Re: [PATCH][ARM] Remove movdi_vfp_cortexa8

[Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>]

ping
    
Kyrill Tkachov wrote:
> On 14/12/16 16:37, Wilco Dijkstra wrote:
>
> > Merge the movdi_vfp_cortexa8 pattern into movdi_vfp and remove it to avoid
> > unnecessary duplication and repeating bugs like PR78439 due to changes being
> > applied only to one of the duplicates.
>
> When this was brought up Ramana requested some more investigations on the codegen impact [1].
> Have you done the archaeology on why we had two patterns in the first place and what the codegen
> effect is of remove the Cortex-A8-specific one?

Yes, the reason to split the pattern was to introduce the '!' to discourage Neon->int moves on Cortex-A8 (https://patches.linaro.org/patch/541/). I am not removing the optimization for Cortex-A8, however I   haven't been able to find an example where it makes a difference, even on high register pressure code.

Wilco


> Bootstrap OK for ARM and Thumb-2 gnueabihf targets. OK for commit?
>
> ChangeLog:
> 2016-11-29  Wilco Dijkstra  <wdijkstr@arm.com>
>
>          * config/arm/vfp.md (movdi_vfp): Merge changes from movdi_vfp_cortexa8.
>          * (movdi_vfp_cortexa8): Remove pattern.
> --
>
> diff --git a/gcc/config/arm/vfp.md b/gcc/config/arm/vfp.md
> index 2051f1018f1cbff9c5bf044e71304d78e615458e..a917aa625a7b15f6c9e2b549ab22e5219bb9b99c 100644
> --- a/gcc/config/arm/vfp.md
> +++ b/gcc/config/arm/vfp.md
> @@ -304,9 +304,9 @@
>   ;; DImode moves
>   
>   (define_insn "*movdi_vfp"
> -  [(set (match_operand:DI 0 "nonimmediate_di_operand" "=r,r,r,r,q,q,m,w,r,w,w, Uv")
> +  [(set (match_operand:DI 0 "nonimmediate_di_operand" "=r,r,r,r,q,q,m,w,!r,w,w, Uv")
>          (match_operand:DI 1 "di_operand"              "r,rDa,Db,Dc,mi,mi,q,r,w,w,Uvi,w"))]
> -  "TARGET_32BIT && TARGET_HARD_FLOAT && arm_tune != TARGET_CPU_cortexa8
> +  "TARGET_32BIT && TARGET_HARD_FLOAT
>      && (   register_operand (operands[0], DImode)
>          || register_operand (operands[1], DImode))
>      && !(TARGET_NEON && CONST_INT_P (operands[1])
> @@ -339,71 +339,25 @@
>       }
>     "
>     [(set_attr "type" "multiple,multiple,multiple,multiple,load2,load2,store2,f_mcrr,f_mrrc,ffarithd,f_loadd,f_stored")
> -   (set (attr "length") (cond [(eq_attr "alternative" "1,4,5,6") (const_int 8)
> +   (set (attr "length") (cond [(eq_attr "alternative" "1") (const_int 8)
>                                 (eq_attr "alternative" "2") (const_int 12)
>                                 (eq_attr "alternative" "3") (const_int 16)
> +                             (eq_attr "alternative" "4,5,6")
> +                              (symbol_ref "arm_count_output_move_double_insns (operands) * 4")
>                                 (eq_attr "alternative" "9")
>                                  (if_then_else
>                                    (match_test "TARGET_VFP_SINGLE")
>                                    (const_int 8)
>                                    (const_int 4))]
>                                 (const_int 4)))
> +   (set_attr "predicable"    "yes")
>      (set_attr "arm_pool_range"     "*,*,*,*,1020,4096,*,*,*,*,1020,*")
>      (set_attr "thumb2_pool_range"     "*,*,*,*,1018,4094,*,*,*,*,1018,*")
>      (set_attr "neg_pool_range" "*,*,*,*,1004,0,*,*,*,*,1004,*")
> +   (set (attr "ce_count") (symbol_ref "get_attr_length (insn) / 4"))
>      (set_attr "arch"           "t2,any,any,any,a,t2,any,any,any,any,any,any")]
>   )
>   
> -(define_insn "*movdi_vfp_cortexa8"
> -  [(set (match_operand:DI 0 "nonimmediate_di_operand" "=r,r,r,r,r,r,m,w,!r,w,w, Uv")
> -       (match_operand:DI 1 "di_operand"              "r,rDa,Db,Dc,mi,mi,r,r,w,w,Uvi,w"))]
> -  "TARGET_32BIT && TARGET_HARD_FLOAT && arm_tune == TARGET_CPU_cortexa8
> -    && (   register_operand (operands[0], DImode)
> -        || register_operand (operands[1], DImode))
> -    && !(TARGET_NEON && CONST_INT_P (operands[1])
> -        && neon_immediate_valid_for_move (operands[1], DImode, NULL, NULL))"
> -  "*
> -  switch (which_alternative)
> -    {
> -    case 0:
> -    case 1:
> -    case 2:
> -    case 3:
> -      return \"#\";
> -    case 4:
> -    case 5:
> -    case 6:
> -      return output_move_double (operands, true, NULL);
> -    case 7:
> -      return \"vmov%?\\t%P0, %Q1, %R1\\t%@ int\";
> -    case 8:
> -      return \"vmov%?\\t%Q0, %R0, %P1\\t%@ int\";
> -    case 9:
> -      return \"vmov%?.f64\\t%P0, %P1\\t%@ int\";
> -    case 10: case 11:
> -      return output_move_vfp (operands);
> -    default:
> -      gcc_unreachable ();
> -    }
> -  "
> -  [(set_attr "type" "multiple,multiple,multiple,multiple,load2,load2,store2,f_mcrr,f_mrrc,ffarithd,f_loadd,f_stored")
> -   (set (attr "length") (cond [(eq_attr "alternative" "1") (const_int 8)
> -                               (eq_attr "alternative" "2") (const_int 12)
> -                               (eq_attr "alternative" "3") (const_int 16)
> -                               (eq_attr "alternative" "4,5,6")
> -                              (symbol_ref
> -                               "arm_count_output_move_double_insns (operands) \
> -                                 * 4")]
> -                              (const_int 4)))
> -   (set_attr "predicable"    "yes")
> -   (set_attr "arm_pool_range"     "*,*,*,*,1018,4094,*,*,*,*,1018,*")
> -   (set_attr "thumb2_pool_range"     "*,*,*,*,1018,4094,*,*,*,*,1018,*")
> -   (set_attr "neg_pool_range" "*,*,*,*,1004,0,*,*,*,*,1004,*")
> -   (set (attr "ce_count")
> -       (symbol_ref "get_attr_length (insn) / 4"))
> -   (set_attr "arch"           "t2,any,any,any,a,t2,any,any,any,any,any,any")]
> - )
> -
>   ;; HFmode moves
>   
>   (define_insn "*movhf_vfp_fp16"
>