Honza figured that variably_modified_type_p uses TREE_VISITED
to not run into an Ada abdomination. That causes havoc during
WPA streaming which happens in multiple forked processes and
thus causes a lot of COW faulting and resident memory usage.
It also stands in the way of using threads here.
LTO bootstrapped and tested on x86_64-unknown-linux-gnu.
Honza - does this look OK?
Thanks,
Richard.
2019-10-15 Richard Biener <rguent...@suse.de>
* lto-streamer-out.c (lto_variably_modified_type_p): New.
(tree_is_indexable): Use it.
* tree-streamer-out.c (pack_ts_type_common_value_fields):
Stream variably_modified_type_p as TYPE_LANG_FLAG_0.
* tree-streamer-in.c (unpack_ts_type_common_value_fields): Likewise.
Index: gcc/lto-streamer-out.c
===================================================================
--- gcc/lto-streamer-out.c (revision 276985)
+++ gcc/lto-streamer-out.c (working copy)
@@ -120,6 +120,17 @@ output_type_ref (struct output_block *ob
lto_output_type_ref_index (ob->decl_state, ob->main_stream, node);
}
+/* Wrapper around variably_modified_type_p avoiding type modification
+ during WPA streaming. */
+
+static bool
+lto_variably_modified_type_p (tree type)
+{
+ return (in_lto_p
+ ? TYPE_LANG_FLAG_0 (TYPE_MAIN_VARIANT (type))
+ : variably_modified_type_p (type, NULL_TREE));
+}
+
/* Return true if tree node T is written to various tables. For these
nodes, we sometimes want to write their phyiscal representation
@@ -134,7 +145,7 @@ tree_is_indexable (tree t)
definition. */
if ((TREE_CODE (t) == PARM_DECL || TREE_CODE (t) == RESULT_DECL)
&& DECL_CONTEXT (t))
- return variably_modified_type_p (TREE_TYPE (DECL_CONTEXT (t)), NULL_TREE);
+ return lto_variably_modified_type_p (TREE_TYPE (DECL_CONTEXT (t)));
/* IMPORTED_DECL is put into BLOCK and thus it never can be shared.
We should no longer need to stream it. */
else if (TREE_CODE (t) == IMPORTED_DECL)
@@ -154,10 +165,10 @@ tree_is_indexable (tree t)
them we have to localize their members as well.
??? In theory that includes non-FIELD_DECLs as well. */
else if (TYPE_P (t)
- && variably_modified_type_p (t, NULL_TREE))
+ && lto_variably_modified_type_p (t))
return false;
else if (TREE_CODE (t) == FIELD_DECL
- && variably_modified_type_p (DECL_CONTEXT (t), NULL_TREE))
+ && lto_variably_modified_type_p (DECL_CONTEXT (t)))
return false;
else
return (TYPE_P (t) || DECL_P (t) || TREE_CODE (t) == SSA_NAME);
Index: gcc/tree-streamer-in.c
===================================================================
--- gcc/tree-streamer-in.c (revision 276985)
+++ gcc/tree-streamer-in.c (working copy)
@@ -378,6 +378,7 @@ unpack_ts_type_common_value_fields (stru
TYPE_RESTRICT (expr) = (unsigned) bp_unpack_value (bp, 1);
TYPE_USER_ALIGN (expr) = (unsigned) bp_unpack_value (bp, 1);
TYPE_READONLY (expr) = (unsigned) bp_unpack_value (bp, 1);
+ TYPE_LANG_FLAG_0 (expr) = (unsigned) bp_unpack_value (bp, 1);
if (RECORD_OR_UNION_TYPE_P (expr))
{
TYPE_TRANSPARENT_AGGR (expr) = (unsigned) bp_unpack_value (bp, 1);
Index: gcc/tree-streamer-out.c
===================================================================
--- gcc/tree-streamer-out.c (revision 276985)
+++ gcc/tree-streamer-out.c (working copy)
@@ -326,6 +326,12 @@ pack_ts_type_common_value_fields (struct
bp_pack_value (bp, TYPE_RESTRICT (expr), 1);
bp_pack_value (bp, TYPE_USER_ALIGN (expr), 1);
bp_pack_value (bp, TYPE_READONLY (expr), 1);
+ unsigned vla_p;
+ if (in_lto_p)
+ vla_p = TYPE_LANG_FLAG_0 (TYPE_MAIN_VARIANT (expr));
+ else
+ vla_p = variably_modified_type_p (expr, NULL_TREE);
+ bp_pack_value (bp, vla_p, 1);
/* We used to stream TYPE_ALIAS_SET == 0 information to let frontends mark
types that are opaque for TBAA. This however did not work as intended,
because TYPE_ALIAS_SET == 0 was regularly lost in type merging. */
