> This is second part which has not a significant speed up but
> it's mentioned in the Value Numbering algorithm as a useful heuristics.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> 2019-06-03 Martin Liska <mli...@suse.cz>
>
> * ipa-icf.c (sem_item_optimizer::add_item_to_class): Count
> number of references.
> (sem_item_optimizer::do_congruence_step):
> (sem_item_optimizer::worklist_push): Dump how references
> a class has.
> (sem_item_optimizer::worklist_pop): Use heap.
> (sem_item_optimizer::process_cong_reduction): Likewise.
> * ipa-icf.h: Use fibonacci_heap insteam of std::list.
I am not quite sure if the patch is not an overkill - fibonacci
heap has quite noticeable constant factors.
But I suppose we will see it in profiles easilly then, so patch
is OK and lets see if this helps in practice.
Honza
> ---
> gcc/ipa-icf.c | 12 +++++++-----
> gcc/ipa-icf.h | 8 ++++++--
> 2 files changed, 13 insertions(+), 7 deletions(-)
>
>
> diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
> index a4705eee936..ac563623ea2 100644
> --- a/gcc/ipa-icf.c
> +++ b/gcc/ipa-icf.c
> @@ -80,6 +80,7 @@ along with GCC; see the file COPYING3. If not see
> #include "print-tree.h"
> #include "ipa-utils.h"
> #include "ipa-icf-gimple.h"
> +#include "fibonacci_heap.h"
> #include "ipa-icf.h"
> #include "stor-layout.h"
> #include "dbgcnt.h"
> @@ -2626,6 +2627,7 @@ sem_item_optimizer::add_item_to_class (congruence_class
> *cls, sem_item *item)
> {
> item->index_in_class = cls->members.length ();
> cls->members.safe_push (item);
> + cls->referenced_by_count += item->referenced_by_count;
> item->cls = cls;
> }
>
> @@ -3188,7 +3190,8 @@ sem_item_optimizer::do_congruence_step
> (congruence_class *cls)
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> fprintf (dump_file, " processing congruence step for class: %u "
> - "(%u items), index: %u\n", cls->id, cls->members.length (), i);
> + "(%u items, %u references), index: %u\n", cls->id,
> + cls->referenced_by_count, cls->members.length (), i);
> do_congruence_step_for_index (cls, i);
>
> if (splitter_class_removed)
> @@ -3208,7 +3211,7 @@ sem_item_optimizer::worklist_push (congruence_class
> *cls)
> return;
>
> cls->in_worklist = true;
> - worklist.push_back (cls);
> + worklist.insert (cls->referenced_by_count, cls);
> }
>
> /* Pops a class from worklist. */
> @@ -3220,8 +3223,7 @@ sem_item_optimizer::worklist_pop (void)
>
> while (!worklist.empty ())
> {
> - cls = worklist.front ();
> - worklist.pop_front ();
> + cls = worklist.extract_min ();
> if (cls->in_worklist)
> {
> cls->in_worklist = false;
> @@ -3253,7 +3255,7 @@ sem_item_optimizer::process_cong_reduction (void)
>
> if (dump_file)
> fprintf (dump_file, "Worklist has been filled with: %lu\n",
> - (unsigned long) worklist.size ());
> + (unsigned long) worklist.nodes ());
>
> if (dump_file && (dump_flags & TDF_DETAILS))
> fprintf (dump_file, "Congruence class reduction\n");
> diff --git a/gcc/ipa-icf.h b/gcc/ipa-icf.h
> index ede4c94dbd3..6b81eb38b2a 100644
> --- a/gcc/ipa-icf.h
> +++ b/gcc/ipa-icf.h
> @@ -29,7 +29,8 @@ class congruence_class
> {
> public:
> /* Congruence class constructor for a new class with _ID. */
> - congruence_class (unsigned int _id): in_worklist (false), id(_id)
> + congruence_class (unsigned int _id): in_worklist (false), id (_id),
> + referenced_by_count (0)
> {
> }
>
> @@ -54,6 +55,9 @@ public:
>
> /* Global unique class identifier. */
> unsigned int id;
> +
> + /* Total number of references to items of this class. */
> + unsigned referenced_by_count;
> };
>
> /* Semantic item type enum. */
> @@ -530,7 +534,7 @@ public:
>
> /* Worklist of congruence classes that can potentially
> refine classes of congruence. */
> - std::list<congruence_class *> worklist;
> + fibonacci_heap<unsigned, congruence_class> worklist;
>
> /* Remove semantic ITEM and release memory. */
> void remove_item (sem_item *item);
>
