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.
Bootstrapping/regtesting x86_64-linux, OK if it suceeds?
* tree-ssa.c (init_tree_ssa): Add argument INIT_SSANAMES_P.
* tree-ssa.h (init_tree_ssa): Update prototype.
* tree-ssanames.c (init_ssanames): Fix handling of explicit size.
* tree-streamer-in.c (init_function): Pass false to init_tree_ssa.
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index b44361f8244..8b009d91830 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1218,15 +1218,18 @@ err:
# pragma GCC diagnostic pop
#endif
-/* Initialize global DFA and SSA structures. */
+/* Initialize global DFA and SSA structures.
+ If INIT_SSANAMES_P is false, do not initialize SSA names. During LTO
+ streaming we do that later once we know number of names. */
void
-init_tree_ssa (struct function *fn)
+init_tree_ssa (struct function *fn, bool init_ssanames_p)
{
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);
+ if (init_ssanames_p)
+ init_ssanames (fn, 0);
}
/* Deallocate memory associated with SSA data structures for FNDECL. */
diff --git a/gcc/tree-ssa.h b/gcc/tree-ssa.h
index 79f2b13fd6a..9a4ff008300 100644
--- a/gcc/tree-ssa.h
+++ b/gcc/tree-ssa.h
@@ -45,7 +45,7 @@ extern void insert_debug_temps_for_defs (gimple_stmt_iterator
*);
extern void reset_debug_uses (gimple *);
extern void release_defs_bitset (bitmap toremove);
extern void verify_ssa (bool, bool);
-extern void init_tree_ssa (function *);
+extern void init_tree_ssa (function *, bool init_ssanames = true);
extern void delete_tree_ssa (function *);
extern bool tree_ssa_useless_type_conversion (tree);
extern tree tree_ssa_strip_useless_type_conversions (tree);
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
diff --git a/gcc/lto-streamer-in.c b/gcc/lto-streamer-in.c
index 64037f74ad3..3150c489401 100644
--- a/gcc/lto-streamer-in.c
+++ b/gcc/lto-streamer-in.c
@@ -1384,7 +1384,7 @@ 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);
+ init_tree_ssa (fn, false);
/* We input IL in SSA form. */
cfun->gimple_df->in_ssa_p = true;
