Hi,
>
> The patch looks reasonable - the wins are not entirely clear to me
> since you mix in LTO streaming format optimizations. You promised
> to improve collisions on the SCC merging side but those are not
> spectacular (if present at all) in the above data?
Thanks for looking into that. Collision ratios was imporving on Firefox
that has more anonymous types and their derivations, but I was currently
seeing an ICE building it. I will debug that.
I think, quite surprisingly, most stream size benefits come from not
streaming hash codes for integer_csts and indentifier_nodes.
These are common and hash codes are large + hard to compress.
I was thinking about trying making them artifically smaller (32bit only)
once we nail down the unecessary scc chains. I will look into that now
- last time i did stats it was mostly anonymous types and that is why I
started to worry about them first.
>
> The patch itself looks really nice. The only comment I have is
> with respect to the new local_tree_p predicate and its relation
> to tree_is_indexable. We should be able to assert that
> local trees are not indexable and indexable trees never are local.
This is not true. Anonymous namespace types are indexable (since they
are shared across function bodies) but they are local to translation
unit. Similarly non-public decls.
> Does this make the predicates equal? ;) It would be nice if
> they would cross-reference each other (maybe even assert at least
> in one way), maybe put next to each other and share parts?
> We can do this as followup.
If you are OK doing more stuff as folowup, I would be happy. I think it
is good base to fix other issues (track down longer chain in merging;
sanify scc streaming more etc).
I just tried to avoid snowballing, since the patch already mixes few
things together.
Thanks,
Honza
>
> Thanks,
> Richard.
>
> > gcc/ChangeLog:
> >
> > 2020-05-19 Jan Hubicka <hubi...@ucw.cz>
> >
> > * lto-streamer-in.c (lto_input_scc): Add SHARED_SCC parameter.
> > (lto_input_tree_1): Strenghten sanity check.
> > (lto_input_tree): Update call of lto_input_scc.
> > * lto-streamer-out.c: Include ipa-utils.h
> > (create_output_block): Initialize local_trees if merigng is going
> > to happen.
> > (destroy_output_block): Destroy local_trees.
> > (DFS): Add max_local_entry.
> > (local_tree_p): New function.
> > (DFS::DFS): Initialize and maintain it.
> > (DFS::DFS_write_tree): Decide on streaming format.
> > (lto_output_tree): Stream inline singleton SCCs
> > * lto-streamer.h (enum LTO_tags): Add LTO_trees.
> > (struct output_block): Add local_trees.
> > (lto_input_scc): Update prototype.
> >
> > gcc/lto/ChangeLog:
> >
> > 2020-05-19 Jan Hubicka <hubi...@ucw.cz>
> >
> > * lto-common.c (compare_tree_sccs_1): Sanity check that we never
> > read TRANSLATION_UNIT_DECL.
> > (process_dref): Break out from ...
> > (unify_scc): ... here.
> > (process_new_tree): Break out from ...
> > (lto_read_decls): ... here; handle streaming of singleton trees.
> > (print_lto_report_1): Update statistics.
> >
> > diff --git a/gcc/lto-streamer-in.c b/gcc/lto-streamer-in.c
> > index 244f5b8aa5c..6d571c4344a 100644
> > --- a/gcc/lto-streamer-in.c
> > +++ b/gcc/lto-streamer-in.c
> > @@ -1424,16 +1424,17 @@ lto_read_tree (class lto_input_block *ib, class
> > data_in *data_in,
> >
> >
> > /* Populate the reader cache with trees materialized from the SCC
> > - following in the IB, DATA_IN stream. */
> > + following in the IB, DATA_IN stream.
