Re: [RFT PATCH, i386]: Optimize zero-extensions from mask registers

[Kirill Yukhin <kirill.yukhin@gmail.com>]

Hello Uroš,
On 05 Aug 14:22, Uros Bizjak wrote:
> Hello!
> 
> Attached patch was inspired by assembly from PR 72805 testcase.
> Currently, the compiler generates:
> 
> test:
>         vpternlogd      $0xFF, %zmm0, %zmm0, %zmm0
>         vpxord  %zmm1, %zmm1, %zmm1
>         vpcmpd  $1, %zmm1, %zmm0, %k1
>         kmovw   %k1, %eax
>         movzwl  %ax, %eax
>         ret
> 
> Please note that kmovw already zero-extended from a mask register.
> 
> 2016-08-05  Uros Bizjak  <ubizjak@gmail.com>
> 
>     * config/i386/i386.md (*zero_extendsidi2): Add (*r,*k) alternative.
>     (zero_extend<mode>di2): Ditto.
>     (*zero_extend<mode>si2): Ditto.
>     (*zero_extendqihi2): Ditto.
> 
> Patch was bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.
> 
> The patch is in RFT state, since I have no means to test AVX512 stuff.
> Kirill, can someone from Intel please test the patch?
I gave a try to your patch and see no regressions or bootstrap failures on i386/x86_64 (run on SDE).

--
Thanks, K
> 
> Uros.

> Index: config/i386/i386.md
> ===================================================================
> --- config/i386/i386.md	(revision 239166)
> +++ config/i386/i386.md	(working copy)
> @@ -3688,10 +3688,10 @@
>  
>  (define_insn "*zero_extendsidi2"
>    [(set (match_operand:DI 0 "nonimmediate_operand"
> -			"=r,?r,?o,r   ,o,?*Ym,?!*y,?r ,?r,?*Yi,?*x")
> +			"=r,?r,?o,r   ,o,?*Ym,?!*y,?r ,?r,?*Yi,?*x,*r")
>  	(zero_extend:DI
>  	 (match_operand:SI 1 "x86_64_zext_operand"
> -	        	"0 ,rm,r ,rmWz,0,r   ,m   ,*Yj,*x,r   ,m")))]
> +	        	"0 ,rm,r ,rmWz,0,r   ,m   ,*Yj,*x,r   ,m  ,*k")))]
>    ""
>  {
>    switch (get_attr_type (insn))
> @@ -3717,6 +3717,9 @@
>  
>        return "%vmovd\t{%1, %0|%0, %1}";
>  
> +    case TYPE_MSKMOV:
> +      return "kmovd\t{%1, %k0|%k0, %1}";
> +
>      default:
>        gcc_unreachable ();
>      }
> @@ -3724,7 +3727,7 @@
>    [(set (attr "isa")
>       (cond [(eq_attr "alternative" "0,1,2")
>  	      (const_string "nox64")
> -	    (eq_attr "alternative" "3,7")
> +	    (eq_attr "alternative" "3,7,11")
>  	      (const_string "x64")
>  	    (eq_attr "alternative" "8")
>  	      (const_string "x64_sse4")
> @@ -3741,6 +3744,8 @@
>  	      (const_string "ssemov")
>  	    (eq_attr "alternative" "8")
>  	      (const_string "sselog1")
> +	    (eq_attr "alternative" "11")
> +	      (const_string "mskmov")
>  	   ]
>  	   (const_string "imovx")))
>     (set (attr "prefix_extra")
> @@ -3792,12 +3797,14 @@
>    "split_double_mode (DImode, &operands[0], 1, &operands[3], &operands[4]);")
>  
>  (define_insn "zero_extend<mode>di2"
> -  [(set (match_operand:DI 0 "register_operand" "=r")
> +  [(set (match_operand:DI 0 "register_operand" "=r,*r")
>  	(zero_extend:DI
> -	 (match_operand:SWI12 1 "nonimmediate_operand" "<r>m")))]
> +	 (match_operand:SWI12 1 "nonimmediate_operand" "<r>m,*k")))]
>    "TARGET_64BIT"
> -  "movz{<imodesuffix>l|x}\t{%1, %k0|%k0, %1}"
> -  [(set_attr "type" "imovx")
> +  "@
> +   movz{<imodesuffix>l|x}\t{%1, %k0|%k0, %1}
> +   kmov<mskmodesuffix>\t{%1, %k0|%k0, %1}"
> +  [(set_attr "type" "imovx,mskmov")
>     (set_attr "mode" "SI")])
>  
>  (define_expand "zero_extend<mode>si2"
> @@ -3841,13 +3848,15 @@
>     (set_attr "mode" "SI")])
>  
>  (define_insn "*zero_extend<mode>si2"
> -  [(set (match_operand:SI 0 "register_operand" "=r")
> +  [(set (match_operand:SI 0 "register_operand" "=r,*r")
>  	(zero_extend:SI
> -	  (match_operand:SWI12 1 "nonimmediate_operand" "<r>m")))]
> +	  (match_operand:SWI12 1 "nonimmediate_operand" "<r>m,*k")))]
>    "!(TARGET_ZERO_EXTEND_WITH_AND && optimize_function_for_speed_p (cfun))"
> -  "movz{<imodesuffix>l|x}\t{%1, %0|%0, %1}"
> -  [(set_attr "type" "imovx")
> -   (set_attr "mode" "SI")])
> +  "@
> +   movz{<imodesuffix>l|x}\t{%1, %0|%0, %1}
> +   kmov<mskmodesuffix>\t{%1, %0|%0, %1}"
> +  [(set_attr "type" "imovx,mskmov")
> +   (set_attr "mode" "SI,<MODE>")])
>  
>  (define_expand "zero_extendqihi2"
>    [(set (match_operand:HI 0 "register_operand")
> @@ -3890,12 +3899,14 @@
>  
>  ; zero extend to SImode to avoid partial register stalls
>  (define_insn "*zero_extendqihi2"
> -  [(set (match_operand:HI 0 "register_operand" "=r")
> -	(zero_extend:HI (match_operand:QI 1 "nonimmediate_operand" "qm")))]
> +  [(set (match_operand:HI 0 "register_operand" "=r,*r")
> +	(zero_extend:HI (match_operand:QI 1 "nonimmediate_operand" "qm,*k")))]
>    "!(TARGET_ZERO_EXTEND_WITH_AND && optimize_function_for_speed_p (cfun))"
> -  "movz{bl|x}\t{%1, %k0|%k0, %1}"
> -  [(set_attr "type" "imovx")
> -   (set_attr "mode" "SI")])
> +  "@
> +   movz{bl|x}\t{%1, %k0|%k0, %1}
> +   kmovb\t{%1, %k0|%k0, %1}"
> +  [(set_attr "type" "imovx,mskmov")
> +   (set_attr "mode" "SI,QI")])
>  
>  (define_insn_and_split "*zext<mode>_doubleword_and"
>    [(set (match_operand:DI 0 "register_operand" "=&<r>")