[llvm-dev] RFC: changing variable naming rules in LLVM codebase

Tue Jul 9 04:31:34 PDT 2019

Thanks Rui! That's essentially what I thought would work.

On Tue, 9 Jul 2019 at 12:14, Rui Ueyama <ruiu at google.com> wrote:

> It should work on downstream lld repositories if exist, though I didn't
> try that personally.
>
> The tool is a batch tool, so you can rename variables in your downstream
> repository using that tool. Given that, here is how to rebase your repo to
> a commit after a mass renaming:
>
> 1. rebase to a commit just before a mass variable renaming,
> 2. apply the tool to a downstream repo to mass-rename variables locally,
> and then
> 3. rebase again to the head.
>
> Most changes made by the tool should be identical for a downstream
> repository and for the head, so at step 3, almost all changes should be
> merged and disappear. I'd expect that there would be some lines that you
> need to merge by hand, but I'd think that that's not too many.
>
> On Tue, Jul 9, 2019 at 7:16 PM James Henderson <
> jh7370.2008 at my.bristol.ac.uk> wrote:
>
>> Hi Rui,
>>
>> Is your tool in a good state to be run on people's downstream
>> repositories? It would be nice to be able to update variable names there
>> too at the same time.
>>
>> James
>>
>> On Tue, 9 Jul 2019 at 08:24, Rui Ueyama via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Thanks, Chris.
>>>
>>> Looks like everybody is at least mildly comfortable with my variable
>>> name renaming change, so I'll to submit that change to lld subdirectory
>>> soon. If you have any objections, please let me know. Note that this is not
>>> the end of my effort but actually the beginning of it. As Chris said, I
>>> believe we should do this to the entire LLVM codebase. I'm planning to do
>>> that directory-by-directory basis.
>>>
>>> On Tue, Jul 9, 2019 at 2:03 PM Chris Lattner <clattner at nondot.org>
>>> wrote:
>>>
>>>> This looks really great to me Rui, and I’m also pleased to see the
>>>> positive comments on the review thread.  Thank you for driving this forward!
>>>>
>>>> -Chris
>>>>
>>>>
>>>> On Jul 4, 2019, at 9:50 PM, Rui Ueyama <ruiu at google.com> wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I wrote a tool <https://reviews.llvm.org/D64123> to batch-rename
>>>> variable names so that they are in camelCase, and I applied the tool to lld
>>>> subdirectory. You can see my change at https://reviews.llvm.org/D64121.
>>>> If you have any comments, please reply.
>>>>
>>>> If people are happy about this change, I can do the same thing for
>>>> other directories including LLVM itself and Clang.
>>>>
>>>> On Mon, Jun 10, 2019 at 6:34 PM Rui Ueyama <ruiu at google.com> wrote:
>>>>
>>>>> On Mon, Jun 10, 2019 at 6:27 PM Michael Platings <
>>>>> Michael.Platings at arm.com> wrote:
>>>>>
>>>>>> Hi Rui,
>>>>>>
>>>>>>
>>>>>>
>>>>>> As per the provisional plan [1] we’re still at step 1: improving git
>>>>>> blame. The status of this is that there are some fairly mature patches in
>>>>>> the Git project’s queue [2], and I’m hopeful that it will be accepted in
>>>>>> something close to its current form.
>>>>>>
>>>>>>
>>>>>>
>>>>>> But if you can get started on steps 2 & 3 i.e. making forks available
>>>>>> with the possible changes applied then that would be great. My hope is that
>>>>>> once everyone can see what the options really look like then it will be
>>>>>> easier to reach consensus.
>>>>>>
>>>>>
>>>>> Sure, I'll try to do that. I'll probably start with finding
>>>>> identifiers and typenames that will conflict after the naming scheme change
>>>>> and rename them so that they won't conflict. The number of such symbols
>>>>> would hopefully be small, and submitting such renaming changes wouldn't be
>>>>> distracting. After that, I think I can create a mechanical change to rename
>>>>> variables to see how it will look like.
>>>>>
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> -Michael
>>>>>>
>>>>>>
>>>>>>
>>>>>> [1]
>>>>>> https://llvm.org/docs/Proposals/VariableNames.html#provisional-plan
>>>>>>
>>>>>> [2]
>>>>>> https://public-inbox.org/git/20190515214503.77162-8-brho@google.com/T/
>>>>>>
>>>>>>
>>>>>>
>>>>>> *From:* Rui Ueyama <ruiu at google.com>