> > + If SHARED_SCC is true we input LTO_tree_scc. */
> >
> > hashval_t
> > lto_input_scc (class lto_input_block *ib, class data_in *data_in,
> > - unsigned *len, unsigned *entry_len)
> > + unsigned *len, unsigned *entry_len, bool shared_scc)
> > {
> > /* A blob of unnamed tree nodes, fill the cache from it and
> > recurse. */
> > unsigned size = streamer_read_uhwi (ib);
> > - hashval_t scc_hash = streamer_read_uhwi (ib);
> > + hashval_t scc_hash = shared_scc ? streamer_read_uhwi (ib) : 0;
> > unsigned scc_entry_len = 1;
> >
> > if (size == 1)
> > @@ -1456,7 +1457,8 @@ lto_input_scc (class lto_input_block *ib, class
> > data_in *data_in,
> > || (tag >= LTO_field_decl_ref && tag <= LTO_global_decl_ref)
> > || tag == LTO_tree_pickle_reference
> > || tag == LTO_integer_cst
> > - || tag == LTO_tree_scc)
> > + || tag == LTO_tree_scc
> > + || tag == LTO_trees)
> > gcc_unreachable ();
> >
> > result = streamer_alloc_tree (ib, data_in, tag);
> > @@ -1522,7 +1524,7 @@ lto_input_tree_1 (class lto_input_block *ib, class
> > data_in *data_in,
> > (a, len, TYPE_PRECISION (type)));
> > streamer_tree_cache_append (data_in->reader_cache, result, hash);
> > }
> > - else if (tag == LTO_tree_scc)
> > + else if (tag == LTO_tree_scc || tag == LTO_trees)
> > gcc_unreachable ();
> > else
> > {
> > @@ -1538,11 +1540,11 @@ lto_input_tree (class lto_input_block *ib, class
> > data_in *data_in)
> > {
> > enum LTO_tags tag;
> >
> > - /* Input and skip SCCs. */
> > - while ((tag = streamer_read_record_start (ib)) == LTO_tree_scc)
> > + /* Input pickled trees needed to stream in the refrence. */
> > + while ((tag = streamer_read_record_start (ib)) == LTO_trees)
> > {
> > unsigned len, entry_len;
> > - lto_input_scc (ib, data_in, &len, &entry_len);
> > + lto_input_scc (ib, data_in, &len, &entry_len, false);
> >
> > /* Register DECLs with the debuginfo machinery. */
> > while (!dref_queue.is_empty ())
> > @@ -1551,7 +1553,15 @@ lto_input_tree (class lto_input_block *ib, class
> > data_in *data_in)
> > debug_hooks->register_external_die (e.decl, e.sym, e.off);
> > }
> > }
> > - return lto_input_tree_1 (ib, data_in, tag, 0);
> > + tree t = lto_input_tree_1 (ib, data_in, tag, 0);
> > +
> > + if (!dref_queue.is_empty ())
> > + {
> > + dref_entry e = dref_queue.pop ();
> > + debug_hooks->register_external_die (e.decl, e.sym, e.off);
> > + gcc_checking_assert (dref_queue.is_empty ());
> > + }
> > + return t;
> > }
> >
> >
> > diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
> > index 3d94324881f..1c5b8f42c9b 100644
> > --- a/gcc/lto-streamer-out.c
> > +++ b/gcc/lto-streamer-out.c
> > @@ -46,6 +46,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "tree-dfa.h"
> > #include "file-prefix-map.h" /* remap_debug_filename() */
> > #include "output.h"
> > +#include "ipa-utils.h"
> >
> >
> > static void lto_write_tree (struct output_block*, tree, bool);
> > @@ -75,6 +76,10 @@ create_output_block (enum lto_section_type section_type)
> >
> > ob->section_type = section_type;
> > ob->decl_state = lto_get_out_decl_state ();
> > + /* Only global decl stream in non-wpa will ever be considered by tree
> > + merging. */
> > + if (!flag_wpa && section_type == LTO_section_decls)
> > + ob->local_trees = new (hash_set <tree>);
> > ob->main_stream = XCNEW (struct lto_output_stream);
> > ob->string_stream = XCNEW (struct lto_output_stream);
> > ob->writer_cache = streamer_tree_cache_create (!flag_wpa, true, false);
> > @@ -100,6 +105,7 @@ destroy_output_block (struct output_block *ob)
> >
> > delete ob->string_hash_table;
> > ob->string_hash_table = NULL;
> > + delete ob->local_trees;
> >
> > free (ob->main_stream);
> > free (ob->string_stream);
> > @@ -532,6 +538,8 @@ private:
> > bool ref_p;
> > bool this_ref_p;
> > };
> > + /* Maximum index of scc stack containing a local tree. */
> > + int max_local_entry;
> >
> > static int scc_entry_compare (const void *, const void *);
> >
> > @@ -550,6 +558,33 @@ private:
> > struct obstack sccstate_obstack;
> > };
> >
> > +/* Return true if type can be merged.
