[BZ#23744]
This refactoring was prompted by a problem when the regex code is
used as part of Gnulib and when the builder’s compiler does not grok
__builtin_expect. Problem reported for Gawk by Nelson H.F. Beebe in:
https://lists.gnu.org/r/bug-gnulib/2018-09/msg00137.html
Although this refactoring does not fix the problem directly,
we might as well have Gawk use the now-preferred glibc style for when
__builtin_expect is unavailable.
* posix/regex_internal.h (BE): Remove.
All uses replaced by __glibc_unlikely or __glibc_likely.
This patch syncs the regex implementation with gnulib (commit 0ee5212).
Only two changes in GLIBC regex testing are required:
1. posix/bug-regex28.c: as previously discussed [1] the change of
expected results on the pattern should be safe.
2. posix/PCRE.tests: the ERE (a)|\1 is malformed (in the sense that
the \1 doesn't mean anything) and although current GLIBC accepts
it has undefined behavior. This patch removes the specific test.
This sync contains some patches from thread 'Regex: Make libc regex
more usable outside GLIBC.' [2] which have been pushed upstream in
gnulib. This patches also fixes some regex issues (BZ #23233,
BZ #21163, BZ #18986, BZ #13762) and I did not add testcases for
both #23233 and #13762 because I couldn't think a simple way to
trigger the expected failure path to trigger them.
Checked on x86_64-linux-gnu and i686-linux-gnu.
[BZ #23233]
[BZ #21163]
[BZ #18986]
[BZ #13762]
* posix/Makefile (tests): Add bug-regex37 and bug-regex38.
* posix/PCRE.tests: Remove invalid test.
* posix/bug-regex28.c: Fix expected values for used syntax.
* posix/bug-regex37.c: New file.
* posix/bug-regex38.c: Likewise.
* posix/regcomp.c: Sync with gnulib.
* posix/regex.c: Likewise.
* posix/regex.h: Likewise.
* posix/regex_internal.c: Likewise.
* posix/regex_internal.h: Likewise.
* posix/regexec.c: Likewise.
[1] https://sourceware.org/ml/libc-alpha/2017-12/msg00807.html
[2] https://sourceware.org/ml/libc-alpha/2017-12/msg00237.html
regcomp brings in references to various wctype functions that aren't
in all the standards including regcomp. This patch fixes this in the
usual way by using the __* versions of these functions (which already
exist, but some didn't have libc_hidden_proto / libc_hidden_def
before).
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch). (Other wide character
function references from the regex code mean that this patch by itself
doesn't fix any XFAILed linknamespace test failures; further patches
will be needed for that.)
[BZ #18495]
* wctype/wcfuncs.c (__iswalnum): Use libc_hidden_def.
(__iswlower): Likewise.
* include/wctype.h (__iswalnum): Declare. Use libc_hidden_proto.
(__iswlower): Likewise.
* posix/regcomp.c (re_compile_fastmap_iter): Call __towlower
instead of towlower.
* posix/regex_internal.c (build_wcs_upper_buffer): Call __iswlower
instead of iswlower. Call __towupper instead of towupper.
* posix/regex_internal.h (IS_WIDE_WORD_CHAR): Call __iswalnum
instead of iswalnum.
2005-09-06 Paul Eggert <eggert@cs.ucla.edu>
Ulrich Drepper <drepper@redhat.com>
[BZ #1302]
Change bitset word type from unsigned int to unsigned long int,
as this has better performance on typical 64-bit hosts. Change
bitset type name to bitset_t.
* posix/regcomp.c (build_equiv_class, build_charclass):
(build_range_exp, build_collating_symbol):
Prefer bitset_t to re_bitset_ptr_t in prototypes, when the actual
argument is a bitset. This is merely a style issue, but it makes
it clearer that an entire array is expected.
(re_compile_fastmap_iter, init_dfa, init_word_char, optimize_subexps,
lower_subexp): Adjust for new bitset_t definition.
(lower_subexp, parse_bracket_exp, built_charclass_op): Likewise.
* posix/regex_internal.h (bitset_set, bitset_clear, bitset_contain,
bitset_not, bitset_merge, bitset_set_all, bitset_mask): Likewise.
* posix/regexec.c (check_dst_limits_calc_pos_1,
check_subexp_matching_top, build_trtable, group_nodes_into_DFAstates):
Likewise.