>>>>>> *Sent:* 07 June 2019 08:42
>>>>>> *To:* Chris Lattner <clattner at nondot.org>
>>>>>> *Cc:* Michael Platings <Michael.Platings at arm.com>;
>>>>>> llvm-dev at lists.llvm.org; nd <nd at arm.com>
>>>>>> *Subject:* Re: [llvm-dev] RFC: changing variable naming rules in
>>>>>> LLVM codebase
>>>>>>
>>>>>>
>>>>>>
>>>>>> This thread is not active for a while, but I'm still interested in
>>>>>> seeing a change.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Reading through this thread, looks like we can agree that we want to
>>>>>> change the local variable naming scheme so that they start with a lowercase
>>>>>> letter. Besides that, there were discussions about lower_case, camelCase,
>>>>>> m_ prefix, and each argument seems as convincing as others. I'm not sure
>>>>>> what is the decision making process in a situation like this.
>>>>>>
>>>>>>
>>>>>>
>>>>>> I'd personally vote for changing local variables to start with a
>>>>>> lowercase letter and keep other naming conventions as-is to make it a
>>>>>> minimum change.
>>>>>>
>>>>>>
>>>>>>
>>>>>> As I stated before, I'm happy to make a change to lld to see how a
>>>>>> naming convention change will look like, but in order to do that I need to
>>>>>> get at least a rough consensus to do that. What is a way to proceed?
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Sat, May 25, 2019 at 3:00 PM Chris Lattner via llvm-dev <
>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>> Hi Michael,
>>>>>>
>>>>>>
>>>>>>
>>>>>> I’m still very interested in seeing a change here.  If someone is
>>>>>> interested in seeing a codebase using the proposed camelBack convention for
>>>>>> variables names, the MLIR codebase is public
>>>>>> <https://github.com/tensorflow/mlir> and uses it.
>>>>>>
>>>>>>
>>>>>>
>>>>>> If you’re curious to see what this looks like in practice, there are
>>>>>> lots of examples in the codebase, here is an example .cpp file
>>>>>> <https://github.com/tensorflow/mlir/blob/master/lib/Transforms/LoopUnrollAndJam.cpp>
>>>>>> , here is another
>>>>>> <https://github.com/tensorflow/mlir/blob/master/lib/Parser/Parser.cpp>,
>>>>>> here is an example header
>>>>>> <https://github.com/tensorflow/mlir/blob/master/include/mlir/IR/Location.h>
>>>>>> .
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> We are still working our way through open sourcing logistics (not all
>>>>>> the code is out yet), but we would still like to contribute at least parts
>>>>>> of this to LLVM if the project is interested.  [[This is just an FYI, not
>>>>>> itself a proposal yet - one will be coming when we’re ready.]]
>>>>>>
>>>>>>
>>>>>>
>>>>>> -Chris
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On May 21, 2019, at 3:01 AM, Michael Platings via llvm-dev <
>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi folks,
>>>>>>
>>>>>> Git is on its way to learning how to ignore commits, allowing us to
>>>>>> do variable renaming and other small refactorings without breaking git
>>>>>> blame.
>>>>>>
>>>>>> It's like git-hyper-blame [1] but significantly more powerful as it
>>>>>> uses fuzzy matching to match lines, including lines that may have been
>>>>>> split or joined.
>>>>>>
>>>>>> A preview release of Git with this new feature is at:
>>>>>> https://github.com/mplatings/git/releases/tag/ignore-rev
>>>>>>
>>>>>> Some of you have told me that you already have to spend time running
>>>>>> git blame multiple times to look past uninteresting commits so I'd love for
>>>>>> you to give this feature a try and see if it helps you. Your feedback will
>>>>>> be very valuable.
>>>>>>
>>>>>> Thanks,
>>>>>> -Michael
>>>>>>
>>>>>> [1]
>>>>>> https://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/git-hyper-blame.html
>>>>>> _______________________________________________
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>>>>>> llvm-dev at lists.llvm.org
>>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>
>>>>>>
>>>>>>
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>>>>>>
>>>>>>
>>>> _______________________________________________
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>>
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