RISC-V: Bugfix for RTL check[PR111533]

RISC-V: Bugfix for RTL check[PR111533]

Consider the flowing situation:
BB5: local_dem(RVV Insn 1, AVL(reg zero))
RVV Insn 1: vmv.s.x, AVL (const_int 1)
RVV Insn 2: vredsum.vs, AVL(reg zero)

vmv.s.x has vl operand, the following code will get
avl (cosnt_int) from RVV Insn 1.
rtx avl = has_vl_op (insn->rtl ()) ? get_vl (insn->rtl ())
                                   : dem.get_avl ();

If use REGNO for const_int, the compiler will crash:

during RTL pass: vsetvl
res_debug.c: In function '__dn_count_labels':
res_debug.c:1050:1: internal compiler error: RTL check: expected code 'reg',
have 'const_int' in rhs_regno, at rtl.h:1934
 1050 | }
      | ^
0x8fb169 rtl_check_failed_code1(rtx_def const*, rtx_code, char const*, int, char const*)
	../.././gcc/gcc/rtl.cc:770
0x1399818 rhs_regno(rtx_def const*)
	../.././gcc/gcc/rtl.h:1934
0x1399818 anticipatable_occurrence_p
	../.././gcc/gcc/config/riscv/riscv-vsetvl.cc:348

So in this case avl should be obtained from dem.

Another issue is caused by the following code:
HOST_WIDE_INT diff = INTVAL (builder.elt (i)) - i;

during RTL pass: expand
../../.././gcc/libgfortran/generated/matmul_c4.c: In function 'matmul_c4':
../../.././gcc/libgfortran/generated/matmul_c4.c:2906:39: internal compiler error: RTL check:
expected code 'const_int', have 'const_poly_int' in expand_const_vector,
at config/riscv/riscv-v.cc:1149

The builder.elt (i) can be either const_int or const_poly_int.

	PR target/111533

gcc/ChangeLog:

	* config/riscv/riscv-v.cc (expand_const_vector): Fix bug.
	* config/riscv/riscv-vsetvl.cc (anticipatable_occurrence_p): Fix bug.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/pr111533-1.c: New test.
	* gcc.target/riscv/rvv/base/pr111533-2.c: New test.