Move V1TI shift/rotate lowering from expand to pre-reload split on x86_64.

Move V1TI shift/rotate lowering from expand to pre-reload split on x86_64.

This patch moves the lowering of 128-bit V1TImode shifts and rotations by
constant bit counts to sequences of SSE operations from the RTL expansion
pass to the pre-reload split pass.  Postponing this splitting of shifts
and rotates enables (will enable) the TImode equivalents of these operations/
instructions to be considered as candidates by the (TImode) STV pass.
Technically, this patch changes the existing expanders to continue to
lower shifts by variable amounts, but constant operands become RTL
instructions, specified by define_insn_and_split that are triggered by
x86_pre_reload_split.  The one minor complication is that logical shifts
by multiples of eight, don't get split, but are handled by existing insn
patterns, such as sse2_ashlv1ti3 and sse2_lshrv1ti3.  There should be no
changes in generated code with this patch, which just adjusts the pass
in which transformations get applied.

2022-08-13  Roger Sayle  <roger@nextmovesoftware.com>
	    Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog
	* config/i386/predicates.md (const_0_to_255_not_mul_8_operand):
	New predicate for values between 0/1 and 255, not multiples of 8.
	* config/i386/sse.md (ashlv1ti3): Delay lowering of logical left
	shifts by constant bit counts.
	(*ashlvti3_internal): New define_insn_and_split that lowers
	logical left shifts by constant bit counts, that aren't multiples
	of 8, before reload.
	(lshrv1ti3): Delay lowering of logical right shifts by constant.
	(*lshrv1ti3_internal): New define_insn_and_split that lowers
	logical right shifts by constant bit counts, that aren't multiples
	of 8, before reload.
	(ashrv1ti3):: Delay lowering of arithmetic right shifts by
	constant bit counts.
	(*ashrv1ti3_internal): New define_insn_and_split that lowers
	arithmetic right shifts by constant bit counts before reload.
	(rotlv1ti3): Delay lowering of rotate left by constant.
	(*rotlv1ti3_internal): New define_insn_and_split that lowers
	rotate left by constant bits counts before reload.
	(rotrv1ti3): Delay lowering of rotate right by constant.
	(*rotrv1ti3_internal): New define_insn_and_split that lowers
	rotate right by constant bits counts before reload.