i386: Some AVX512 ternlog expansion refinements.

i386: Some AVX512 ternlog expansion refinements.

This patch replaces the calls to force_reg in ix86_expand_ternlog_binop
and ix86_expand_ternlog with gen_reg_rtx and emit_move_insn.
This patch also cleans up whitespace, consistently uses CONST_VECTOR_P
instead of GET_CODE and tweaks checks for ix86_ternlog_leaf_p (for
example where vpandn may take a memory operand).

2024-07-12  Roger Sayle  <roger@nextmovesoftware.com>
	    Hongtao Liu  <hongtao.liu@intel.com>

gcc/ChangeLog
	* config/i386/i386-expand.cc (ix86_broadcast_from_constant):
	Use CONST_VECTOR_P instead of comparison against GET_CODE.
	(ix86_gen_bcst_mem): Likewise.
	(ix86_ternlog_leaf_p): Likewise.
	(ix86_ternlog_operand_p): ix86_ternlog_leaf_p is always true for
	vector_all_ones_operand.
	(ix86_expand_ternlog_bin_op): Use CONST_VECTOR_P instead of
	equality comparison against GET_CODE.  Replace call to force_reg
	with gen_reg_rtx and emit_move_insn (for VEC_DUPLICATE broadcast).
	Check for !register_operand instead of memory_operand.
	Support CONST_VECTORs by calling force_const_mem.
	(ix86_expand_ternlog): Fix indentation whitespace.
	Allow ix86_ternlog_leaf_p as ix86_expand_ternlog_andnot's second
	operand. Use CONST_VECTOR_P instead of equality against GET_CODE.
	Use gen_reg_rtx and emit_move_insn for ~a, ~b and ~c cases.