#define KEEPIT flags
#define KEEPITTYPE int
+#include <assert.h>
#include <string.h> /* For strchr and friends */
#include "bfd.h"
#include <sysdep.h>
bfd * abfd AND
int *statep)
{
+ cache_ptr->symbol.section = 0;
if (*statep)
{
/* This is an indirect symbol */
if ((cache_ptr->type | N_EXT) == (N_INDR | N_EXT))
{
/* Two symbols in a row for an INDR message. The first symbol
- contains the name we will match, the second symbol contains the
- name the first name is translated into. It is supplied to us
- undefined. This is good, since we want to pull in any files which
- define it */
+ contains the name we will match, the second symbol contains
+ the name the first name is translated into. It is supplied to
+ us undefined. This is good, since we want to pull in any files
+ which define it */
cache_ptr->symbol.flags = BSF_DEBUGGING | BSF_INDIRECT;
cache_ptr->symbol.value = (bfd_vma) ((cache_ptr + 1));
cache_ptr->symbol.section = &bfd_ind_section;
}
}
}
+ if (cache_ptr->symbol.section == 0)
+ abort ();
}
struct external_nlist *syms;
char *strings;
aout_symbol_type *cached;
-
+
/* If there's no work to be done, don't do any */
if (obj_aout_symbols (abfd) != (aout_symbol_type *)NULL) return true;
symbol_size = exec_hdr(abfd)->a_syms;
- if (symbol_size == 0) {
- bfd_error = no_symbols;
- return false;
- }
-
+ if (symbol_size == 0)
+ {
+ bfd_error = no_symbols;
+ return false;
+ }
+
bfd_seek (abfd, obj_str_filepos (abfd), SEEK_SET);
if (bfd_read ((PTR)string_chars, BYTES_IN_WORD, 1, abfd) != BYTES_IN_WORD)
return false;
string_size = GET_WORD (abfd, string_chars);
-
+
strings =(char *) bfd_alloc(abfd, string_size + 1);
cached = (aout_symbol_type *)
bfd_zalloc(abfd, (bfd_size_type)(bfd_get_symcount (abfd) * sizeof(aout_symbol_type)));
might want to allocate onto the bfd's obstack */
syms = (struct external_nlist *) bfd_xmalloc(symbol_size);
bfd_seek (abfd, obj_sym_filepos (abfd), SEEK_SET);
- if (bfd_read ((PTR)syms, 1, symbol_size, abfd) != symbol_size) {
- bailout:
- if (syms) free (syms);
- if (cached) bfd_release (abfd, cached);
- if (strings)bfd_release (abfd, strings);
- return false;
- }
-
+ if (bfd_read ((PTR)syms, 1, symbol_size, abfd) != symbol_size)
+ {
+ bailout:
+ if (syms)
+ free (syms);
+ if (cached)
+ bfd_release (abfd, cached);
+ if (strings)
+ bfd_release (abfd, strings);
+ return false;
+ }
+
bfd_seek (abfd, obj_str_filepos (abfd), SEEK_SET);
- if (bfd_read ((PTR)strings, 1, string_size, abfd) != string_size) {
- goto bailout;
- }
- strings[string_size] = 0; /* Just in case. */
-
- /* OK, now walk the new symtable, cacheing symbol properties */
+ if (bfd_read ((PTR)strings, 1, string_size, abfd) != string_size)
{
- register struct external_nlist *sym_pointer;
- int state = 0;
- register struct external_nlist *sym_end = syms + bfd_get_symcount (abfd);
- register aout_symbol_type *cache_ptr = cached;
-
- /* Run through table and copy values */
- for (sym_pointer = syms, cache_ptr = cached;
- sym_pointer < sym_end; sym_pointer ++, cache_ptr++)
- {
- long x = GET_WORD(abfd, sym_pointer->e_strx);
- cache_ptr->symbol.the_bfd = abfd;
- if (x >= 0 && x < string_size)
- cache_ptr->symbol.name = x + strings;
- else
- goto bailout;
-
- cache_ptr->symbol.value = GET_SWORD(abfd, sym_pointer->e_value);
- cache_ptr->desc = bfd_h_get_16(abfd, sym_pointer->e_desc);
- cache_ptr->other = bfd_h_get_8(abfd, sym_pointer->e_other);
- cache_ptr->type = bfd_h_get_8(abfd, sym_pointer->e_type);
- cache_ptr->symbol.udata = 0;
- translate_from_native_sym_flags (sym_pointer, cache_ptr,
- abfd, &state);
- }
+ goto bailout;
}
-
+ strings[string_size] = 0; /* Just in case. */
+
+ /* OK, now walk the new symtable, cacheing symbol properties */
+ {
+ register struct external_nlist *sym_pointer;
+ int state = 0;
+ register struct external_nlist *sym_end = syms + bfd_get_symcount (abfd);
+ register aout_symbol_type *cache_ptr = cached;
+
+ /* Run through table and copy values */
+ for (sym_pointer = syms, cache_ptr = cached;
+ sym_pointer < sym_end; sym_pointer ++, cache_ptr++)
+ {
+ long x = GET_WORD(abfd, sym_pointer->e_strx);
