Re: A support function for loop infrastructure change

[Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>]

Hello.

>  > This function is used several times in new loop infrastructure (and also
>  > in new loop optimizer) in cfg branch.  Bootstrapped on i686 (both mainline
>  > and branch).
>  > 
>  > Zdenek Dvorak
>  > 
>  > Changelog:
>  > 
>  > 	* basic-block.h (dfs_enumerate_from): Declare.
>  > 	* cfganal.c (dfs_enumerate_from): New.
> These may sound like nits, but can you please try to use more descriptive
> variable names.  
> 
> rslt -> result_list
> rslt_max -> max_blocks (?)
> st->stack
> tv->num_blocks_found
> 
> What is "data" used for?  

Satisfied?

Zdenek Dvorak

Changelog:
	* basic-block.h (dfs_enumerate_from): Declare.
	* cfganal.c (dfs_enumerate_from): New.

Index: basic-block.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/basic-block.h,v
retrieving revision 1.137
diff -c -3 -p -r1.137 basic-block.h
*** basic-block.h	2002/03/07 15:37:59	1.137
--- basic-block.h	2002/03/11 09:08:09
*************** extern void alloc_aux_for_edges		PARAMS 
*** 663,668 ****
--- 663,672 ----
  extern void clear_aux_for_edges		PARAMS ((void));
  extern void free_aux_for_edges		PARAMS ((void));
  
+ extern int dfs_enumerate_from		PARAMS ((basic_block, int,
+ 						 bool (*)(basic_block, void *),
+ 						 basic_block *, int, void *));
+ 
  /* This function is always defined so it can be called from the
     debugger, and it is declared extern so we don't get warnings about
     it being unused.  */
Index: cfganal.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfganal.c,v
retrieving revision 1.16
diff -c -3 -p -r1.16 cfganal.c
*** cfganal.c	2002/03/06 10:17:13	1.16
--- cfganal.c	2002/03/11 09:08:09
*************** flow_dfs_compute_reverse_finish (data)
*** 1178,1180 ****
--- 1178,1240 ----
    free (data->stack);
    sbitmap_free (data->visited_blocks);
  }
+ 
+ /* Performs dfs search from BB over vertices satisfying PREDICATE;
+    if REVERSE, go against direction of edges.  Returns number of blocks
+    found and their list in RESULT.  RESULT can contain at most RSLT_MAX items.
+    DATA is passed to PREDICATE.  */
+ int
+ dfs_enumerate_from (bb, reverse, predicate, result, rslt_max, data)
+      basic_block bb;
+      int reverse;
+      bool (*predicate) (basic_block, void *);
+      basic_block *result;
+      int rslt_max;
+      void *data;
+ {
+   basic_block *stack, lbb;
+   int sp = 0, bbs_found = 0;
+   sbitmap visited;
+   
+   visited = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
+   sbitmap_zero (visited);
+ 
+   stack = xcalloc (rslt_max, sizeof (basic_block));
+   result[bbs_found++] = stack[sp++] = bb;
+   SET_BIT (visited, bb->index - (INVALID_BLOCK + 1));
+ 
+   while (sp)
+     {
+       edge e;
+       lbb = stack[--sp];
+       if (reverse)
+         {
+           for (e = lbb->pred; e; e = e->pred_next)
+ 	    if (!TEST_BIT(visited, e->src->index - (INVALID_BLOCK + 1))
+ 		&& predicate (e->src, data))
+ 	      {
+ 	        if (bbs_found == rslt_max)
+ 	          abort ();
+ 	        result[bbs_found++] = stack[sp++] = e->src;
+ 		SET_BIT (visited, e->src->index - (INVALID_BLOCK + 1));
+ 	      }
+         }
+       else
+         {
+           for (e = lbb->succ; e; e = e->succ_next)
+ 	    if (!TEST_BIT(visited, e->dest->index - (INVALID_BLOCK + 1))
+ 		&& predicate (e->dest, data))
+ 	      {
+ 	        if (bbs_found == rslt_max)
+ 	          abort ();
+ 	        result[bbs_found++] = stack[sp++] = e->dest;
+ 		SET_BIT (visited, e->dest->index - (INVALID_BLOCK + 1));
+ 	      }
+ 	}
+     }
+ 
+   free (stack);
+   sbitmap_free (visited);
+ 
+   return bbs_found;
+ }