[Valgrind-users] How to make instrumentation run AFTER its corresponding guest instruction

[Jersey <luc...@gm...>]

> Hi, all:
> 
> I am trying to use valgrind to do value profiling at specified address of guest instruction.
> 
> By adding my own instrumentation codes for each Ist_Mark in the MC_(instrument) function, as the way Lackey does, I am able to pause the guest program at specific instruction address and then do value profiling thanks to Memcheck  . 
> 
> However, in this way, the instrumentation codes RUNS BEFORE the corresponding guest instructions. for example:
>     int j=10;
>       8048416: ... movl $0xa,0x18(%esp)
> 8048416 is the address of guest instruction.If I check the value of j in the instrumentation codes, i will get a garbage value instead of 10, because the movl instruction has not executed yet. 
> I want to check the value of j, AFTER this instruction(movl) executed. But I don't know how?
> 
> My guess is it has something to do with the JIT dispatcher, is there an command option that I could use or there is a better way to add instrumentation code?
> 
> Thanks a lot for your time and efforts.
> 
> -- 
> Regards
> Jersey Zhang