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Re: [PATCH] Fix PR81175, make gather builtins pure


On Tue, 27 Jun 2017, Jakub Jelinek wrote:

> On Fri, Jun 23, 2017 at 02:54:35PM +0200, Richard Biener wrote:
> > 2017-06-23  Richard Biener  <rguenther@suse.de>
> > 
> > 	PR target/81175
> > 	* config/i386/i386.c (struct builtin_isa): Add pure_p member.
> > 	(def_builtin2): Initialize pure_p.
> > 	(ix86_add_new_builtins): Honor pure_p.
> > 	(def_builtin_pure): New function.
> > 	(ix86_init_mmx_sse_builtins): Use def_builtin_pure for all
> > 	gather builtins.
> 
> > *************** ix86_init_mmx_sse_builtins (void)
> > *** 31985,32002 ****
> >   	       IX86_BUILTIN_SCATTERALTDIV16SI);
> >   
> >     /* AVX512PF */
> > !   def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdpd",
> > ! 	       VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
> > ! 	       IX86_BUILTIN_GATHERPFDPD);
> > !   def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdps",
> > ! 	       VOID_FTYPE_HI_V16SI_PCVOID_INT_INT,
> > ! 	       IX86_BUILTIN_GATHERPFDPS);
> > !   def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqpd",
> > ! 	       VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> > ! 	       IX86_BUILTIN_GATHERPFQPD);
> > !   def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqps",
> > ! 	       VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> > ! 	       IX86_BUILTIN_GATHERPFQPS);
> >     def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_scatterpfdpd",
> >   	       VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
> >   	       IX86_BUILTIN_SCATTERPFDPD);
> > --- 32004,32021 ----
> >   	       IX86_BUILTIN_SCATTERALTDIV16SI);
> >   
> >     /* AVX512PF */
> > !   def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdpd",
> > ! 		    VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
> > ! 		    IX86_BUILTIN_GATHERPFDPD);
> > !   def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdps",
> > ! 		    VOID_FTYPE_HI_V16SI_PCVOID_INT_INT,
> > ! 		    IX86_BUILTIN_GATHERPFDPS);
> > !   def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqpd",
> > ! 		    VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> > ! 		    IX86_BUILTIN_GATHERPFQPD);
> > !   def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqps",
> > ! 		    VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> > ! 		    IX86_BUILTIN_GATHERPFQPS);
> >     def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_scatterpfdpd",
> >   	       VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
> >   	       IX86_BUILTIN_SCATTERPFDPD);
> 
> The above hunk looks wrong and regresses
> +FAIL: gcc.target/i386/avx512pf-vgatherpf0dpd-1.c scan-assembler-times vgatherpf0dpd[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf0dps-1.c scan-assembler-times vgatherpf0dps[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf0qpd-1.c scan-assembler-times vgatherpf0qpd[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf0qps-1.c scan-assembler-times vgatherpf0qps[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf1dpd-1.c scan-assembler-times vgatherpf1dpd[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf1dps-1.c scan-assembler-times vgatherpf1dps[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf1qpd-1.c scan-assembler-times vgatherpf1qpd[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> +FAIL: gcc.target/i386/avx512pf-vgatherpf1qps-1.c scan-assembler-times vgatherpf1qps[ \\\\t]+[^{\\n]*{%k[1-7]}(?:\\n|[ \\\\t]+#) 2
> The prefetch intrinsics can't be pure, after all they return void, so
> as pure are always optimized away.
> 
> Ok for trunk if it passes bootstrap/regtest?

Ok.

Whoops - sorry for not noticing.  Looks like "pf" means prefetch here,
so technically they are pure (do not write to memory) but we don't want to 
DCE them as they have additional side-effects.  We could mark them
looping-const-or-pure I guess, or "volatile" (which we can't express for
calls IIRC).

Richard.

> 2017-06-27  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR target/81175
> 	* config/i386/i386.c (ix86_init_mmx_sse_builtins): Use def_builtin
> 	rather than def_builtin_pure for __builtin_ia32_gatherpf*.
> 
> --- gcc/config/i386/i386.c.jj	2017-06-27 09:16:09.000000000 +0200
> +++ gcc/config/i386/i386.c	2017-06-27 11:47:21.610627628 +0200
> @@ -32886,18 +32886,18 @@ ix86_init_mmx_sse_builtins (void)
>  	       IX86_BUILTIN_SCATTERALTDIV16SI);
>  
>    /* AVX512PF */
> -  def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdpd",
> -		    VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
> -		    IX86_BUILTIN_GATHERPFDPD);
> -  def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdps",
> -		    VOID_FTYPE_HI_V16SI_PCVOID_INT_INT,
> -		    IX86_BUILTIN_GATHERPFDPS);
> -  def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqpd",
> -		    VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> -		    IX86_BUILTIN_GATHERPFQPD);
> -  def_builtin_pure (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqps",
> -		    VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> -		    IX86_BUILTIN_GATHERPFQPS);
> +  def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdpd",
> +	       VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
> +	       IX86_BUILTIN_GATHERPFDPD);
> +  def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfdps",
> +	       VOID_FTYPE_HI_V16SI_PCVOID_INT_INT,
> +	       IX86_BUILTIN_GATHERPFDPS);
> +  def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqpd",
> +	       VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> +	       IX86_BUILTIN_GATHERPFQPD);
> +  def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_gatherpfqps",
> +	       VOID_FTYPE_QI_V8DI_PCVOID_INT_INT,
> +	       IX86_BUILTIN_GATHERPFQPS);
>    def_builtin (OPTION_MASK_ISA_AVX512PF, "__builtin_ia32_scatterpfdpd",
>  	       VOID_FTYPE_QI_V8SI_PCVOID_INT_INT,
>  	       IX86_BUILTIN_SCATTERPFDPD);
> 
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)


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