> > + TRANSLATION_UNIT_DECL is handled specially since references to it does
> > + not make other trees local as well. */
> > +
> > +static bool
> > +local_tree_p (tree t)
> > +{
> > + switch (TREE_CODE (t))
> > + {
> > + case LABEL_DECL:
> > + return true;
> > + case NAMESPACE_DECL:
> > + return !DECL_NAME (t);
> > + case VAR_DECL:
> > + case FUNCTION_DECL:
> > + return !TREE_PUBLIC (t) && !DECL_EXTERNAL (t);
> > + case RECORD_TYPE:
> > + case UNION_TYPE:
> > + case ENUMERAL_TYPE:
> > + return TYPE_MAIN_VARIANT (t) == t
> > + && odr_type_p (t) && type_with_linkage_p (t)
> > + && type_in_anonymous_namespace_p (t);
> > + default:
> > + return false;
> > + }
> > +}
> > +
> > /* Emit the physical representation of tree node EXPR to output block OB,
> > using depth-first search on the subgraph. If THIS_REF_P is true, the
> > leaves of EXPR are emitted as references via lto_output_tree_ref.
> > @@ -560,6 +595,8 @@ DFS::DFS (struct output_block *ob, tree expr, bool
> > ref_p, bool this_ref_p,
> > bool single_p)
> > {
> > unsigned int next_dfs_num = 1;
> > +
> > + max_local_entry = -1;
> > gcc_obstack_init (&sccstate_obstack);
> > DFS_write_tree (ob, NULL, expr, ref_p, this_ref_p);
> > while (!worklist_vec.is_empty ())
> > @@ -586,6 +623,8 @@ DFS::DFS (struct output_block *ob, tree expr, bool
> > ref_p, bool this_ref_p,
> > scc_entry e = { expr, 0 };
> > /* Not yet visited. DFS recurse and push it onto the stack. */
> > *slot = cstate = XOBNEW (&sccstate_obstack, struct sccs);
> > + if (ob->local_trees && local_tree_p (expr))
> > + max_local_entry = sccstack.length ();
> > sccstack.safe_push (e);
> > cstate->dfsnum = next_dfs_num++;
> > cstate->low = cstate->dfsnum;
> > @@ -640,7 +679,26 @@ DFS::DFS (struct output_block *ob, tree expr, bool
> > ref_p, bool this_ref_p,
> > any merging there. */
> > hashval_t scc_hash = 0;
> > unsigned scc_entry_len = 0;
> > - if (!flag_wpa)
> > + bool local_to_unit = !ob->local_trees
> > + || max_local_entry >= (int)first;
> > +
> > + /* Remember that trees are local so info gets propagated to other
> > + SCCs. */
> > + if (local_to_unit && ob->local_trees)
> > + {
> > + for (unsigned i = 0; i < size; ++i)
> > + ob->local_trees->add (sccstack[first + i].t);
> > + }
> > +
> > + /* As a special case do not stream TRANSLATION_UNIT_DECL as shared
> > + tree. We can not mark it local because references to it does not
> > + make other trees local (all global decls reffer to it via
> > + CONTEXT). */
> > + if (size == 1
> > + && TREE_CODE (sccstack[first].t) == TRANSLATION_UNIT_DECL)
> > + local_to_unit = true;
> > +
> > + if (!local_to_unit)
> > {
> > scc_hash = hash_scc (ob, first, size, ref_p, this_ref_p);
> >
> > @@ -672,10 +730,44 @@ DFS::DFS (struct output_block *ob, tree expr, bool
> > ref_p, bool this_ref_p,
> > gcc_checking_assert (scc_entry_len == 1);
> > }
> >
> > - /* Write LTO_tree_scc. */
> > - streamer_write_record_start (ob, LTO_tree_scc);
> > - streamer_write_uhwi (ob, size);
> > - streamer_write_uhwi (ob, scc_hash);
> > + worklist_vec.pop ();
> > +
> > + /* If we are not streaming global section tree sharing will not
> > + be done, but we must mark block of trees so streamer can
> > + distinguish it from reference being streamed. */
> > + if (ob->section_type != LTO_section_decls)
> > + {
> > + /* If this is the original tree we stream and it forms SCC
> > + by itself then we do not need to stream SCC at all. */
> > + if (worklist_vec.is_empty () && first == 0 && size == 1)
> > + return;
> > + streamer_write_record_start (ob, LTO_trees);
> > + streamer_write_uhwi (ob, size);
> > + }
> > + /* Write LTO_tree_scc if sharing is going to be performned. */
> > + else if (!local_to_unit
> > + /* These are special since sharing is not done by tree
> > + merging machinery. We can not special case them earlier
> > + because we still need to compute hash for further sharing
> > + of trees referring to them. */
> > + && (size != 1
> > + || (TREE_CODE (sccstack[first].t) != IDENTIFIER_NODE
> > + && (TREE_CODE (sccstack[first].t) != INTEGER_CST
> > + || TREE_OVERFLOW (sccstack[first].t)))))
> > +
> > + {
> > + gcc_checking_assert (ob->section_type == LTO_section_decls);
> > + streamer_write_record_start (ob, LTO_tree_scc);
> > + streamer_write_uhwi (ob, size);
> > + streamer_write_uhwi (ob, scc_hash);
> > + }
> > + /* Non-trivial SCCs must be packed to trees blocks so forward
> > + references work correctly. */
> > + else if (size != 1)
> > + {
> > + streamer_write_record_start (ob, LTO_trees);
> > + streamer_write_uhwi (ob, size);
> > + }
> >
> > /* Write size-1 SCCs without wrapping them inside SCC bundles.
