Re: [MI400] opcode encoding

["Steve Richter" <srichter@xxxxxxxxxxxxx>]

----- Original Message -----
From: "Leif Svalgaard" <leif@leif.org>
> >
>
> my standard question: how does this help you? what are you trying to do?
>
>

Specifically, I am using the heap quite a bit in my work. A bug has surfaced
where individual heap allocations ( ALCHSS ) are being corrupted somehow. As
the pgm runs, somehow data is being written into the allocation area that
should not be written.

I want to run my pgm in trace mode and trap the instruction which is writing
to a specific heap allocation ( an address range ).

So the plan is to:
1. StrDbg
2. AddTrc  stmt(*AllInst)  TraceHandlingPgm( TracePlus )
3. TracePlus is called for every instruction executed in the pgm.
4. It uses MATINAT to materialize the instruction being executed.
5. MATINAT returns the opcode of the instruction and info on each
instruction operand.
6. Instruction operand info contains the data defn of the operand and a ptr
to its value.
7. The ptr to the operand value will be compared to the address range that I
am trapping. Any reference within the range will sound an alarm and report
to the user in bold letters that the bug has been found.

So far the MATINAT instruction works as I understand it.  One problem:  It
cannot be used in a trace of a pgm in a batch job.

-Steve Richter