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There is a recurring pattern in assembly files generated by a compiler where a lot of jumps in a function are going to the same place. When these jumps are relaxed with trampolines the assembler generates a separate jump thread from each source. Create an index of trampoline jump targets for each segment and see if a jump being relaxed goes to a location from that index, in which case replace its target with a location of existing trampoline jump that results in the shortest path to the original target. gas/ 2017-11-27 Max Filippov <jcmvbkbc@gmail.com> * config/tc-xtensa.c (trampoline_chain_entry, trampoline_chain) (trampoline_chain_index): New structures. (trampoline_index): Add chain_index field. (xg_order_trampoline_chain_entry, xg_sort_trampoline_chain) (xg_find_chain_entry, xg_get_best_chain_entry) (xg_order_trampoline_chain, xg_get_trampoline_chain) (xg_find_best_eq_target, xg_add_location_to_chain) (xg_create_trampoline_chain, xg_get_single_symbol_slot): New functions. (xg_relax_fixups): Call xg_find_best_eq_target to adjust jump target to point to an existing jump. Call xg_create_trampoline_chain to create new jump target. Call xg_add_location_to_chain to add newly created trampoline jump to the corresponding chain. (add_jump_to_trampoline): Extract loop searching for a single slot with a symbol into a separate function, replace that code with a call to that function. (relax_frag_immed): Call xg_find_best_eq_target to adjust jump target to point to an existing jump. * testsuite/gas/xtensa/all.exp: Add trampoline-2 test. * testsuite/gas/xtensa/trampoline.d: Adjust absolute addresses as many duplicate trampoline chains are now coalesced. * testsuite/gas/xtensa/trampoline.s: Add _nop so that objdump stays in sync with instruction stream. * testsuite/gas/xtensa/trampoline-2.l: New test result file. * testsuite/gas/xtensa/trampoline-2.s: New test source file.
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.