[PATCH] [graphite] dump reasons why graphite failed to detect a scop

[Tobias Grosser]

On 07/25/2015 12:36 AM, Sebastian Pop wrote:
> When trying to analyze why Graphite does not handle a loop nest, it is easy to
> look in the dumps of -fdump-tree-graphite-all to guess what has to be changed to
> catch the loop.  This patch makes the dumps a bit more verbose and useful.
> ---
>   gcc/graphite-scop-detection.c | 72 +++++++++++++++++++++++++++++++++++++++----
>   1 file changed, 66 insertions(+), 6 deletions(-)

LGTM.

Tobias
>
> diff --git a/gcc/graphite-scop-detection.c b/gcc/graphite-scop-detection.c
> index 686f495..fb7247e 100644
> --- a/gcc/graphite-scop-detection.c
> +++ b/gcc/graphite-scop-detection.c
> @@ -51,6 +51,7 @@ along with GCC; see the file COPYING3.  If not see
>   #include "graphite-poly.h"
>   #include "tree-ssa-propagate.h"
>   #include "graphite-scop-detection.h"
> +#include "gimple-pretty-print.h"
>
>   /* Forward declarations.  */
>   static void make_close_phi_nodes_unique (basic_block);
> @@ -350,13 +351,31 @@ stmt_simple_for_scop_p (basic_block scop_entry, loop_p outermost_loop,
>         || (gimple_code (stmt) == GIMPLE_CALL
>   	  && !(gimple_call_flags (stmt) & (ECF_CONST | ECF_PURE)))
>         || (gimple_code (stmt) == GIMPLE_ASM))
> -    return false;
> +    {
> +      if (dump_file && (dump_flags & TDF_DETAILS))
> +	{
> +	  fprintf (dump_file, "[scop-detection-fail] ");
> +	  fprintf (dump_file, "Graphite cannot handle this stmt:\n");
> +	  print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
> +	}
> +
> +      return false;
> +    }
>
>     if (is_gimple_debug (stmt))
>       return true;
>
>     if (!stmt_has_simple_data_refs_p (outermost_loop, stmt))
> -    return false;
> +    {
> +      if (dump_file && (dump_flags & TDF_DETAILS))
> +	{
> +	  fprintf (dump_file, "[scop-detection-fail] ");
> +	  fprintf (dump_file, "Graphite cannot handle data-refs in stmt:\n");
> +	  print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
> +	}
> +
> +      return false;
> +    }
>
>     switch (gimple_code (stmt))
>       {
> @@ -375,7 +394,16 @@ stmt_simple_for_scop_p (basic_block scop_entry, loop_p outermost_loop,
>   	      || code == GE_EXPR
>   	      || code == EQ_EXPR
>   	      || code == NE_EXPR))
> -          return false;
> +          {
> +	    if (dump_file && (dump_flags & TDF_DETAILS))
> +	      {
> +		fprintf (dump_file, "[scop-detection-fail] ");
> +		fprintf (dump_file, "Graphite cannot handle cond stmt:\n");
> +		print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
> +	      }
> +
> +	    return false;
> +	  }
>
>   	for (unsigned i = 0; i < 2; ++i)
>   	  {
> @@ -383,7 +411,16 @@ stmt_simple_for_scop_p (basic_block scop_entry, loop_p outermost_loop,
>   	    if (!graphite_can_represent_expr (scop_entry, loop, op)
>   		/* We can not handle REAL_TYPE. Failed for pr39260.  */
>   		|| TREE_CODE (TREE_TYPE (op)) == REAL_TYPE)
> -	      return false;
> +	      {
> +		if (dump_file && (dump_flags & TDF_DETAILS))
> +		  {
> +		    fprintf (dump_file, "[scop-detection-fail] ");
> +		    fprintf (dump_file, "Graphite cannot represent stmt:\n");
> +		    print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
> +		  }
> +
> +		return false;
> +	      }
>   	  }
>
>   	return true;
> @@ -395,6 +432,12 @@ stmt_simple_for_scop_p (basic_block scop_entry, loop_p outermost_loop,
>
>       default:
>         /* These nodes cut a new scope.  */
> +      if (dump_file && (dump_flags & TDF_DETAILS))
> +	{
> +	  fprintf (dump_file, "[scop-detection-fail] ");
> +	  fprintf (dump_file, "Gimple stmt not handled in Graphite:\n");
> +	  print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
> +	}
>         return false;
>       }
>
> @@ -488,7 +531,16 @@ scopdet_basic_block_info (basic_block bb, loop_p outermost_loop,
>   	 with make_forwarder_block.  */
>         if (!single_succ_p (bb)
>   	  || bb_has_abnormal_pred (single_succ (bb)))
> -	result.difficult = true;
> +	{
> +	  if (dump_file && (dump_flags & TDF_DETAILS))
> +	    {
> +	      fprintf (dump_file, "[scop-detection-fail] ");
> +	      fprintf (dump_file, "BB %d cannot be part of a scop.\n",
> +		       bb->index);
> +	    }
> +
> +	  result.difficult = true;
> +	}
>         else
>   	result.exit = single_succ (bb);
>
> @@ -509,7 +561,15 @@ scopdet_basic_block_info (basic_block bb, loop_p outermost_loop,
>   	sinfo = build_scops_1 (bb, outermost_loop, &regions, loop);
>
>   	if (!graphite_can_represent_loop (entry_block, loop))
> -	  result.difficult = true;
> +	  {
> +	    if (dump_file && (dump_flags & TDF_DETAILS))
> +	      {
> +		fprintf (dump_file, "[scop-detection-fail] ");
> +		fprintf (dump_file, "Graphite cannot represent loop %d.\n",
> +			 loop->num);
> +	      }
> +	    result.difficult = true;
> +	  }
>
>   	result.difficult |= sinfo.difficult;
>
>