* posix/regcomp.c (utf8_sb_map): Don't assume initializer
== 0xffffffff.
* posix/regex_internal.h (BITSET_WORD_BITS): Renamed from UINT_BITS.
All uses changed.
(BITSET_WORDS): Renamed from BITSET_UINTS. All uses changed.
(bitset_word_t): New type, replacing 'unsigned int' for bitset uses.
All uses changed.
(BITSET_WORD_MAX): New macro.
(bitset_set, bitset_clear, bitset_contain, bitset_empty,
(bitset_set_all, bitset_copy): Adjust for bitset_t change.
(bitset_empty, bitset_copy):
Prefer sizeof (bitset_t) to multiplying it out ourselves.
(bitset_not_merge): Remove; unused.
(bitset_contain): Return bool, not unsigned int with one bit on.
All callers changed.
* posix/regexec.c (build_trtable): Don't assume bitset_t has no
stricter alignment than re_node_set; do this by defining a new
internal type struct dests_alloc and using it to allocate memory.
mbrtowc for very simple UTF-8 case.
2005-09-01 Paul Eggert <eggert@cs.ucla.edu>
* posix/regex_internal.c (build_wcs_upper_buffer): Fix portability
bugs in int versus size_t comparisons.
2005-09-06 Ulrich Drepper <drepper@redhat.com>
* posix/regex_internal.c (re_acquire_state): Make DFA pointer arg
a pointer-to-const.
(re_acquire_state_context): Likewise.
* posix/regex_internal.h: Adjust prototypes.
2005-08-31 Jim Meyering <jim@meyering.net>
* posix/regcomp.c (search_duplicated_node): Make first pointer arg
a pointer-to-const.
* posix/regex_internal.c (create_ci_newstate, create_cd_newstate,
register_state): Likewise.
* posix/regexec.c (search_cur_bkref_entry, check_dst_limits):
(check_dst_limits_calc_pos_1, check_dst_limits_calc_pos):
(group_nodes_into_DFAstates): Likewise.
* posix/regexec.c (re_search_internal): Simplify update of
rm_so and rm_eo by replacing "if (A == B) A += C - B;"
with the equivalent of "if (A == B) A = C;".
2005-09-06 Ulrich Drepper <drepper@redhat.com>
* posix/regcomp.c (re_compile_internal): Change third parameter type
to size_t.
(init_dfa): Likewise. Make sure that arithmetic on pat_len doesn't
overflow.
* posix/regex_internal.h (struct re_dfa_t): Change type of nodes_alloc
and nodes_len to size_t.
* posix/regex_internal.c (re_dfa_add_node): Use size_t as type for
new_nodes_alloc. Check for overflow.
2005-08-31 Paul Eggert <eggert@cs.ucla.edu>
* posix/regcomp.c (re_compile_fastmap_iter, init_dfa, init_word_char):
(optimize_subexps, lower_subexp):
Don't assume 1<<31 has defined behavior on hosts with 32-bit int,
since the signed shift might overflow. Use 1u<<31 instead.
* posix/regex_internal.h (bitset_set, bitset_clear, bitset_contain):
Likewise.
* posix/regexec.c (check_dst_limits_calc_pos_1): Likewise.
(check_subexp_matching_top): Likewise.
* posix/regcomp.c (optimize_subexps, lower_subexp):
Use CHAR_BIT rather than 8, for clarity.
* posix/regexec.c (check_dst_limits_calc_pos_1):
(check_subexp_matching_top): Likewise.
* posix/regcomp.c (init_dfa): Make table_size unsigned, so that we
don't have to worry about portability issues when shifting it left.
Remove no-longer-needed test for table_size > 0.
* posix/regcomp.c (parse_sub_exp): Do not shift more bits than there
are in a word, as the resulting behavior is undefined.
* posix/regexec.c (check_dst_limits_calc_pos_1): Likewise;
in one case, a <= should have been an <, and in another case the
whole test was missing.
* posix/regex_internal.h (BYTE_BITS): Remove. All uses changed to
the standard name CHAR_BIT.
next_last_offset.
(struct re_dfa_t): Remove unused member states_alloc.
* posix/regcomp.c (init_dfa): Don't initialize unused members.
2005-08-25 Paul Eggert <eggert@cs.ucla.edu>
* posix/regexec.c (set_regs): Don't alloca with an unbounded size.
alloca modernization/simplification for regex.
