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Commit b9843260 by Eric Botcazou
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lto.c (lto_balanced_map): Fix typos in head comment. 

	* lto.c (lto_balanced_map): Fix typos in head comment.
	(lto_promote_cross_file_statics): Fix long lines and remove redundant
	test.

From-SVN: r172584
parent e7f23018
Showing with 70 additions and 56 deletions
gcc/lto/ChangeLog
2011-04-16 Eric Botcazou <ebotcazou@adacore.com>
* lto.c (lto_balanced_map): Fix typos in head comment.
(lto_promote_cross_file_statics): Fix long lines and remove redundant
test.
2011-04-16 Jan Hubicka <jh@suse.cz>
* lto.c (lto_balanced_map): Update.
......@@ -5,7 +11,8 @@
2011-04-14 Jan Hubicka <jh@suse.cz>
* lto.c: Include ipa-inline.h
(add_cgraph_node_to_partition, undo_partition): Use inline_summary accessor.
(add_cgraph_node_to_partition, undo_partition): Use inline_summary
accessor.
(ipa_node_duplication_hook): Fix declaration.
* Make-lang.in (lto.o): Update dependencies.
......@@ -77,8 +84,8 @@
PR lto/45721
PR lto/45375
* lto.c (partition_cgraph_node_p, partition_varpool_node_p): Weakrefs are
not partitioned.
* lto.c (partition_cgraph_node_p, partition_varpool_node_p): Weakrefs
are not partitioned.
2010-12-22 Nathan Froyd <froydnj@codesourcery.com>
......@@ -376,11 +383,12 @@
* lto.c (add_cgraph_node_to_partition): Forward declare; walk also
nodes from same comdat group as well as all comdat functions referenced
here.
(add_varpool_node_to_partition, add_references_to_partition): New function.
(lto_1_1_map): Skip COMDAT fnctions/variables; use add_varpool_node_to_partition;
clear aux flags when done.
(lto_promote_cross_file_statics): Do not promote stuff that gets duplicated to
each ltrans.
(add_varpool_node_to_partition, add_references_to_partition): New
function.
(lto_1_1_map): Skip COMDAT fnctions/variables; use
add_varpool_node_to_partition; clear aux flags when done.
(lto_promote_cross_file_statics): Do not promote stuff that gets
duplicated to each ltrans.
2010-07-04 Jan Hubicka <jh@suse.cz>
......@@ -588,8 +596,8 @@
2010-04-30 Jan Hubicka <jh@suse.cz>
* lto.c (get_filename_for_set): Look for cgraph node and if none found, use
default name.
* lto.c (get_filename_for_set): Look for cgraph node and if none found,
use default name.
(lto_wpa_write_files): Write any non-empty partition.
2010-04-30 Jan Hubicka <jh@suse.cz>
......
gcc/lto/lto.c
/* Top-level LTO routines.
Copyright 2009, 2010 Free Software Foundation, Inc.
Copyright 2009, 2010, 2011 Free Software Foundation, Inc.
Contributed by CodeSourcery, Inc.
This file is part of GCC.
......@@ -962,40 +962,43 @@ lto_1_to_1_map (void)
}
/* Group cgraph nodes in qually sized partitions.
/* Group cgraph nodes into equally-sized partitions.
The algorithm deciding paritions are simple: nodes are taken in predefined
order. The order correspond to order we wish to have functions in final
output. In future this will be given by function reordering pass, but at
the moment we use topological order that serve a good approximation.
The partitioning algorithm is simple: nodes are taken in predefined order.
The order corresponds to the order we want functions to have in the final
output. In the future this will be given by function reordering pass, but
at the moment we use the topological order, which is a good approximation.
The goal is to partition this linear order into intervals (partitions) such
that all partitions have approximately the same size and that the number of
callgraph or IPA reference edgess crossing boundaries is minimal.
The goal is to partition this linear order into intervals (partitions) so
that all the partitions have approximately the same size and the number of
callgraph or IPA reference edges crossing boundaries is minimal.
This is a lot faster (O(n) in size of callgraph) than algorithms doing
priority based graph clustering that are generally O(n^2) and since WHOPR
is designed to make things go well across partitions, it leads to good results.
We compute the expected size of partition as
max (total_size / lto_partitions, min_partition_size).
We use dynamic expected size of partition, so small programs
are partitioning into enough partitions to allow use of multiple CPUs while
large programs are not partitioned too much. Creating too many partition
increase streaming overhead significandly.
