Re: Basic Block Statistics

[Jeff Law <law at redhat dot com>]

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.

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.

jeff