[Lazarus] Need testers for the a new debugger

C Western l at c-m-w.me.uk
Mon Aug 25 12:26:02 CEST 2014

On 24/08/14 16:44, Joost van der Sluis wrote:
> On 07/21/2014 10:11 PM, C Western wrote:
>> Managed to create a small test program:
>> program tproj;
>> uses sysutils;
>> procedure a(const s: string);
>> var
>>   a: string;
>>   r: array [0..10] of Double;
>> begin
>>   a := s+s+s;
>>   r[8] := StrToFloat(a);
>>   WriteLn(a, ' ', r[8])
>> end;
>> begin
>>   a('6'); <<-Set break point here, and hit step into here twice
>> end.
>> First step into ends on begin in procedure, second on final end.
>> Seems to be related to size of stack frame - if I didn't have the
>> array in, it works as expected. I compiled it with all stack checks on.
>> I know this stuff can be difficult - I have certainly seen some odd
>> things with Delphi and gdb. My hope is we can resolve some of these
>> things as we now have control over all parts of the system.
> Solving this particular problem was easy, but debugging your
> test-application opened a whole new can of worms.
> I've re-written the step-into-line code completely. It's not fool-proof,
> but at least it works stepping into a procedure one level deep. (That
> means: if the procedure being called has debug-info.) If it does not
> have debug-info but another procedure with debug info is called
> further-on, it will probably work.
> The problem lies in functions that do not set the stack-frame. Among
> those are the compiler-procedures. If two of those are called after each
> other, the debugger can loose track...
> So, please test. I'm convinced that a solution that always works and is
> also reasonable fast is impossible. (gdb also makes comparable mistakes)
> Oh, and I added re-direction of the console in- and output to the
> console-debug screen.

Thanks for looking at this - I will try it out. Two things strike me:

1. How about a "slow step" option?

2. Could the compiler add more information to make this easier? Or is it 
simply a matter of compiling everything with a stack frame?


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