[PATCH] arm: Initialize vector costing fields

Kyrylo Tkachov Kyrylo.Tkachov@arm.com
Wed Nov 10 15:34:14 GMT 2021


Hi Christophe

> -----Original Message-----
> From: Gcc-patches <gcc-patches-
> bounces+kyrylo.tkachov=arm.com@gcc.gnu.org> On Behalf Of Christophe
> Lyon via Gcc-patches
> Sent: Monday, November 8, 2021 6:13 PM
> To: gcc-patches@gcc.gnu.org
> Subject: [PATCH] arm: Initialize vector costing fields
> 
> The movi, dup and extract costing fields were recently added to struct
> vector_cost_table, but there initialization is missing for the arm
> (aarch32) specific descriptions.
> 
> Although the arm port does not use these fields (only aarch64 does),
> this is causing warnings during the build, and even build failures
> when using gcc-4.8.5 as host compiler:
> 
> /gccsrc/gcc/config/arm/arm.c:1194:1: error: uninitialized const member
> 'vector_cost_table::movi'
>  };
>   ^
> /gccsrc/gcc/config/arm/arm.c:1194:1: warning: missing initializer for member
> 'vector_cost_table::movi' [-Wmissing-field-initializers]
> /gccsrc/gcc/config/arm/arm.c:1194:1: error: uninitialized const member
> 'vector_cost_table::dup'
> /gccsrc/gcc/config/arm/arm.c:1194:1: warning: missing initializer for member
> 'vector_cost_table::dup' [-Wmissing-field-initializers]
> /gccsrc/gcc/config/arm/arm.c:1194:1: error: uninitialized const member
> 'vector_cost_table::extract'
> /gccsrc/gcc/config/arm/arm.c:1194:1: warning: missing initializer for member
> 'vector_cost_table::extract' [-Wmissing-field-initializers]
> 
> This patch uses the same initialization values as in aarch64 for
> consistency:
> +    COSTS_N_INSNS (1),  /* movi.  */
> +    COSTS_N_INSNS (2),  /* dup.  */
> +    COSTS_N_INSNS (2)   /* extract.  */
> 
> But given these fields are not used, maybe a dummy value should be
> used instead? (zero?)

They're dummy values for now, but there's no reason why the backend couldn't be extended to use them in the future.
Anyway, this patch is okay as is.

Thanks,
Kyrill

> 
> 2021-11-08  Christophe Lyon  <christophe.lyon@foss.st.com>
> 
> 	gcc/
> 	* config/arm/arm.c (cortexa9_extra_costs, cortexa8_extra_costs,
> 	cortexa5_extra_costs, cortexa7_extra_costs,
> 	cortexa12_extra_costs, cortexa15_extra_costs, v7m_extra_costs):
> 	Initialize movi, dup and extract costing fields.
> ---
>  gcc/config/arm/arm.c | 35 ++++++++++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index 6c6e77fab66..3f5e1162853 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -1197,7 +1197,10 @@ const struct cpu_cost_table cortexa9_extra_costs
> =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> @@ -1301,7 +1304,10 @@ const struct cpu_cost_table cortexa8_extra_costs
> =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> @@ -1406,7 +1412,10 @@ const struct cpu_cost_table cortexa5_extra_costs
> =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> @@ -1512,7 +1521,10 @@ const struct cpu_cost_table cortexa7_extra_costs
> =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> @@ -1616,7 +1628,10 @@ const struct cpu_cost_table
> cortexa12_extra_costs =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> @@ -1720,7 +1735,10 @@ const struct cpu_cost_table
> cortexa15_extra_costs =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> @@ -1824,7 +1842,10 @@ const struct cpu_cost_table v7m_extra_costs =
>    /* Vector */
>    {
>      COSTS_N_INSNS (1),	/* alu.  */
> -    COSTS_N_INSNS (4)	/* mult.  */
> +    COSTS_N_INSNS (4),	/* mult.  */
> +    COSTS_N_INSNS (1),	/* movi.  */
> +    COSTS_N_INSNS (2),	/* dup.  */
> +    COSTS_N_INSNS (2)	/* extract.  */
>    }
>  };
> 
> --
> 2.25.1



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