Andrew Pinski <quic_apin...@quicinc.com> writes:
> This fixes the cost model for BFI instructions which don't
> use directly zero_extract on the LHS.
> aarch64_bfi_rtx_p does the heavy lifting by matching of
> the patterns.
>
> Note this alone does not fix PR 107270, it is a step in the right
> direction. There we get z zero_extend for the non-shifted part
> which we don't currently match.
>
> Built and tested on aarch64-linux-gnu with no regressions.
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64.cc (aarch64_bfi_rtx_p): New function.
> (aarch64_rtx_costs): For IOR, try calling aarch64_bfi_rtx_p.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/config/aarch64/aarch64.cc | 94 +++++++++++++++++++++++++++++++++++
> 1 file changed, 94 insertions(+)
>
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index 3d8341c17fe..dc5c5c23cb3 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -13776,6 +13776,90 @@ aarch64_extr_rtx_p (rtx x, rtx *res_op0, rtx
> *res_op1)
> return false;
> }
>
> +/* Return true iff X is an rtx that will match an bfi instruction
> + i.e. as described in the *aarch64_bfi<mode>5 family of patterns.
> + OP0 and OP1 will be set to the operands of the insert involved
> + on success and will be NULL_RTX otherwise. */
> +
> +static bool
> +aarch64_bfi_rtx_p (rtx x, rtx *res_op0, rtx *res_op1)
I think it'd be slightly neater to pass an XEXP index in as well,
and use it...
> +{
> + rtx op0, op1;
> + scalar_int_mode mode;
> +
> + *res_op0 = NULL_RTX;
> + *res_op1 = NULL_RTX;
> + if (!is_a <scalar_int_mode> (GET_MODE (x), &mode))
> + return false;
> +
> + if (GET_CODE (x) != IOR)
> + return false;
> +
> + unsigned HOST_WIDE_INT mask1;
> + unsigned HOST_WIDE_INT shft_amnt;
> + unsigned HOST_WIDE_INT mask2;
> + rtx shiftop;
> +
> + rtx iop0 = XEXP (x, 0);
> + rtx iop1 = XEXP (x, 1);
...here as opno and 1 - opno. That way we don't need to...
> +
> + if (GET_CODE (iop0) == AND
> + && CONST_INT_P (XEXP (iop0, 1))
> + && GET_CODE (XEXP (iop0, 0)) != ASHIFT)
> + {
> + op0 = XEXP (iop0, 0);
> + mask1 = UINTVAL (XEXP (iop0, 1));
> + shiftop = iop1;
> + }
> + else if (GET_CODE (iop1) == AND
> + && CONST_INT_P (XEXP (iop1, 1))
> + && GET_CODE (XEXP (iop1, 0)) != ASHIFT)
> + {
> + op0 = XEXP (iop1, 0);
> + mask1 = UINTVAL (XEXP (iop1, 1));
> + shiftop = iop0;
> + }
> + else
> + return false;
...handle this both ways, and don't need to exclude ASHIFT.
Maybe some variation on "insert_op" would be better than "shiftop",
since the operand might not include a shift.
Looks generally good to me otherwise FWIW, but obviously GCC 15 material.
Thanks,
Richard
> +
> + /* Shifted with no mask. */
> + if (GET_CODE (shiftop) == ASHIFT
> + && CONST_INT_P (XEXP (shiftop, 1)))
> + {
> + shft_amnt = UINTVAL (XEXP (shiftop, 1));
> + mask2 = HOST_WIDE_INT_M1U << shft_amnt;
> + op1 = XEXP (shiftop, 0);
> + }
> + else if (GET_CODE (shiftop) == AND
> + && CONST_INT_P (XEXP (shiftop, 1)))
> + {
> + mask2 = UINTVAL (XEXP (shiftop, 1));
> + if (GET_CODE (XEXP (shiftop, 0)) == ASHIFT
> + && CONST_INT_P (XEXP (XEXP (shiftop, 0), 1)))
> + {
> + op1 = XEXP (XEXP (shiftop, 0), 0);
> + shft_amnt = UINTVAL (XEXP (XEXP (shiftop, 0), 1));
> + }
> + else
> + {
> + op1 = XEXP (shiftop, 0);
> + shft_amnt = 0;
> + }
> + }
> + else
> + return false;
> +
> + if (shft_amnt >= GET_MODE_BITSIZE (mode))
> + return false;
> +
> + if (!aarch64_masks_and_shift_for_bfi_p (mode, mask1, shft_amnt, mask2))
> + return false;
> +
> + *res_op0 = op0;
> + *res_op1 = op1;
> + return true;
> +}
> +
> /* Calculate the cost of calculating (if_then_else (OP0) (OP1) (OP2)),
> storing it in *COST. Result is true if the total cost of the operation
> has now been calculated. */
> @@ -14662,6 +14746,16 @@ cost_plus:
> return true;
> }
>
> + if (aarch64_bfi_rtx_p (x, &op0, &op1))
> + {
> + *cost += rtx_cost (op0, mode, IOR, 0, speed);
> + *cost += rtx_cost (op0, mode, IOR, 1, speed);
> + if (speed)
> + *cost += extra_cost->alu.bfi;
> +
> + return true;
> + }
> +
> if (aarch64_extr_rtx_p (x, &op0, &op1))
> {
> *cost += rtx_cost (op0, mode, IOR, 0, speed);
