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invoke.texi (-flto-partition, [...]): Document.

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* doc/invoke.texi (-flto-partition, lto-partitions, lto-minpartition):
	Document.
	* opts.c (decode_options): Handle lto partitions.
	* common.opt (flto-partition=1to1, flto-partition=balanced): New.
	* params.def (PARAM_LTO_PARTITIONS, MIN_PARTITION_SIZE): New.

	* lto.c:  Include params.h.
	(add_cgraph_node_to_partition, add_varpool_node_to_partition): Do
	refcounting in aux field.
	(undo_partition, partition_cgraph_node_p, partition_varpool_node_p):
	New functions.
	(lto_1_to_1_map): Simplify.
	(lto_balanced_map): New function.
	(do_whole_program_analysis): Chose proper partitioning alg.
	* Make-lang.in (lto.o): Add dependency on params.h

From-SVN: r164995
This commit is contained in:
Jan Hubicka 2010-10-05 19:57:09 +02:00 • committed by Jan Hubicka
parent 5806d9ac5d
commit 852e4bd21f
8 changed files with 438 additions and 33 deletions
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10
gcc/ChangeLog
View file

@ -1,4 +1,12 @@
2010-09-29 Jan Hubicka <jh@suse.cz>
2010-10-05 Jan Hubicka <jh@suse.cz>
* doc/invoke.texi (-flto-partition, lto-partitions, lto-minpartition):
Document.
* opts.c (decode_options): Handle lto partitions.
* common.opt (flto-partition=1to1, flto-partition=balanced): New.
* params.def (PARAM_LTO_PARTITIONS, MIN_PARTITION_SIZE): New.
2010-10-05 Jan Hubicka <jh@suse.cz>
* cgraphunit.c (assemble_function): Output thunks and aliases before
the function itself.

8
gcc/common.opt
View file

@ -1049,6 +1049,14 @@ flto
Common Var(flag_lto)
Enable link-time optimization.
flto-partition=1to1
Common Var(flag_lto_partition_1to1)
Partition functions and vars at linktime based on object files they originate from
flto-partition=balanced
Common Var(flag_lto_partition_balanced)
Partition functions and vars at linktime into approximately same sized buckets
; The initial value of -1 comes from Z_DEFAULT_COMPRESSION in zlib.h.
flto-compression-level=
Common Joined RejectNegative UInteger Var(flag_lto_compression_level) Init(-1)

25
gcc/doc/invoke.texi
View file

@ -354,10 +354,10 @@ Objective-C and Objective-C++ Dialects}.
-fno-ira-share-spill-slots -fira-verbose=@var{n} @gol
-fivopts -fkeep-inline-functions -fkeep-static-consts @gol
-floop-block -floop-flatten -floop-interchange -floop-strip-mine @gol
-floop-parallelize-all -flto -flto-compression-level -flto-report @gol
-fltrans -fltrans-output-list -fmerge-all-constants -fmerge-constants @gol
-fmodulo-sched -fmodulo-sched-allow-regmoves -fmove-loop-invariants @gol
-fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
-floop-parallelize-all -flto -flto-compression-level -flto-partition=@var{alg} @gol
-flto-report -fltrans -fltrans-output-list -fmerge-all-constants @gol
-fmerge-constants -fmodulo-sched -fmodulo-sched-allow-regmoves @gol
-fmove-loop-invariants fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
-fno-default-inline @gol
-fno-defer-pop -fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
@ -7596,6 +7596,13 @@ GNU make.
Disabled by default.
@item -flto-partition=@var{alg}
@opindex flto-partition
Specify partitioning algorithm used by @option{-fwhopr} mode. The value is
either @code{1to1} to specify partitioning corresponding to source files
or @code{balanced} to specify partitioning into, if possible, equally sized
chunks. The default value is @code{balanced}.
@item -fwpa
@opindex fwpa
This is an internal option used by GCC when compiling with
@ -8789,6 +8796,16 @@ parameter in order to perform devirtualization.
@option{devirt-type-list-size} is the maximum number of types it
stores per a single formal parameter of a function.
@item lto-partitions
Specify desired nuber of partitions produced during WHOPR copmilation.
Number of partitions should exceed number of CPUs used for compilatoin.
Default value is 32.
@item lto-minpartition
Size of minimal paritition for WHOPR (in estimated instructions).
This prevents expenses of splitting very small programs into too many
partitions.
@end table
@end table