+ cache_ptr->symbol.the_bfd = abfd;
+ if (x == 0)
+ cache_ptr->symbol.name = "";
+ else if (x >= 0 && x < string_size)
+ cache_ptr->symbol.name = x + strings;
+ else
+ goto bailout;
+
+ cache_ptr->symbol.value = GET_SWORD(abfd, sym_pointer->e_value);
+ cache_ptr->desc = bfd_h_get_16(abfd, sym_pointer->e_desc);
+ cache_ptr->other = bfd_h_get_8(abfd, sym_pointer->e_other);
+ cache_ptr->type = bfd_h_get_8(abfd, sym_pointer->e_type);
+ cache_ptr->symbol.udata = 0;
+ translate_from_native_sym_flags (sym_pointer, cache_ptr,
+ abfd, &state);
+ }
+ }
+
obj_aout_symbols (abfd) = cached;
free((PTR)syms);
-
+
return true;
}
+\f
+/* Possible improvements:
+ + look for strings matching trailing substrings of other strings
+ + better data structures? balanced trees?
+ + smaller per-string or per-symbol data? re-use some of the symbol's
+ data fields?
+ + also look at reducing memory use elsewhere -- maybe if we didn't have to
+ construct the entire symbol table at once, we could get by with smaller
+ amounts of VM? (What effect does that have on the string table
+ reductions?)
+ + rip this out of here, put it into its own file in bfd or libiberty, so
+ coff and elf can use it too. I'll work on this soon, but have more
+ pressing tasks right now.
+
+ A hash table might(?) be more efficient for handling exactly the cases that
+ are handled now, but for trailing substring matches, I think we want to
+ examine the `nearest' values (reverse-)lexically, not merely impose a strict
+ order, nor look only for exact-match or not-match. I don't think a hash
+ table would be very useful for that, and I don't feel like fleshing out two
+ completely different implementations. [raeburn:930419.0331EDT] */
+
+#if __GNUC__ >= 2
+#define INLINE __inline__
+#else
+#define INLINE
+#endif
+
+struct stringtab_entry {
+ /* Hash value for this string. Only useful so long as we aren't doing
+ substring matches. */
+ int hash;
+
+ /* Next node to look at, depending on whether the hash value of the string
+ being searched for is less than or greater than the hash value of the
+ current node. For now, `equal to' is lumped in with `greater than', for
+ space efficiency. It's not a common enough case to warrant another field
+ to be used for all nodes. */
+ struct stringtab_entry *less;
+ struct stringtab_entry *greater;
+
+ /* The string itself. */
+ CONST char *string;
+
+ /* The index allocated for this string. */
+ bfd_size_type index;
+
+#ifdef GATHER_STATISTICS
+ /* How many references have there been to this string? (Not currently used;
+ could be dumped out for anaylsis, if anyone's interested.) */
+ unsigned long count;
+#endif
+
+ /* Next node in linked list, in suggested output order. */
+ struct stringtab_entry *next_to_output;
+};
+
+struct stringtab_data {
+ /* Tree of string table entries. */
+ struct stringtab_entry *strings;
+
+ /* Fudge factor used to center top node of tree. */
+ int hash_zero;
+
+ /* Next index value to issue. */
+ bfd_size_type index;
+
+ /* Index used for empty strings. Cached here because checking for them
+ is really easy, and we can avoid searching the tree. */
+ bfd_size_type empty_string_index;
+
+ /* These fields indicate the two ends of a singly-linked list that indicates
+ the order strings should be written out in. Use this order, and no
+ seeking will need to be done, so output efficiency should be maximized. */
+ struct stringtab_entry **end;
+ struct stringtab_entry *output_order;
+
+#ifdef GATHER_STATISTICS
+ /* Number of strings which duplicate strings already in the table. */
+ unsigned long duplicates;
+
+ /* Number of bytes saved by not having to write all the duplicate strings. */
+ unsigned long bytes_saved;
+
+ /* Number of zero-length strings. Currently, these all turn into
+ references to the null byte at the end of the first string. In some
+ cases (possibly not all? explore this...), it should be possible to
+ simply write out a zero index value. */
+ unsigned long empty_strings;
+
+ /* Number of times the hash values matched but the strings were different.