> > All INTEGER_CSTs need to be handled this way as we need
> > @@ -722,10 +814,11 @@ DFS::DFS (struct output_block *ob, tree expr, bool
> > ref_p, bool this_ref_p,
> >
> > /* Finally truncate the vector. */
> > sccstack.truncate (first);
> > + if ((int)first <= max_local_entry)
> > + max_local_entry = first - 1;
> >
> > if (from_state)
> > from_state->low = MIN (from_state->low, cstate->low);
> > - worklist_vec.pop ();
> > continue;
> > }
> >
> > @@ -1569,7 +1662,14 @@ DFS::DFS_write_tree (struct output_block *ob, sccs
> > *from_state,
> >
> > /* Check if we already streamed EXPR. */
> > if (streamer_tree_cache_lookup (ob->writer_cache, expr, NULL))
> > - return;
> > + {
> > + /* Refernece to a local tree makes entry also local. We always
> > process
> > + top of stack entry, so set max to number of entries in stack - 1. */
> > + if (ob->local_trees
> > + && ob->local_trees->contains (expr))
> > + max_local_entry = sccstack.length () - 1;
> > + return;
> > + }
> >
> > worklist w;
> > w.expr = expr;
> > @@ -1641,15 +1741,20 @@ lto_output_tree (struct output_block *ob, tree expr,
> > DFS (ob, expr, ref_p, this_ref_p, false);
> > in_dfs_walk = false;
> >
> > - /* Finally append a reference to the tree we were writing.
> > - ??? If expr ended up as a singleton we could have
> > - inlined it here and avoid outputting a reference. */
> > + /* Finally append a reference to the tree we were writing. */
> > existed_p = streamer_tree_cache_lookup (ob->writer_cache, expr, &ix);
> > - gcc_assert (existed_p);
> > - streamer_write_record_start (ob, LTO_tree_pickle_reference);
> > - streamer_write_uhwi (ob, ix);
> > - streamer_write_enum (ob->main_stream, LTO_tags, LTO_NUM_TAGS,
> > - lto_tree_code_to_tag (TREE_CODE (expr)));
> > +
> > + /* DFS walk above possibly skipped streaming EXPR itself to let us
> > inline
> > + it. */
> > + if (!existed_p)
> > + lto_output_tree_1 (ob, expr, 0, ref_p, this_ref_p);
> > + else
> > + {
> > + streamer_write_record_start (ob, LTO_tree_pickle_reference);
> > + streamer_write_uhwi (ob, ix);
> > + streamer_write_enum (ob->main_stream, LTO_tags, LTO_NUM_TAGS,
> > + lto_tree_code_to_tag (TREE_CODE (expr)));
> > + }
> > if (streamer_dump_file)
> > {
> > print_node_brief (streamer_dump_file, " Finished SCC of ",
> > diff --git a/gcc/lto-streamer.h b/gcc/lto-streamer.h
> > index 76aa6fe34b8..a466fb8b329 100644
> > --- a/gcc/lto-streamer.h
> > +++ b/gcc/lto-streamer.h
> > @@ -178,6 +178,9 @@ enum LTO_tags
> > /* Special for global streamer. A blob of unnamed tree nodes. */
> > LTO_tree_scc,
> >
> > + /* Sequence of trees. */
> > + LTO_trees,
> > +
> > /* References to indexable tree nodes. These objects are stored in
> > tables that are written separately from the function bodies that
> > reference them. This way they can be instantiated even when the
> > @@ -751,6 +754,9 @@ struct output_block
> > /* Cache of nodes written in this section. */
> > struct streamer_tree_cache_d *writer_cache;
> >
> > + /* All trees identified as local to the unit streamed. */
> > + hash_set<tree> *local_trees;
> > +
> > /* All data persistent across whole duration of output block
> > can go here. */
> > struct obstack obstack;
