gdb futures

[Nelson H. F. Beebe]

This is not a bug report, but rather, a small proposal for future gdb
development.  It was not clear where such a posting should be made,
and this list should reach the gdb developers.

Occasionally in the past, and again this week, I've had occasion to
need a facility that no debugger I've ever encountered, including gdb,
appears to offer: animation.  By that, I mean the ability to run the
debugger in a mode where it gets an apparently unbounded stream of
"next" or "step" instructions which it reads, executes, displays the
current statement, and continues.

The "next NNN" or "step NNN" statements in gdb do not work, because
they suppress output of statements 1, 2, ..., NNN-1.  If they offered
a verbose option, in which each line would be echoed to the screen,
then I'd have exactly what I need.

I was able to fake this approximately in gdb by creating a file with
tens of thousands of "step" commands, then inputting it with the
"source" command.  However, gdb then obnoxiously paused and asked for
confirmation at the end of every screenful, making the animation
attempt exceedingly tedious to complete.

The reason I want a facility like this is to help track down a problem
where the same program compiled by two different compilers
inexplicably produces different results.  The program in question has
very complex control flow, and complex data structures, most of them
dynmically allocated, so I've been unsuccessful in using breakpoints
and watchpoints to determine where the two executables diverge in
execution.  With two animations in hand, and the diff utility, it
should be straightforward to find the source of the divergence.

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- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- Center for Scientific Computing       FAX: +1 801 585 1640, +1 801 581 4148 -
- University of Utah                    Internet e-mail: address@hidden  -
- Department of Mathematics, 322 INSCC      address@hidden  address@hidden -
- 155 S 1400 E RM 233                       address@hidden                    -
- Salt Lake City, UT 84112-0090, USA    URL: http://www.math.utah.edu/~beebe  -
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