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 ;)
Richard.
> * tree-cfg.c (remove_bb): Release SSA defs.
> * tree-ssa.c (verify_flow_sensitive_alias_info): Do not walk dead nodes.
> * tree-tailcall.c (eliminate_tail_call): Release SSA name.
> Index: tree-cfg.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-cfg.c,v
> retrieving revision 2.47
> diff -c -3 -p -r2.47 tree-cfg.c
> *** tree-cfg.c 6 Sep 2004 10:07:56 -0000 2.47
> --- tree-cfg.c 7 Sep 2004 13:26:46 -0000
> *************** remove_bb (basic_block bb)
> *** 1818,1823 ****
> --- 1818,1824 ----
> for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
> {
> tree stmt = bsi_stmt (i);
> + release_defs (stmt);
>
> set_bb_for_stmt (stmt, NULL);
>
> Index: tree-tailcall.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-tailcall.c,v
> retrieving revision 2.23
> diff -c -3 -p -r2.23 tree-tailcall.c
> *** tree-tailcall.c 6 Sep 2004 10:08:13 -0000 2.23
> --- tree-tailcall.c 7 Sep 2004 13:26:47 -0000
> *************** eliminate_tail_call (struct tailcall *t)
> *** 681,692 ****
> bsi_next (&bsi);
> while (!bsi_end_p (bsi))
> {
> /* Do not remove the return statement, so that
> redirect_edge_and_branch
> sees how the block ends. */
> ! if (TREE_CODE (bsi_stmt (bsi)) == RETURN_EXPR)
> break;
>
> bsi_remove (&bsi);
> }
>
> /* Replace the call by a jump to the start of function. */
> --- 681,694 ----
> bsi_next (&bsi);
> while (!bsi_end_p (bsi))
> {
> + tree t = bsi_stmt (bsi);
> /* Do not remove the return statement, so that
> redirect_edge_and_branch
> sees how the block ends. */
> ! if (TREE_CODE (t) == RETURN_EXPR)
> break;
>
> bsi_remove (&bsi);
> + release_defs (t);
> }
>
> /* Replace the call by a jump to the start of function. */
> *************** eliminate_tail_call (struct tailcall *t)
> *** 772,777 ****
> --- 774,780 ----
> }
>
> bsi_remove (&t->call_bsi);
> + release_defs (call);
> }
>
> /* Optimizes the tailcall described by T. If OPT_TAILCALLS is true, also
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imend