> > @@ -901,7 +907,7 @@ tree lto_input_tree_ref (class lto_input_block *, class
> > data_in *,
> > void lto_tag_check_set (enum LTO_tags, int, ...);
> > void lto_init_eh (void);
> > hashval_t lto_input_scc (class lto_input_block *, class data_in *,
> > - unsigned *, unsigned *);
> > + unsigned *, unsigned *, bool);
> > tree lto_input_tree_1 (class lto_input_block *, class data_in *,
> > enum LTO_tags, hashval_t hash);
> > tree lto_input_tree (class lto_input_block *, class data_in *);
> > diff --git a/gcc/lto/lto-common.c b/gcc/lto/lto-common.c
> > index 682a82d61ba..d04b1c9ca7b 100644
> > --- a/gcc/lto/lto-common.c
> > +++ b/gcc/lto/lto-common.c
> > @@ -56,6 +56,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "builtins.h"
> > #include "lto-common.h"
> > #include "tree-pretty-print.h"
> > +#include "print-tree.h"
> >
> > /* True when no new types are going to be streamd from the global stream.
> > */
> >
> > @@ -1054,6 +1055,7 @@ static unsigned long num_prevailing_types;
> > static unsigned long num_type_scc_trees;
> > static unsigned long total_scc_size;
> > static unsigned long num_sccs_read;
> > +static unsigned long num_unshared_trees_read;
> > static unsigned long total_scc_size_merged;
> > static unsigned long num_sccs_merged;
> > static unsigned long num_scc_compares;
> > @@ -1088,6 +1090,10 @@ compare_tree_sccs_1 (tree t1, tree t2, tree **map)
> > compare_values (TREE_CODE);
> > code = TREE_CODE (t1);
> >
> > + /* If we end up comparing translation unit decls we either forgot to mark
> > + some SCC as local or we compare too much. */
> > + gcc_checking_assert (code != TRANSLATION_UNIT_DECL);
> > +
> > if (!TYPE_P (t1))
> > {
> > compare_values (TREE_SIDE_EFFECTS);
> > @@ -1626,6 +1632,28 @@ cmp_tree (const void *p1_, const void *p2_)
> > return ((uintptr_t)p1[1] < (uintptr_t)p2[1]) ? -1 : 1;
> > }
> >
> > +/* New scc of size 1 containing T was streamed in from DATA_IN and not
> > merged.
> > + Register it to reader cache at index FROM. */
> > +
> > +static void
> > +process_dref (class data_in *data_in, tree t, unsigned from)
> > +{
> > + struct streamer_tree_cache_d *cache = data_in->reader_cache;
> > + /* If we got a debug reference queued, see if the prevailing
> > + tree has a debug reference and if not, register the one
> > + for the tree we are about to throw away. */
> > + if (dref_queue.length () == 1)
> > + {
> > + dref_entry e = dref_queue.pop ();
> > + gcc_assert (e.decl
> > + == streamer_tree_cache_get_tree (cache, from));
> > + const char *sym;
> > + unsigned HOST_WIDE_INT off;
> > + if (!debug_hooks->die_ref_for_decl (t, &sym, &off))
> > + debug_hooks->register_external_die (t, e.sym, e.off);
> > + }
> > +}
> > +
> > /* Try to unify the SCC with nodes FROM to FROM + LEN in CACHE and
> > hash value SCC_HASH with an already recorded SCC. Return true if
> > that was successful, otherwise return false. */
> > @@ -1646,22 +1674,16 @@ unify_scc (class data_in *data_in, unsigned from,
> > {
> > tree t = streamer_tree_cache_get_tree (cache, from + i);
> > scc->entries[i] = t;
> > - /* Do not merge SCCs with local entities inside them. Also do
> > - not merge TRANSLATION_UNIT_DECLs and anonymous namespaces
> > - and types therein types. */
