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* ld.texinfo (Builtin Functions) <DEFINED>: Say that only symbols

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defined before the statement using DEFINED yield 1.
	* ldexp.c (fold_name) <case DEFINED>: In lang_first_phase_enum,
	call lang_track_definedness on symbol.  In subsequent phases, use
	lang_symbol_definition_iteration and lang_statement_iteration to
	check whether the symbol was defined before the current statement.
	(exp_fold_tree) <case etree_assign et al>: Call
	lang_update_definedness before updating symbol type when setting
	symbol.
	* ldlang.c (lang_definedness_table): New variable.
	(lang_definedness_newfunc, lang_track_definedness)
	(lang_symbol_definition_iteration, lang_update_definedness): New
	functions.
	(lang_init): Initialize lang_definedness_table and
	lang_statement_iteration.
	(lang_finish): Destroy bfd_hash_table_free.
	(lang_size_sections): Increment lang_statement_iteration.
	(lang_do_assignments_1): New function with former
	lang_do_assignments contents.  Change recursive calls to call this
	function.
	(lang_do_assignments): Evacuate contents.  Increment
	lang_statement_iteration, then just call lang_do_assignments_1.
	* ldlang.h (struct lang_definedness_hash_entry)
	(lang_statement_iteration, lang_track_definedness)
	(lang_symbol_definition_iteration, lang_update_definedness):
	Declare.
This commit is contained in:
Hans-Peter Nilsson 2003-10-11 09:16:20 +00:00
parent a8f4cde1ae
commit 420e579cc4
5 changed files with 184 additions and 17 deletions
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29
ld/ChangeLog
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@ -1,3 +1,32 @@
2003-10-11 Hans-Peter Nilsson <hp@bitrange.com>
* ld.texinfo (Builtin Functions) <DEFINED>: Say that only symbols
defined before the statement using DEFINED yield 1.
* ldexp.c (fold_name) <case DEFINED>: In lang_first_phase_enum,
call lang_track_definedness on symbol. In subsequent phases, use
lang_symbol_definition_iteration and lang_statement_iteration to
check whether the symbol was defined before the current statement.
(exp_fold_tree) <case etree_assign et al>: Call
lang_update_definedness before updating symbol type when setting
symbol.
* ldlang.c (lang_definedness_table): New variable.
(lang_definedness_newfunc, lang_track_definedness)
(lang_symbol_definition_iteration, lang_update_definedness): New
functions.
(lang_init): Initialize lang_definedness_table and
lang_statement_iteration.
(lang_finish): Destroy bfd_hash_table_free.
(lang_size_sections): Increment lang_statement_iteration.
(lang_do_assignments_1): New function with former
lang_do_assignments contents. Change recursive calls to call this
function.
(lang_do_assignments): Evacuate contents. Increment
lang_statement_iteration, then just call lang_do_assignments_1.
* ldlang.h (struct lang_definedness_hash_entry)
(lang_statement_iteration, lang_track_definedness)
(lang_symbol_definition_iteration, lang_update_definedness):
Declare.
2003-10-09 H.J. Lu <hongjiu.lu@intel.com>
* scripttempl/elf.sc (__executable_start): Provide.

3
ld/ld.texinfo
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@ -4452,7 +4452,8 @@ evaluation purposes.
@kindex DEFINED(@var{symbol})
@cindex symbol defaults
Return 1 if @var{symbol} is in the linker global symbol table and is
defined, otherwise return 0. You can use this function to provide
defined before the statement using DEFINED in the script, otherwise
return 0. You can use this function to provide
default values for symbols. For example, the following script fragment
shows how to set a global symbol @samp{begin} to the first location in
the @samp{.text} section---but if a symbol called @samp{begin} already

12
ld/ldexp.c
View File

@ -485,10 +485,15 @@ fold_name (etree_type *tree,
break;
case DEFINED:
if (allocation_done == lang_first_phase_enum)
result.valid_p = FALSE;
{
lang_track_definedness (tree->name.name);
result.valid_p = FALSE;
}
else
{
struct bfd_link_hash_entry *h;
int def_iteration
= lang_symbol_definition_iteration (tree->name.name);
h = bfd_wrapped_link_hash_lookup (output_bfd, &link_info,
tree->name.name,
@ -496,7 +501,9 @@ fold_name (etree_type *tree,
result.value = (h != NULL
&& (h->type == bfd_link_hash_defined
|| h->type == bfd_link_hash_defweak
|| h->type == bfd_link_hash_common));
|| h->type == bfd_link_hash_common)
&& (def_iteration == lang_statement_iteration
|| def_iteration == -1));
result.section = abs_output_section;
result.valid_p = TRUE;
}
@ -738,6 +745,7 @@ exp_fold_tree (etree_type *tree,
{
/* FIXME: Should we worry if the symbol is already
defined? */
lang_update_definedness (tree->assign.dst, h);
h->type = bfd_link_hash_defined;
h->u.def.value = result.value;
h->u.def.section = result.section->bfd_section;