+ Note that this includes the number of times the other string(s) occurs, so
+ there may only be two strings hashing to the same value, even if this
+ number is very large. */
+ unsigned long bad_hash_matches;
+
+ /* Null strings aren't counted in this one.
+ This will probably only be nonzero if we've got an input file
+ which was produced by `ld -r' (i.e., it's already been processed
+ through this code). Under some operating systems, native tools
+ may make all empty strings have the same index; but the pointer
+ check won't catch those, because to get to that stage we'd already
+ have to compute the checksum, which requires reading the string,
+ so we short-circuit that case with empty_string_index above. */
+ unsigned long pointer_matches;
+
+ /* Number of comparisons done. I figure with the algorithms in use below,
+ the average number of comparisons done (per symbol) should be roughly
+ log-base-2 of the number of unique strings. */
+ unsigned long n_compares;
+#endif
+};
+
+/* Some utility functions for the string table code. */
+
+static INLINE int
+hash (string)
+ char *string;
+{
+ unsigned int sum = 0;
+ while (*string)
+ {
+#if 0
+ /* This expression borrowed from some code in gnu make. */
+ sum += *string++, sum = (sum << 7) + (sum >> 20);
+#endif
+ /* This appears to get a better distribution, at least for my one
+ test case. Do some analysis on this later, get a real hash
+ algorithm. */
+ sum ^= sum >> 20;
+ sum ^= sum << 7;
+ sum += *string++;
+ }
+ return sum;
+}
+
+static INLINE void
+stringtab_init (tab)
+ struct stringtab_data *tab;
+{
+ tab->strings = 0;
+ tab->output_order = 0;
+ tab->end = &tab->output_order;
+
+ /* Initial string table length includes size of length field. */
+ tab->index = BYTES_IN_WORD;
+ tab->empty_string_index = -1;
+#ifdef GATHER_STATISTICS
+ tab->duplicates = 0;
+ tab->empty_strings = 0;
+ tab->bad_hash_matches = 0;
+ tab->pointer_matches = 0;
+ tab->bytes_saved = 0;
+ tab->n_compares = 0;
+#endif
+}
+
+static INLINE int
+compare (entry, str, hash)
+ struct stringtab_entry *entry;
+ CONST char *str;
+ int hash;
+{
+ if (hash == entry->hash)
+ return 0;
+ if (hash > entry->hash)
+ return 1;
+ if (hash < entry->hash)
+ return -1;
+ abort ();
+}
+
+#ifdef GATHER_STATISTICS
+/* Don't want to have to link in math library with all bfd applications... */
+static INLINE double
+log2 (num)
+ int num;
+{
+ double d = num;
+#if defined (__i386__) && __GNUC__ >= 2
+ asm ("fyl2x" : "=t" (d) : "0" (d), "u" (1.0));
+ return d;
+#else
+ int n = 0;
+ while (d >= 2.0)
+ n++, d /= 2.0;
+ return ((d > 1.41) ? 0.5 : 0) + n;
+#endif
+}
+#endif
+
+/* Main string table routines. */
+/* Returns index in string table. Whether or not this actually adds an
+ entry into the string table should be irrelevant -- it just has to
+ return a valid index. */
+static bfd_size_type
+add_to_stringtab (abfd, str, tab, check)
+ bfd *abfd;
+ CONST char *str;
+ struct stringtab_data *tab;
+ int check;
+{
+ struct stringtab_entry **ep;
+ struct stringtab_entry *entry;
+ int hashval, len;
+
+ if (str[0] == 0)
+ {
+ bfd_size_type index;
+ CONST bfd_size_type minus_one = -1;
+
+#ifdef GATHER_STATISTICS
+ tab->empty_strings++;
+#endif
+ index = tab->empty_string_index;
