On Mon, 23 Nov 2020, Jan Hubicka wrote:
> > On Mon, 23 Nov 2020, Jan Hubicka wrote:
> >
> > > > On Mon, 23 Nov 2020, Jan Hubicka wrote:
> > > >
> > > > > Hi,
> > > > > tree-streamer-in currently calls init_tree_ssa that calls
> > > > > init_ssanames
> > > > > that allocates space in ssa_names array for 50 names. Later it
> > > > > streams
> > > > > in the count and calls init_tree_ssa again, this time with correct
> > > > > count, which is rounded up to 50 and allocated again leaking the first
> > > > > array.
> > > > >
> > > > > This patch fixes it by adding extra argument to init_tree_ssa
> > > > > specifing
> > > > > whether ssa names should be initialized. There are few places where
> > > > > we
> > > > > initialize ssa and only lto streaming is special, so i think extra arg
> > > > > works well here.
> > > > >
> > > > > I am not quite sure about the 50MB default. I think it was made
> > > > > before
> > > > > ggc_free was implemented (so resizing vectors was expensive) and when
> > > > > we
> > > > > had only one function in SSA form at a time. Most of functions in C++
> > > > > will probably need fewer than 50 SSA names until inlining.
> > > > >
> > > > > This saves 21MB of WPA linking libxul.
> > > >
> > > > Why do we input SSA names at WPA?
> > >
> > > To ICF compare function bodies. It tends to load tons of small bodies.
> > > We also may load body when merging BB profile etc.
> > > >
> > > > > Bootstrapping/regtesting x86_64-linux, OK if it suceeds?
> > > >
> > > > I think calling init_ssanames again is bogus. Please simply
> > > > do that in input_ssa_names after we know how many we need
> > > > adding a number of SSA names to reserve argument to init_tree_ssa
> > > > and passing that down instead.
> > >
> > > I tried that originally but it hit ICE in init_ssa_operands. Seems that
> > > reloacating them is last change I need though. Does this look better?
> >
> > Patch below looks completely unrelated but is OK as well if it passes
> > testing ;)
>
> Glad to hear since it is in mainline for a while :)
> Here is correct pathc. Sorry.
LGTM.
Thanks,
Richard.
> * lto-streamer-in.c (input_cfg): Do not init ssa operands.
> (input_function): Do not init tree_ssa and set in_ssa_p.
> (input_ssa_names): Do it here.
> * tree-ssa.c (init_tree_ssa): Add additional SIZE parameter, default
> to 0
> * tree-ssanames.c (init_ssanames): Do not round size up to 50, allocate
> precisely.
> diff --git a/gcc/lto-streamer-in.c b/gcc/lto-streamer-in.c
> index 64037f74ad3..a20d64b0089 100644
> --- a/gcc/lto-streamer-in.c
> +++ b/gcc/lto-streamer-in.c
> @@ -1017,7 +1017,6 @@ input_cfg (class lto_input_block *ib, class data_in
> *data_in,
> int index;
>
> init_empty_tree_cfg_for_function (fn);
> - init_ssa_operands (fn);
>
> profile_status_for_fn (fn) = streamer_read_enum (ib, profile_status_d,
> PROFILE_LAST);
> @@ -1144,7 +1143,9 @@ input_ssa_names (class lto_input_block *ib, class
> data_in *data_in,
> unsigned int i, size;
>
> size = streamer_read_uhwi (ib);
> - init_ssanames (fn, size);
> + init_tree_ssa (fn, size);
> + cfun->gimple_df->in_ssa_p = true;
> + init_ssa_operands (fn);
>
> i = streamer_read_uhwi (ib);
> while (i)
> @@ -1384,9 +1385,6 @@ input_function (tree fn_decl, class data_in *data_in,
>
> push_struct_function (fn_decl);
> fn = DECL_STRUCT_FUNCTION (fn_decl);
> - init_tree_ssa (fn);
> - /* We input IL in SSA form. */
> - cfun->gimple_df->in_ssa_p = true;
>
> gimple_register_cfg_hooks ();
>
> diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
> index b44361f8244..24a5154620d 100644
> --- a/gcc/tree-ssa.c
> +++ b/gcc/tree-ssa.c
> @@ -1218,15 +1218,16 @@ err:
> # pragma GCC diagnostic pop
> #endif
>
> -/* Initialize global DFA and SSA structures. */
> +/* Initialize global DFA and SSA structures.
> + If SIZE is non-zero allocated ssa names array of a given size. */
>
> void
> -init_tree_ssa (struct function *fn)
> +init_tree_ssa (struct function *fn, int size)
> {
> fn->gimple_df = ggc_cleared_alloc<gimple_df> ();
> fn->gimple_df->default_defs = hash_table<ssa_name_hasher>::create_ggc (20);
> pt_solution_reset (&fn->gimple_df->escaped);
> - init_ssanames (fn, 0);
> + init_ssanames (fn, size);
> }
>
> /* Deallocate memory associated with SSA data structures for FNDECL. */
> diff --git a/gcc/tree-ssanames.c b/gcc/tree-ssanames.c
> index 6ac97fe39c4..ec4681f85cb 100644
> --- a/gcc/tree-ssanames.c
> +++ b/gcc/tree-ssanames.c
> @@ -77,10 +77,10 @@ unsigned int ssa_name_nodes_created;
> void
> init_ssanames (struct function *fn, int size)
> {
> - if (size < 50)
> - size = 50;
> -
> - vec_alloc (SSANAMES (fn), size);
> + if (!size)
> + vec_alloc (SSANAMES (fn), 50);
> + else
> + vec_safe_reserve (SSANAMES (fn), size, true);
>
> /* Version 0 is special, so reserve the first slot in the table. Though
> currently unused, we may use version 0 in alias analysis as part of
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imend
