Re: [PATCH v2 06/10] perf annotate: Track arithmetic instructions on pointers

[Namhyung Kim <namhyung@kernel.org>]

Hi Zecheng,

On Wed, Sep 03, 2025 at 04:26:50PM -0400, Zecheng Li wrote:
> > I was thinking we can use TSR_KIND_POINTER here.  Probably we need to
> > distinguish it from the existing percpu base use case. Maybe you want
> > to rename it.  Then you don't need to find a pointer type in the DWARF.
> 
> Hi Namhyung, thanks for the review.
> 
> Yes. I think that's a better way to represent a pointer to a type.
> With that tag we can also support registers representing addresses
> (is_reg_var_addr == true). And when moving an address register to a
> memory location we probably can simply add the * to denote a pointer
> without finding the exact pointer type.
> 
> >
> > > +                     tsr->offset = 0;
> >
> > I think it can refer to a member in a struct.  How about this?
> >
> >                         tsr->offset = state->offset - offset;
> 
> True, it may load an address of a struct member. Do you mean
> stack->offset - offset?

Yep.

> 
> > > @@ -388,6 +493,7 @@ static void update_insn_state_x86(struct type_state *state,
> > >               tsr->type = state->regs[src->reg1].type;
> > >               tsr->kind = state->regs[src->reg1].kind;
> > >               tsr->imm_value = state->regs[src->reg1].imm_value;
> > > +             tsr->offset = 0;
> > >               tsr->ok = true;
> 
> I also find for mov register to register this should be
> 
> tsr->offset = state->regs[src->reg1].offset;
> 
> Let me update the patch.

Great, thanks!
Namhyung