* posix/regex.c: Remove portability cruft for alloca. This no longer
needs to be at the start of the file, and can be moved into
regex_internal.h and simplified.
* posix/regex_internal.h: Include <alloca.h>.
(__libc_use_alloca) [!defined _LIBC]: New macro.
* posix/regexec.c (build_trtable): Remove "#ifdef _LIBC",
since the code now works outside glibc.
2005-09-06 Ulrich Drepper <drepper@redhat.com>
* include/regex.h: Remove use of _RE_ARGS.
2005-08-25 Paul Eggert <eggert@cs.ucla.edu>
* posix/regexec.c (find_recover_state): Change "err" to "*err".
2005-08-24 Paul Eggert <eggert@cs.ucla.edu>
* posix/regcomp.c (regerror): Pointer args are 'restrict',
as per POSIX.
* posix/regex.h (regerror): Likewise.
* manual/pattern.texi (POSIX Regexp Compilation): Likewise.
Similarly for regcomp and regexec. Also, first 2 args of regexec
and 2nd arg of regerror are const.
* posix/regex.c: Do not include <sys/types.h>, as POSIX no longer
requires this. (The code never needed it.)
2005-08-20 Paul Eggert <eggert@cs.ucla.edu>
* posix/regexec.c (sift_states_bkref): re_node_set_insert returns
int, not reg_errcode_t.
* posix/regex_internal.c (calc_state_hash): Put 'inline' before type,
since some broken compilers warn about it otherwise.
* posix/regcomp.c (create_initial_state): Remove duplicate decl.
2005-08-20 Paul Eggert <eggert@cs.ucla.edu>
* posix/regex.h (_RE_ARGS): Remove. No longer needed, since we assume
C89 or better. All uses removed.
2005-09-06 Ulrich Drepper <drepper@redhat.com>
* posix/regex.c: Prevent using C++ compilers.
2005-08-19 Paul Eggert <eggert@cs.ucla.edu>
* posix/regcomp.c (duplicate_node): Return new index, not an error
code, and let the caller return REG_ESPACE if out of space. This
removes an uninitialied-variable warning with GCC 4.0.1, and also
avoids taking the address of a local variable. All callers
changed.
2005-09-06 Ulrich Drepper <drepper@redhat.com>
* include/time.h (__strptime_internal): Rename parameter to avoid
bogus compiler warning.
2005-08-19 Jim Meyering <jim@meyering.net>
* posix/regexec.c (proceed_next_node): Redo local variables to
avoid GCC shadowing warnings.
2005-09-06 Ulrich Drepper <drepper@redhat.com>
* posix/regex_internal.c (re_acquire_state): Minor code rearrangement.
(re_acquire_state_context): Likewise.
2005-08-19 Paul Eggert <eggert@cs.ucla.edu>
* posix/regex_internal.c (re_string_realloc_buffers):
(re_node_set_insert, re_node_set_insert_last, re_dfa_add_node):
Rename local variables to avoid GCC shadowing warnings.
2005-07-08 Eric Blake <ebb9@byu.net>
Paul Eggert <eggert@cs.ucla.edu>
* posix/regcomp.c (init_dfa): Store __btowc value in wint_t, not
wchar_t. Remove now-unnecessary cast.
(build_range_exp): Likewise.
* intl/dcigettext.c (_nl_find_msg): Add a cast.
* nis/nis_clone_dir.c (nis_clone_directory): Use char * for ADDR.
* nis/nis_clone_obj.c (nis_clone_object): Likewise.
* nis/nis_clone_res.c (nis_clone_result): Likewise.
* resolv/nss_dns/dns-network.c (getanswer_r): Use const unsigned char *
for END_OF_MESSAGE and CP.
* resolv/res_send.c (send_dg): Add else branch for case impossible
unless `poll' is buggy.
* crypt/crypt_util.c (__setkey_r): Add a cast.
* locale/programs/linereader.c (get_toplvl_escape): Use size_t for
NBYTES, and unsigned char * for BYTES.
* locale/programs/charmap.c (charmap_new_char): Use size_t and
unsighed char * for NBYTES, BYTES parameters.
* sysdeps/generic/dl-hash.h (_dl_elf_hash): Take const char * argument
and cast it.
* sysdeps/i386/i686/dl-hash.h (_dl_elf_hash): Likewise.
* sunrpc/create_xid.c (_create_xid): Don't use unsigned long for RES.
