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tree-ssa-dce.c (nr_walks): New variable. 

2009-11-26  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-dce.c (nr_walks): New variable.
	(mark_aliased_reaching_defs_necessary): Adjust oracle cut-off.
	(perform_tree_ssa_dce): Init nr_walks.

From-SVN: r154676
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Richard Guenther 2009-11-26 17:00:19 +00:00 committed by Richard Biener
parent 6780e186fc
commit a61f9cc067
2 changed files with 18 additions and 4 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2009-11-26 Richard Guenther <rguenther@suse.de>
* tree-ssa-dce.c (nr_walks): New variable.
(mark_aliased_reaching_defs_necessary): Adjust oracle cut-off.
(perform_tree_ssa_dce): Init nr_walks.
2009-11-26 Michael Matz <matz@suse.de>
PR tree-optimization/41905

16
gcc/tree-ssa-dce.c
View File

@ -489,6 +489,7 @@ ref_may_be_aliased (tree ref)
static bitmap visited = NULL;
static unsigned int longest_chain = 0;
static unsigned int total_chain = 0;
static unsigned int nr_walks = 0;
static bool chain_ovfl = false;
/* Worker for the walker that marks reaching definitions of REF,
@ -557,6 +558,7 @@ mark_aliased_reaching_defs_necessary (gimple stmt, tree ref)
if (chain > longest_chain)
longest_chain = chain;
total_chain += chain;
nr_walks++;
}
/* Worker for the walker that marks reaching definitions of REF, which
@ -803,11 +805,16 @@ propagate_necessity (struct edge_list *el)
gcc_unreachable ();
/* If we over-used our alias oracle budget drop to simple
mode. The cost metric allows quadratic behavior up to
a constant maximal chain and after that falls back to
mode. The cost metric allows quadratic behavior
(number of uses times number of may-defs queries) up to
a constant maximal number of queries and after that falls back to
super-linear complexity. */
if (longest_chain > 256
&& total_chain > 256 * longest_chain)
if (/* Constant but quadratic for small functions. */
total_chain > 128 * 128
/* Linear in the number of may-defs. */
&& total_chain > 32 * longest_chain
/* Linear in the number of uses. */
&& total_chain > nr_walks * 32)
{
chain_ovfl = true;
if (visited)
@ -1376,6 +1383,7 @@ perform_tree_ssa_dce (bool aggressive)
longest_chain = 0;
total_chain = 0;
nr_walks = 0;
chain_ovfl = false;
visited = BITMAP_ALLOC (NULL);
propagate_necessity (el);