[llvm-dev] Renaming passes

[Philip Reames via llvm-dev]

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 <mailto: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.
>
> 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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