143
ld/ldlang.c
View File

@ -60,6 +60,7 @@ static const char *current_target;
static const char *output_target;
static lang_statement_list_type statement_list;
static struct lang_phdr *lang_phdr_list;
static struct bfd_hash_table lang_definedness_table;
/* Forward declarations. */
static void exp_init_os (etree_type *);
@ -67,6 +68,8 @@ static bfd_boolean wildcardp (const char *);
static lang_input_statement_type *lookup_name (const char *);
static bfd_boolean load_symbols (lang_input_statement_type *,
lang_statement_list_type *);
static struct bfd_hash_entry *lang_definedness_newfunc
(struct bfd_hash_entry *, struct bfd_hash_table *, const char *);
static void insert_undefined (const char *);
static void print_statement (lang_statement_union_type *,
lang_output_section_statement_type *);
@ -95,6 +98,7 @@ bfd_boolean delete_output_file_on_failure = FALSE;
struct lang_nocrossrefs *nocrossref_list;
struct unique_sections *unique_section_list;
static bfd_boolean ldlang_sysrooted_script = FALSE;
int lang_statement_iteration = 0;
etree_type *base; /* Relocation base - or null */
@ -477,6 +481,19 @@ lang_init (void)
lang_output_section_statement_lookup (BFD_ABS_SECTION_NAME);
abs_output_section->bfd_section = bfd_abs_section_ptr;
/* The value "3" is ad-hoc, somewhat related to the expected number of
DEFINED expressions in a linker script. For most default linker
scripts, there are none. Why a hash table then? Well, it's somewhat
simpler to re-use working machinery than using a linked list in terms
of code-complexity here in ld, besides the initialization which just
looks like other code here. */
if (bfd_hash_table_init_n (&lang_definedness_table,
lang_definedness_newfunc, 3) != TRUE)
einfo (_("%P%F: out of memory during initialization"));
/* Callers of exp_fold_tree need to increment this. */
lang_statement_iteration = 0;
}
/*----------------------------------------------------------------------
@ -1867,6 +1884,85 @@ lang_reasonable_defaults (void)
#endif
}
/* Add a symbol to a hash of symbols used in DEFINED (NAME) expressions. */
void
lang_track_definedness (const char *name)
{
if (bfd_hash_lookup (&lang_definedness_table, name, TRUE, FALSE) == NULL)
einfo (_("%P%F: bfd_hash_lookup failed creating symbol %s\n"), name);
}
/* New-function for the definedness hash table. */
static struct bfd_hash_entry *
lang_definedness_newfunc (struct bfd_hash_entry *entry,
struct bfd_hash_table *table ATTRIBUTE_UNUSED,
const char *name ATTRIBUTE_UNUSED)
{
struct lang_definedness_hash_entry *ret
= (struct lang_definedness_hash_entry *) entry;
if (ret == NULL)
ret = (struct lang_definedness_hash_entry *)
bfd_hash_allocate (table, sizeof (struct lang_definedness_hash_entry));
if (ret == NULL)
einfo (_("%P%F: bfd_hash_allocate failed creating symbol %s\n"), name);
ret->iteration = -1;
return &ret->root;
}
/* Return the iteration when the definition of NAME was last updated. A
value of -1 means that the symbol is not defined in the linker script
or the command line, but may be defined in the linker symbol table. */
int
lang_symbol_definition_iteration (const char *name)
{
struct lang_definedness_hash_entry *defentry
= (struct lang_definedness_hash_entry *)
bfd_hash_lookup (&lang_definedness_table, name, FALSE, FALSE);
/* We've already created this one on the presence of DEFINED in the
script, so it can't be NULL unless something is borked elsewhere in
the code. */
if (defentry == NULL)
FAIL ();
return defentry->iteration;
}
/* Update the definedness state of NAME. */
void
lang_update_definedness (const char *name, struct bfd_link_hash_entry *h)
{
struct lang_definedness_hash_entry *defentry
= (struct lang_definedness_hash_entry *)
bfd_hash_lookup (&lang_definedness_table, name, FALSE, FALSE);
/* We don't keep track of symbols not tested with DEFINED. */
if (defentry == NULL)
return;
/* If the symbol was already defined, and not from an earlier statement
iteration, don't update the definedness iteration, because that'd
make the symbol seem defined in the linker script at this point, and
it wasn't; it was defined in some object. If we do anyway, DEFINED
