On Wed, Apr 27, 2016 at 04:13:33PM -0500, Evandro Menezes wrote:
> gcc/
> * config/aarch64/aarch64-protos.h
> (AARCH64_APPROX_MODE): New macro.
> (AARCH64_APPROX_{NONE,SP,DP,DFORM,QFORM,SCALAR,VECTOR,ALL}):
> Likewise.
> (tune_params): New member "approx_rsqrt_modes".
> * config/aarch64/aarch64-tuning-flags.def
> (AARCH64_EXTRA_TUNE_APPROX_RSQRT): Remove macro.
> * config/aarch64/aarch64.c
> (generic_tunings): New member "approx_rsqrt_modes".
> (cortexa35_tunings): Likewise.
> (cortexa53_tunings): Likewise.
> (cortexa57_tunings): Likewise.
> (cortexa72_tunings): Likewise.
> (exynosm1_tunings): Likewise.
> (thunderx_tunings): Likewise.
> (xgene1_tunings): Likewise.
> (use_rsqrt_p): New argument for the mode and use new member from
> "tune_params".
> (aarch64_builtin_reciprocal): Devise mode from builtin.
> (aarch64_optab_supported_p): New argument for the mode.
> * doc/invoke.texi (-mlow-precision-recip-sqrt): Reword description.
>
> diff --git a/gcc/config/aarch64/aarch64-protos.h
> b/gcc/config/aarch64/aarch64-protos.h
> index f22a31c..50f1d24 100644
> --- a/gcc/config/aarch64/aarch64-protos.h
> +++ b/gcc/config/aarch64/aarch64-protos.h
> @@ -178,6 +178,32 @@ struct cpu_branch_cost
> const int unpredictable; /* Unpredictable branch or optimizing for speed.
> */
> };
>
> +/* Control approximate alternatives to certain FP operators. */
> +#define AARCH64_APPROX_MODE(MODE) \
> + ((MIN_MODE_FLOAT <= (MODE) && (MODE) <= MAX_MODE_FLOAT) \
> + ? (1 << ((MODE) - MIN_MODE_FLOAT)) \
> + : (MIN_MODE_VECTOR_FLOAT <= (MODE) && (MODE) <= MAX_MODE_VECTOR_FLOAT) \
> + ? (1 << ((MODE) - MIN_MODE_VECTOR_FLOAT \
> + + MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1)) \
> + : (0))
> +#define AARCH64_APPROX_NONE (0)
> +#define AARCH64_APPROX_SP (AARCH64_APPROX_MODE (SFmode) \
> + | AARCH64_APPROX_MODE (V2SFmode) \
> + | AARCH64_APPROX_MODE (V4SFmode))
> +#define AARCH64_APPROX_DP (AARCH64_APPROX_MODE (DFmode) \
> + | AARCH64_APPROX_MODE (V2DFmode))
> +#define AARCH64_APPROX_DFORM (AARCH64_APPROX_MODE (SFmode) \
> + | AARCH64_APPROX_MODE (DFmode) \
> + | AARCH64_APPROX_MODE (V2SFmode))
> +#define AARCH64_APPROX_QFORM (AARCH64_APPROX_MODE (V4SFmode) \
> + | AARCH64_APPROX_MODE (V2DFmode))
> +#define AARCH64_APPROX_SCALAR (AARCH64_APPROX_MODE (SFmode) \
> + | AARCH64_APPROX_MODE (DFmode))
> +#define AARCH64_APPROX_VECTOR (AARCH64_APPROX_MODE (V2SFmode) \
> + | AARCH64_APPROX_MODE (V4SFmode) \
> + | AARCH64_APPROX_MODE (V2DFmode))
> +#define AARCH64_APPROX_ALL (-1)
> +
Thanks for providing these various subsets, but I think they are
unneccesary for the final submission. From what I can see, only
AARCH64_APPROX_ALL and AARCH64_APPROX_NONE are used. Please remove the
rest, they are easy enough to add back if a subtarget wants them.
> struct tune_params
> {
> const struct cpu_cost_table *insn_extra_cost;
> @@ -218,6 +244,7 @@ struct tune_params
> } autoprefetcher_model;
>
> unsigned int extra_tuning_flags;
> + unsigned int approx_rsqrt_modes;
As we're going to add a few of these, lets follow the approach for some
of the other costs (e.g. branch costs, vector costs) and bury them in a
structure of their own.
> };
>
> #define AARCH64_FUSION_PAIR(x, name) \
> diff --git a/gcc/config/aarch64/aarch64-tuning-flags.def
> b/gcc/config/aarch64/aarch64-tuning-flags.def
> index 7e45a0c..048c2a3 100644
> --- a/gcc/config/aarch64/aarch64-tuning-flags.def
> +++ b/gcc/config/aarch64/aarch64-tuning-flags.def
> @@ -29,5 +29,3 @@
> AARCH64_TUNE_ to give an enum name. */
>
> AARCH64_EXTRA_TUNING_OPTION ("rename_fma_regs", RENAME_FMA_REGS)
> -AARCH64_EXTRA_TUNING_OPTION ("approx_rsqrt", APPROX_RSQRT)
> -
Did you want to add another way to tune these by command line (not
neccessary now, but as a follow-up)? See how instruction fusion is
handled by the -moverride code for an example.
Thanks,
James