12
gcc/lto/ChangeLog
View file

@ -1,3 +1,15 @@
2010-10-05 Jan Hubicka <jh@suse.cz>
* lto.c: Include params.h.
(add_cgraph_node_to_partition, add_varpool_node_to_partition): Do
refcounting in aux field.
(undo_partition, partition_cgraph_node_p, partition_varpool_node_p):
New functions.
(lto_1_to_1_map): Simplify.
(lto_balanced_map): New function.
(do_whole_program_analysis): Chose proper partitioning alg.
* Make-lang.in (lto.o): Add dependency on params.h
2010-10-04 Andi Kleen <ak@linux.intel.com>
* Make-lang.in (lto1): Add + to build rule.

2
gcc/lto/Make-lang.in
View file

@ -85,7 +85,7 @@ lto/lto.o: lto/lto.c $(CONFIG_H) $(SYSTEM_H) coretypes.h opts.h \
$(CGRAPH_H) $(GGC_H) tree-ssa-operands.h $(TREE_PASS_H) \
langhooks.h $(VEC_H) $(BITMAP_H) pointer-set.h $(IPA_PROP_H) \
$(COMMON_H) debug.h $(TIMEVAR_H) $(GIMPLE_H) $(LTO_H) $(LTO_TREE_H) \
$(LTO_TAGS_H) $(LTO_STREAMER_H) $(SPLAY_TREE_H) gt-lto-lto.h
$(LTO_TAGS_H) $(LTO_STREAMER_H) $(SPLAY_TREE_H) gt-lto-lto.h $(PARAMS_H)
lto/lto-elf.o: lto/lto-elf.c $(CONFIG_H) coretypes.h $(SYSTEM_H) \
toplev.h $(LTO_H) $(TM_H) $(LIBIBERTY_H) $(GGC_H) $(LTO_STREAMER_H)
lto/lto-coff.o: lto/lto-coff.c $(CONFIG_H) coretypes.h $(SYSTEM_H) \

