[llvm-dev] Renaming passes

[Arthur Eubanks via llvm-dev]

On Wed, Jun 24, 2020 at 12:23 PM Philip Reames <listmail at philipreames.com>
wrote:

>
> On 6/24/20 11:21 AM, Matt Arsenault via llvm-dev wrote:
>
>
>
> On Jun 24, 2020, at 14:13, Arthur Eubanks via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Hi,
>
> As part of new pass manager work, I've been trying to get something like
> `opt -foo` working under the NPM, where `foo` is the name of a pass.
>
> In the past there's been no reason to keep the names of passes consistent
> between NPM and legacy PM. But now there is a reason to make them match, so
> that we don't have to touch every single test that uses `opt`.
>
> There are a couple of names that don't match though, for example the
> "basic alias analysis" pass is named "basicaa" under the legacy PM
> INITIALIZE_PASS_BEGIN(BasicAAWrapperPass, "basicaa",
>                       "Basic Alias Analysis (stateless AA impl)", true,
> true)
> but named "basic-aa" under the NPM
> FUNCTION_ALIAS_ANALYSIS("basic-aa", BasicAA())
> . Almost all the other AA passes have a dash in them so I think it makes
> sense to rename "basicaa" -> "basic-aa".
>
> Is there accepted wisdom on renaming pass names? Is a pass name a stable
> interface? When is it ok to rename a pass? If there are 800 usages of a
> flag, should I rename them atomically?
>
>
> I think the pass naming scheme needs a lot of work. The naming conventions
> seem random at times. For instance, I can never remember how to refer to
> PrologEpilogInserter. The DEBUG_TYPE name is “prologepilog”, the pass class
> name is “PEI”. I would expect this to be prolog-epilog-inserter to match
> the file and formal pass name, and consistently use dashes as word
> separators.
>
> Can I suggest we allow aliases?  We can except all of these names, pick a
> canonical name, migrate tests, and only remove the aliases once the new
> canonical names are widely known.
>
An alias sounds good.

>
> Unfortunately, I recently discovered some optimization pass remarks expose
> pass names to the user (since you use the name of the pass to filter
> relevant remarks). I’m not sure how stable this is supposed to be though.
>
> -Matt
>
>
>
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