Step commands in debugger are throwing exceptions in console

[Dr. MefistO]

"z" or "t" command after landing at some breakpoint, doesn't work. It throws many exceptions in debugger console, looses current state, and program continues executes without a debugger, then finishes its execution.

Could you fix that annoying behavior?

Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 25, PC=00F86462
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 27, PC=00FE4F50
Exception 26, PC=00FE4F50
Exception 27, PC=00FE4F50
Exception 26, PC=00FE4F50
Exception 27, PC=00FE4F50
Exception 27, PC=00FE4F50
Exception 27, PC=00FE4F50
Exception 27, PC=00FE4F50
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 26, PC=00E2235E
Exception 8, PC=00F86BB4
Exception 25, PC=00F86462
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 8, PC=00F86BB4
Exception 27, PC=00FE4F50
Exception 26, PC=00FE4F50
Exception 27, PC=00FE4F50
Exception 27, PC=00FE4F50

After some investigation:

/* ORSR.W #<data>.W */
uae_u32 REGPARAM2 CPUFUNC(op_007c_11)(uae_u32 opcode)
{
	int count_cycles = 0;
{if (!regs.s) { Exception (8); goto l_110018; }

After execution breakpoints, regs.s equals to zero here. And because exception_debugging variable is set to 1 after breakpoint, it shows these exceptions.

It is strange, that on the same commands, stepping doesn't execute "uae_u32 REGPARAM2 CPUFUNC(op_007c_11)(uae_u32 opcode)" function. It looks like the execution context of other threads breaks with execution context of my program.

[Toni Wilen]

JIT enabled? It causes undefined behavior.

Debugger also does not care about contexts or threads, it is mainly designed for debugging programs (games/demos) that take over the system. (for example t will not skip interrupts)

[Dr. MefistO]

Originally Posted by Toni Wilen

JIT enabled? It causes undefined behavior.

I'll try to switch off it and check.

Originally Posted by Toni Wilen

Debugger also does not care about contexts or threads, it is mainly designed for debugging programs (games/demos) that take over the system. (for example t will not skip interrupts)

So, Only steps are allowed? I have a console program, that takes over the system. But when WinUAE switches to some system task, it breaks the registers state.

[Dr. MefistO]

It doesn't work without JIT too.

[Toni Wilen]

It works as designed (if JIT is off), it follows CPU execution 1:1, it does not care about interrupts or task switches. For example 't' always stops after next instruction, whatever the previous one did, even if previous instruction caused an exception. ('z' is not good idea if exceptions can happen)

If you want to enter debugger and you run program you can modify, it is usually better idea to use memory watch breakpoints and do something like "clr.w $100" in your program and set memwatch to break when $100 is modified.

Or use 'f <address>' break point command instead of 'z'. Or disable all interrupts

EDIT: updating 'z' to handle exceptions have been planned but it has never been important enough feature to bother with it..

[StingRay]

EDIT: updating 'z' to handle exceptions have been planned but it has never been important enough feature to bother with it..

I for one would like this! It can be kinda annoying at times. If one day you don't know what to improve anymore in WinUAE you may fix this.

[Dr. MefistO]

Just try to break somewhere, then step by "t" after that breakpoint. It throws exceptions.

P.S. Hmm... I think it works. But I can't understand how)

[Dr. MefistO]

How to disable these f**king exceptions or context switching?

[Toni Wilen]

Originally Posted by Dr. MefistO

How to disable these f**king exceptions or context switching?

You don't, it is designed (if you can call it having any design) for tracing programs totally side-effect free (for example programs that are timing sensitive, use prefetch tricks or have encrypted copy protection code) that is impossible to trace with any normal debugger.

It has no helper functions for "normal" programs.

Debugger keeps reporting exceptions (it is only reporting them) after any trace operation. It is normal.

You still haven't explained what exactly are you trying to do. I assume you want to skip interrupts when tracing? Anything else?