ae45162705
This patch fixes a problem with using the MI -var-update command to access the values of registers in frames other than the current frame. The patch includes a test that demonstrates the problem: * run so there are several frames on the stack * create a fixed varobj for $pc in each frame, #'s 1 and above * step one instruction, to modify the value of $pc * call -var-update for each of the previously created varobjs to verify that they are not reported as having changed. Without the patch, the -var-update command reported that $pc for all frames 1 and above had changed to the value of $pc in frame 0. A varobj is created as either fixed, the expression is evaluated within the context of a specific frame, or floating, the expression is evaluated within the current frame, whatever that may be. When a varobj is created by -var-create we set two fields of the varobj to track the context in which the varobj was created, these two fields are varobj->root->frame and var->root->valid_block. If a varobj is of type fixed, then, when we subsequently try to reevaluate the expression associated with the varobj we must determine if the original frame (and block) is still available, if it is not then the varobj can no longer be evaluated. The problem is that for register expressions varobj->root->valid_block is not set correctly. This block tracking is done using the global 'innermost_block' which is set in the various parser files (for example c-exp.y). However, this is not set for register expressions. The fix then seems like it should be to just update the innermost block when parsing register expressions, however, that solution causes several test regressions. The problem is that in some cases we rely on the expression parsing code not updating the innermost block for registers, one example is when we parse the expression for a 'display' command. The display commands treats registers like floating varobjs, but symbols are treated like fixed varobjs. So 'display $reg_name' will always show the value of '$reg_name' even as the user moves from frame to frame, while 'display my_variable' will only show 'my_variable' while it is in the current frame and/or block, when the user moves to a new frame and/or block (even one with a different 'my_variable' in) then the display of 'my_variable' stops. For the case of 'display', without the option to force fixed or floating expressions, the current behaviour is probably the best choice. For the varobj system though, we can choose between floating and fixed, and we should try to make this work for registers. There's only one existing test case that needs to be updated, in that test a fixed varobj is created using a register, the MI output now include the thread-id in which the varobj should be evaluated, which I believe is correct behaviour. I also added a new floating test case into the same test script, however, right now this also includes the thread-id in the expected output, which I believe is an existing gdb bug, which I plan to fix next. Tested on x86_64 Linux native and native-gdbserver, no regressions. gdb/ChangeLog: PR mi/20395 * ada-exp.y (write_var_from_sym): Pass extra parameter when updating innermost block. * parse.c (innermost_block_tracker::update): Take extra type parameter, and check types match before updating innermost block. (write_dollar_variable): Update innermost block for registers. * parser-defs.h (enum innermost_block_tracker_type): New enum. (innermost_block_tracker::innermost_block_tracker): Initialise m_types member. (innermost_block_tracker::reset): Take type parameter. (innermost_block_tracker::update): Take type parameter, and pass type through as needed. (innermost_block_tracker::m_types): New member. * varobj.c (varobj_create): Pass type when reseting innermost block. gdb/testsuite/ChangeLog: * gdb.mi/basics.c: Add new global. * gdb.mi/mi-frame-regs.exp: New file. * gdb.mi/mi-var-create-rtti.exp: Update expected results, add new case. |
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README
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.