CC for review.
On Tue, May 21, 2024 at 1:12 PM liuhongt <hongtao....@intel.com> wrote:
>
> When mask is (1 << (prec - imm) - 1) which is used to clear upper bits
> of A, then it can be simplified to LSHIFTRT.
>
> i.e Simplify
> (and:v8hi
> (ashifrt:v8hi A 8)
> (const_vector 0xff x8))
> to
> (lshifrt:v8hi A 8)
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok of trunk?
>
> gcc/ChangeLog:
>
> PR target/114428
> * simplify-rtx.cc
> (simplify_context::simplify_binary_operation_1):
> Simplify (AND (ASHIFTRT A imm) mask) to (LSHIFTRT A imm) for
> specific mask.
> ---
> gcc/simplify-rtx.cc | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
> index 53f54d1d392..6c91409200e 100644
> --- a/gcc/simplify-rtx.cc
> +++ b/gcc/simplify-rtx.cc
> @@ -4021,6 +4021,31 @@ simplify_context::simplify_binary_operation_1
> (rtx_code code,
> return tem;
> }
>
> + /* (and:v4si
> + (ashiftrt:v4si A 16)
> + (const_vector: 0xffff x4))
> + is just (lshiftrt:v4si A 16). */
> + if (VECTOR_MODE_P (mode) && GET_CODE (op0) == ASHIFTRT
> + && (CONST_INT_P (XEXP (op0, 1))
> + || (GET_CODE (XEXP (op0, 1)) == CONST_VECTOR
> + && CONST_VECTOR_DUPLICATE_P (XEXP (op0, 1))))
> + && GET_CODE (op1) == CONST_VECTOR
> + && CONST_VECTOR_DUPLICATE_P (op1))
> + {
> + unsigned HOST_WIDE_INT shift_count
> + = (CONST_INT_P (XEXP (op0, 1))
> + ? UINTVAL (XEXP (op0, 1))
> + : UINTVAL (XVECEXP (XEXP (op0, 1), 0, 0)));
> + unsigned HOST_WIDE_INT inner_prec
> + = GET_MODE_PRECISION (GET_MODE_INNER (mode));
> +
> + /* Avoid UD shift count. */
> + if (shift_count < inner_prec
> + && (UINTVAL (XVECEXP (op1, 0, 0))
> + == (HOST_WIDE_INT_1U << (inner_prec - shift_count)) - 1))
> + return simplify_gen_binary (LSHIFTRT, mode, XEXP (op0, 0), XEXP
> (op0, 1));
> + }
> +
> tem = simplify_byte_swapping_operation (code, mode, op0, op1);
> if (tem)
> return tem;
> --
> 2.31.1
>
--
BR,
Hongtao
