RISC-V: Support VLS modes reduction[PR111153]

This patch supports VLS reduction vectorization.

It can optimize the current reduction vectorization codegen with current COST model.

TYPE __attribute__ ((noinline, noclone))	\
reduc_plus_##TYPE (TYPE * __restrict a, int n)		\
{						\
  TYPE r = 0;					\
  for (int i = 0; i < n; ++i)			\
    r += a[i];					\
  return r;					\
}

  T (int32_t)					\

TEST_PLUS (DEF_REDUC_PLUS)

Before this patch:

        vle32.v v2,0(a5)
        addi    a5,a5,16
        vadd.vv v1,v1,v2
        bne     a5,a4,.L4
        lui     a4,%hi(.LC0)
        lui     a5,%hi(.LC1)
        addi    a4,a4,%lo(.LC0)
        vlm.v   v0,0(a4)
        addi    a5,a5,%lo(.LC1)
        andi    a1,a1,-4
        vmv1r.v v2,v3
        vlm.v   v4,0(a5)
        vcompress.vm    v2,v1,v0
        vmv1r.v v0,v4
        vadd.vv v1,v2,v1
        vcompress.vm    v3,v1,v0
        vadd.vv v3,v3,v1
        vmv.x.s a0,v3
        sext.w  a0,a0
        beq     a3,a1,.L12

After this patch:

	vle32.v	v2,0(a5)
	addi	a5,a5,16
	vadd.vv	v1,v1,v2
	bne	a5,a4,.L4
	li	a5,0
	andi	a1,a1,-4
	vmv.s.x	v2,a5
	vredsum.vs	v1,v1,v2
	vmv.x.s	a0,v1
	beq	a3,a1,.L12

	PR target/111153

gcc/ChangeLog:

	* config/riscv/autovec.md: Add VLS modes.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vls/def.h: Add VLS mode reduction case.
	* gcc.target/riscv/rvv/autovec/vls/reduc-1.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-10.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-11.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-12.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-13.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-14.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-15.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-16.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-17.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-18.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-19.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-2.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-20.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-21.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-3.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-4.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-5.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-6.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-7.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-8.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/reduc-9.c: New test.