Re: [hsa 7/12] Disabling the vectorizer for GPU kernels/functions

[Richard Biener <rguenther at suse dot de>]

On Tue, 10 Nov 2015, Martin Jambor wrote:

> On Fri, Nov 06, 2015 at 09:38:21AM +0100, Richard Biener wrote:
> > On Thu, 5 Nov 2015, Martin Jambor wrote:
> > 
> > > Hi,
> > > 
> > > in the previous email I wrote we need to "change behavior" of a few
> > > optimization passes.  One was the flattening of GPU functions and the
> > > other two are in the patch below.  It all comes to that, at the
> > > moment, we need to switch off the vectorizer (only for the GPU
> > > functions, of course).
> > > 
> > > We are actually quite close to being able to handle gimple vector
> > > input in HSA back-end but not all the way yet, and before allowing the
> > > vectorizer again, we will have to make sure it never produces vectors
> > > bigger than 128bits (in GPU functions).
> > 
> > Hmm.  I'd rather have this modify
> > DECL_FUNCTION_SPECIFIC_OPTIMIZATION of the hsa function to get this
> > effect.  I think I mentioned this to the OACC guys as well for a
> > similar needs of them.
> 
> I see, that is a good idea.  I have reverted changes to
> tree-ssa-loop.c and tree-vectorizer.c and on top of that committed the
> following patch to the branch which makes modifications to HSA fndecls
> at a more convenient spot and disables vectorization in the following
> way:
> 
>   tree gdecl = gpu->decl;
>   tree fn_opts = DECL_FUNCTION_SPECIFIC_OPTIMIZATION (gdecl);
>   if (fn_opts == NULL_TREE)
>     fn_opts = optimization_default_node;
>   fn_opts = copy_node (fn_opts);
>   TREE_OPTIMIZATION (fn_opts)->x_flag_tree_loop_vectorize = false;
>   TREE_OPTIMIZATION (fn_opts)->x_flag_tree_slp_vectorize = false;
>   DECL_FUNCTION_SPECIFIC_OPTIMIZATION (gdecl) = fn_opts;
> 
> I hope that is what you meant.  I have also verified that it works.

Yes, that's what I meant.

Thanks,
Richard.