+ if (index != minus_one)
+ {
+ got_empty:
+#ifdef GATHER_STATISTICS
+ tab->bytes_saved++;
+ tab->duplicates++;
+#endif
+ return index;
+ }
+
+ /* Need to find it. */
+ entry = tab->strings;
+ if (entry)
+ {
+ index = entry->index + strlen (entry->string);
+ tab->empty_string_index = index;
+ goto got_empty;
+ }
+ len = 0;
+ }
+ else
+ len = strlen (str);
+
+ /* The hash_zero value is chosen such that the first symbol gets a value of
+ zero. With a balanced tree, this wouldn't be very useful, but without it,
+ we might get a more even split at the top level, instead of skewing it
+ badly should hash("/usr/lib/crt0.o") (or whatever) be far from zero. */
+ hashval = hash (str) ^ tab->hash_zero;
+ ep = &tab->strings;
+ if (!*ep)
+ {
+ tab->hash_zero = hashval;
+ hashval = 0;
+ goto add_it;
+ }
+
+ while (*ep)
+ {
+ int cmp;
+ entry = *ep;
+#ifdef GATHER_STATISTICS
+ tab->n_compares++;
+#endif
+ cmp = compare (entry, str, hashval);
+ if (cmp == 0)
+ {
+ if (entry->string == str)
+ {
+#ifdef GATHER_STATISTICS
+ tab->pointer_matches++;
+#endif
+ goto match;
+ }
+ if (!strcmp (entry->string, str))
+ {
+ match:
+#ifdef GATHER_STATISTICS
+ entry->count++;
+ tab->bytes_saved += len + 1;
+ tab->duplicates++;
+#endif
+ /* If we're in the linker, and the new string is from a new
+ input file which might have already had these reductions
+ run over it, we want to keep the new string pointer. I
+ don't think we're likely to see any (or nearly as many,
+ at least) cases where a later string is in the same location
+ as an earlier one rather than this one. */
+ entry->string = str;
+ return entry->index;
+ }
+#ifdef GATHER_STATISTICS
+ tab->bad_hash_matches++;
+#endif
+ ep = &entry->greater;
+ }
+ else if (cmp > 0)
+ ep = &entry->greater;
+ else
+ /* cmp < 0 */
+ ep = &entry->less;
+ }
+
+ /* If we get here, nothing that's in the table already matched.
+ EP points to the `next' field at the end of the chain; stick a
+ new entry on here. */
+ add_it:
+ entry = (struct stringtab_entry *) bfd_alloc_by_size_t (abfd,
+ sizeof (struct stringtab_entry));
+
+ entry->less = entry->greater = 0;
+ entry->hash = hashval;
+ entry->index = tab->index;
+ entry->string = str;
+ entry->next_to_output = 0;
+#ifdef GATHER_STATISTICS
+ entry->count = 1;
+#endif
+
+ assert (*tab->end == 0);
+ *(tab->end) = entry;
+ tab->end = &entry->next_to_output;
+ assert (*tab->end == 0);
+
+ {
+ tab->index += len + 1;
+ if (len == 0)
+ tab->empty_string_index = entry->index;
+ }
+ assert (*ep == 0);
+ *ep = entry;
+ return entry->index;
+}
+
+static void
+emit_strtab (abfd, tab)
+ bfd *abfd;
+ struct stringtab_data *tab;
+{
+ struct stringtab_entry *entry;
+#ifdef GATHER_STATISTICS
+ int count = 0;
+#endif
+
+ /* Be sure to put string length into correct byte ordering before writing
+ it out. */
+ char buffer[BYTES_IN_WORD];
+
+ PUT_WORD (abfd, tab->index, (unsigned char *) buffer);
+ bfd_write ((PTR) buffer, 1, BYTES_IN_WORD, abfd);
+
+ for (entry = tab->output_order; entry; entry = entry->next_to_output)
+ {
+ bfd_write ((PTR) entry->string, 1, strlen (entry->string) + 1, abfd);
+#ifdef GATHER_STATISTICS
+ count++;
+#endif
+ }
+
+#ifdef GATHER_STATISTICS
+ /* Short form only, for now.