would start to yield false before this point and the construct "sym =
DEFINED (sym) ? sym : X;" would change sym to X despite being defined
in an object. */
if (h->type != bfd_link_hash_undefined
&& h->type != bfd_link_hash_common
&& h->type != bfd_link_hash_new
&& defentry->iteration == -1)
return;
defentry->iteration = lang_statement_iteration;
}
/* Add the supplied name to the symbol table as an undefined reference.
This is a two step process as the symbol table doesn't even exist at
the time the ld command line is processed. First we put the name
@ -3132,6 +3228,9 @@ lang_size_sections
{
bfd_vma result;
/* Callers of exp_fold_tree need to increment this. */
lang_statement_iteration++;
exp_data_seg.phase = exp_dataseg_none;
result = lang_size_sections_1 (s, output_section_statement, prev, fill,
dot, relax, check_regions);
@ -3157,8 +3256,10 @@ lang_size_sections
return result;
}
bfd_vma
lang_do_assignments
/* Worker function for lang_do_assignments. Recursiveness goes here. */
static bfd_vma
lang_do_assignments_1
(lang_statement_union_type *s,
lang_output_section_statement_type *output_section_statement,
fill_type *fill,
@ -3172,10 +3273,10 @@ lang_do_assignments
switch (s->header.type)
{
case lang_constructors_statement_enum:
dot = lang_do_assignments (constructor_list.head,
output_section_statement,
fill,
dot);
dot = lang_do_assignments_1 (constructor_list.head,
output_section_statement,
fill,
dot);
break;
case lang_output_section_statement_enum:
@ -3186,8 +3287,8 @@ lang_do_assignments
if (os->bfd_section != NULL)
{
dot = os->bfd_section->vma;
(void) lang_do_assignments (os->children.head, os,
os->fill, dot);
(void) lang_do_assignments_1 (os->children.head, os,
os->fill, dot);
dot = os->bfd_section->vma + os->bfd_section->_raw_size / opb;
}
@ -3206,9 +3307,9 @@ lang_do_assignments
break;
case lang_wild_statement_enum:
dot = lang_do_assignments (s->wild_statement.children.head,
output_section_statement,
fill, dot);
dot = lang_do_assignments_1 (s->wild_statement.children.head,
output_section_statement,
fill, dot);
break;
@ -3301,9 +3402,9 @@ lang_do_assignments
break;
case lang_group_statement_enum:
dot = lang_do_assignments (s->group_statement.children.head,
output_section_statement,
fill, dot);
dot = lang_do_assignments_1 (s->group_statement.children.head,
output_section_statement,
fill, dot);
break;
@ -3318,6 +3419,18 @@ lang_do_assignments
return dot;
}
bfd_vma
lang_do_assignments (lang_statement_union_type *s,
lang_output_section_statement_type
*output_section_statement,
fill_type *fill,
bfd_vma dot)
{
/* Callers of exp_fold_tree need to increment this. */
lang_statement_iteration++;
lang_do_assignments_1 (s, output_section_statement, fill, dot);
}
/* Fix any .startof. or .sizeof. symbols. When the assemblers see the
operator .startof. (section_name), it produces an undefined symbol
.startof.section_name. Similarly, when it sees
@ -3445,6 +3558,8 @@ lang_finish (void)
}
}
}
bfd_hash_table_free (&lang_definedness_table);
}
/* This is a small function used when we want to ignore errors from

14
ld/ldlang.h
View File

@ -361,6 +361,14 @@ struct unique_sections {
const char *name;
};
/* This structure records symbols for which we need to keep track of
definedness for use in the DEFINED () test. */
struct lang_definedness_hash_entry {
struct bfd_hash_entry root;
int iteration;
};
extern struct unique_sections *unique_section_list;
extern lang_output_section_statement_type *abs_output_section;
@ -375,6 +383,8 @@ extern const char *entry_section;
extern bfd_boolean entry_from_cmdline;
extern lang_statement_list_type file_chain;
extern int lang_statement_iteration;
extern void lang_init
(void);
extern struct memory_region_struct *lang_memory_region_lookup
@ -517,5 +527,9 @@ extern void lang_add_unique
(const char *);
extern const char *lang_get_output_target
(void);
extern void lang_track_definedness (const char *);
extern int lang_symbol_definition_iteration (const char *);
extern void lang_update_definedness
(const char *, struct bfd_link_hash_entry *);
#endif