396
gcc/lto/lto.c
View file

@ -44,6 +44,7 @@ along with GCC; see the file COPYING3. If not see
#include "lto-tree.h"
#include "lto-streamer.h"
#include "splay-tree.h"
#include "params.h"
/* This needs to be included after config.h. Otherwise, _GNU_SOURCE will not
be defined in time to set __USE_GNU in the system headers, and strsignal
@ -759,12 +760,8 @@ add_cgraph_node_to_partition (ltrans_partition part, struct cgraph_node *node)
part->insns += node->local.inline_summary.self_size;
if (node->aux)
{
gcc_assert (node->aux != part);
node->in_other_partition = 1;
}
else
node->aux = part;
node->in_other_partition = 1;
node->aux = (void *)((size_t)node->aux + 1);
cgraph_node_set_add (part->cgraph_set, node);
@ -788,12 +785,8 @@ add_varpool_node_to_partition (ltrans_partition part, struct varpool_node *vnode
varpool_node_set_add (part->varpool_set, vnode);
if (vnode->aux)
{
gcc_assert (vnode->aux != part);
vnode->in_other_partition = 1;
}
else
vnode->aux = part;
vnode->in_other_partition = 1;
vnode->aux = (void *)((size_t)vnode->aux + 1);
add_references_to_partition (part, &vnode->ref_list);
@ -802,6 +795,70 @@ add_varpool_node_to_partition (ltrans_partition part, struct varpool_node *vnode
add_varpool_node_to_partition (part, vnode->same_comdat_group);
}
/* Undo all additions until number of cgraph nodes in PARITION is N_CGRAPH_NODES
and number of varpool nodes is N_VARPOOL_NODES. */
static void
undo_partition (ltrans_partition partition, unsigned int n_cgraph_nodes,
unsigned int n_varpool_nodes)
{
while (VEC_length (cgraph_node_ptr, partition->cgraph_set->nodes) >
n_cgraph_nodes)
{
struct cgraph_node *node = VEC_index (cgraph_node_ptr,
partition->cgraph_set->nodes,
n_cgraph_nodes);
partition->insns -= node->local.inline_summary.self_size;
cgraph_node_set_remove (partition->cgraph_set, node);
node->aux = (void *)((size_t)node->aux - 1);
}
while (VEC_length (varpool_node_ptr, partition->varpool_set->nodes) >
n_varpool_nodes)
{
struct varpool_node *node = VEC_index (varpool_node_ptr,
partition->varpool_set->nodes,
n_varpool_nodes);
varpool_node_set_remove (partition->varpool_set, node);
node->aux = (void *)((size_t)node->aux - 1);
}
}
/* Return true if NODE should be partitioned.
This means that partitioning algorithm should put NODE into one of partitions.
This apply to most functions with bodies. Functions that are not partitions
are put into every unit needing them. This is the case of i.e. COMDATs. */
static bool
partition_cgraph_node_p (struct cgraph_node *node)
{
/* We will get proper partition based on function they are inlined to. */
if (node->global.inlined_to)
return false;
/* Nodes without a body do not need partitioning. */
if (!node->analyzed)
return false;
/* Extern inlines and comdat are always only in partitions they are needed. */
if (DECL_EXTERNAL (node->decl)
|| DECL_COMDAT (node->decl))
return false;
return true;
}
/* Return true if VNODE should be partitioned.
This means that partitioning algorithm should put VNODE into one of partitions. */
static bool
partition_varpool_node_p (struct varpool_node *vnode)
{
if (vnode->alias || !vnode->needed)
return false;
/* Constant pool and comdat are always only in partitions they are needed. */
if (DECL_IN_CONSTANT_POOL (vnode->decl)
|| DECL_COMDAT (vnode->decl))
return false;
return true;
}
/* Group cgrah nodes by input files. This is used mainly for testing
right now. */
@ -822,15 +879,7 @@ lto_1_to_1_map (void)
for (node = cgraph_nodes; node; node = node->next)
{
/* We will get proper partition based on function they are inlined to. */
if (node->global.inlined_to)
continue;
/* Nodes without a body do not need partitioning. */
if (!node->analyzed)
continue;
/* Extern inlines and comdat are always only in partitions they are needed. */
if (DECL_EXTERNAL (node->decl)
|| DECL_COMDAT (node->decl))
if (!partition_cgraph_node_p (node))
continue;
file_data = node->local.lto_file_data;
@ -865,11 +914,7 @@ lto_1_to_1_map (void)
for (vnode = varpool_nodes; vnode; vnode = vnode->next)
{
if (vnode->alias || !vnode->needed)
continue;
/* Constant pool and comdat are always only in partitions they are needed. */
if (DECL_IN_CONSTANT_POOL (vnode->decl)
|| DECL_COMDAT (vnode->decl))
if (!partition_varpool_node_p (vnode))
continue;
file_data = vnode->lto_file_data;
slot = pointer_map_contains (pmap, file_data);
@ -903,6 +948,300 @@ lto_1_to_1_map (void)
ltrans_partitions);
}
