[llvm-dev] What version comes after 3.9? (Was: [3.9 Release] Release plan and call for testers)

Adve, Vikram Sadanand via llvm-dev llvm-dev at lists.llvm.org
Mon Jun 20 22:46:33 PDT 2016

> On Jun 20, 2016, at 11:56 PM, Chris Lattner <clattner at apple.com> wrote:
> On Jun 19, 2016, at 10:21 AM, Adve, Vikram Sadanand via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>>> Let me clarify. What I’m trying to say is that:
>>>> a) LLVM has a time-based release cycle, not a schedule-based one. As
>>>> such, a simple and predictable version number makes sense.
>>>> b) The LLVM project as a whole is a lot bigger than LLVM IR, even
>>>> given its centrality to the project in some ways.
>>>> c) I think that it makes sense to keep adding 0.1 to each major
>>>> release going forward well into the future.
>> Now you’re making the versions sound like floating point numbers :-).  Just to be clear, you are proposing we use 3.10/3.11/etc. rather than 4.0/4.1/etc.?
> No, I’m suggesting that we continue the progression we’ve had from the start and proceed from 3.8 to 3.9 to 4.0 to 4.1.
>> If so, I agree with that for a couple of reasons.  First, as several people said, version numbers should not be driven primarily by IR changes: the LLVM project is a lot more than the IR, even though the IR is a fundamental component.  Our releases are time-based and the predictability of that has worked pretty well.
>> A second reason is that major version numbers also have a useful communication value: signifying a major step forward in the system along some dimension.  It just so happens that these major changes have been IR changes in the past -- and perhaps opaque pointer types will turn out to be the next major change -- but regardless of what the change is, I think there is some value in reserving major version increments (like 3.x.y to 4.0) when major changes happen.
> These seem like contradictory points: on the one hand you’re observing that we have an inherently schedule driven process, but are also saying that major version numbers are important to signify “major” changes.  

Not contradictory at all.  The schedule is for *when* we release new versions; it is unrelated to any numbering scheme.  The major vs. minor version numbers capture something about how important a release is.  I don’t really have a preference one way or another, but I do think people are missing a basic point about the numbering.

> Given the scope of LLVM, I suspect we’ll never have a “major” change that lines up across all of the sub-projects, so this doesn’t seem like something we should bank on.

Agreed, but you could introduce a new major version when there is something really major in any major part of the ecosystem.  E.g., making Clang the primary C/C++ compiler instead of llvm-gcc could have qualified.

> I don’t think that there is really a problem to solve here, but if we were sufficiently motivated to “solve” this problem, then the answer is obvious: instead of 4.0, we should just go to 40, and add one for every release after that.

Sounds like a stretch to me, but whatever!

> -Chris


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