On 21/02/17 16:54, charles.bay...@linaro.org wrote:
> From: Charles Baylis <charles.bay...@linaro.org>
>
> This patch adds support for modelling the varying costs of
> different addressing modes. The generic cost table treats
> all addressing modes as having equal cost. The cost table
> for Cortex-A57 is derived from
> http://infocenter.arm.com/help/topic/com.arm.doc.uan0015b/Cortex_A57_Software_Optimization_Guide_external.pdf
> and treats addressing modes with write-back as having a
> cost equal to one additional instruction.
>
> gcc/ChangeLog:
>
> <date> Charles Baylis <charles.bay...@linaro.org>
>
> * config/arm/aarch-common-protos.h (enum arm_addr_mode_op): New.
> (struct addr_mode_cost_table): New.
> (struct cpu_cost_table): Add pointer to an addr_mode_cost_table.
> * config/arm/aarch-cost-tables.h: (generic_addr_mode_costs): New.
> (generic_extra_costs) Initialise aarch32_addr_mode.
> (cortexa53_extra_costs) Likewise.
> (addr_mode_costs_cortexa57) New.
> (cortexa57_extra_costs) Initialise aarch32_addr_mode.
> (exynosm1_extra_costs) Likewise.
> (xgene1_extra_costs) Likewise.
> (qdf24xx_extra_costs) Likewise.
> * config/arm/arm.c (cortexa9_extra_costs) Initialise aarch32_addr_mode.
> (cortexa9_extra_costs) Likewise.
> (cortexa8_extra_costs) Likewise.
> (cortexa5_extra_costs) Likewise.
> (cortexa7_extra_costs) Likewise.
> (cortexa12_extra_costs) Likewise.
> (cortexv7m_extra_costs) Likewise.
> (arm_mem_costs): Use table lookup to calculate cost of addressing
> mode.
>
> Change-Id: If71bd7c4f4bb876c5ed82dc28791130efb8bf89e
> ---
> gcc/config/arm/aarch-common-protos.h | 16 +++++++++++
> gcc/config/arm/aarch-cost-tables.h | 54 ++++++++++++++++++++++++++++++----
> gcc/config/arm/arm.c | 56
> ++++++++++++++++++++++++++++++------
> 3 files changed, 113 insertions(+), 13 deletions(-)
>
> diff --git a/gcc/config/arm/aarch-common-protos.h
> b/gcc/config/arm/aarch-common-protos.h
> index 7c2bb4c..f6fcc94 100644
> --- a/gcc/config/arm/aarch-common-protos.h
> +++ b/gcc/config/arm/aarch-common-protos.h
> @@ -130,6 +130,21 @@ struct vector_cost_table
> const int alu;
> };
>
> +enum arm_addr_mode_op
> +{
> + AMO_DEFAULT,
> + AMO_NO_WB,
> + AMO_WB,
> + AMO_MAX /* for array size */
Comment style: Capital letter at start, full stop and two spaces at the end.
The enum and structure below should have some comments explaining what
they are for.
> +};
> +
> +struct addr_mode_cost_table
> +{
> + const int integer[AMO_MAX];
> + const int fp[AMO_MAX];
> + const int vector[AMO_MAX];
> +};
> +
> struct cpu_cost_table
> {
> const struct alu_cost_table alu;
> @@ -137,6 +152,7 @@ struct cpu_cost_table
> const struct mem_cost_table ldst;
> const struct fp_cost_table fp[2]; /* SFmode and DFmode. */
> const struct vector_cost_table vect;
> + const struct addr_mode_cost_table *aarch32_addr_mode;
> };
>
>
> diff --git a/gcc/config/arm/aarch-cost-tables.h
> b/gcc/config/arm/aarch-cost-tables.h
> index 68f84b0..e3d257f 100644
> --- a/gcc/config/arm/aarch-cost-tables.h
> +++ b/gcc/config/arm/aarch-cost-tables.h
> @@ -22,6 +22,16 @@
> #ifndef GCC_AARCH_COST_TABLES_H
> #define GCC_AARCH_COST_TABLES_H
>
> +const struct addr_mode_cost_table generic_addr_mode_costs =
> +{
> + /* int */
> + { 0, 0, 0 },
Elements need to be commented, otherwise minor changes to the contents
of the arrays is hard to update and maintain.
