Re: [Valgrind-users] Using valgrind to detect when a given value is written to/read from memory

[Julian S. <js...@ac...>]

> for each statement s in the IRBB
>       if s is an Ist_Store
>       then
>               insert helper function with argument s->Ist.Store.data
>        endif
>
>       if s is an Ist_Tmp
>       then
>               if tag of IRExpr in s->Ist.Tmp.Data is Iex_Load
>               insert helper function with argument s->Ist.Tmp.tmp
>       endif
> end

To get 100% coverage, you also need to handle Ist_Dirty, which is tricky.

> * Issue: The VEX core only handles arguments of type Ity_I32 passed to
> helper functions. [...]
> Solution 1: at instrumentation time, use the tyenv array in the basic block
> to check
> the type of the temporary variable tX . If tX is not Ity_I32, insert a new
> IRStmt which allocates a new temporary tZ and inserts a conversion from the
> type of tX to Ity_I32, then inserts a call to checkValueAndPrintST(tZ). I
> have not actually done this, but it "should work."

Yes - it's by far the simplest solution, and is used in various
tools.  Basically widen the arg using Iop_{1,8,16}Uto32 before 
handing it to the helper call.

J