RISC-V: Add RVV narrow shift right lowering auto-vectorization

Optimize the following auto-vectorization codes:
void foo (int16_t * __restrict a, int32_t * __restrict b, int32_t c, int n)
{
    for (int i = 0; i < n; i++)
      a[i] = b[i] >> c;
}

Before this patch:
foo:
        ble     a3,zero,.L5
.L3:
        vsetvli a5,a3,e32,m1,ta,ma
        vle32.v v1,0(a1)
        vsetvli a4,zero,e32,m1,ta,ma
        vsra.vx v1,v1,a2
        vsetvli zero,zero,e16,mf2,ta,ma
        slli    a7,a5,2
        vncvt.x.x.w     v1,v1
        slli    a6,a5,1
        vsetvli zero,a5,e16,mf2,ta,ma
        sub     a3,a3,a5
        vse16.v v1,0(a0)
        add     a1,a1,a7
        add     a0,a0,a6
        bne     a3,zero,.L3
.L5:
        ret

After this patch:
foo:
	ble	a3,zero,.L5
.L3:
	vsetvli	a5,a3,e32,m1,ta,ma
	vle32.v	v1,0(a1)
	vsetvli	a7,zero,e16,mf2,ta,ma
	slli	a6,a5,2
	vnsra.wx	v1,v1,a2
	slli	a4,a5,1
	vsetvli	zero,a5,e16,mf2,ta,ma
	sub	a3,a3,a5
	vse16.v	v1,0(a0)
	add	a1,a1,a6
	add	a0,a0,a4
	bne	a3,zero,.L3
.L5:
	ret

gcc/ChangeLog:

	* config/riscv/autovec-opt.md
	(*v<any_shiftrt:optab><any_extend:optab>trunc<mode>): New pattern.
	(*<any_shiftrt:optab>trunc<mode>): Ditto.
	* config/riscv/autovec.md (<optab><mode>3): Change to
	define_insn_and_split.
	(v<optab><mode>3): Ditto.
	(trunc<mode><v_double_trunc>2): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/binop/narrow-1.c: New test.
	* gcc.target/riscv/rvv/autovec/binop/narrow-2.c: New test.
	* gcc.target/riscv/rvv/autovec/binop/narrow-3.c: New test.
	* gcc.target/riscv/rvv/autovec/binop/narrow_run-1.c: New test.
	* gcc.target/riscv/rvv/autovec/binop/narrow_run-2.c: New test.
	* gcc.target/riscv/rvv/autovec/binop/narrow_run-3.c: New test.

0 files changed, 0 insertions, 0 deletions