* sunrpc/svcauth_des.c (_svcauth_des): Fix cast type.
* sunrpc/auth_des.c (authdes_create): Don't use u_char for PKEY_DATA.
(authdes_marshal): Don't use unsigned int for LEN.
* sunrpc/xdr.c (xdr_hyper): Don't use unsigned long for T2.
(xdr_u_hyper): Likewise.
(xdr_u_short): Don't use u_long for L.
* sunrpc/xdr_intXX_t.c (xdr_int64_t): Don't use uint32_t for T2.
* inet/rexec.c (rexec_af): Use socklen_t.
* sunrpc/key_call.c (getkeyserv_handle): Likewise.
* sunrpc/rtime.c (rtime): Likewise.
* resolv/res_send.c (send_vc, send_dg): Likewise.
* nis/nis_callback.c (__nis_create_callback): Likewise.
* sysdeps/generic/libc-start.c: Use unsigned int for nthreads ptr.
* sysdeps/posix/getaddrinfo.c (gaih_inet): Fix type of ADDR local.
* libio/libio.h (_IO_BE): Add parenthesis around EXPR.
* intl/dcigettext.c (INTVARDEF, INTUSE): Macros removed.
(_nl_default_dirname): Use libc_hidden_data_def instead of INTVARDEF.
(libc_freeres_fn, DCIGETTEXT): Don't use INTUSE.
* intl/bindtextdom.c (INTUSE): Macro removed.
(_nl_default_dirname): Use libc_hidden_proto.
(set_binding_values): Don't use INTUSE.
* include/libintl.h (_libc_intl_domainname_internal): Decl removed.
(_libc_intl_domainname): Use libc_hidden_proto.
* posix/regex_internal.h (gettext): Remove INTUSE on it.
* locale/SYS_libc.c (_libc_intl_domainname): Use libc_hidden_data_def
rather than INTDEF.
* include/libintl.h (_): Don't use *_internal name.
* ctype/ctype-extn.c (__ctype_tolower, __ctype_toupper): Use int32_t,
not uint32_t.
* locale/lc-ctype.c (_nl_postload_ctype): Likewise for assignments.
* iconv/gconv_open.c (__gconv_open): Remove useless cast.
[BZ #721]
* sysdeps/i386/dl-machine.h (ELF_MACHINE_NO_RELA): Define this outside
of [RESOLVE_MAP].
* sysdeps/sh/dl-machine.h (ELF_MACHINE_NO_REL): Likewise.
* sysdeps/powerpc/powerpc32/dl-machine.h
(elf_machine_rel, elf_machine_rel_relative): Removed.
* sysdeps/powerpc/powerpc64/dl-machine.h
(elf_machine_rel, elf_machine_rel_relative): Removed.
2005-02-03 Alexandre Oliva <aoliva@redhat.com>
[BZ #721]
* elf/dynamic-link.h: Don't declare nested auto functions that are
not going to be defined.
2004-07-23 Jakub Jelinek <jakub@redhat.com>
[BZ #284]
* include/features.h (_POSIX_SOURCE, _POSIX_C_SOURCE): Define
if _XOPEN_SOURCE >= 500 even if __STRICT_ANSI__ is defined.
2005-02-16 Roland McGrath <roland@redhat.com>
Update.
2004-12-13 Paolo Bonzini <bonzini@gnu.org>
Separate parsing and creation of the NFA. Avoided recursion on
the (very unbalanced) parse tree.
[BZ #611]
* posix/regcomp.c (struct subexp_optimize, analyze_tree, calc_epsdest,
re_dfa_add_tree_node, mark_opt_subexp_iter): Removed.
(optimize_subexps, duplicate_tree, calc_first, calc_next,
mark_opt_subexp): Rewritten.
(preorder, postorder, lower_subexps, lower_subexp, link_nfa_nodes,
create_token_tree, free_tree, free_token): New.
(analyze): Accept a regex_t *. Invoke the passes via the preorder and
postorder generic visitors. Do not initialize the fields in the
re_dfa_t that represent the transitions.
(free_dfa_content): Use free_token.
(re_compile_internal): Analyze before UTF-8 optimizations. Do not
include optimization of subexpressions.
(create_initial_state): Fetch the DFA node index from the first node's
bin_tree_t *.
(optimize_utf8): Abort on unexpected nodes, including OP_DUP_QUESTION.