> > - if (TREE_CODE (t) == TRANSLATION_UNIT_DECL
> > - || (VAR_OR_FUNCTION_DECL_P (t)
> > - && !(TREE_PUBLIC (t) || DECL_EXTERNAL (t)))
> > - || TREE_CODE (t) == LABEL_DECL
> > - || (TREE_CODE (t) == NAMESPACE_DECL && !DECL_NAME (t))
> > - || (TYPE_P (t)
> > - && type_with_linkage_p (TYPE_MAIN_VARIANT (t))
> > - && type_in_anonymous_namespace_p (TYPE_MAIN_VARIANT (t))))
> > - {
> > - /* Avoid doing any work for these cases and do not worry to
> > - record the SCCs for further merging. */
> > - return false;
> > - }
> > + /* These types should be streamed as unshared. */
> > + gcc_checking_assert
> > + (!(TREE_CODE (t) == TRANSLATION_UNIT_DECL
> > + || (VAR_OR_FUNCTION_DECL_P (t)
> > + && !(TREE_PUBLIC (t) || DECL_EXTERNAL (t)))
> > + || TREE_CODE (t) == LABEL_DECL
> > + || (TREE_CODE (t) == NAMESPACE_DECL && !DECL_NAME (t))
> > + || (TYPE_P (t)
> > + && type_with_linkage_p (TYPE_MAIN_VARIANT (t))
> > + && type_in_anonymous_namespace_p (TYPE_MAIN_VARIANT (t)))));
> > }
> >
> > /* Look for the list of candidate SCCs to compare against. */
> > @@ -1712,21 +1734,7 @@ unify_scc (class data_in *data_in, unsigned from,
> > to the tree node mapping computed by compare_tree_sccs. */
> > if (len == 1)
> > {
> > - /* If we got a debug reference queued, see if the prevailing
> > - tree has a debug reference and if not, register the one
> > - for the tree we are about to throw away. */
> > - if (dref_queue.length () == 1)
> > - {
> > - dref_entry e = dref_queue.pop ();
> > - gcc_assert (e.decl
> > - == streamer_tree_cache_get_tree (cache, from));
> > - const char *sym;
> > - unsigned HOST_WIDE_INT off;
> > - if (!debug_hooks->die_ref_for_decl (pscc->entries[0], &sym,
> > - &off))
> > - debug_hooks->register_external_die (pscc->entries[0],
> > - e.sym, e.off);
> > - }
> > + process_dref (data_in, pscc->entries[0], from);
> > lto_maybe_register_decl (data_in, pscc->entries[0], from);
> > streamer_tree_cache_replace_tree (cache, pscc->entries[0], from);
> > }
> > @@ -1785,7 +1793,65 @@ unify_scc (class data_in *data_in, unsigned from,
> > return unified_p;
> > }
> >
> > +typedef int_hash<unsigned, 0, UINT_MAX> code_id_hash;
> > +
> > +/* Do registering necessary once new tree fully streamed in (including all
> > + trees it reffers to). */
> > +
> > +static void
> > +process_new_tree (tree t, hash_map <code_id_hash, unsigned> *hm,
> > + unsigned index, unsigned *total, class data_in *data_in)
> > +{
> > + /* Reconstruct the type variant and pointer-to/reference-to
> > + chains. */
> > + if (TYPE_P (t))
> > + {
> > + /* Map the tree types to their frequencies. */
> > + if (flag_lto_dump_type_stats)
> > + {
> > + unsigned key = (unsigned) TREE_CODE (t);
> > + unsigned *countp = hm->get (key);
> > + hm->put (key, countp ? (*countp) + 1 : 1);
> > + (*total)++;
> > + }
> > +
> > + num_prevailing_types++;
> > + lto_fixup_prevailing_type (t);
> >
> > + /* Compute the canonical type of all non-ODR types.
> > + Delay ODR types for the end of merging process - the canonical
> > + type for those can be computed using the (unique) name however
> > + we want to do this only if units in other languages do not
> > + contain structurally equivalent type.
