mirror of
https://github.com/espressif/binutils-gdb.git
synced 2025-08-02 19:46:09 +08:00
8bcb520897
Supply default gdbarch methods for gdbarch_dummy_id, gdbarch_unwind_pc, and gdbarch_unwind_sp. This patch doesn't actually convert any targets to use these methods, and so, there will be no user visible changes after this commit. The implementations for default_dummy_id and default_unwind_sp are fairly straight forward, these just take on the pattern used by most targets. Once these default methods are in place then most targets will be able to switch over. The implementation for default_unwind_pc is also fairly straight forward, but maybe needs some explanation. This patch has gone through a number of iterations: https://sourceware.org/ml/gdb-patches/2018-03/msg00165.html https://sourceware.org/ml/gdb-patches/2018-03/msg00306.html https://sourceware.org/ml/gdb-patches/2018-06/msg00090.html https://sourceware.org/ml/gdb-patches/2018-09/msg00127.html and the implementation of default_unwind_pc has changed over this time. Originally, I took an implementation like this: CORE_ADDR default_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame) { int pc_regnum = gdbarch_pc_regnum (gdbarch); return frame_unwind_register_unsigned (next_frame, pc_regnum); } This is basically a clone of default_unwind_sp, but using $pc. It was pointed out that we could potentially do better, and in version 2 the implementation became: CORE_ADDR default_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame) { struct type *type; int pc_regnum; CORE_ADDR addr; struct value *value; pc_regnum = gdbarch_pc_regnum (gdbarch); value = frame_unwind_register_value (next_frame, pc_regnum); type = builtin_type (gdbarch)->builtin_func_ptr; addr = extract_typed_address (value_contents_all (value), type); addr = gdbarch_addr_bits_remove (gdbarch, addr); release_value (value); value_free (value); return addr; } The idea was to try split out some of the steps of unwinding the $pc, steps that are on some (or many) targets no-ops, and so allow targets that do override these methods, to make use of default_unwind_pc. This implementation remained in place for version 2, 3, and 4. However, I realised that I'd made a mistake, most targets simply use frame_unwind_register_unsigned to unwind the $pc, and this throws an error if the register value is optimized out or unavailable. My new proposed implementation doesn't do this, I was going to end up breaking many targets. I considered duplicating the code from frame_unwind_register_unsigned that throws the errors into my new default_unwind_pc, however, this felt really overly complex. So, what I instead went with was to simply revert back to using frame_unwind_register_unsigned. Almost all existing targets already use this. Some of the ones that don't can be converted to, which means almost all targets could end up using the default. One addition I have made over the version 1 implementation is to add a call to gdbarch_addr_bits_remove. For most targets this is a no-op, but for a handful, having this call in place will mean that they can use the default method. After all this, the new default_unwind_pc now looks like this: CORE_ADDR default_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame) { int pc_regnum = gdbarch_pc_regnum (gdbarch); CORE_ADDR pc = frame_unwind_register_unsigned (next_frame, pc_regnum); pc = gdbarch_addr_bits_remove (gdbarch, pc); return pc; } gdb/ChangeLog: * gdb/dummy-frame.c (default_dummy_id): Defined new function. * gdb/dummy-frame.h (default_dummy_id): Declare new function. * gdb/frame-unwind.c (default_unwind_pc): Define new function. (default_unwind_sp): Define new function. * gdb/frame-unwind.h (default_unwind_pc): Declare new function. (default_unwind_sp): Declare new function. * gdb/frame.c (frame_unwind_pc): Assume gdbarch_unwind_pc is available. (get_frame_sp): Assume that gdbarch_unwind_sp is available. * gdb/gdbarch.c: Regenerate. * gdb/gdbarch.h: Regenerate. * gdb/gdbarch.sh: Update definition of dummy_id, unwind_pc, and unwind_sp. Add additional header files to be included in generated 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.