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Re: [PATCH] ASAN: handle addressable params (PR sanitize/81040).


On Tue, Jun 20, 2017 at 11:23:36AM +0200, Martin Liška wrote:
> > Then something needs to be done for debugging too.  If it is without VTA,
> > then probably just having DECL_VALUE_EXPR is good enough, otherwise
> > (VTA) you probably don't want that (or can reset it at that point), but
> > instead emit after the initialization stmt a debug stmt that the variable
> > value now lives in a different var.  Though ideally we want the debugger
> > to be able to also change the value of the var, that might be harder.
> > With DECL_VALUE_EXPR on the other side the debug info will be incorrect in
> > the prologue until it is assigned to the slot.
> 
> Here I'm not sure about how to distinguish whether to build or not to build
> the debug statement. According to flag_var_tracking?

More like if (target_for_debug_bind (arg))
And if that is false, just make sure DECL_VALUE_EXPR is set to var.

> You mean something like:
> g = gimple_build_debug_bind (arg, var, g);
> ?

Well, there is no stmt, so the last argument would be just NULL.

> > I don't understand the distinction.  If you turn the original parm
> > for complex/vector DECL_GIMPLE_REG_P, you should need the exact same code
> > (but I think it would be better to use the default SSA_NAME of the PARM_DECL
> > if it is a gimple reg type, rather than use the PARM_DECL itself
> > and wait for update_ssa).
> 
> Yes, the test-case /gcc/testsuite/g++.dg/asan/function-argument-3.C fails for me
> as one needs to have a temporary SSA name, otherwise:
> 
> /home/marxin/Programming/gcc/gcc/testsuite/g++.dg/asan/function-argument-3.C:13:1: error: invalid rhs for gimple memory store
>  foo (v4si arg)
>  ^~~
> arg
> 
> arg
> 
> # .MEM_4 = VDEF <.MEM_1(D)>
> arg = arg;
> during GIMPLE pass: sanopt
> 
> If I see correctly the function in my test-case does not have default def SSA name for the parameter.
> Thus I guess I need to create a SSA name?

I'd expect if you have DECL_GIMPLE_REG_P set on the PARM_DECL and
use the default def, you shouldn't run into this.

	Jakub


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