Return on COMPLEX_BRACKET.
(duplicate_node_closure): Fix comment.
(duplicate_node): Do not initialize the fields in the
re_dfa_t that represent the transitions.
(calc_eclosure, calc_inveclosure): Do not handle OP_DELETED_SUBEXP.
(create_tree): Remove final argument. All callers adjusted. Rewritten
to use create_token_tree.
(parse_reg_exp, parse_branch, parse_expression, parse_bracket_exp,
build_charclass_op): Use create_tree or create_token_tree instead
of re_dfa_add_tree_node.
(parse_dup_op): Likewise. Also free the tree using free_tree for
"<re>{0}", and lower OP_DUP_QUESTION to OP_ALT: "a?" is equivalent
to "a|". Adjust invocation of mark_opt_subexp.
(parse_sub_exp): Create a single SUBEXP node.
* posix/regex_internal.c (re_dfa_add_node): Remove last parameter,
always perform as if it was 1. Do not initialize OPT_SUBEXP and
DUPLICATED, and initialize the DFA fields representing the transitions.
* posix/regex_internal.h (re_dfa_add_node): Adjust prototype.
(re_token_type_t): Move OP_DUP_PLUS and OP_DUP_QUESTION to the tokens
section. Add a tree-only code SUBEXP. Remove OP_DELETED_SUBEXP.
(bin_tree_t): Include a full re_token_t for TOKEN. Turn FIRST and
NEXT into pointers to trees. Remove ECLOSURE.
2004-12-28 Paolo Bonzini <bonzini@gnu.org >
[BZ #605]
* posix/regcomp.c (parse_bracket_exp): Do not modify DFA nodes
that were already created.
* posix/regex_internal.c (re_dfa_add_node): Set accept_mb field
in the token if needed.
(create_ci_newstate, create_cd_newstate): Set accept_mb field
from the tokens' field.
* posix/regex_internal.h (re_token_t): Add accept_mb field.
(ACCEPT_MB_NODE): Removed.
* posix/regexec.c (proceed_next_node, transit_states_mb,
build_sifted_states, check_arrival_add_next_nodes): Use
accept_mb instead of ACCEPT_MB_NODE.
2004-04-27 Paolo Bonzini <bonzini@gnu.org>
* posix/regex_internal.h (struct re_dfastate_t): Make
word_trtable a pointer to the 512-item transition table.
* posix/regexec.c (build_trtable): Fill in either state->trtable
or state->word_trtable. Return a boolean indicating success.
(transit_state): Expect state->trtable to be a 256-item
transition table. Reorganize code to have less tests in
the common case, and to save an indentation level.
2004-12-07 Paolo Bonzini <bonzini@gnu.org>
* posix/regexec.c (proceed_next_node): Simplify treatment of epsilon
nodes. Pass the pushed node to push_fail_stack.
(push_fail_stack): Accept a single node rather than an array
of two epsilon destinations.
(build_sifted_states): Only walk non-epsilon nodes.
(check_arrival): Don't pass epsilon nodes to
check_arrival_add_next_nodes.
(check_arrival_add_next_nodes) [DEBUG]: Abort if an epsilon node is
found.
(check_node_accept): Do expensive checks later.
(add_epsilon_src_nodes): Cache result of merging the inveclosures.
* posix/regex_internal.h (re_dfastate_t): Add non_eps_nodes and
inveclosure.
(re_string_elem_size_at, re_string_char_size_at, re_string_wchar_at,
re_string_context_at, re_string_peek_byte_case,
re_string_fetch_byte_case, re_node_set_compare, re_node_set_contains):
Declare as pure.
* posix/regex_internal.c (create_newstate_common): Remove.
(register_state): Move part of it here. Initialize non_eps_nodes.
(free_state): Free inveclosure and non_eps_nodes.
(create_cd_newstate, create_ci_newstate): Allocate the new
re_dfastate_t here.
2004-12-01 Paolo Bonzini <bonzini@gnu.org>
* posix/regcomp.c (free_dfa_content, init_dfa): Remove
references to re_dfa_t's subexps field.
(parse_sub_exp, parse_expression): Do not use it. Use
completed_bkref_map instead.
(create_initial_state, peek_token): Store a backreference \N
with opr.idx = N-1.
* posix/regexec.c (proceed_next_node, check_dst_limits, get_subexp):
Likewise.
(check_subexp_limits): Remove useless condition.
