On Tue, 24 Nov 2020, Jan Hubicka wrote:
> Hi,
> at the end of processing function body we loop over basic blocks and
> free all edges while we do not free the rest. I think this is leftover
> from time eges was not garbage collected and we was not using ggc_free.
> It makes more sense to free all associated structures (which is
> importnat for WPA memory footprint).
>
> Bootstrapped/regtested x86_64-linux, OK?
OK.
> Honza
>
> * cfg.c (free_block): New function.
> (clear_edges): Rename to ....
> (free_cfg): ... this one; also free BBs and vectors.
> (expunge_block): Update comment.
> * cfg.h (clear_edges): Rename to ...
> (free_cfg): ... this one.
> * cgraph.c (release_function_body): Use free_cfg.
> diff --git a/gcc/cfg.c b/gcc/cfg.c
> index de0e71db850..fc78e48d6e1 100644
> --- a/gcc/cfg.c
> +++ b/gcc/cfg.c
> @@ -25,7 +25,7 @@ along with GCC; see the file COPYING3. If not see
>
> Available functionality:
> - Initialization/deallocation
> - init_flow, clear_edges
> + init_flow, free_cfg
> - Low level basic block manipulation
> alloc_block, expunge_block
> - Edge manipulation
> @@ -83,7 +83,7 @@ init_flow (struct function *the_fun)
> the_fun->cfg->bb_flags_allocated = BB_ALL_FLAGS;
> }
>
> -/* Helper function for remove_edge and clear_edges. Frees edge structure
> +/* Helper function for remove_edge and free_cffg. Frees edge structure
> without actually removing it from the pred/succ arrays. */
>
> static void
> @@ -93,29 +93,41 @@ free_edge (function *fn, edge e)
> ggc_free (e);
> }
>
> -/* Free the memory associated with the edge structures. */
> +/* Free basic block BB. */
> +
> +static void
> +free_block (basic_block bb)
> +{
> + vec_free (bb->succs);
> + vec_free (bb->preds);
> + ggc_free (bb);
> +}
> +
> +/* Free the memory associated with the CFG in FN. */
>
> void
> -clear_edges (struct function *fn)
> +free_cfg (struct function *fn)
> {
> - basic_block bb;
> edge e;
> edge_iterator ei;
> + basic_block next;
>
> - FOR_EACH_BB_FN (bb, fn)
> + for (basic_block bb = ENTRY_BLOCK_PTR_FOR_FN (fn); bb; bb = next)
> {
> + next = bb->next_bb;
> FOR_EACH_EDGE (e, ei, bb->succs)
> free_edge (fn, e);
> - vec_safe_truncate (bb->succs, 0);
> - vec_safe_truncate (bb->preds, 0);
> + free_block (bb);
> }
>
> - FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR_FOR_FN (fn)->succs)
> - free_edge (fn, e);
> - vec_safe_truncate (EXIT_BLOCK_PTR_FOR_FN (fn)->preds, 0);
> - vec_safe_truncate (ENTRY_BLOCK_PTR_FOR_FN (fn)->succs, 0);
> -
> gcc_assert (!n_edges_for_fn (fn));
> + /* Sanity check that dominance tree is freed. */
> + gcc_assert (!fn->cfg->x_dom_computed[0] && !fn->cfg->x_dom_computed[1]);
> +
> + vec_free (fn->cfg->x_label_to_block_map);
> + vec_free (basic_block_info_for_fn (fn));
> + ggc_free (fn->cfg);
> + fn->cfg = NULL;
> }
>
> /* Allocate memory for basic_block. */
> @@ -190,8 +202,8 @@ expunge_block (basic_block b)
> /* We should be able to ggc_free here, but we are not.
> The dead SSA_NAMES are left pointing to dead statements that are
> pointing
> to dead basic blocks making garbage collector to die.
> - We should be able to release all dead SSA_NAMES and at the same time we
> should
> - clear out BB pointer of dead statements consistently. */
> + We should be able to release all dead SSA_NAMES and at the same time we
> + should clear out BB pointer of dead statements consistently. */
> }
>
> /* Connect E to E->src. */
> diff --git a/gcc/cfg.h b/gcc/cfg.h
> index 93fde6df2bf..a9c8300f173 100644
> --- a/gcc/cfg.h
> +++ b/gcc/cfg.h
> @@ -82,7 +82,7 @@ struct GTY(()) control_flow_graph {
>
>
> extern void init_flow (function *);
> -extern void clear_edges (function *);
> +extern void free_cfg (function *);
> extern basic_block alloc_block (void);
> extern void link_block (basic_block, basic_block);
> extern void unlink_block (basic_block);
> diff --git a/gcc/cgraph.c b/gcc/cgraph.c
> index 19dfe2be23b..5c48a1bb92b 100644
> --- a/gcc/cgraph.c
> +++ b/gcc/cgraph.c
> @@ -1811,7 +1811,7 @@ release_function_body (tree decl)
> gcc_assert (!dom_info_available_p (fn, CDI_DOMINATORS));
> gcc_assert (!dom_info_available_p (fn, CDI_POST_DOMINATORS));
> delete_tree_cfg_annotations (fn);
> - clear_edges (fn);
> + free_cfg (fn);
> fn->cfg = NULL;
> }
> if (fn->value_histograms)
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imend
