* config/mips/mips-protos.h (mips_idiv_insns): Declare.

	* config/mips/mips-protos.h (mips_idiv_insns): Declare.
	* config/mips/mips.h (MASK_FIX_SB1): Bump.
	(MASK_FIX_R4000, TARGET_FIX_R4000): New macros.
	(TARGET_SWITCHES): Add -mfix-r4000 and -mno-fix-r4000.
	* config/mips/mips.c (mips_idiv_insns): New function.
	(override_options): Make -march=r4000 imply -mfix-r4000 by default.
	(mips_output_division): Add a workaround for the R4000 divide/shift
	errata.
	* config/mips/mips.md (length): Use mips_idiv_insns() to calculate
	the length of an "idiv" instruction.
	* doc/invoke.texi: Document the new switches.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@78621 138bc75d-0d04-0410-961f-82ee72b054a4