[LLVMdev] RFC - Adding an optimization report facility?

[Xinliang David Li]

On Thu, Mar 6, 2014 at 12:22 PM, Diego Novillo <dnovillo at google.com> wrote:

> On Thu, Mar 6, 2014 at 2:44 PM, Tobias Grosser <tobias at grosser.es> wrote:
>
> as others already pointed out, I committed the first piece of such an
>> infrastructure in LLVM commit 202474 and clang commit 202475. This is
>> mostly the backend and printing infrastructure.
>>
>
>
> Thanks, Tobias.  I've browsed the two patches and I think they're going to
> be exactly what I need. IIUC, the patches add two new LLVM instructions
> remark and note. These are inserted in the IL by the passes and the
> compiler emits them as diagnostic if the right -W flag is enabled?
>
> One question I have from the Clang patch. If I compile with -Weverything,
> will this enable all warnings *and* remarks? In this context, I only want
> to enable all remarks.  In fact, I want to enable a family of remarks: the
> optimization remarks.
>
> There will be other modifiers to these remarks as well:
>
>
>    1. Report *missed* optimizations, instead of the successful ones.
>    2. Increase verbosity of the report. This would be done using note
>    nodes, I expect. But we may want varying degrees of verbosity.
>    3. Group families of optimizations. For example, i want to report on
>    all loop-related optimizations.
>    4. IIRC, GCC's -fopt-info will also allow you to collect the reports
>    into a separate text file. Not sure how useful I find this feature myself.
>
>
Re. 4, to name a few that can be handy sometimes: 1) not contaminate
stderr; 2) per TU report; 3) Per opt-group report etc.

Also in GCC's original design, per-pass report filtering was supported, but
that was considered too developer oriented.

David

>
>
>
> Thanks. Diego.
>
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