* posix/regex_internal.h (re_subexp_t): Remove.
(re_dfa_t): Remove subexps and subexps_alloc field, add
completed_bkref_map.
2004-11-23 Paolo Bonzini <bonzini@gnu.org>
* posix/regcomp.c (analyze_tree): Always call calc_epsdest.
(calc_inveclosure): Use re_node_set_insert_last.
(parse_dup_op): Lower X{1,5} to (X(X(X(XX?)?)?)?)?
rather than X?X?X?X?X?.
* posix/regex_internal.h (re_node_set_insert_last): New declaration.
* posix/regex_internal.c (re_node_set_insert_last): New function.
* posix/PCRE.tests: Add testcases.
Update.
2004-11-18 Jakub Jelinek <jakub@redhat.com>
[BZ #544]
* posix/regex.h (RE_NO_SUB): New define.
* posix/regex_internal.h (OP_DELETED_SUBEXP): New.
(re_dfa_t): Add subexp_map.
* posix/regcomp.c (struct subexp_optimize): New type.
(optimize_subexps): New routine.
(re_compile_internal): Call it.
(re_compile_pattern): Set preg->no_sub to 1 if RE_NO_SUB.
(free_dfa_content): Free subexp_map.
(calc_inveclosure, calc_eclosure): Skip OP_DELETED_SUBEXP
nodes.
* posix/regexec.c (re_search_internal): If subexp_map
is not NULL, duplicate registers as needed.
* posix/Makefile: Add rules to build and run tst-regex2.
* posix/tst-regex2.c: New test.
* posix/rxspencer/tests: Fix last two tests (\0 -> \1).
Add some new tests for nested subexpressions.
2004-11-12 Ulrich Drepper <drepper@redhat.com>
* posix/Makefile (tests): Add bug-regex24.
* posix/bug-regex24.c: New file.
2004-11-12 Paolo Bonzini <bonzini@gnu.org>
* posix/regexec.c (check_dst_limits_calc_pos_1): Use the map to
cut recursive paths. Make exit condition more precise.
(match_ctx_add_entry): Initialize the map.
* posix/regex_internal.h (struct re_backref_cache_entry): Add a map of
reachable subexpression nodes from each backreference cache entry.
2004-11-08 Ulrich Drepper <drepper@redhat.com>
* posix/regcomp.c (utf8_sb_map): Define.
(free_dfa_content): Don't free dfa->sb_char if it's a pointer to
utf8_sb_map.
(init_dfa): Use utf8_sb_map instead of initializing memory when the
encoding is UTF-8.
* posix/regcomp.c (init_dfa): Get the codeset name outside glibc as
well. Check if it is spelled UTF8 as well as UTF-8, and check
case-insensitively. Set dfa->map_notascii manually when outside
glibc.
* posix/regex_internal.c (build_wcs_upper_buffer) [!_LIBC]: Enable
optimizations based on map_notascii.
* posix/regex_internal.h [HAVE_LANGINFO_H || HAVE_LANGINFO_CODESET
|| _LIBC]: Include langinfo.h.
* posix/regex_internal.h (struct re_backref_cache_entry): Add "more"
field.
* posix/regexec.c (check_dst_limits): Hoist computation of the source
and destination bkref_idx out of the loop. Pass it to
check_dst_limits_calc_pos.
(check_dst_limits_calc_pos_1): New function, containing the recursive
loop of check_dst_limits_calc_pos; uses the "more" field of
struct re_backref_cache to control the loop.
(check_dst_limits_calc_pos): Store into "boundaries" the position
relative to lim's start and end positions. Do not accept eclosures,
accept bkref_idx instead. Call check_dst_limits_calc_pos_1 to do the
work.
(sift_states_bkref): Use the "more" field of struct re_backref_cache
to control the loop. A big "if" was turned into a continue and the
function was reindented.
(get_subexp): Use the "more" field of struct re_backref_cache
to control the loop.
(match_ctx_add_entry): Initialize the bkref_ents' "more" field.
(search_cur_bkref_entry): Return -1 if out of bounds.
* posix/regexec.c (empty_set): Remove.
(sift_states_backward): Remove cur_src variable. Move inner loop
to build_sifted_states.
(build_sifted_states): Extract from sift_states_backward. Do not
use empty_set.
(update_cur_sifted_state): Do not use empty_set. Special case
dest_nodes->nelem == 0.
