Re: Basic Block Statistics

[Will Hawkins <whh8b at virginia dot edu>]

On Fri, May 19, 2017 at 4:40 PM, Jeff Law <law@redhat.com> wrote:
> On 05/17/2017 08:22 PM, Will Hawkins wrote:
>> On Wed, May 17, 2017 at 2:59 PM, Will Hawkins <whh8b@virginia.edu> wrote:
>>> On Wed, May 17, 2017 at 2:41 PM, Will Hawkins <whh8b@virginia.edu> wrote:
>>>> On Wed, May 17, 2017 at 1:04 PM, Will Hawkins <whh8b@virginia.edu> wrote:
>>>>> On Wed, May 17, 2017 at 1:02 PM, Jeff Law <law@redhat.com> wrote:
>>>>>> On 05/17/2017 10:36 AM, Will Hawkins wrote:
>>>>>>> As I started looking into this, it seems like PLUGIN_FINISH is where
>>>>>>> my plugin will go. Everything is great so far. However, when plugins
>>>>>>> at that event are invoked, they get no data. That means I will have to
>>>>>>> look into global structures for information regarding the compilation.
>>>>>>> Are there pointers to the documentation that describe the relevant
>>>>>>> global data structures that are accessible at this point?
>>>>>>>
>>>>>>> I am looking through the source code and documentation and can't find
>>>>>>> what I am looking for. I am happy to continue working, but thought I'd
>>>>>>> ask just in case I was missing something silly.
>>>>>>>
>>>>>>> Thanks again for all your help getting me started on this!
>>>>>> FOR_EACH_BB (bb) is what you're looking for.  That will iterate over the
>>>>>> basic blocks.
>>>>>
>>>>> Thank you so much for your response!
>>>>>
>>>>> I just found this as soon as you sent it. Sorry for wasting your time!
>>>>>
>>>>>
>>>>>>
>>>>>> Assuming you're running late, you'll then want to walk each insn within
>>>>>> the bb.  So something like this
>>>>>>
>>>>>> basic_block bb
>>>>>> FOR_EACH_BB (bb)
>>>>>>   {
>>>>>>     rtx_insn *insn;
>>>>>>     FOR_BB_INSNS (bb, insn)
>>>>>>       {
>>>>>>         /* Do something with INSN.  */
>>>>>>       }
>>>>>>   }
>>>>>>
>>>>>>
>>>>>> Note that if you're running too late the CFG may have been released, in
>>>>>> which case this code wouldn't do anything.
>>>>
>>>> This macro seems to require that there be a valid cfun. This seems to
>>>> imply that the macro will work only where the plugin callback is
>>>> invoked before/after a pass that does some optimization for a
>>>> particular function. In particular, at PLUGIN_FINISH, cfun is NULL.
>>>> This makes perfect sense.
>>>>
>>>> Since PLUGIN_FINISH is the place where diagnostics are supposed to be
>>>> printed, I was wondering if there was an equivalent iterator for all
>>>> translation units (from which I could derive functions, from which I
>>>> could derive basic blocks) that just "FINISH"ed compiling?
>>>
>>>
>>> Answering my own question for historical purposes and anyone else who
>>> might need this:
>>>
>>>   FOR_EACH_VEC_ELT(*all_translation_units, i, t)
>>>
>>> is exactly what I was looking for!
>>>
>>> Sorry for the earlier spam and thank you for your patience!
>>> Will
>>
>>
>> Well, I thought that this was what I wanted, but it turns out perhaps
>> I was wrong. So, I am turning back for some help. Again, i apologize
>> for the incessant emails.
>>
>> I would have thought that a translation unit tree node's chain would
>> point to all the nested tree nodes. This does not seem to be the case,
>> however. Am I missing something? Or is this the intended behavior?
> I think there's a fundamental misunderstanding.

You are right, Mr. Law. I'm really sorry for the confusion. I got
things straightened out in my head and now I am making great progress.
>
> We don't hold the RTL IR for all the functions in a translation unit in
> memory at the same time.  You have to look at the RTL IR for each as its
> generated.

Thank you, as ever, for your continued input. I am going to continue
to work and I will keep everyone on the list posted and let you know
when it is complete.

Thanks again and have a great rest of the weekend!

Will
>
> jeff