[intercu] Twiddle memory allocation, remove global obstack
Daniel Jacobowitz
drow@false.org
Fri Apr 2 17:40:00 GMT 2004
Misc. cleanups. This patch removes the last user of dwarf2_tmp_obstack;
while the comments describing its marginal utility were accurate, there's no
point in maintaining a global obstack when everything on it has lifetimes
associated with a particular compilation unit, and we have an obstack with
the appropriate shorter lifetime anyway. Everything but the
still-xmalloc-allocated full DIEs is now on the compilation unit obstack
(except for the abbrevs; it was easy enough to free them when we're done
with them, which is before we process full or partial DIEs).
Committed to the intercu branch.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
2004-04-02 Daniel Jacobowitz <drow@mvista.com>
* dwarf2read.c (struct dwarf2_cu): Add comments. Rename
partial_die_obstack to comp_unit_obstack.
(struct partial_die_info): Move higher in file. Add comments.
Use ENUM_BITFIELD.
(dwarf2_tmp_obstack, dwarf2_free_tmp_obstack): Remove.
(partial_die_hash, partial_die_eq): Move lower in file.
(hashtab_obstack_allocate): Likewise. Renamed from
hash_obstack_allocate.
(dummy_obstack_deallocate): Likewise. Renamed from
splay_tree_obstack_deallocate.
(dwarf2_build_psymtabs_hard): Remove references to
dwarf2_tmp_obstack. Update names of changed variables/functions.
(load_comp_unit, create_comp_unit_tree, partial_die_parent_scope)
(guess_structure_name, psymtab_to_symtab_1, load_full_comp_unit)
(add_to_cu_func_list, load_partial_dies, dwarf_alloc_block)
(free_one_comp_unit, clear_per_cu_pointer, set_die_type)
(dwarf2_add_dependence): Likewise.
Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.135.2.39
diff -u -p -r1.135.2.39 dwarf2read.c
--- dwarf2read.c 2 Apr 2004 16:47:45 -0000 1.135.2.39
+++ dwarf2read.c 2 Apr 2004 17:32:27 -0000
@@ -312,8 +312,12 @@ struct dwarf2_cu
/* Storage for the abbrev table. */
struct obstack abbrev_obstack;
+ /* Hash table holding all the loaded partial DIEs. */
htab_t partial_dies;
- struct obstack partial_die_obstack;
+
+ /* Storage for things with the same lifetime as this read-in compilation
+ unit, including partial DIEs. */
+ struct obstack comp_unit_obstack;
/* When multiple dwarf2_cu structures are living in memory, this field
chains them all together, so that they can be released efficiently.
@@ -415,6 +419,63 @@ struct line_header
char *statement_program_start, *statement_program_end;
};
+/* When we construct a partial symbol table entry we only
+ need this much information. */
+struct partial_die_info
+ {
+ /* Offset of this DIE. */
+ unsigned int offset;
+
+ /* DWARF-2 tag for this DIE. */
+ ENUM_BITFIELD(dwarf_tag) tag : 16;
+
+ /* Language code associated with this DIE. This is only used
+ for the compilation unit DIE. */
+ unsigned int language : 8;
+
+ /* Assorted flags describing the data found in this DIE. */
+ unsigned int has_children : 1;
+ unsigned int is_external : 1;
+ unsigned int is_declaration : 1;
+ unsigned int has_type : 1;
+ unsigned int has_specification : 1;
+ unsigned int has_pc_info : 1;
+
+ /* Flag set if the SCOPE field of this structure has been
+ computed. */
+ unsigned int scope_set : 1;
+
+ /* The name of this DIE. Normally the value of DW_AT_name, but
+ sometimes DW_TAG_MIPS_linkage_name or a string computed in some
+ other fashion. */
+ char *name;
+
+ /* The scope to prepend to our children. This is generally
+ allocated on the comp_unit_obstack, so will disappear
+ when this compilation unit leaves the cache. */
+ char *scope;
+
+ /* The location description associated with this DIE, if any. */
+ struct dwarf_block *locdesc;
+
+ /* If HAS_PC_INFO, the PC range associated with this DIE. */
+ CORE_ADDR lowpc;
+ CORE_ADDR highpc;
+
+ /* Pointer into the info_buffer pointing at the target of
