GitLab

 src/bidi.c (BIDI_CACHE_MAX_ELTS_PER_SLOT): New macro.
 (bidi_cache_max_elts): New global variable.
 (bidi_shelve_header_size): Add the sizeof bidi_cache_max_elts.
 (bidi_cache_shrink, bidi_initialize): Reset bidi_cache_max_elts to
 its initial value.
 (bidi_cache_search): Handle overflown cache.  Improve commentary.
 (bidi_cache_ensure_space): Limit allocations to the current value
 of bidi_cache_max_elts.  Force xpalloc not to over-allocate.  If
 less than a full BIDI_CACHE_CHUNK is left to the limit, decrease
 the increment to not exceed the limit.
 (bidi_cache_iterator_state): Now returns non-zero if succeeded to
 cache, zero otherwise (meaning the cache overflowed).  In the
 latter case, set bidi_cache_last_idx to -1.
 (bidi_peek_at_next_level): Handle overflown cache.
 (bidi_push_it): Increase the cache limit for iterating the new
 object.
 (bidi_pop_it): Decrease the cache limit back to previous value.
 (bidi_shelve_cache): Shelve the current value of the cache limit.
 (bidi_unshelve_cache): Restore the value of cache limit.
 (bidi_find_bracket_pairs): If the cache overflows while looking
 for the paired bracket, give up and let bidi_resolve_neutrals
 process the bracket as a simple neutral.
 (bidi_find_other_level_edge): If the cache overflows, fall back on
 Plan B, which effectively stops the reordering and restarts it on
 the next character (after resetting the cache).
 (bidi_move_to_visually_next): When the cache overflows, reset it
 after processing the last cached character.

 src/dispextern.h (enum bidi_dir_t): Force NEUTRAL_DIR to be zero.
 (struct bidi_stack): Reduce size by using bit fields and by
 packing sos, override, and isolate_status into a single 8-bit
 byte called 'flags'.
 src/bidi.c (ISOLATE_STATUS, OVERRIDE): New macros.
 (bidi_push_embedding_level): Construct flags from individual
 bits.  Adapt to changes in prev_for_neutral and next_for_neutral
 members.
 (bidi_pop_embedding_level): Use ISOLATE_STATUS.  Extract 'sos'
 from flags.  Adapt to changes in prev_for_neutral,
 next_for_neutral, and last_strong members.
 (bidi_line_init): Initialize flags to zero.
 (bidi_resolve_explicit, bidi_resolve_weak, bidi_resolve_brackets)
 (bidi_resolve_neutral): Use ISOLATE_STATUS and OVERRIDE.

 src/bidi.c (bidi_find_first_overridden): New function.
 src/xdisp.c (Fbidi_find_overridden_directionality): New function.
 (syms_of_xdisp): Defsubr it.
 src/dispextern.h (bidi_find_first_overridden): Add prototype.

 doc/lispref/display.texi (Bidirectional Display): Document
 'bidi-find-overridden-directionality'.

 etc/NEWS: Mention 'bidi-find-overridden-directionality'.

 src/bidi.c (bidi_cache_reset_to): Invalidate bidi_cache_last_idx by
 setting it to -1.
 (bidi_find_bracket_pairs): Pass to bidi_cache_reset_to a relative
 index, not an absolute one, as that's what the function expects.

 src/bidi.c (bidi_resolve_explicit, bidi_find_bracket_pairs)
 (bidi_resolve_brackets): Use end of string position rather than ZV
 when iterating over a string.

 src/bidi.c (bidi_cache_reset_to): New function.
 (bidi_cache_reset): Call it.
 (bidi_init_it, bidi_line_init): Initialize the bracket_pairing_pos
 member to -1.
 (bidi_resolve_explicit): Reset bracket_pairing_pos and
 bracket_enclosed_type only if bracket_pairing_pos's value is not
 ZV.
 (MAX_BPA_STACK): Make sure the value is signed.
 (PUSH_BPA_STACK): If the BPA stack overflows, don't bail out, but
 stop pushing values onto the stack.
 (bidi_find_bracket_pairs): If the bracketed text is only on the
 base embedding level, remove all the states cached by this
 function from the cache, and return zero, so that the brackets in
 this segment of text are processed as normal neutrals.
 (bidi_resolve_brackets): Detect the brackets that are to be
 processed as neutrals, and don't call bidi_find_bracket_pairs on
 them.

This pacifies GCC 4.9.1 with --enable-gcc-warnings.
It's not clear to me whether the initialization is needed,
but it can't hurt so I played it safe.

Scrolled successfully through the entire biditest.txt file.
The parentheses are still not implemented.

Improve glyphless glyph display in .gdbinit/pgx.

bidi_resolve_neutral needs to be fixed, as it now aborts at line 2432.

This still crashes in TUTORIAL.he.