i386: Improve vector mode and TFmode ABS and NEG patterns

i386: Improve vector mode and TFmode ABS and NEG patterns

gcc/ChangeLog:

2020-05-18  Uroš Bizjak  <ubizjak@gmail.com>

	* config/i386/i386-expand.c (ix86_expand_fp_absneg_operator):
	Do not emit FLAGS_REG clobber for TFmode.
	* config/i386/i386.md (*<code>tf2_1): Rewrite as
	define_insn_and_split.  Mark operands 1 and 2 commutative.
	(*nabstf2_1): Ditto.
	(absneg SSE splitter): Use MODEF mode iterator instead of SSEMODEF.
	Do not swap memory operands.  Simplify RTX generation.
	(neg abs SSE splitter): Ditto.
	* config/i386/sse.md (*<code><mode>2): Mark operands 1 and 2
	commutative.  Do not swap operands.  Simplify RTX generation.
	(*nabs<mode>2): Ditto.