> Thanks,
> 
> Martin
> 
> 
> 2015-11-10  Martin Jambor  <mjambor@suse.cz>
> 
> 	* hsa.h (hsa_summary_t): Add a comment to method link_functions.
> 	(hsa_summary_t::link_functions): Moved...
> 	* hsa.c (hsa_summary_t::link_functions): ...here.  Added common fndecl
> 	modifications.
> 	Include stringpool.h.
> 	* ipa-hsa.c (process_hsa_functions): Do not add flatten attribute
> 	here.  Fixed comments.
> 
> diff --git a/gcc/hsa.c b/gcc/hsa.c
> index ab05a1d..e63be95 100644
> --- a/gcc/hsa.c
> +++ b/gcc/hsa.c
> @@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "alloc-pool.h"
>  #include "cgraph.h"
>  #include "print-tree.h"
> +#include "stringpool.h"
>  #include "symbol-summary.h"
>  #include "hsa.h"
>  
> @@ -693,6 +694,40 @@ hsa_get_declaration_name (tree decl)
>    return NULL;
>  }
>  
> +/* Couple GPU and HOST as gpu-specific and host-specific implementation of the
> +   same function.  KIND determines whether GPU is a host-invokable kernel or
> +   gpu-callable function.  */
> +
> +inline void
> +hsa_summary_t::link_functions (cgraph_node *gpu, cgraph_node *host,
> +			       hsa_function_kind kind)
> +{
> +  hsa_function_summary *gpu_summary = get (gpu);
> +  hsa_function_summary *host_summary = get (host);
> +
> +  gpu_summary->m_kind = kind;
> +  host_summary->m_kind = kind;
> +
> +  gpu_summary->m_gpu_implementation_p = true;
> +  host_summary->m_gpu_implementation_p = false;
> +
> +  gpu_summary->m_binded_function = host;
> +  host_summary->m_binded_function = gpu;
> +
> +  tree gdecl = gpu->decl;
> +  DECL_ATTRIBUTES (gdecl)
> +    = tree_cons (get_identifier ("flatten"), NULL_TREE,
> +		 DECL_ATTRIBUTES (gdecl));
> +
> +  tree fn_opts = DECL_FUNCTION_SPECIFIC_OPTIMIZATION (gdecl);
> +  if (fn_opts == NULL_TREE)
> +    fn_opts = optimization_default_node;
> +  fn_opts = copy_node (fn_opts);
> +  TREE_OPTIMIZATION (fn_opts)->x_flag_tree_loop_vectorize = false;
> +  TREE_OPTIMIZATION (fn_opts)->x_flag_tree_slp_vectorize = false;
> +  DECL_FUNCTION_SPECIFIC_OPTIMIZATION (gdecl) = fn_opts;
> +}
> +
>  /* Add a HOST function to HSA summaries.  */
>  
>  void
> diff --git a/gcc/hsa.h b/gcc/hsa.h
> index 025de67..b6855ea 100644
> --- a/gcc/hsa.h
> +++ b/gcc/hsa.h
> @@ -1161,27 +1161,14 @@ public:
>    hsa_summary_t (symbol_table *table):
>      function_summary<hsa_function_summary *> (table) { }
>  
> +  /* Couple GPU and HOST as gpu-specific and host-specific implementation of
> +     the same function.  KIND determines whether GPU is a host-invokable kernel
> +     or gpu-callable function.  */
> +
>    void link_functions (cgraph_node *gpu, cgraph_node *host,
>  		       hsa_function_kind kind);
>  };
>  
> -inline void
> -hsa_summary_t::link_functions (cgraph_node *gpu, cgraph_node *host,
> -			       hsa_function_kind kind)
> -{
> -  hsa_function_summary *gpu_summary = get (gpu);
> -  hsa_function_summary *host_summary = get (host);
> -
> -  gpu_summary->m_kind = kind;
> -  host_summary->m_kind = kind;
> -
> -  gpu_summary->m_gpu_implementation_p = true;
> -  host_summary->m_gpu_implementation_p = false;
> -
> -  gpu_summary->m_binded_function = host;
> -  host_summary->m_binded_function = gpu;
> -}
> -
>  /* in hsa.c */
>  extern struct hsa_function_representation *hsa_cfun;
>  extern hash_map <tree, vec <const char *> *> *hsa_decl_kernel_dependencies;
> diff --git a/gcc/ipa-hsa.c b/gcc/ipa-hsa.c
> index b4cb58e..d77fa6b 100644
> --- a/gcc/ipa-hsa.c
> +++ b/gcc/ipa-hsa.c
> @@ -90,16 +90,12 @@ process_hsa_functions (void)
>  	  cgraph_node *clone = node->create_virtual_clone
>  	    (vec <cgraph_edge *> (), NULL, NULL, "hsa");
>  	  TREE_PUBLIC (clone->decl) = TREE_PUBLIC (node->decl);
> -	  if (s->m_kind == HSA_KERNEL)
> -	    DECL_ATTRIBUTES (clone->decl)
> -	      = tree_cons (get_identifier ("flatten"), NULL_TREE,
> -			   DECL_ATTRIBUTES (clone->decl));
>  
>  	  clone->force_output = true;
>  	  hsa_summaries->link_functions (clone, node, s->m_kind);
>  
>  	  if (dump_file)
> -	    fprintf (dump_file, "HSA creates a new clone: %s, type: %s\n",
> +	    fprintf (dump_file, "Created a new HSA clone: %s, type: %s\n",
>  		     clone->name (),
>  		     s->m_kind == HSA_KERNEL ? "kernel" : "function");
>  	}
> @@ -116,7 +112,7 @@ process_hsa_functions (void)
>  	  hsa_summaries->link_functions (clone, node, HSA_FUNCTION);
>  
>  	  if (dump_file)
> -	    fprintf (dump_file, "HSA creates a new function clone: %s\n",
> +	    fprintf (dump_file, "Created a new HSA function clone: %s\n",
>  		     clone->name ());
>  	}
>      }
> 
> 

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