On Tue, Feb 26, 2019 at 3:30 PM Martin Liška <mli...@suse.cz> wrote:
>
> 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?
+ /* Get bitmap descriptor UID casted to an unsigned integer pointer. */
+ unsigned *get_descriptor ()
+ {
+ return (unsigned *)(ptrdiff_t)alloc_descriptor;
+ }
this one is a bit ugly and together with
template <typename Type>
inline hashval_t
pointer_hash <Type>::hash (const value_type &candidate)
{
/* This is a really poor hash function, but it is what the current code uses,
so I am reusing it to avoid an additional axis in testing. */
return (hashval_t) ((intptr_t)candidate >> 3);
will give quite some hash collisions. So I guess you should shift
the descriptor << 3 at least (and then make it at most 29 bits in
size?). Not sure what to do about the descriptor wrapping btw.
Richard.
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> 2019-02-26 Martin Liska <mli...@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(-)
>
>
