OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Enable clustering for switch statements.

Browse Source 
2018-06-20  Martin Liska  <mliska@suse.cz>

	* tree-switch-conversion.c (jump_table_cluster::find_jump_tables):
        New.
	(bit_test_cluster::find_bit_tests): Likewise.
	(switch_decision_tree::analyze_switch_statement): Find clusters.
	* tree-switch-conversion.h (struct jump_table_cluster): Document
        hierarchy.

From-SVN: r261794
This commit is contained in:
Martin Liska 2018-06-20 10:52:35 +02:00 committed by Martin Liska
parent dc223ad489
commit 2f928c1b63
3 changed files with 183 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
gcc/ChangeLog
View File

@ -1,3 +1,12 @@
2018-06-20 Martin Liska <mliska@suse.cz>
* tree-switch-conversion.c (jump_table_cluster::find_jump_tables):
New.
(bit_test_cluster::find_bit_tests): Likewise.
(switch_decision_tree::analyze_switch_statement): Find clusters.
* tree-switch-conversion.h (struct jump_table_cluster): Document
hierarchy.
2018-06-20 Martin Liska <mliska@suse.cz>
* tree-switch-conversion.c (switch_conversion::collect):

174
gcc/tree-switch-conversion.c
View File

@ -1088,6 +1088,67 @@ jump_table_cluster::emit (tree index_expr, tree,
gsi_insert_after (&gsi, s, GSI_NEW_STMT);
}
/* Find jump tables of given CLUSTERS, where all members of the vector
are of type simple_cluster. New clusters are returned. */
vec<cluster *>
jump_table_cluster::find_jump_tables (vec<cluster *> &clusters)
{
unsigned l = clusters.length ();
auto_vec<min_cluster_item> min;
min.reserve (l + 1);
min.quick_push (min_cluster_item (0, 0, 0));
for (unsigned i = 1; i <= l; i++)
{
/* Set minimal # of clusters with i-th item to infinite. */
min.quick_push (min_cluster_item (INT_MAX, INT_MAX, INT_MAX));
for (unsigned j = 0; j < i; j++)
{
unsigned HOST_WIDE_INT s = min[j].m_non_jt_cases;
if (i - j < case_values_threshold ())
s += i - j;
/* Prefer clusters with smaller number of numbers covered. */
if ((min[j].m_count + 1 < min[i].m_count
|| (min[j].m_count + 1 == min[i].m_count
&& s < min[i].m_non_jt_cases))
&& can_be_handled (clusters, j, i - 1))
min[i] = min_cluster_item (min[j].m_count + 1, j, s);
}
}
/* No result. */
if (min[l].m_count == INT_MAX)
return clusters.copy ();
vec<cluster *> output;
output.create (4);
/* Find and build the clusters. */
for (int end = l;;)
{
int start = min[end].m_start;
/* Do not allow clusters with small number of cases. */
if (is_beneficial (clusters, start, end - 1))
output.safe_push (new jump_table_cluster (clusters, start, end - 1));
else
for (int i = end - 1; i >= start; i--)
output.safe_push (clusters[i]);
end = start;
if (start <= 0)
break;
}
output.reverse ();
return output;
}
/* Return true when cluster starting at START and ending at END (inclusive)
can build a jump-table. */
@ -1142,6 +1203,59 @@ jump_table_cluster::is_beneficial (const vec<cluster *> &,
return end - start + 1 >= case_values_threshold ();
}
/* Find bit tests of given CLUSTERS, where all members of the vector
are of type simple_cluster. New clusters are returned. */
vec<cluster *>
bit_test_cluster::find_bit_tests (vec<cluster *> &clusters)
{
vec<cluster *> output;
output.create (4);
unsigned l = clusters.length ();
auto_vec<min_cluster_item> min;
min.reserve (l + 1);
min.quick_push (min_cluster_item (0, 0, 0));
for (unsigned i = 1; i <= l; i++)
{
/* Set minimal # of clusters with i-th item to infinite. */
min.quick_push (min_cluster_item (INT_MAX, INT_MAX, INT_MAX));
for (unsigned j = 0; j < i; j++)
{
if (min[j].m_count + 1 < min[i].m_count
&& can_be_handled (clusters, j, i - 1))
min[i] = min_cluster_item (min[j].m_count + 1, j, INT_MAX);
}
}
/* No result. */
if (min[l].m_count == INT_MAX)
return clusters.copy ();
/* Find and build the clusters. */
for (int end = l;;)
{
int start = min[end].m_start;
if (is_beneficial (clusters, start, end - 1))
output.safe_push (new bit_test_cluster (clusters, start, end - 1));
else
for (int i = end - 1; i >= start; i--)
output.safe_push (clusters[i]);
end = start;
if (start <= 0)
break;
}
output.reverse ();
return output;
}
/* Return true when RANGE of case values with UNIQ labels
can build a bit test. */
@ -1485,33 +1599,57 @@ switch_decision_tree::analyze_switch_statement ()
reset_out_edges_aux ();
vec<cluster *> output;
output.create (1);
/* Find jump table clusters. */
vec<cluster *> output = jump_table_cluster::find_jump_tables (clusters);
/* Find whether the switch statement can be expanded with a method
different from decision tree. */
unsigned end = clusters.length () - 1;
if (jump_table_cluster::can_be_handled (clusters, 0, end)
&& jump_table_cluster::is_beneficial (clusters, 0, end))
output.safe_push (new jump_table_cluster (clusters, 0, end));
else if (bit_test_cluster::can_be_handled (clusters, 0, end)
&& bit_test_cluster::is_beneficial (clusters, 0, end))
output.safe_push (new bit_test_cluster (clusters, 0, end));
else
output = clusters;
/* Find jump table clusters. */
vec<cluster *> output2;
auto_vec<cluster *> tmp;
output2.create (1);
tmp.create (1);
for (unsigned i = 0; i < output.length (); i++)
{
cluster *c = output[i];
if (c->get_type () != SIMPLE_CASE)
{
if (!tmp.is_empty ())
{
vec<cluster *> n = bit_test_cluster::find_bit_tests (tmp);
output2.safe_splice (n);
n.release ();
tmp.truncate (0);
}
output2.safe_push (c);
}
else
tmp.safe_push (c);
}
/* We still can have a temporary vector to test. */
if (!tmp.is_empty ())
{
vec<cluster *> n = bit_test_cluster::find_bit_tests (tmp);
output2.safe_splice (n);
n.release ();
}
if (dump_file)
{
fprintf (dump_file, ";; GIMPLE switch case clusters: ");
for (unsigned i = 0; i < output.length (); i++)
output[i]->dump (dump_file, dump_flags & TDF_DETAILS);
for (unsigned i = 0; i < output2.length (); i++)
output2[i]->dump (dump_file, dump_flags & TDF_DETAILS);
fprintf (dump_file, "\n");
}
bool expanded = try_switch_expansion (output);
output.release ();
for (unsigned i = 0; i < output.length (); i++)
delete output[i];
bool expanded = try_switch_expansion (output2);
for (unsigned i = 0; i < output2.length (); i++)
delete output2[i];
output2.release ();
return expanded;
}

