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[PATCH]: Use bitmapped sets in PRE


This patch removes the annoying dual set representation PRE was using,
where half the sets were linked lists, and half were bitmapped.

Besides being a hassle maintenance wise, it had some very bad worst
case behavior.

This patch changes PRE to only use a bitmapped set representation.  In
small cases, this tends to be a slight lose.  In large cases, this
tends to be a large win (in some cases, PRE time goes from 300 seconds
to 4 seconds), mainly because compute_antic is now O(expression) set
operations.  (We could have done these same speedups on the linked
list representation).

In order to enable PRE to use bitmaps to represent sets of
expressions, we need a uniform ID over expressions (including
calls/ssa_names/_EXPR nodes).  We do this by allocating one as
necessary, and reusing them for value expressions that end up the
same.
We also need to be able to put the bitmaps into a topologically sorted
array for some functions, and we do this using a qsort functions.

Most of this change is futzing around with the existing functions to
work with bitmapped sets.

There is also a change in compute_antic to use postorder as the
iteration ordering, and to only iterate over changed sets.  This
becomes necessary when the later optimality patch comes (that solves
27755), as the old ordering took 188 iterations when the new one
takes, say, 4.  It also only iterates over blocks that could possibly
change, instead of iterating over all basic blocks for no good reasn.
It was somewhat tricky to pull out and not get massive conflicts, and
being small, i just left it in.



Bootstrapped and regtested on i686-pc-linux-gnu an i686-darwin.
Committed to mainline.

2006-10-29 Daniel Berlin <dberlin@dberlin.org>

	* tree.h (tree_value_handle): Remove struct value_set declaration.	
	Change value_set to bitmap_set.
	* tree-pretty-print.c (dump_generic_node): Use has_stmt_ann.
	* tree-vn.c (get_value_handle): Made inline and moved to
	tree-flow-inline.h.
	* tree-flow-inline.h: (has_stmt_ann): New function.
	* tree-ssa-pre.c (expressions): New variable.
	(next_expression_id): Ditto.
	(alloc_expression_id): New function.
	(struct value_set): Remove.
	(get_expression_id): New function.
	(get_or_alloc_expression_id): Ditto.
	(expression_for_id): Ditto.
	(clear_expression_ids): Ditto.
	(FOR_EACH_EXPR_ID_IN_SET): New macro.
	(bb_value_sets): Renamed to bb_bitmap_sets.
	All value sets replaced with bitmap_sets.
	Add visited member.
	(BB_VISITED): New macro.
	(postorder): New variable.
	(add_to_value): Removed.
	(value_exists_in_set_bitmap): Ditto.
	(value_insert_into_set_bitmap): Ditto.
	(set_new): Ditto.
	(set_copy): Ditto.
	(set_remove): Ditto.
	(set_contains_value): Ditto.
	(insert_into_set): Ditto.
	(set_equal): Ditto.
	(find_leader): Ditto.
	(bitmap_set_subtract_from_value_set): Ditto.
	(value_insert_into_set): Ditto.
	(print_value_set): Ditto.
	(debug_value_set): Ditto.
	(constant_expr_p): New function.
	(bitmap_remove_from_set): Ditto.
	(bitmap_insert_into_set): Ditto.
	(bitmap_set_free): Ditto.
	(vh_compare): Ditto.
	(sorted_array_from_bitmap_set): Ditto.
	(bitmap_set_subtract): Ditto.
	(bitmap_set_equal): Ditto.
	(debug_bitmap_set): Ditto.
	(find_leader_in_sets): Ditto.
	(bitmap_set_replace_value): Modify for bitmapped sets.
	(phi_translate): Ditto.
	(phi_translate_set): Ditto.
	(bitmap_find_leader): Ditto.
	(valid_in_sets): Ditto.
	(union_contains_value): Ditto.
	(clean): Ditto.
	(compute_antic_aux): Ditto.  Mark changed blocks.
	(compute_antic): Ditto. Iterate in postorder and only over
	changing blocks.
	(compute_rvuse_and_antic_safe): Reuse postorder.
	(create_component_ref_by_pieces): Modify for bitmapped sets.
	(find_or_generate_expression): Ditto.
	(create_expression_by_pieces): Ditto.
	(insert_into_preds_of_block): Ditto.
	(changed_blocks): New variable.
	(do_regular_insertion): Broken out from insert_aux.
	(insert_aux): Modified for bitmapped sets.
	(find_existing_value_expr): New function.
	(create_value_expr_from): Use it.
	(insert_extra_phis): Removed.
	(print_bitmap_set): Renamed from bitmap_print_value_set.
	(compute_avail): Handle RETURN_EXPR.
	(init_pre): Modify for bitmapped sets.
	* tree-flow.h (has_stmt_ann): New function.

Attachment: prebitmapsonly.diff.txt
Description: Text document


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