> > +
> > + Because SCC components are streamed in random (hash) order
> > + we may have encountered the type before while registering
> > + type canonical of a derived type in the same SCC. */
> > + if (!TYPE_CANONICAL (t))
> > + {
> > + if (!RECORD_OR_UNION_TYPE_P (t)
> > + || !TYPE_CXX_ODR_P (t))
> > + gimple_register_canonical_type (t);
> > + else if (COMPLETE_TYPE_P (t))
> > + vec_safe_push (types_to_register, t);
> > + }
> > + if (TYPE_MAIN_VARIANT (t) == t && odr_type_p (t))
> > + register_odr_type (t);
> > + }
> > + /* Link shared INTEGER_CSTs into TYPE_CACHED_VALUEs of its
> > + type which is also member of this SCC. */
> > + if (TREE_CODE (t) == INTEGER_CST
> > + && !TREE_OVERFLOW (t))
> > + cache_integer_cst (t);
> > + if (!flag_ltrans)
> > + {
> > + lto_maybe_register_decl (data_in, t, index);
> > + /* Scan the tree for references to global functions or
> > + variables and record those for later fixup. */
> > + if (mentions_vars_p (t))
> > + vec_safe_push (tree_with_vars, t);
> > + }
> > +}
> >
> > /* Read all the symbols from buffer DATA, using descriptors in DECL_DATA.
> > RESOLUTIONS is the set of symbols picked by the linker (read from the
> > @@ -1813,7 +1879,6 @@ lto_read_decls (struct lto_file_decl_data *decl_data,
> > const void *data,
> > /* We do not uniquify the pre-loaded cache entries, those are middle-end
> > internal types that should not be merged. */
> >
> > - typedef int_hash<unsigned, 0, UINT_MAX> code_id_hash;
> > hash_map <code_id_hash, unsigned> hm;
> > unsigned total = 0;
> >
> > @@ -1824,31 +1889,41 @@ lto_read_decls (struct lto_file_decl_data
> > *decl_data, const void *data,
> > unsigned from = data_in->reader_cache->nodes.length ();
> > /* Read and uniquify SCCs as in the input stream. */
> > enum LTO_tags tag = streamer_read_record_start (&ib_main);
> > - if (tag == LTO_tree_scc)
> > + if (tag == LTO_tree_scc || tag == LTO_trees)
> > {
> > unsigned len_;
> > unsigned scc_entry_len;
> > +
> > + /* Because we stream in SCC order we know that all unshared trees
> > + are now fully streamed. Process them. */
> > hashval_t scc_hash = lto_input_scc (&ib_main, data_in, &len_,
> > - &scc_entry_len);
> > + &scc_entry_len,
> > + tag == LTO_tree_scc);
> > unsigned len = data_in->reader_cache->nodes.length () - from;
> > gcc_assert (len == len_);
> >
> > - total_scc_size += len;
> > - num_sccs_read++;
> > + if (tag == LTO_tree_scc)
> > + {
> > + total_scc_size += len;
> > + num_sccs_read++;
> > + }
> > + else
> > + num_unshared_trees_read += len;
> >
> > /* We have the special case of size-1 SCCs that are pre-merged
> > by means of identifier and string sharing for example.
> > ??? Maybe we should avoid streaming those as SCCs. */
> > tree first = streamer_tree_cache_get_tree (data_in->reader_cache,
> > from);
> > - if (len == 1
> > - && (TREE_CODE (first) == IDENTIFIER_NODE
> > - || (TREE_CODE (first) == INTEGER_CST
> > - && !TREE_OVERFLOW (first))))
> > - continue;
> > + /* Identifier and integers are shared specially, they should never
> > + go by the tree merging path. */
> > + gcc_checking_assert ((TREE_CODE (first) != IDENTIFIER_NODE
> > + && (TREE_CODE (first) != INTEGER_CST
> > + || TREE_OVERFLOW (first)))
> > + || len != 1);
> >
> > /* Try to unify the SCC with already existing ones. */
> > - if (!flag_ltrans
> > + if (!flag_ltrans && tag != LTO_trees
> > && unify_scc (data_in, from,
> > len, scc_entry_len, scc_hash))
> > continue;
> > @@ -1862,56 +1937,9 @@ lto_read_decls (struct lto_file_decl_data
> > *decl_data, const void *data,
> > {
> > tree t = streamer_tree_cache_get_tree (data_in->reader_cache,
> > from + i);
> > - /* Reconstruct the type variant and pointer-to/reference-to
> > - chains. */
> > + process_new_tree (t, &hm, from + i, &total, data_in);
> > if (TYPE_P (t))
> > - {
> > - /* Map the tree types to their frequencies. */
> > - if (flag_lto_dump_type_stats)
> > - {
> > - unsigned key = (unsigned) TREE_CODE (t);
> > - unsigned *countp = hm.get (key);
> > - hm.put (key, countp ? (*countp) + 1 : 1);
> > - total++;
> > - }
> > -
> > - seen_type = true;
> > - num_prevailing_types++;
> > - lto_fixup_prevailing_type (t);
> > -
> > - /* Compute the canonical type of all non-ODR types.
