Hi.

I've rewritten bitmap memory statistics which abused unsigned
type via register_overhead (map, -((int)sizeof (bitmap_head))).
I come up with a concept that each bitmap has assigned a unique ID
which is used for stats tracking. It's caused by fact that e.g. DF is
heavily reallocating bitmaps that then have a different address.

Survives bootstrap with --enable-gather-detailed-mem-stats.

Ready for next stage1?
Thanks,
Martin

gcc/ChangeLog:

2019-02-26  Martin Liska  <mliska@suse.cz>

	* bitmap.c (bitmap_register): Come up with
	alloc_descriptor_max_uid and assign it for
	a new bitmap.
	(register_overhead): Use get_descriptor as
	a descriptor.
	(release_overhead): New.
	(bitmap_elem_to_freelist): Call it.
	(bitmap_elt_clear_from): Likewise.
	(bitmap_obstack_free): Likewise.
	(bitmap_move): Sensitively release memory.
	* bitmap.h (struct GTY): Add alloc_descriptor.
	(bitmap_initialize): Initialize alloc_descriptor to zero.
	* tree-ssa-pre.c (do_hoist_insertion): Use bitmap_move.
---
 gcc/bitmap.c       | 39 ++++++++++++++++++++++++++++-----------
 gcc/bitmap.h       | 17 ++++++++++++++---
 gcc/tree-ssa-pre.c |  2 +-
 3 files changed, 43 insertions(+), 15 deletions(-)