[discuss] semantics, "replay debugging" vs. "reverse debugging"

teawater teawater@gmail.com
Wed Oct 22 16:19:00 GMT 2008


I think your mean that add is a X86 instruction or ARM insn. But some
arch's add not set flag such as MIPS.

addiu $1, $1, 10

It not set anything except $1.

And I said add insn just a example, I am not say for each arch and
each insn? just some of them.



On Wed, Oct 22, 2008 at 21:37, Daniel Jacobowitz <drow@false.org> wrote:
>
> On Wed, Oct 22, 2008 at 11:25:17AM +0800, teawater wrote:
> > I think your not clear my idea.
> >
> > > I think maybe some instruction can do it.
> > > Such as add instruction. When it forward execute, it add some number
> > > to a value of register. When it reverse, it can sub this number from
> > > the value of register. It can reverse without record.
> >
> > Maybe you can read this part again.
> >
> > And what is the status of program? Most of time, it's just the values
> > of registers and memory. Do not think anything that complex.
>
> Jakob is right.  For instance, if the add instruction sets an overflow
> flag in the status register, you can not figure out what the previous
> version of the overflow flag was after the instruction.
>
> --
> Daniel Jacobowitz
> CodeSourcery



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