[LLVMdev] stability of llvm ir across releases

Jeremy Lakeman Jeremy.Lakeman at gmail.com
Sat Mar 14 17:45:57 PDT 2015

The general principle I've seen applied in mailing list discussions;
Textual IR could change significantly, the complexity of preserving
backwards compatibility in the parser is often too high.
Binary IR, is a much more structured format, backwards compatibility is
easier to support. IR Correctness should be preserved, but some language
features might be ignored. eg old meta-data formats will be silently
stripped out.

On Sun, Mar 15, 2015 at 3:13 AM, Hayden Livingston <halivingston at gmail.com>

> Are you saying the textual form of IR can change, but bitcode doesn't? I
> don't know what you mean by assembly syntax.
> Is there a changlog entry when the textual IR changes?
> On Sat, Mar 14, 2015 at 5:22 AM, Jeremy Lakeman <Jeremy.Lakeman at gmail.com>
> wrote:
>> Assembly syntax can and will break between versions. But bitcode should
>> generally be upgradeable, or a bug should be filed.
>> On Sat, Mar 14, 2015 at 4:41 PM, Hayden Livingston <
>> halivingston at gmail.com> wrote:
>>> Is it safe to assume that LLVM IR will live more-or-less the same for
>>> most releases, and that significant changes will be communicated?
>>> Or is it something that can change at any time and you must not rely on
>>> it ever being same.
>>> To me, it seems like the IR has evolved slowly but no spectacularly
>>> large changes were made in the 1-1.5 years I've been watching it, -- sure
>>> some experimental patch point, gc stuff, but not your day-to-day types etc
>>> I'm asking because I'm going to take somewhat major dependencies in my
>>> upcoming system on the IR, and being able to store it across multiple
>>> releases of my system.
>>> I don't anticipate moving to newer versions of LLVM every time I
>>> release, but I do imagine wanting to upgrade to let's say LLVM 3.7 or
>>> whatever releases come by.
>>> Hayden
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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