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ORStackInspect - Inspect stack variables when printing a backtrace

Description

NOTE: Unlike other modifications, this modification is not standalone. It requires that you applied the DoubleTrap, TrapBacktrace, ZeroLocalVariables and ORInspect modifications before this modification.

Debugging capabilities of Project Oberon are limited. You can output things to System.Log or you can get raw memory dumps. This is far from what you can expect from other debuggers. The ORInspect improves this situation, so that you can inspect global and heap variables.

To extend this inspection capabilities to variables on the stack (when printing a stack backtrace), this modification adds an extra .ssy (stack inspect symbol) file type (written by the compiler), and modifies the stack frames on the stack that they include an additional word, which encodes the corresponding .ssy entry as well as the size of the stack frame and whether it contains a return address to the previous stack frame. This information can be used when printing a backtrace, to reduce the risk of false positive return addresses, as well as to augment the backtrace with local variable information. As the stack frame format has changed, the whole system needs to be recompiled.

As the printing of the backtrace is a constrained environment (both in respect to the available stack and in potential heap memory pressure), backtrace output is not changed by default. You can execute ORStackInspect.OnTrap and/or ORStackInspect.OnAbort to enable the functionality. Regardless, you can embed calls to ORStackInspect.Backtrace to your code to print backtraces programmatically. By default, .ssy files are ignored and therefore no local variables are printed. You can call ORStackInspect.Load YourModule to load YourModule.ssy, or you can call ORStackInspect.LoadAll to load all available .ssy files (for loaded modules).

During compilation, generation of .ssy files is also bound to the /d switch, just like .isy files.

Installation

  • Apply DoubleTrap, TrapBacktrace, ZeroLocalVariables and ORInspect, if not already applied.

  • Push ORStackInspect.Mod.txt and ORStackInspect.Tool.txt.

  • Apply StackSymbols.patch to ORB.Mod, ORG.Mod, ORP.Mod, System.Mod and Oberon.Mod.

  • Recompile the whole system, as the stack layout has changed:

    ORP.Compile Kernel.Mod/s FileDir.Mod/s Files.Mod/s Modules.Mod/s ~
ORL.Link Modules ~
ORL.Load Modules.bin ~

ORP.Compile Input.Mod/s Display.Mod/s Viewers.Mod/s ~
ORP.Compile Fonts.Mod/s Texts.Mod/s ~
ORP.Compile Oberon.Mod/s ~
ORP.Compile MenuViewers.Mod/s ~
ORP.Compile TextFrames.Mod/s ~
ORP.Compile System.Mod/s ~
ORP.Compile Edit.Mod/s ~
ORP.Compile ORS.Mod/s ORB.Mod/s ~
ORP.Compile ORG.Mod/s ORP.Mod/s ~
ORP.Compile ORStackInspect.Mod/s ~

  • Restart the system.

  • Recompile all modules that you want to inspect, with the /d switch.

  • Open ORStackInspect.Tool and start inspecting.