+ To do: Specify output file. Conditionalize on environment? Detailed
+ analysis if desired. */
+ {
+ int n_syms = bfd_get_symcount (abfd);
+
+ fprintf (stderr, "String table data for output file:\n");
+ fprintf (stderr, " %8d symbols output\n", n_syms);
+ fprintf (stderr, " %8d duplicate strings\n", tab->duplicates);
+ fprintf (stderr, " %8d empty strings\n", tab->empty_strings);
+ fprintf (stderr, " %8d unique strings output\n", count);
+ fprintf (stderr, " %8d pointer matches\n", tab->pointer_matches);
+ fprintf (stderr, " %8d bytes saved\n", tab->bytes_saved);
+ fprintf (stderr, " %8d bad hash matches\n", tab->bad_hash_matches);
+ fprintf (stderr, " %8d hash-val comparisons\n", tab->n_compares);
+ if (n_syms)
+ {
+ double n_compares = tab->n_compares;
+ double avg_compares = n_compares / n_syms;
+ /* The second value here should usually be near one. */
+ fprintf (stderr, "\t average %f per symbol (%f * log2 nstrings)\n",
+ avg_compares, avg_compares / log2 (count));
+ }
+ }
+#endif
+
+/* Old code:
+ unsigned int count;
+ generic = bfd_get_outsymbols(abfd);
+ for (count = 0; count < bfd_get_symcount(abfd); count++)
+ {
+ asymbol *g = *(generic++);
+
+ if (g->name)
+ {
+ size_t length = strlen(g->name)+1;
+ bfd_write((PTR)g->name, 1, length, abfd);
+ }
+ g->KEEPIT = (KEEPITTYPE) count;
+ } */
+}
void
DEFUN(NAME(aout,write_syms),(abfd),
bfd *abfd)
- {
- unsigned int count ;
- asymbol **generic = bfd_get_outsymbols (abfd);
-
- bfd_size_type stindex = BYTES_IN_WORD; /* initial string length */
-
- for (count = 0; count < bfd_get_symcount (abfd); count++) {
+{
+ unsigned int count ;
+ asymbol **generic = bfd_get_outsymbols (abfd);
+ struct stringtab_data strtab;
+
+ stringtab_init (&strtab);
+
+ for (count = 0; count < bfd_get_symcount (abfd); count++)
+ {
asymbol *g = generic[count];
struct external_nlist nsp;
+ if (g->name)
+ PUT_WORD (abfd, add_to_stringtab (abfd, g->name, &strtab),
+ (unsigned char *) nsp.e_strx);
+ else
+ PUT_WORD (abfd, 0, (unsigned char *)nsp.e_strx);
- if (g->name) {
- unsigned int length = strlen(g->name) +1;
- PUT_WORD (abfd, stindex, (unsigned char *)nsp.e_strx);
- stindex += length;
- }
- else
-
- {
- PUT_WORD (abfd, 0, (unsigned char *)nsp.e_strx);
- }
-
- if (bfd_asymbol_flavour(g) == abfd->xvec->flavour)
- {
- bfd_h_put_16(abfd, aout_symbol(g)->desc, nsp.e_desc);
- bfd_h_put_8(abfd, aout_symbol(g)->other, nsp.e_other);
- bfd_h_put_8(abfd, aout_symbol(g)->type, nsp.e_type);
- }
+ if (bfd_asymbol_flavour(g) == abfd->xvec->flavour)
+ {
+ bfd_h_put_16(abfd, aout_symbol(g)->desc, nsp.e_desc);
+ bfd_h_put_8(abfd, aout_symbol(g)->other, nsp.e_other);
+ bfd_h_put_8(abfd, aout_symbol(g)->type, nsp.e_type);
+ }
else
- {
- bfd_h_put_16(abfd,0, nsp.e_desc);
- bfd_h_put_8(abfd, 0, nsp.e_other);
- bfd_h_put_8(abfd, 0, nsp.e_type);
- }
+ {
+ bfd_h_put_16(abfd,0, nsp.e_desc);
+ bfd_h_put_8(abfd, 0, nsp.e_other);
+ bfd_h_put_8(abfd, 0, nsp.e_type);
+ }
translate_to_native_sym_flags (&nsp, g, abfd);
bfd_write((PTR)&nsp,1,EXTERNAL_NLIST_SIZE, abfd);
- }
-
- /* Now output the strings. Be sure to put string length into correct
- byte ordering before writing it. */
- {
- char buffer[BYTES_IN_WORD];
- PUT_WORD (abfd, stindex, (unsigned char *)buffer);
-
- bfd_write((PTR)buffer, 1, BYTES_IN_WORD, abfd);
- }
- generic = bfd_get_outsymbols(abfd);
- for (count = 0; count < bfd_get_symcount(abfd); count++)
- {
- asymbol *g = *(generic++);
-
- if (g->name)
- {
- size_t length = strlen(g->name)+1;
- bfd_write((PTR)g->name, 1, length, abfd);
- }
- g->KEEPIT = (KEEPITTYPE) count;
- }
- }
+ /* NB: `KEEPIT' currently overlays `flags', so set this only
+ here, at the end. */
+ g->KEEPIT = count;
+ }
+ emit_strtab (abfd, &strtab);
+}
+\f
unsigned int
DEFUN(NAME(aout,get_symtab),(abfd, location),
bfd *abfd AND
if (bfd_is_com_section (output_section)
|| output_section == &bfd_abs_section
- || output_section == &bfd_und_section)
+ || output_section == &bfd_und_section)
{
if (bfd_abs_section.symbol == sym)
{
projects / external / binutils.git / commitdiff