+ DW_AT_sibling, if any. */
+ char *sibling;
+
+ /* If HAS_SPECIFICATION, the offset of the DIE referred to by
+ DW_AT_specification (or DW_AT_abstract_origin or
+ DW_AT_extension). */
+ unsigned int spec_offset;
+
+ /* Pointers to this DIE's parent, first child, and next sibling,
+ if any. */
+ struct partial_die_info *die_parent, *die_child, *die_sibling;
+ };
+
/* This data structure holds the information of an abbrev. */
struct abbrev_info
{
@@ -493,42 +554,10 @@ struct dwarf_block
char *data;
};
-/* When we construct a partial symbol table entry we only
- need this much information. */
-struct partial_die_info
- {
- unsigned int offset;
- unsigned int tag : 16;
- unsigned int language : 8;
- unsigned int has_children : 1;
- unsigned int is_external : 1;
- unsigned int is_declaration : 1;
- unsigned int has_type : 1;
- unsigned int has_specification : 1;
- unsigned int has_pc_info : 1;
- unsigned int scope_set : 1;
- char *name;
-
- /* The scope to prepend to our children. This is generally
- allocated on the partial_die_obstack, so will disappear
- when this compilation unit leaves the cache. */
- char *scope;
-
- struct dwarf_block *locdesc;
- CORE_ADDR lowpc;
- CORE_ADDR highpc;
- char *sibling;
- unsigned int spec_offset;
- struct partial_die_info *die_parent, *die_child, *die_sibling;
- };
-
#ifndef ATTR_ALLOC_CHUNK
#define ATTR_ALLOC_CHUNK 4
#endif
-/* Obstack for allocating temporary storage used during symbol reading. */
-static struct obstack dwarf2_tmp_obstack;
-
/* Allocate fields for structs, unions and enums in this size. */
#ifndef DW_FIELD_ALLOC_CHUNK
#define DW_FIELD_ALLOC_CHUNK 4
@@ -958,8 +987,6 @@ static struct type *dwarf2_fundamental_t
/* memory allocation interface */
-static void dwarf2_free_tmp_obstack (void *);
-
static struct dwarf_block *dwarf_alloc_block (struct dwarf2_cu *);
static struct abbrev_info *dwarf_alloc_abbrev (struct dwarf2_cu *);
@@ -1020,42 +1047,19 @@ static void dwarf2_clear_marks (struct d
static char *skip_one_die (char *info_ptr, struct abbrev_info *abbrev,
struct dwarf2_cu *cu);
-/* Allocation function for the libiberty splay tree which uses an obstack. */
-static void *
-splay_tree_obstack_allocate (int size, void *data)
-{
- return obstack_alloc ((struct obstack *) data, size);
-}
+static void *hashtab_obstack_allocate (void *data, size_t size, size_t count);
-/* Trivial deallocation function for the libiberty splay tree. */
-static void
-splay_tree_obstack_deallocate (void *object, void *data)
-{
- return;
-}
+static void dummy_obstack_deallocate (void *object, void *data);
-static void *
-hash_obstack_allocate (void *data, size_t size, size_t count)
-{
- unsigned int total = size * count;
- void *ptr = obstack_alloc ((struct obstack *) data, total);
- memset (ptr, 0, total);
- return ptr;
-}
+static hashval_t partial_die_hash (const void *item);
-static hashval_t
-partial_die_hash (const void *item)
-{
- const struct partial_die_info *part_die = item;
- return part_die->offset;
-}
+static int partial_die_eq (const void *item_lhs, const void *item_rhs);
-static int
-partial_die_eq (const void *item_lhs, const void *item_rhs)
+/* Allocation function for the libiberty splay tree which uses an obstack. */
+static void *
+splay_tree_obstack_allocate (int size, void *data)
{
- const struct partial_die_info *part_die_lhs = item_lhs;
- const struct partial_die_info *part_die_rhs = item_rhs;
- return part_die_lhs->offset == part_die_rhs->offset;
+ return obstack_alloc ((struct obstack *) data, size);
}
/* Try to locate the sections we need for DWARF 2 debugging
@@ -1328,40 +1332,9 @@ dwarf2_build_psymtabs_hard (struct objfi
info_ptr = dwarf2_per_objfile->info_buffer;
- /* We use dwarf2_tmp_obstack for objects that don't need to survive
- the partial symbol scan, like attribute values.