> > - Delay ODR types for the end of merging process - the
> > canonical
> > - type for those can be computed using the (unique) name
> > however
> > - we want to do this only if units in other languages do not
> > - contain structurally equivalent type.
> > -
> > - Because SCC components are streamed in random (hash) order
> > - we may have encountered the type before while registering
> > - type canonical of a derived type in the same SCC. */
> > - if (!TYPE_CANONICAL (t))
> > - {
> > - if (!RECORD_OR_UNION_TYPE_P (t)
> > - || !TYPE_CXX_ODR_P (t))
> > - gimple_register_canonical_type (t);
> > - else if (COMPLETE_TYPE_P (t))
> > - vec_safe_push (types_to_register, t);
> > - }
> > - if (TYPE_MAIN_VARIANT (t) == t && odr_type_p (t))
> > - register_odr_type (t);
> > - }
> > - /* Link shared INTEGER_CSTs into TYPE_CACHED_VALUEs of its
> > - type which is also member of this SCC. */
> > - if (TREE_CODE (t) == INTEGER_CST
> > - && !TREE_OVERFLOW (t))
> > - cache_integer_cst (t);
> > - if (!flag_ltrans)
> > - {
> > - lto_maybe_register_decl (data_in, t, from + i);
> > - /* Scan the tree for references to global functions or
> > - variables and record those for later fixup. */
> > - if (mentions_vars_p (t))
> > - vec_safe_push (tree_with_vars, t);
> > - }
> > + seen_type = true;
> > }
> >
> > /* Register DECLs with the debuginfo machinery. */
> > @@ -1926,9 +1954,26 @@ lto_read_decls (struct lto_file_decl_data
> > *decl_data, const void *data,
> > }
> > else
> > {
> > - /* Pickle stray references. */
> > t = lto_input_tree_1 (&ib_main, data_in, tag, 0);
> > - gcc_assert (t && data_in->reader_cache->nodes.length () == from);
> > + /* We streamed in new tree. Add it to cache and process dref. */
> > + if (data_in->reader_cache->nodes.length () == from + 1)
> > + {
> > + num_unshared_trees_read++;
> > + data_in->location_cache.accept_location_cache ();
> > + process_dref (data_in, t, from);
> > + if (TREE_CODE (t) == IDENTIFIER_NODE
> > + || (TREE_CODE (t) == INTEGER_CST
> > + && !TREE_OVERFLOW (t)))
> > + ;
> > + else
> > + {
> > + lto_maybe_register_decl (data_in, t, from);
> > + process_new_tree (t, &hm, from, &total, data_in);
> > + }
> > + }
> > + else
> > + /* FIXME: It seems useless to pickle stray references. */
> > + gcc_assert (data_in->reader_cache->nodes.length () == from);
> > }
> > }
> >
> > @@ -2953,10 +2998,13 @@ print_lto_report_1 (void)
> > const char *pfx = (flag_lto) ? "LTO" : (flag_wpa) ? "WPA" : "LTRANS";
> > fprintf (stderr, "%s statistics\n", pfx);
> >
> > - fprintf (stderr, "[%s] read %lu SCCs of average size %f\n",
> > + fprintf (stderr, "[%s] read %lu unshared trees\n",
> > + pfx, num_unshared_trees_read);
> > + fprintf (stderr, "[%s] read %lu mergeable SCCs of average size %f\n",
> > pfx, num_sccs_read, total_scc_size / (double)num_sccs_read);
> > - fprintf (stderr, "[%s] %lu tree bodies read in total\n", pfx,
> > total_scc_size);
> > - if (flag_wpa && tree_scc_hash)
> > + fprintf (stderr, "[%s] %lu tree bodies read in total\n", pfx,
> > + total_scc_size + num_unshared_trees_read);
> > + if (flag_wpa && tree_scc_hash && num_sccs_read)
> > {
> > fprintf (stderr, "[%s] tree SCC table: size %ld, %ld elements, "
> > "collision ratio: %f\n", pfx,
> >
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
