[PATCH][1/2] Speedup PTA (PR38474)

[Richard Biener <rguenther at suse dot de>]

This is a first patch speeding up PTA for PR38474 (this patch not
so much for this particular testcase, but it should in general).

The reduced testcase now compiles in 197s for me (down from 207s).

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2013-12-09  Richard Biener  <rguenther@suse.de>

	PR middle-end/38474
	* tree-ssa-structalias.c (set_union_with_increment): Remove
	unreachable code.
	(do_complex_constraint): Call set_union_with_increment with
	the solution delta, not the full solution.
	(make_transitive_closure_constraints): Merge the two
	constraints.

Index: gcc/tree-ssa-structalias.c
===================================================================
*** gcc/tree-ssa-structalias.c	(revision 205803)
--- gcc/tree-ssa-structalias.c	(working copy)
*************** set_union_with_increment  (bitmap to, bi
*** 962,971 ****
    if (bitmap_bit_p (from, anything_id))
      return bitmap_set_bit (to, anything_id);
  
-   /* For zero offset simply union the solution into the destination.  */
-   if (inc == 0)
-     return bitmap_ior_into (to, from);
- 
    /* If the offset is unknown we have to expand the solution to
       all subfields.  */
    if (inc == UNKNOWN_OFFSET)
--- 962,967 ----
*************** do_complex_constraint (constraint_graph_
*** 1788,1801 ****
    else
      {
        bitmap tmp;
-       bitmap solution;
        bool flag = false;
  
!       gcc_checking_assert (c->rhs.type == SCALAR && c->lhs.type == SCALAR);
!       solution = get_varinfo (c->rhs.var)->solution;
        tmp = get_varinfo (c->lhs.var)->solution;
  
!       flag = set_union_with_increment (tmp, solution, c->rhs.offset);
  
        if (flag)
  	bitmap_set_bit (changed, c->lhs.var);
--- 1784,1796 ----
    else
      {
        bitmap tmp;
        bool flag = false;
  
!       gcc_checking_assert (c->rhs.type == SCALAR && c->lhs.type == SCALAR
! 			   && c->rhs.offset != 0 && c->lhs.offset == 0);
        tmp = get_varinfo (c->lhs.var)->solution;
  
!       flag = set_union_with_increment (tmp, delta, c->rhs.offset);
  
        if (flag)
  	bitmap_set_bit (changed, c->lhs.var);
*************** make_transitive_closure_constraints (var
*** 3712,3726 ****
    lhs.offset = 0;
    rhs.type = DEREF;
    rhs.var = vi->id;
-   rhs.offset = 0;
-   process_constraint (new_constraint (lhs, rhs));
- 
-   /* VAR = VAR + UNKNOWN;  */
-   lhs.type = SCALAR;
-   lhs.var = vi->id;
-   lhs.offset = 0;
-   rhs.type = SCALAR;
-   rhs.var = vi->id;
    rhs.offset = UNKNOWN_OFFSET;
    process_constraint (new_constraint (lhs, rhs));
  }
--- 3707,3712 ----