LoongArch: New options -mrecip and -mrecip= with ffast-math.

LoongArch: New options -mrecip and -mrecip= with ffast-math.

When both the -mrecip and -mfrecipe options are enabled, use approximate reciprocal
instructions and approximate reciprocal square root instructions with additional
Newton-Raphson steps to implement single precision floating-point division, square
root and reciprocal square root operations, for a better performance.

gcc/ChangeLog:

	* config/loongarch/genopts/loongarch.opt.in (recip_mask): New variable.
	(-mrecip, -mrecip): New options.
	* config/loongarch/lasx.md (div<mode>3): New expander.
	(*div<mode>3): Rename.
	(sqrt<mode>2): New expander.
	(*sqrt<mode>2): Rename.
	(rsqrt<mode>2): New expander.
	* config/loongarch/loongarch-protos.h (loongarch_emit_swrsqrtsf): New prototype.
	(loongarch_emit_swdivsf): Ditto.
	* config/loongarch/loongarch.cc (loongarch_option_override_internal): Set
	recip_mask for -mrecip and -mrecip= options.
	(loongarch_emit_swrsqrtsf): New function.
	(loongarch_emit_swdivsf): Ditto.
	* config/loongarch/loongarch.h (RECIP_MASK_NONE, RECIP_MASK_DIV, RECIP_MASK_SQRT
	RECIP_MASK_RSQRT, RECIP_MASK_VEC_DIV, RECIP_MASK_VEC_SQRT, RECIP_MASK_VEC_RSQRT
	RECIP_MASK_ALL): New bitmasks.
	(TARGET_RECIP_DIV, TARGET_RECIP_SQRT, TARGET_RECIP_RSQRT, TARGET_RECIP_VEC_DIV
	TARGET_RECIP_VEC_SQRT, TARGET_RECIP_VEC_RSQRT): New tests.
	* config/loongarch/loongarch.md (sqrt<mode>2): New expander.
	(*sqrt<mode>2): Rename.
	(rsqrt<mode>2): New expander.
	* config/loongarch/loongarch.opt (recip_mask): New variable.
	(-mrecip, -mrecip): New options.
	* config/loongarch/lsx.md (div<mode>3): New expander.
	(*div<mode>3): Rename.
	(sqrt<mode>2): New expander.
	(*sqrt<mode>2): Rename.
	(rsqrt<mode>2): New expander.
	* config/loongarch/predicates.md (reg_or_vecotr_1_operand): New predicate.
	* doc/invoke.texi (LoongArch Options): Document new options.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/divf.c: New test.
	* gcc.target/loongarch/recip-divf.c: New test.
	* gcc.target/loongarch/recip-sqrtf.c: New test.
	* gcc.target/loongarch/sqrtf.c: New test.
	* gcc.target/loongarch/vector/lasx/lasx-divf.c: New test.
	* gcc.target/loongarch/vector/lasx/lasx-recip-divf.c: New test.
	* gcc.target/loongarch/vector/lasx/lasx-recip-sqrtf.c: New test.
	* gcc.target/loongarch/vector/lasx/lasx-recip.c: New test.
	* gcc.target/loongarch/vector/lasx/lasx-sqrtf.c: New test.
	* gcc.target/loongarch/vector/lsx/lsx-divf.c: New test.
	* gcc.target/loongarch/vector/lsx/lsx-recip-divf.c: New test.
	* gcc.target/loongarch/vector/lsx/lsx-recip-sqrtf.c: New test.
	* gcc.target/loongarch/vector/lsx/lsx-recip.c: New test.
	* gcc.target/loongarch/vector/lsx/lsx-sqrtf.c: New test.