gcc/
	PR target/28911
	* config/m68k/m68k.md (negsf2, negdf2, negxf2): Use
	-2147483647 - 1 instead of 0x80000000.

gcc/testsuite/
	PR target/28911
	* gcc.dg/pr28911.c: New.

From-SVN: r117181