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tree-optimization/109143 - improve PTA compile time

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The following improves solution_set_expand to require one less
iteration over the bitmap and avoid changing the bitmap we iterate
over.  Plus we handle adjacent subvars in the ID space (the common case)
and use bitmap_set_range.  This cuts a bit less than 10% off the PTA
time from the testcase in the PR.

	PR tree-optimization/109143
	* tree-ssa-structalias.cc (solution_set_expand): Avoid
	one bitmap iteration and optimize bit range setting.
This commit is contained in:
Richard Biener 2023-05-31 14:28:37 +02:00
parent 4d1e4ce986
commit 21bf2b2fd9
1 changed files with 26 additions and 14 deletions
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40
gcc/tree-ssa-structalias.cc
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@ -966,28 +966,40 @@ solution_set_expand (bitmap set, bitmap *expanded)
*expanded = BITMAP_ALLOC (&iteration_obstack);
/* In a first pass expand to the head of the variables we need to
add all sub-fields off. This avoids quadratic behavior. */
/* In a first pass expand variables, once for each head to avoid
quadratic behavior, to include all sub-fields. */
unsigned prev_head = 0;
EXECUTE_IF_SET_IN_BITMAP (set, 0, j, bi)
{
varinfo_t v = get_varinfo (j);
if (v->is_artificial_var
|| v->is_full_var)
continue;
bitmap_set_bit (*expanded, v->head);
if (v->head != prev_head)
{
varinfo_t head = get_varinfo (v->head);
unsigned num = 1;
for (varinfo_t n = vi_next (head); n != NULL; n = vi_next (n))
{
if (n->id != head->id + num)
{
/* Usually sub variables are adjacent but since we
create pointed-to restrict representatives there
can be gaps as well. */
bitmap_set_range (*expanded, head->id, num);
head = n;
num = 1;
}
else
num++;
}
bitmap_set_range (*expanded, head->id, num);
prev_head = v->head;
}
}
/* In the second pass now expand all head variables with subfields. */
EXECUTE_IF_SET_IN_BITMAP (*expanded, 0, j, bi)
{
varinfo_t v = get_varinfo (j);
if (v->head != j)
continue;
for (v = vi_next (v); v != NULL; v = vi_next (v))
bitmap_set_bit (*expanded, v->id);
}
/* And finally set the rest of the bits from SET. */
/* And finally set the rest of the bits from SET in an efficient way. */
bitmap_ior_into (*expanded, set);
return *expanded;