re PR target/6753 (gcc 3.1 produces wrong code when optimizing for pentium4)

re PR target/6753 (gcc 3.1 produces wrong code when optimizing for pentium4)

	PR target/6753
	* config/i386/i386.md (sse_movdfcc, sse_movdfcc_eq): Use Y instead
	of x in constraints for clarity.
	(sse_mov?fcc split): abort if op2 == op3.
	(sse_movsfcc_const0_1, sse_movsfcc_const0_2, sse_movsfcc_const0_3,
	sse_movsfcc_const0_4): Add earlyclobber.
	(sse_movdfcc_const0_1, sse_movdfcc_const0_2, sse_movdfcc_const0_3,
	sse_movdfcc_const0_4): Likewise.  Use DFmode, not SFmode.
	Use Y instead of x in constraints.

	* gcc.dg/20020523-1.c: New test.

From-SVN: r53784