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This patch teaches GDB to take advantage of target-assisted range stepping. It adds a new 'r ADDR1,ADDR2' action to vCont (vCont;r), meaning, "step once, and keep stepping as long as the thread is in the [ADDR1,ADDR2) range". Rationale: When user issues the "step" command on the following line of source, a = b + c + d * e - a; GDB single-steps every single instruction until the program reaches a new different line. E.g., on x86_64, that line compiles to: 0x08048434 <+65>: mov 0x1c(%esp),%eax 0x08048438 <+69>: mov 0x30(%esp),%edx 0x0804843c <+73>: add %eax,%edx 0x0804843e <+75>: mov 0x18(%esp),%eax 0x08048442 <+79>: imul 0x2c(%esp),%eax 0x08048447 <+84>: add %edx,%eax 0x08048449 <+86>: sub 0x34(%esp),%eax 0x0804844d <+90>: mov %eax,0x34(%esp) 0x08048451 <+94>: mov 0x1c(%esp),%eax and the following is the RSP traffic between GDB and GDBserver: --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:3c840408;thread:p2e13.2e13;core:1; --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:3e840408;thread:p2e13.2e13;core:2; --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:42840408;thread:p2e13.2e13;core:2; --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:47840408;thread:p2e13.2e13;core:0; --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:49840408;thread:p2e13.2e13;core:0; --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:4d840408;thread:p2e13.2e13;core:0; --> vCont;s:p2e13.2e13;c <-- T0505:68efffbf;04:30efffbf;08:51840408;thread:p2e13.2e13;core:0; IOW, a lot of roundtrips between GDB and GDBserver. If we add a new command to the RSP, meaning "keep stepping and don't report a stop until the program goes out of the [0x08048434, 0x08048451) address range", then the RSP traffic can be reduced down to: --> vCont;r8048434,8048451:p2db0.2db0;c <-- T0505:68efffbf;04:30efffbf;08:51840408;thread:p2db0.2db0;core:1; As number of packets is reduced dramatically, the performance of stepping source lines is much improved. In case something is wrong with range stepping on the stub side, the debug info or even gdb, this adds a "set/show range-stepping" command to be able to turn range stepping off. gdb/ 2013-05-23 Yao Qi <yao@codesourcery.com> Pedro Alves <palves@redhat.com> * gdbthread.h (struct thread_control_state) <may_range_step>: New field. * infcmd.c (step_once, until_next_command): Enable range stepping. * infrun.c (displaced_step_prepare): Disable range stepping. (resume): Disable range stepping if stepping over a breakpoint or we have software watchpoints. If range stepping is enabled, assert the thread is in the stepping range. (clear_proceed_status_thread): Clear may_range_step. (handle_inferior_event): Disable range stepping as soon as we know the thread that hit the event. Re-enable it whenever we're going to step with a step range. * remote.c (struct vCont_action_support) <r>: New field. (use_range_stepping): New global. (remote_vcont_probe): Handle 'r' action. (append_resumption): Append an 'r' action if the thread may range step. (show_range_stepping): New function. (set_range_stepping): New function. (_initialize_remote): Call add_setshow_boolean_cmd to register the 'set range-stepping' and 'show range-stepping' commands. * NEWS: Mention range stepping, the new vCont;r action, and the new "set/show range-stepping" commands. gdb/doc/ 2013-05-23 Yao Qi <yao@codesourcery.com> Pedro Alves <palves@redhat.com> * gdb.texinfo (Packets): Document 'vCont;r'. (Continuing and Stepping): Document target-assisted range stepping, and the 'set range-stepping' and 'show range-stepping' commands.
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.