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The original check_section_ebb_pcrels_fit algorithm checks that text
actions proposed for current EBB are OK for every relocation in a
section. There's no need to check every relocation, because text actions
for EBB can only change size of that EBB, thus only affecting
relocations that in any way cross that EBB. In addition EBBs are
iterated in ascending order of their VMA, making it easier to track
relevant relocations.
Introduce a structure that can track relocations that cross the range of
VMAs of EBB and use it to only check relocations relevant to current EBB
in check_section_ebb_pcrels_fit.
It takes O(N log N) operations to build it and O(N) operations to move
current EBB VMA window through its entire range, where N is the number
of relocations in a section. The resulting complexity of
compute_text_actions is thus reduced from O(N^2) to O(N log N + N * M),
where M is the average number of relocations crossing each EBB.
Original profile:
% time self children called name
-----------------------------------------
44.26 71.53 6429/6429 compute_text_actions
50.2 44.26 71.53 6429 check_section_ebb_pcrels_fit
1.16 20.12 347506666/347576152 pcrel_reloc_fits
2.95 16.52 347506666/348104944 get_relocation_opnd
2.01 9.74 347575100/361252208 r_reloc_init
0.55 7.53 347575100/363381467 r_reloc_get_section
5.76 0.02 695013332/695013332 xlate_offset_with_removed_text
0.68 3.89 347575100/363483827 bfd_octets_per_byte
0.32 0.00 347506666/349910253 is_alt_relocation
0.18 0.11 6391/6391 build_xlate_map
0.00 0.00 6429/19417168 get_xtensa_relax_info
0.00 0.00 6391/6391 free_xlate_map
-----------------------------------------
Same data, after optimization:
% time self children called name
-----------------------------------------
2.56 3.08 6429/6429 compute_text_actions
8.2 2.56 3.08 6429 check_section_ebb_pcrels_fit
0.08 0.91 17721075/17790561 pcrel_reloc_fits
0.17 0.47 17721075/31685977 r_reloc_init
0.43 0.00 35442150/35442150 xlate_offset_with_removed_text
0.02 0.37 17721075/33815236 r_reloc_get_section
0.22 0.11 6391/6391 build_xlate_map
0.05 0.22 17721075/33917596 bfd_octets_per_byte
0.03 0.00 17721075/20405299 is_alt_relocation
0.01 0.00 6429/6429 reloc_range_list_update_range
0.00 0.00 6429/19417168 get_xtensa_relax_info
0.00 0.00 6391/6391 free_xlate_map
-----------------------------------------
2015-04-01 Max Filippov <jcmvbkbc@gmail.com>
bfd/
* elf32-xtensa.c (reloc_range_list, reloc_range_list_entry,
reloc_range): new typedef.
(reloc_range_list_struct, reloc_range_list_entry_struct,
reloc_range_struct): new structures.
(reloc_range_compare, build_reloc_ranges,
reloc_range_list_append, reloc_range_list_remove,
reloc_range_list_update_range, free_reloc_range_list): new
functions.
(compute_text_actions): precompute relocation opcodes before the
loop. Add relevant_relocs variable, initialize it before the
loop, pass it to the check_section_ebb_pcrels_fit.
(check_section_ebb_pcrels_fit): add new parameter:
relevant_relocs. Update address range in the relevant_relocs if
it's non-NULL and iterate only over relevant relocations.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.