-
- We could reduce our peak memory consumption during partial symbol
- table construction by freeing stuff from this obstack more often
- --- say, after processing each compilation unit, or each die ---
- but it turns out that this saves almost nothing. For an
- executable with 11Mb of Dwarf 2 data, I found about 64k allocated
- on dwarf2_tmp_obstack. Some investigation showed:
-
- 1) 69% of the attributes used forms DW_FORM_addr, DW_FORM_data*,
- DW_FORM_flag, DW_FORM_[su]data, and DW_FORM_ref*. These are
- all fixed-length values not requiring dynamic allocation.
-
- 2) 30% of the attributes used the form DW_FORM_string. For
- DW_FORM_string, read_attribute simply hands back a pointer to
- the null-terminated string in info_buffer, so no dynamic
- allocation is needed there either.
-
- 3) The remaining 1% of the attributes all used DW_FORM_block1.
- 75% of those were DW_AT_frame_base location lists for
- functions; the rest were DW_AT_location attributes, probably
- for the global variables.
-
- Anyway, what this all means is that the memory the dwarf2
- reader uses as temporary space reading partial symbols is about
- 0.5% as much as we use for dwarf_*_buffer. That's noise. */
-
- obstack_init (&dwarf2_tmp_obstack);
- back_to = make_cleanup (dwarf2_free_tmp_obstack, NULL);
-
/* Any cached compilation units will be linked by the per-objfile
read_in_chain. Make sure to free them when we're done. */
- make_cleanup (free_cached_comp_units, NULL);
+ back_to = make_cleanup (free_cached_comp_units, NULL);
/* Since the objects we're extracting from .debug_info vary in
length, only the individual functions to extract them (like
@@ -1474,15 +1447,15 @@ dwarf2_build_psymtabs_hard (struct objfi
lowpc = ((CORE_ADDR) -1);
highpc = ((CORE_ADDR) 0);
- obstack_init (&cu.partial_die_obstack);
+ obstack_init (&cu.comp_unit_obstack);
cu.partial_dies
= htab_create_alloc_ex (cu.header.length / 12,
partial_die_hash,
partial_die_eq,
NULL,
- &cu.partial_die_obstack,
- hash_obstack_allocate,
- splay_tree_obstack_deallocate);
+ &cu.comp_unit_obstack,
+ hashtab_obstack_allocate,
+ dummy_obstack_deallocate);
first_die = load_partial_dies (abfd, info_ptr, 1, &cu);
@@ -1574,15 +1547,15 @@ load_comp_unit (struct dwarf2_per_cu_dat
{
struct partial_die_info *first_die;
- obstack_init (&cu->partial_die_obstack);
+ obstack_init (&cu->comp_unit_obstack);
cu->partial_dies
= htab_create_alloc_ex (cu->header.length / 12,
partial_die_hash,
partial_die_eq,
NULL,
- &cu->partial_die_obstack,
- hash_obstack_allocate,
- splay_tree_obstack_deallocate);
+ &cu->comp_unit_obstack,
+ hashtab_obstack_allocate,
+ dummy_obstack_deallocate);
first_die = load_partial_dies (abfd, info_ptr, 0, cu);
}
@@ -1605,7 +1578,7 @@ create_comp_unit_tree (struct objfile *o
cu_tree = splay_tree_new_with_allocator (splay_tree_compare_ints,
NULL, NULL,
splay_tree_obstack_allocate,
- splay_tree_obstack_deallocate,
+ dummy_obstack_deallocate,
&objfile->objfile_obstack);
dwarf2_per_objfile->cu_tree = cu_tree;