/* Group cgraph nodes in qually 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 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.
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. */
static void
lto_balanced_map (void)
{
int n_nodes = 0;
struct cgraph_node **postorder =
XCNEWVEC (struct cgraph_node *, cgraph_n_nodes);
struct cgraph_node **order = XNEWVEC (struct cgraph_node *, cgraph_max_uid);
int i, postorder_len;
struct cgraph_node *node;
int total_size = 0;
int partition_size;
ltrans_partition partition;
unsigned int last_visited_cgraph_node = 0, last_visited_varpool_node = 0;
struct varpool_node *vnode;
int cost = 0, internal = 0;
int best_n_nodes = 0, best_n_varpool_nodes = 0, best_i = 0, best_cost =
INT_MAX, best_internal = 0;
int npartitions;
/* Until we have better ordering facility, use toplogical order.
Include only nodes we will partition and compute estimate of program
size. Note that since nodes that are not partitioned might be put into
multiple partitions, this is just an estimate of real size. This is why
we keep partition_size updated after every partition is finalized. */
postorder_len = cgraph_postorder (postorder);
for (i = 0; i < postorder_len; i++)
{
node = postorder[i];
if (partition_cgraph_node_p (node))
{
order[n_nodes++] = node;
total_size += node->local.inline_summary.self_size;
}
}
free (postorder);
/* Compute partition size and create the first partition. */
partition_size = total_size / PARAM_VALUE (PARAM_LTO_PARTITIONS);
if (partition_size < PARAM_VALUE (MIN_PARTITION_SIZE))
partition_size = PARAM_VALUE (MIN_PARTITION_SIZE);
npartitions = 1;
partition = new_partition ("");
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "Total unit size: %i, partition size: %i\n",
total_size, partition_size);
for (i = 0; i < n_nodes; i++)
{
add_cgraph_node_to_partition (partition, order[i]);
/* Once we added a new node to the partition, we also want to add
all referenced variables unless they was already added into some
earlier partition.
add_cgraph_node_to_partition adds possibly multiple nodes and
variables that are needed to satisfy needs of ORDER[i].
We remember last visited cgraph and varpool node from last iteration
of outer loop that allows us to process every new addition.
At the same time we compute size of the boundary into COST. Every
callgraph or IPA reference edge leaving the partition contributes into
COST. Every edge inside partition was earlier computed as one leaving
it and thus we need to subtract it from COST. */
while (last_visited_cgraph_node <
VEC_length (cgraph_node_ptr, partition->cgraph_set->nodes)
|| last_visited_varpool_node < VEC_length (varpool_node_ptr,
partition->varpool_set->
nodes))
{
struct ipa_ref_list *refs;
int j;
struct ipa_ref *ref;
bool cgraph_p = false;
if (last_visited_cgraph_node <
VEC_length (cgraph_node_ptr, partition->cgraph_set->nodes))
{
struct cgraph_edge *edge;
cgraph_p = true;
node = VEC_index (cgraph_node_ptr, partition->cgraph_set->nodes,
last_visited_cgraph_node);
refs = &node->ref_list;
total_size -= node->local.inline_summary.self_size;
last_visited_cgraph_node++;
gcc_assert (node->analyzed);
/* Compute boundary cost of callgrpah edges. */
for (edge = node->callees; edge; edge = edge->next_callee)
if (edge->callee->analyzed)
{
int edge_cost = edge->frequency;
cgraph_node_set_iterator csi;
if (!edge_cost)
edge_cost = 1;
gcc_assert (edge_cost > 0);
csi = cgraph_node_set_find (partition->cgraph_set, edge->callee);
if (!csi_end_p (csi)
&& csi.index < last_visited_cgraph_node - 1)
cost -= edge_cost, internal+= edge_cost;
else
cost += edge_cost;
}
for (edge = node->callers; edge; edge = edge->next_caller)
{
int edge_cost = edge->frequency;
cgraph_node_set_iterator csi;
gcc_assert (edge->caller->analyzed);
if (!edge_cost)
edge_cost = 1;
gcc_assert (edge_cost > 0);
csi = cgraph_node_set_find (partition->cgraph_set, edge->caller);
if (!csi_end_p (csi)
&& csi.index < last_visited_cgraph_node)
cost -= edge_cost;
else
cost += edge_cost;
}
}
else
{
refs =
&VEC_index (varpool_node_ptr, partition->varpool_set->nodes,
last_visited_varpool_node)->ref_list;
last_visited_varpool_node++;
}
/* Compute boundary cost of IPA REF edges and at the same time look into
variables referenced from current partition and try to add them. */
for (j = 0; ipa_ref_list_reference_iterate (refs, j, ref); j++)
if (ref->refered_type == IPA_REF_VARPOOL)
{
varpool_node_set_iterator vsi;
vnode = ipa_ref_varpool_node (ref);
if (!vnode->finalized)
continue;
if (!vnode->aux && partition_varpool_node_p (vnode))
