[lno][PATCH] API to access ddg info

[Devang Patel <dpatel at apple dot com>]

This patch adds two routines to access data dependence info from DDG.
Bootstrapped on powerpc-darwin. Next patch will add use of it in
auto vectorizer.

--
Devang

2004-02-20  Devang Patel  <dpatel@apple.com>

        * tree-data-ref.h (data_dependence_direction): Add new member  
dir_independent.
        * tree-dg.h (tree-data-ref.h): Include.
        (ddg_direction_between_stmts, ddg_distance_between_stmts): New  
decls.
        * tree-dg.c (find_ddr_between_stmts,  
ddg_direction_between_stmts,
        ddg_distance_between_stmts): New functions.


Index: tree-data-ref.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-data-ref.h,v
retrieving revision 1.1.2.5
diff -Idpatel.pbxuser -c -3 -p -r1.1.2.5 tree-data-ref.h
*** tree-data-ref.h     16 Feb 2004 21:59:28 -0000      1.1.2.5
--- tree-data-ref.h     20 Feb 2004 19:58:46 -0000
*************** enum data_dependence_direction {
*** 55,61 ****
    dir_positive_or_negative,
    dir_positive_or_equal,
    dir_negative_or_equal,
!   dir_star
  };

  /* What is a subscript?  Given two array accesses a subscript is the
--- 55,62 ----
    dir_positive_or_negative,
    dir_positive_or_equal,
    dir_negative_or_equal,
!   dir_star,
!   dir_independent
  };

  /* What is a subscript?  Given two array accesses a subscript is the
Index: tree-dg.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-dg.h,v
retrieving revision 1.1.2.2
diff -Idpatel.pbxuser -c -3 -p -r1.1.2.2 tree-dg.h
*** tree-dg.h   20 Feb 2004 01:32:36 -0000      1.1.2.2
--- tree-dg.h   20 Feb 2004 19:58:46 -0000
*************** Software Foundation, 59 Temple Place - S
*** 22,27 ****
--- 22,29 ----
  #ifndef GCC_TREE_SSA_DG_H
  #define GCC_TREE_SSA_DG_H

+ #include "tree-data-ref.h"
+
  struct dependence_edge_def GTY (())
  {
    /* Dependence relation */
*************** void dg_delete_edge (dependence_edge);
*** 75,78 ****
--- 77,87 ----

  /* Debug dependence graph.  */
  extern void debug_dg (int);
+
+ /* Find data dependence direction between two statements.  */
+ enum ddg_dependence_direction data_direction_between_stmts (tree,  
tree, int);
+
+ /* Find data dependence distance between two statements.  */
+ tree ddg_distance_between_stmts (tree, tree, int);
+
  #endif
Index: tree-dg.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-dg.c,v
retrieving revision 1.1.2.2
diff -Idpatel.pbxuser -c -3 -p -r1.1.2.2 tree-dg.c
*** tree-dg.c   20 Feb 2004 01:32:36 -0000      1.1.2.2
--- tree-dg.c   20 Feb 2004 19:58:47 -0000
*************** static bool gate_ddg (void);
*** 64,69 ****
--- 64,70 ----
  static void dump_dg (FILE *, int);
  static void dg_delete_edges (void);
  static void dg_delete_node (dependence_node);
+ static struct data_dependence_relation * find_ddr_between_stmts  
(tree, tree);

  /* Initial dependence graph capacity.  */
  static int dependence_graph_size = 25;
*************** set_dg_node_for_stmt (tree t, dependence
*** 424,429 ****
--- 425,512 ----

    ann->dg_node = dg_node;
  }
+
+  
/ 
*----------------------------------------------------------------------- 
----
+                          Dependence Info Access
+  
------------------------------------------------------------------------ 
---*/
+
+ /* Find data dependence relation between two statements.  If there is  
no
+    relation between two statements then return NULL. */
+
+ static struct data_dependence_relation *
+ find_ddr_between_stmts (tree stmt1, tree stmt2)
+ {
+   dependence_edge e = NULL;
+   dependence_node n1 = NULL;
+   dependence_node n2 = NULL;
+
+
+ #ifdef ENABLE_CHECKING
+   if (!stmt1 || !stmt2)
+     abort ();
+ #endif
+
+   /* First find nodes for the statements.  */
+   n1 = dg_node_for_stmt (stmt1);
+   n2 = dg_node_for_stmt (stmt2);
+
+   /* If associated dependence node does not exist then this
+      two statements are independent.  */
+   if (!n1 || !n2)
+     return NULL;
+
+   /* Find edge between these two statements.  */
+   e = dg_find_edge (n1, n2, false /* Do not create new edge */);
+
+   /* Absence of edge indicates that this two statements are  
independent.  */
+   if (!e)
+     return NULL;
+
+   return e->ddr;
+
+ }
+
+ /* Find data dependence direction between two statements.  */
+
+ enum data_dependence_direction
+ ddg_direction_between_stmts (tree stmt1, tree stmt2, int loop_num)
+ {
+   struct subscript *sub = NULL;
+   struct data_dependence_relation *ddr = find_ddr_between_stmts  
(stmt1, stmt2);
+
+   /* If there is no relation then statements are independent.  */
+   if (!ddr)
+     return dir_independent;
+
+   /* Get subscript info.  */
+   sub = DDR_SUBSCRIPT (ddr, loop_num);
+   if (!sub)
+     abort ();
+
+   return SUB_DIRECTION (sub);
+ }
+
+ /* Find data dependence distance between two statements.  */
+
+ tree
+ ddg_distance_between_stmts (tree stmt1, tree stmt2, int loop_num)
+ {
+   struct subscript *sub = NULL;
+   struct data_dependence_relation *ddr = find_ddr_between_stmts  
(stmt1, stmt2);
+
+   /* If there is no relation then statements are independent.  */
+   if (!ddr)
+     return NULL_TREE;
+
+   /* Get subscript info.  */
+   sub = DDR_SUBSCRIPT (ddr, loop_num);
+   if (!sub)
+     abort ();
+
+   return SUB_DISTANCE (sub);
+ }
+
+

   
/ 
*----------------------------------------------------------------------- 
----
                           Pass management