@@ -1750,7 +1723,7 @@ scan_partial_symbols (struct partial_die
/* Compute the scope prefix associated with PDI's parent, in
compilation unit CU. The result will be allocated on CU's
- partial_die_obstack, or a copy of the already allocated PDI->NAME
+ comp_unit_obstack, or a copy of the already allocated PDI->NAME
field. NULL is returned if no prefix is necessary. */
static char *
partial_die_parent_scope (struct partial_die_info *pdi,
@@ -1787,7 +1760,7 @@ partial_die_parent_scope (struct partial
if (grandparent_scope == NULL)
parent->scope = parent->name;
else
- parent->scope = obconcat (&cu->partial_die_obstack, grandparent_scope,
+ parent->scope = obconcat (&cu->comp_unit_obstack, grandparent_scope,
"::", parent->name);
}
else if (parent->tag == DW_TAG_enumeration_type)
@@ -2079,7 +2052,7 @@ guess_structure_name (struct partial_die
struct_pdi->name
= obsavestring (actual_class_name,
strlen (actual_class_name),
- &cu->partial_die_obstack);
+ &cu->comp_unit_obstack);
xfree (actual_class_name);
}
break;
@@ -2429,10 +2402,7 @@ dwarf2_release_queue (void *dummy)
static void
psymtab_to_symtab_1 (struct partial_symtab *pst)
{
- struct cleanup *back_to;
-
- obstack_init (&dwarf2_tmp_obstack);
- back_to = make_cleanup (dwarf2_free_tmp_obstack, NULL);
+ struct cleanup *back_to = make_cleanup (null_cleanup, NULL);
if (dwarf2_per_objfile->cu_tree == NULL)
{
@@ -2509,7 +2479,7 @@ load_full_comp_unit (struct partial_symt
per_cu->cu = cu;
/* We use this obstack for block values in dwarf_alloc_block. */
- obstack_init (&cu->partial_die_obstack);
+ obstack_init (&cu->comp_unit_obstack);
cu->dies = read_comp_unit (info_ptr, abfd, cu);
@@ -2825,7 +2795,7 @@ add_to_cu_func_list (const char *name, C
struct function_range *thisfn;
thisfn = (struct function_range *)
- obstack_alloc (&dwarf2_tmp_obstack, sizeof (struct function_range));
+ obstack_alloc (&cu->comp_unit_obstack, sizeof (struct function_range));
thisfn->name = name;
thisfn->lowpc = lowpc;
thisfn->highpc = highpc;
@@ -5078,7 +5048,7 @@ load_partial_dies (bfd *abfd, char *info
parent_die = NULL;
last_die = NULL;
- part_die = obstack_alloc (&cu->partial_die_obstack,
+ part_die = obstack_alloc (&cu->comp_unit_obstack,
sizeof (struct partial_die_info));
while (1)
@@ -5090,7 +5060,7 @@ load_partial_dies (bfd *abfd, char *info
if (--nesting_level == 0)
{
/* This was the last thing allocated. */
- obstack_free (&cu->partial_die_obstack, part_die);
+ obstack_free (&cu->comp_unit_obstack, part_die);
return first_die;
}
info_ptr += bytes_read;
@@ -5221,7 +5191,7 @@ load_partial_dies (bfd *abfd, char *info
*slot = part_die;
}
- part_die = obstack_alloc (&cu->partial_die_obstack,
+ part_die = obstack_alloc (&cu->comp_unit_obstack,
sizeof (struct partial_die_info));
/* For some DIEs we want to follow their children (if any). For C
@@ -8654,21 +8624,13 @@ decode_locdesc (struct dwarf_block *blk,
return (stack[stacki]);
}
-/* memory allocation interface */
-
-static void
-dwarf2_free_tmp_obstack (void *ignore)