> + /* float */
> + { 0, 0, 0 },
> + /* vector */
> + { 0, 0, 0 }
> +};
> +
> const struct cpu_cost_table generic_extra_costs =
> {
> /* ALU */
> @@ -122,7 +132,9 @@ const struct cpu_cost_table generic_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
Comment style.
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table cortexa53_extra_costs =
> @@ -225,6 +237,30 @@ const struct cpu_cost_table cortexa53_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> +};
> +
> +const struct addr_mode_cost_table addr_mode_costs_cortexa57 =
> +{
> + /* int */
> + {
> + 0,
> + 0,
> + COSTS_N_INSNS (1),
> + },
> + /* float */
> + {
> + 0,
> + 0,
> + COSTS_N_INSNS (1),
> + },
> + /* vector */
> + {
> + 0,
> + 0,
> + COSTS_N_INSNS (1),
> }
> };
>
> @@ -328,7 +364,9 @@ const struct cpu_cost_table cortexa57_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &addr_mode_costs_cortexa57
> };
>
> const struct cpu_cost_table exynosm1_extra_costs =
> @@ -431,7 +469,9 @@ const struct cpu_cost_table exynosm1_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (0) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table xgene1_extra_costs =
> @@ -534,7 +574,9 @@ const struct cpu_cost_table xgene1_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (2) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table qdf24xx_extra_costs =
> @@ -637,7 +679,9 @@ const struct cpu_cost_table qdf24xx_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> #endif /* GCC_AARCH_COST_TABLES_H */
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index 7f002f1..fe4cd73 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -1099,7 +1099,9 @@ const struct cpu_cost_table cortexa9_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table cortexa8_extra_costs =
> @@ -1202,7 +1204,9 @@ const struct cpu_cost_table cortexa8_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table cortexa5_extra_costs =
> @@ -1306,7 +1310,9 @@ const struct cpu_cost_table cortexa5_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
>
> @@ -1411,7 +1417,9 @@ const struct cpu_cost_table cortexa7_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table cortexa12_extra_costs =
> @@ -1514,7 +1522,9 @@ const struct cpu_cost_table cortexa12_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table cortexa15_extra_costs =
> @@ -1617,7 +1627,9 @@ const struct cpu_cost_table cortexa15_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct cpu_cost_table v7m_extra_costs =
> @@ -1720,7 +1732,9 @@ const struct cpu_cost_table v7m_extra_costs =
> /* Vector */
> {
> COSTS_N_INSNS (1) /* alu. */
> - }
> + },
> + /* Addressing mode */
> + &generic_addr_mode_costs
> };
>
> const struct tune_params arm_slowmul_tune =
> @@ -9093,7 +9107,33 @@ arm_mem_costs (rtx x, const struct cpu_cost_table
> *extra_cost,
> /* Calculate cost of the addressing mode. */
> if (speed_p)
> {
> - /* TODO: Add table-driven costs for addressing modes. */
> + arm_addr_mode_op op_type;
> + switch (GET_CODE(XEXP (x, 0)))
> + {
> + case REG:
> + default:
> + op_type = AMO_DEFAULT;
Why would REG and default share the same cost? Presumably default is
too complex to recognize, but then it's unlikely to be cheap.
> + break;
> + case PLUS:
> + case MINUS:
> + op_type = AMO_NO_WB;
GCC doesn't support MINUS in addresses, even though the architecture
could in theory handle this.
Also, I think you need a different cost for scaled offset addressing,
and possibly even for different scaling factors and types of scaling.
> + break;
> + case PRE_INC:
> + case PRE_DEC:
> + case POST_INC:
> + case POST_DEC:
> + case PRE_MODIFY:
> + case POST_MODIFY:
> + op_type = AMO_WB;
Pre and post might also need separate entries (plus further entries for
scaling). A post operation might happen in parallel with the data
fetch, while a pre operation must happen before the address can be sent
to the load/store pipe.
> + break;
> + }
blank line between the switch block and the subsequent statements.
Also, the following needs to laid out in GNU style.
> + if (VECTOR_MODE_P (mode)) {
> + *cost += extra_cost->aarch32_addr_mode->vector[op_type];
> + } else if (FLOAT_MODE_P (mode)) {
> + *cost += extra_cost->aarch32_addr_mode->fp[op_type];
> + } else {
> + *cost += extra_cost->aarch32_addr_mode->integer[op_type];
> + }
> }
>
> /* cost of memory access */
>