19
gcc/tree-switch-conversion.h
View File

@ -33,7 +33,16 @@ enum cluster_type
#define PRINT_CASE(f,c) print_generic_expr (f, c)
/* Abstract base class for representing a cluster of cases. */
/* Abstract base class for representing a cluster of cases.
Here is the inheritance hierarachy, and the enum_cluster_type
values for the concrete subclasses:
cluster
|-simple_cluster (SIMPLE_CASE)
`-group_cluster
|-jump_table_cluster (JUMP_TABLE)
`-bit_test_cluster (BIT_TEST). */
struct cluster
{
@ -228,6 +237,10 @@ struct jump_table_cluster: public group_cluster
void emit (tree index_expr, tree index_type,
tree default_label_expr, basic_block default_bb);
/* Find jump tables of given CLUSTERS, where all members of the vector
are of type simple_cluster. New clusters are returned. */
static vec<cluster *> find_jump_tables (vec<cluster *> &clusters);
/* Return true when cluster starting at START and ending at END (inclusive)
can build a jump-table. */
static bool can_be_handled (const vec<cluster *> &clusters, unsigned start,
@ -336,6 +349,10 @@ struct bit_test_cluster: public group_cluster
void emit (tree index_expr, tree index_type,
tree default_label_expr, basic_block default_bb);
/* Find bit tests of given CLUSTERS, where all members of the vector
are of type simple_cluster. New clusters are returned. */
static vec<cluster *> find_bit_tests (vec<cluster *> &clusters);
/* Return true when RANGE of case values with UNIQ labels
can build a bit test. */
static bool can_be_handled (unsigned HOST_WIDE_INT range, unsigned uniq);