Ping.
On Sun, 2024-06-16 at 01:50 +0800, Xi Ruoyao wrote:
> Consider
>
> c &= 0xfff;
> a &= ~0xfff;
> b &= ~0xfff;
> a |= c;
> b |= c;
>
> This can be done with 2 bstrins instructions. But we need to
> recognize
> it in loongarch_rtx_costs or the compiler will not propagate "c &
> 0xfff"
> forward.
>
> gcc/ChangeLog:
>
> * config/loongarch/loongarch.cc:
> (loongarch_use_bstrins_for_ior_with_mask): Split the main
> logic
> into ...
> (loongarch_use_bstrins_for_ior_with_mask_1): ... here.
> (loongarch_rtx_costs): Special case for IOR those can be
> implemented with bstrins.
>
> gcc/testsuite/ChangeLog;
>
> * gcc.target/loongarch/bstrins-3.c: New test.
> ---
>
> Bootstrapped and regtested on loongarch64-linux-gnu. Ok for trunk?
>
> gcc/config/loongarch/loongarch.cc | 73 ++++++++++++++----
> -
> .../gcc.target/loongarch/bstrins-3.c | 16 ++++
> 2 files changed, 72 insertions(+), 17 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/loongarch/bstrins-3.c
>
> diff --git a/gcc/config/loongarch/loongarch.cc
> b/gcc/config/loongarch/loongarch.cc
> index 6ec3ee62502..256b76d044b 100644
> --- a/gcc/config/loongarch/loongarch.cc
> +++ b/gcc/config/loongarch/loongarch.cc
> @@ -3681,6 +3681,27 @@ loongarch_set_reg_reg_piece_cost (machine_mode
> mode, unsigned int units)
> return COSTS_N_INSNS ((GET_MODE_SIZE (mode) + units - 1) / units);
> }
>
> +static int
> +loongarch_use_bstrins_for_ior_with_mask_1 (machine_mode mode,
> + unsigned HOST_WIDE_INT
> mask1,
> + unsigned HOST_WIDE_INT
> mask2)
> +{
> + if (mask1 != ~mask2 || !mask1 || !mask2)
> + return 0;
> +
> + /* Try to avoid a right-shift. */
> + if (low_bitmask_len (mode, mask1) != -1)
> + return -1;
> +
> + if (low_bitmask_len (mode, mask2 >> (ffs_hwi (mask2) - 1)) != -1)
> + return 1;
> +
> + if (low_bitmask_len (mode, mask1 >> (ffs_hwi (mask1) - 1)) != -1)
> + return -1;
> +
> + return 0;
> +}
> +
> /* Return the cost of moving between two registers of mode MODE. */
>
> static int
> @@ -3812,6 +3833,38 @@ loongarch_rtx_costs (rtx x, machine_mode mode,
> int outer_code,
> /* Fall through. */
>
> case IOR:
> + {
> + rtx op[2] = {XEXP (x, 0), XEXP (x, 1)};
> + if (GET_CODE (op[0]) == AND && GET_CODE (op[1]) == AND
> + && (mode == SImode || (TARGET_64BIT && mode == DImode)))
> + {
> + rtx rtx_mask0 = XEXP (op[0], 1), rtx_mask1 = XEXP (op[1],
> 1);
> + if (CONST_INT_P (rtx_mask0) && CONST_INT_P (rtx_mask1))
> + {
> + unsigned HOST_WIDE_INT mask0 = UINTVAL (rtx_mask0);
> + unsigned HOST_WIDE_INT mask1 = UINTVAL (rtx_mask1);
> + if (loongarch_use_bstrins_for_ior_with_mask_1 (mode,
> + mask0,
> +
> mask1))
> + {
> + /* A bstrins instruction */
> + *total = COSTS_N_INSNS (1);
> +
> + /* A srai instruction */
> + if (low_bitmask_len (mode, mask0) == -1
> + && low_bitmask_len (mode, mask1) == -1)
> + *total += COSTS_N_INSNS (1);
> +
> + for (int i = 0; i < 2; i++)
> + *total += set_src_cost (XEXP (op[i], 0), mode,
> speed);
> +
> + return true;
> + }
> + }
> + }
> + }
> +
> + /* Fall through. */
> case XOR:
> /* Double-word operations use two single-word operations. */
> *total = loongarch_binary_cost (x, COSTS_N_INSNS (1),
> COSTS_N_INSNS (2),
> @@ -5796,23 +5849,9 @@ bool loongarch_pre_reload_split (void)
> int
> loongarch_use_bstrins_for_ior_with_mask (machine_mode mode, rtx *op)
> {
> - unsigned HOST_WIDE_INT mask1 = UINTVAL (op[2]);
> - unsigned HOST_WIDE_INT mask2 = UINTVAL (op[4]);
> -
> - if (mask1 != ~mask2 || !mask1 || !mask2)
> - return 0;
> -
> - /* Try to avoid a right-shift. */
> - if (low_bitmask_len (mode, mask1) != -1)
> - return -1;
> -
> - if (low_bitmask_len (mode, mask2 >> (ffs_hwi (mask2) - 1)) != -1)
> - return 1;
> -
> - if (low_bitmask_len (mode, mask1 >> (ffs_hwi (mask1) - 1)) != -1)
> - return -1;
> -
> - return 0;
> + return loongarch_use_bstrins_for_ior_with_mask_1 (mode,
> + UINTVAL (op[2]),
> + UINTVAL (op[4]));
> }
>
> /* Rewrite a MEM for simple load/store under -mexplicit-relocs=auto
> diff --git a/gcc/testsuite/gcc.target/loongarch/bstrins-3.c
> b/gcc/testsuite/gcc.target/loongarch/bstrins-3.c
> new file mode 100644
> index 00000000000..13762bdef42
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/loongarch/bstrins-3.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-rtl-final" } */
> +/* { dg-final { scan-rtl-dump-times "insv\[sd\]i" 2 "final" } } */
> +
> +struct X {
> + long a, b;
> +};
> +
> +struct X
> +test (long a, long b, long c)
> +{
> + c &= 0xfff;
> + a &= ~0xfff;
> + b &= ~0xfff;
> + return (struct X){.a = a | c, .b = b | c};
> +}
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
