Question on Gimple Tree

Question on Gimple Tree

[Srinivas Pasupuleti]

Hello,

I have written a pass to traverse gimple tree and include some print
function calls with arguments as the LHS(lval) variable of every
gimple modify statement. (this is part of my profiling work)
I would like to know if it is possible to access the address of the
gimple variables.

 for e.g.,

The following is a gimple statement (all are int variables):
D.2629_17 = D.2629_27 + D.2629_22 ;

In my pass I have added a print function call as below
print(D.2629_17)

The above works perfect

I want to pass address of the gimple variable
print(&D.2629_17)

Is the above possible to do. If so, how to do it??
I need to do for memory profiling and dynamic dependency testing.

Please provide your comments. It will be greatly helpful.

Thanks,
Srinivas

Re: Question on Gimple Tree

[Ian Lance Taylor]

Srinivas Pasupuleti <vaasu1234@gmail.com> writes:

> I have written a pass to traverse gimple tree and include some print
> function calls with arguments as the LHS(lval) variable of every
> gimple modify statement. (this is part of my profiling work)
> I would like to know if it is possible to access the address of the
> gimple variables.
>
>  for e.g.,
>
> The following is a gimple statement (all are int variables):
> D.2629_17 = D.2629_27 + D.2629_22 ;
>
> In my pass I have added a print function call as below
> print(D.2629_17)
>
> The above works perfect
>
> I want to pass address of the gimple variable
> print(&D.2629_17)
>
> Is the above possible to do. If so, how to do it??
> I need to do for memory profiling and dynamic dependency testing.

You can't take the address of a gimple variable; think of a gimple
variable as a register in an imaginary machine.  You will have to
create a real, albeit temporary, variable and assign the gimple
variable to it.  If you want your function to change the value of the
variable, you will have to copy the value back as well.

Ian

Re: Question on Gimple Tree

[Srinivas Pasupuleti]

Thanks Ian for your prompt response.

So, what is the alternate way to do memory read/write profiling....I'm
aware of CIL source transformation package which allows to log memory
reads and memory writes..

Is something similar possible to do in GCC... Do I have to work on AST
level instead of GIMPLE and include statements to log all memory reads
and writes? Please suggest.

Thanks,
Srinivas

On Wed, Dec 23, 2009 at 10:16 AM, Ian Lance Taylor <iant@google.com> wrote:
> Srinivas Pasupuleti <vaasu1234@gmail.com> writes:
>
>> I have written a pass to traverse gimple tree and include some print
>> function calls with arguments as the LHS(lval) variable of every
>> gimple modify statement. (this is part of my profiling work)
>> I would like to know if it is possible to access the address of the
>> gimple variables.
>>
>>  for e.g.,
>>
>> The following is a gimple statement (all are int variables):
>> D.2629_17 = D.2629_27 + D.2629_22 ;
>>
>> In my pass I have added a print function call as below
>> print(D.2629_17)
>>
>> The above works perfect
>>
>> I want to pass address of the gimple variable
>> print(&D.2629_17)
>>
>> Is the above possible to do. If so, how to do it??
>> I need to do for memory profiling and dynamic dependency testing.
>
> You can't take the address of a gimple variable; think of a gimple
> variable as a register in an imaginary machine.  You will have to
> create a real, albeit temporary, variable and assign the gimple
> variable to it.  If you want your function to change the value of the
> variable, you will have to copy the value back as well.
>
> Ian
>

Re: Question on Gimple Tree

[Ian Lance Taylor]

Srinivas Pasupuleti <vaasu1234@gmail.com> writes:

> So, what is the alternate way to do memory read/write profiling....I'm
> aware of CIL (http://hal.cs.berkeley.edu/cil/)  source transformation
> package which allows to log memory reads and memory writes..
>
> Is something similar possible to do in GCC... Do I have to work on AST
> level instead of GIMPLE and include statements to log all memory reads
> and writes? Please suggest.

I think it depends on what you mean by memory reads and writes.  If
you want to track every single memory read and write, you will need to
work at the RTL level.  If you want to track all changes to user
variables, then do that at the GIMPLE level; I don't think of a user
variable as a GIMPLE variable.

Ian

> On Wed, Dec 23, 2009 at 10:16 AM, Ian Lance Taylor <iant@google.com> wrote:
>> Srinivas Pasupuleti <vaasu1234@gmail.com> writes:
>>
>>> I have written a pass to traverse gimple tree and include some print
>>> function calls with arguments as the LHS(lval) variable of every
>>> gimple modify statement. (this is part of my profiling work)
>>> I would like to know if it is possible to access the address of the
>>> gimple variables.
>>>
>>>  for e.g.,
>>>
>>> The following is a gimple statement (all are int variables):
>>> D.2629_17 = D.2629_27 + D.2629_22 ;
>>>
>>> In my pass I have added a print function call as below
>>> print(D.2629_17)
>>>
>>> The above works perfect
>>>
>>> I want to pass address of the gimple variable
>>> print(&D.2629_17)
>>>
>>> Is the above possible to do. If so, how to do it??
>>> I need to do for memory profiling and dynamic dependency testing.
>>
>> You can't take the address of a gimple variable; think of a gimple
>> variable as a register in an imaginary machine.  You will have to
>> create a real, albeit temporary, variable and assign the gimple
>> variable to it.  If you want your function to change the value of the
>> variable, you will have to copy the value back as well.
>>
>> Ian
>>