-{
- obstack_free (&dwarf2_tmp_obstack, NULL);
-}
-
static struct dwarf_block *
dwarf_alloc_block (struct dwarf2_cu *cu)
{
struct dwarf_block *blk;
blk = (struct dwarf_block *)
- obstack_alloc (&cu->partial_die_obstack, sizeof (struct dwarf_block));
+ obstack_alloc (&cu->comp_unit_obstack, sizeof (struct dwarf_block));
return (blk);
}
@@ -9197,7 +9159,7 @@ free_one_comp_unit (void *data)
cu->per_cu->cu = NULL;
cu->per_cu = NULL;
- obstack_free (&cu->partial_die_obstack, NULL);
+ obstack_free (&cu->comp_unit_obstack, NULL);
if (cu->dies)
free_die_list (cu->dies);
@@ -9267,7 +9229,7 @@ clear_per_cu_pointer (void *data)
if (cu->per_cu != NULL)
{
- obstack_free (&cu->partial_die_obstack, NULL);
+ obstack_free (&cu->comp_unit_obstack, NULL);
cu->partial_dies = NULL;
/* This compilation unit is on the stack in our caller, so we
@@ -9340,8 +9302,8 @@ set_die_type (struct die_info *die, stru
offset_and_type_eq,
NULL,
&cu->objfile->objfile_obstack,
- hash_obstack_allocate,
- splay_tree_obstack_deallocate);
+ hashtab_obstack_allocate,
+ dummy_obstack_deallocate);
PST_PRIVATE (cu->per_cu->psymtab)->type_hash = type_hash;
}
ofs.offset = die->offset;
@@ -9394,8 +9356,8 @@ dwarf2_add_dependence (struct dwarf2_cu
= splay_tree_new_with_allocator (splay_tree_compare_ints,
NULL, NULL,
splay_tree_obstack_allocate,
- splay_tree_obstack_deallocate,
- &cu->partial_die_obstack);
+ dummy_obstack_deallocate,
+ &cu->comp_unit_obstack);
if (splay_tree_lookup (cu->dependencies, ref_per_cu->offset) == NULL)
splay_tree_insert (cu->dependencies, ref_per_cu->offset,
@@ -9439,6 +9401,49 @@ dwarf2_clear_marks (struct dwarf2_per_cu
per_cu->cu->mark = 0;
per_cu = per_cu->cu->read_in_chain;
}
+}
+
+/* Allocation function for the libiberty hash table which uses an
+ obstack. */
+
+static void *
+hashtab_obstack_allocate (void *data, size_t size, size_t count)
+{
+ unsigned int total = size * count;
+ void *ptr = obstack_alloc ((struct obstack *) data, total);
+ memset (ptr, 0, total);
+ return ptr;
+}
+
+/* Trivial deallocation function for the libiberty splay tree and hash
+ table - don't deallocate anything. Rely on later deletion of the
+ obstack. */
+
+static void
+dummy_obstack_deallocate (void *object, void *data)
+{
+ return;
+}
+
+/* Trivial hash function for partial_die_info: the hash value of a DIE
+ is its offset in .debug_info for this objfile. */
+
+static hashval_t
+partial_die_hash (const void *item)
+{
+ const struct partial_die_info *part_die = item;
+ return part_die->offset;
+}
+
+/* Trivial comparison function for partial_die_info structures: two DIEs
+ are equal if they have the same offset. */
+
+static int
+partial_die_eq (const void *item_lhs, const void *item_rhs)
+{
+ const struct partial_die_info *part_die_lhs = item_lhs;
+ const struct partial_die_info *part_die_rhs = item_rhs;
+ return part_die_lhs->offset == part_die_rhs->offset;
}
void _initialize_dwarf2_read (void);
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