise.
	* gcc.target/i386/pieces-memcpy-3.c: Likewise.
	* gcc.target/i386/pieces-memcpy-4.c: Likewise.
	* gcc.target/i386/pieces-memcpy-5.c: Likewise.
	* gcc.target/i386/pieces-memcpy-6.c: Likewise.

From-SVN: r239378