In the future we would like to bound maximal size of partition to avoid
ltrans stage consuming too much memory. At the moment however WPA stage is
most memory intensive phase at large benchmark since too many types and
declarations are read into memory.
The function implement simple greedy algorithm. Nodes are begin added into
current partition until 3/4th of expected partition size is reached.
After this threshold we keep track of boundary size (number of edges going to
other partitions) and continue adding functions until the current partition
grows into a double of expected partition size. Then the process is undone
till the point when minimal ration of boundary size and in partition calls
was reached. */
priority-based graph clustering that are generally O(n^2) and, since
WHOPR is designed to make things go well across partitions, it leads
to good results.
We compute the expected size of a partition as:
max (total_size / lto_partitions, min_partition_size)
We use dynamic expected size of partition so small programs are partitioned
into enough partitions to allow use of multiple CPUs, while large programs
are not partitioned too much. Creating too many partitions significantly
increases the streaming overhead.
In the future, we would like to bound the maximal size of partitions so as
to prevent the LTRANS stage from consuming too much memory. At the moment,
however, the WPA stage is the most memory intensive for large benchmarks,
since too many types and declarations are read into memory.
The function implements a simple greedy algorithm. Nodes are being added
to the current partition until after 3/4 of the expected partition size is
reached. Past this threshold, we keep track of boundary size (number of
edges going to other partitions) and continue adding functions until after
the current partition has grown to twice the expected partition size. Then
the process is undone to the point where the minimal ratio of boundary size
and in-partition calls was reached. */
static void
lto_balanced_map (void)
......@@ -1330,7 +1333,8 @@ lto_promote_cross_file_statics (void)
n_sets = VEC_length (ltrans_partition, ltrans_partitions);
for (i = 0; i < n_sets; i++)
{
ltrans_partition part = VEC_index (ltrans_partition, ltrans_partitions, i);
ltrans_partition part
= VEC_index (ltrans_partition, ltrans_partitions, i);
set = part->cgraph_set;
vset = part->varpool_set;
......@@ -1361,16 +1365,15 @@ lto_promote_cross_file_statics (void)
promote_var (vnode);
}
/* We export initializers of read-only var into each partition
referencing it. Folding might take declarations from the
initializers and use it; so everything referenced from the
initializers needs can be accessed from this partition after
folding.
/* We export the initializer of a read-only var into each partition
referencing the var. Folding might take declarations from the
initializer and use them, so everything referenced from the
initializer can be accessed from this partition after folding.
This means that we need to promote all variables and functions
referenced from all initializers from readonly vars referenced
from this partition that are not in this partition.
This needs to be done recursively. */
referenced from all initializers of read-only vars referenced
from this partition that are not in this partition. This needs
to be done recursively. */
for (vnode = varpool_nodes; vnode; vnode = vnode->next)
if (const_value_known_p (vnode->decl)
&& DECL_INITIAL (vnode->decl)
......@@ -1378,13 +1381,16 @@ lto_promote_cross_file_statics (void)
&& referenced_from_this_partition_p (&vnode->ref_list, set, vset)
&& !pointer_set_insert (inserted, vnode))
VEC_safe_push (varpool_node_ptr, heap, promoted_initializers, vnode);
while (!VEC_empty (varpool_node_ptr, promoted_initializers))
{
int i;
struct ipa_ref *ref;
vnode = VEC_pop (varpool_node_ptr, promoted_initializers);
for (i = 0; ipa_ref_list_reference_iterate (&vnode->ref_list, i, ref); i++)
for (i = 0;
ipa_ref_list_reference_iterate (&vnode->ref_list, i, ref);
i++)
{
if (ref->refered_type == IPA_REF_CGRAPH)
{
......@@ -1399,17 +1405,17 @@ lto_promote_cross_file_statics (void)
struct varpool_node *v = ipa_ref_varpool_node (ref);
if (varpool_node_in_set_p (v, vset))
continue;
/* Constant pool references use internal labels and thus can not
be made global. It is sensible to keep those ltrans local to
allow better optimization. */
/* Constant pool references use internal labels and thus
cannot be made global. It is sensible to keep those
ltrans local to allow better optimization. */
if (DECL_IN_CONSTANT_POOL (v->decl))
{
if (!pointer_set_insert (inserted, vnode))
VEC_safe_push (varpool_node_ptr, heap,
promoted_initializers, v);
}
else if (!DECL_IN_CONSTANT_POOL (v->decl)
&& !v->externally_visible && v->analyzed)
else if (!v->externally_visible && v->analyzed)
{
if (promote_var (v)
&& DECL_INITIAL (v->decl)
......
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