[patch] Enable record_bounds pass

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

Hello,

this pass records estimates on number of iterations of a loop.
This may enable the ivopts to decide that a value that is
zero/sign extended is an induction variable (i.e. that the value
does not overflow in the shorter mode), and optimize it
(often removing the zero/sign extend in the process).
This is a must-have on architectures where
sizeof (int) != sizeof (void *), since there basically every
array access contains such a zero extend.

Bootstrapped & regtested on i686 and x86_64.

Zdenek

	* tree-optimize.c (init_tree_optimization_passes): Add
	pass_record_bounds.
	* tree-pass.h (pass_record_bounds): Declare.
	* tree-ssa-loop.c (tree_ssa_loop_bounds, pass_record_bounds):
	New pass.

Index: tree-optimize.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-optimize.c,v
retrieving revision 2.45
diff -c -3 -p -r2.45 tree-optimize.c
*** tree-optimize.c	9 Sep 2004 20:53:36 -0000	2.45
--- tree-optimize.c	11 Sep 2004 19:44:56 -0000
*************** init_tree_optimization_passes (void)
*** 392,397 ****
--- 392,398 ----
    NEXT_PASS (pass_loop_init);
    NEXT_PASS (pass_lim);
    NEXT_PASS (pass_iv_canon);
+   NEXT_PASS (pass_record_bounds);
    NEXT_PASS (pass_if_conversion);
    NEXT_PASS (pass_vectorize);
    NEXT_PASS (pass_linear_transform);
Index: tree-pass.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-pass.h,v
retrieving revision 2.15
diff -c -3 -p -r2.15 tree-pass.h
*** tree-pass.h	9 Sep 2004 20:53:37 -0000	2.15
--- tree-pass.h	11 Sep 2004 19:44:56 -0000
*************** extern struct tree_opt_pass pass_loop;
*** 126,131 ****
--- 126,132 ----
  extern struct tree_opt_pass pass_loop_init;
  extern struct tree_opt_pass pass_lim;
  extern struct tree_opt_pass pass_iv_canon;
+ extern struct tree_opt_pass pass_record_bounds;
  extern struct tree_opt_pass pass_if_conversion;
  extern struct tree_opt_pass pass_vectorize;
  extern struct tree_opt_pass pass_complete_unroll;
Index: tree-ssa-loop.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-loop.c,v
retrieving revision 2.17
diff -c -3 -p -r2.17 tree-ssa-loop.c
*** tree-ssa-loop.c	8 Sep 2004 15:28:56 -0000	2.17
--- tree-ssa-loop.c	11 Sep 2004 19:44:57 -0000
*************** struct tree_opt_pass pass_iv_canon =
*** 263,268 ****
--- 263,297 ----
    0					/* letter */
  };
  
+ /* Record bounds on numbers of iterations of loops.  */
+ 
+ static void
+ tree_ssa_loop_bounds (void)
+ {
+   if (!current_loops)
+     return;
+ 
+   estimate_numbers_of_iterations (current_loops);
+   scev_reset ();
+ }
+ 
+ struct tree_opt_pass pass_record_bounds =
+ {
+   "bounds",				/* name */
+   NULL,					/* gate */
+   tree_ssa_loop_bounds,		       	/* execute */
+   NULL,					/* sub */
+   NULL,					/* next */
+   0,					/* static_pass_number */
+   0,			  		/* tv_id */
+   PROP_cfg | PROP_ssa,			/* properties_required */
+   0,					/* properties_provided */
+   0,					/* properties_destroyed */
+   0,					/* todo_flags_start */
+   0,			              	/* todo_flags_finish */
+   0					/* letter */
+ };
+ 
  /* Complete unrolling of loops.  */
  
  static void