add_varpool_node_to_partition (partition, vnode);
vsi = varpool_node_set_find (partition->varpool_set, vnode);
if (!vsi_end_p (vsi)
&& vsi.index < last_visited_varpool_node - !cgraph_p)
cost--, internal++;
else
cost++;
}
else
{
cgraph_node_set_iterator csi;
node = ipa_ref_node (ref);
if (!node->analyzed)
continue;
csi = cgraph_node_set_find (partition->cgraph_set, node);
if (!csi_end_p (csi)
&& csi.index < last_visited_cgraph_node - cgraph_p)
cost--, internal++;
else
cost++;
}
for (j = 0; ipa_ref_list_refering_iterate (refs, j, ref); j++)
if (ref->refering_type == IPA_REF_VARPOOL)
{
varpool_node_set_iterator vsi;
vnode = ipa_ref_refering_varpool_node (ref);
gcc_assert (vnode->finalized);
if (!vnode->aux && partition_varpool_node_p (vnode))
add_varpool_node_to_partition (partition, vnode);
vsi = varpool_node_set_find (partition->varpool_set, vnode);
if (!vsi_end_p (vsi)
&& vsi.index < last_visited_varpool_node)
cost--;
else
cost++;
}
else
{
cgraph_node_set_iterator csi;
node = ipa_ref_refering_node (ref);
gcc_assert (node->analyzed);
csi = cgraph_node_set_find (partition->cgraph_set, node);
if (!csi_end_p (csi)
&& csi.index < last_visited_cgraph_node)
cost--;
else
cost++;
}
}
/* If the partition is large enough, start looking for smallest boundary cost. */
if (partition->insns < partition_size * 3 / 4
|| best_cost == INT_MAX
|| ((!cost
|| (best_internal * (HOST_WIDE_INT) cost
> (internal * (HOST_WIDE_INT)best_cost)))
&& partition->insns < partition_size * 5 / 4))
{
best_cost = cost;
best_internal = internal;
best_i = i;
best_n_nodes = VEC_length (cgraph_node_ptr,
partition->cgraph_set->nodes);
best_n_varpool_nodes = VEC_length (varpool_node_ptr,
partition->varpool_set->nodes);
}
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "Step %i: added %s, size %i, cost %i/%i best %i/%i, step %i\n", i,
cgraph_node_name (order[i]), partition->insns, cost, internal,
best_cost, best_internal, best_i);
/* Partition is too large, unwind into step when best cost was reached and
start new partition. */
if (partition->insns > 2 * partition_size)
{
if (best_i != i)
{
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "Unwinding %i insertions to step %i\n",
i - best_i, best_i);
undo_partition (partition, best_n_nodes, best_n_varpool_nodes);
}
i = best_i;
partition = new_partition ("");
last_visited_cgraph_node = 0;
last_visited_varpool_node = 0;
cost = 0;
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "New partition\n");
best_n_nodes = 0;
best_n_varpool_nodes = 0;
best_cost = INT_MAX;
/* Since the size of partitions is just approximate, update the size after
we finished current one. */
if (npartitions < PARAM_VALUE (PARAM_LTO_PARTITIONS))
partition_size = total_size
/ (PARAM_VALUE (PARAM_LTO_PARTITIONS) - npartitions);
else
partition_size = INT_MAX;
if (partition_size < PARAM_VALUE (MIN_PARTITION_SIZE))
partition_size = PARAM_VALUE (MIN_PARTITION_SIZE);
npartitions ++;
}
}
/* Varables that are not reachable from the code go into last partition. */
for (vnode = varpool_nodes; vnode; vnode = vnode->next)
if (partition_varpool_node_p (vnode) && !vnode->aux)
add_varpool_node_to_partition (partition, vnode);
free (order);
}
/* Promote variable VNODE to be static. */
static bool
@ -1990,7 +2329,10 @@ do_whole_program_analysis (void)
/* We are about to launch the final LTRANS phase, stop the WPA timer. */
timevar_pop (TV_WHOPR_WPA);
lto_1_to_1_map ();
if (flag_lto_partition_1to1)
lto_1_to_1_map ();
else
lto_balanced_map ();
if (!quiet_flag)
{

7
gcc/opts.c
View file

@ -1081,6 +1081,13 @@ decode_options (unsigned int argc, const char **argv,
error ("LTO support has not been enabled in this configuration");
#endif
}
if (flag_lto_partition_balanced || flag_lto_partition_1to1)
{
if (flag_lto_partition_balanced && flag_lto_partition_1to1)
error ("Only one -flto-partitoin value can be specified");
if (!flag_whopr)
error ("-flto-partitoin has effect only with -fwhopr");
}
/* Reconcile -flto and -fwhopr. Set additional flags as appropriate and
check option consistency. */

11
gcc/params.def
View file

@ -838,6 +838,17 @@ DEFPARAM (PARAM_DEVIRT_TYPE_LIST_SIZE,
"devirtualization",
8, 0, 0)
/* WHOPR partitioning configuration. */
DEFPARAM (PARAM_LTO_PARTITIONS,
"lto-partitions",
"Number of paritions program should be split to",
32, 0, 0)
DEFPARAM (MIN_PARTITION_SIZE,
"lto-min-partition",
"Size of minimal paritition for WHOPR (in estimated instructions)",
1000, 0, 0)
/*
Local variables:
mode:c