[Mesa-dev] How to know which exact llvm version to build/link against?

[Eric Engestrom]

On Tuesday, 2018-02-13 01:44:53 -0800, Andrew A. wrote:
> On Wed, Feb 7, 2018 at 1:37 AM, Michel Dänzer <michel at daenzer.net> wrote:
> > For a non-current snapshot of Mesa Git master, one may have to find an
> > LLVM SVN snapshot from around the same time.
> 
> Just so I understand, a statement like "Try repro'ing the bug in svn
> commit x of mesa from last year" doesn't wind up being very precise,
> since the llvm version used by the author of commit x was never
> documented/codified anywhere. Do you suppose there could be value in
> codifying this a bit more? Perhaps some kind of client-side pre-commit
> hook could notate the llvm version/commit/tag somewhere in the mesa
> checkin...
> 
> I realize the same criticism could be made of not tracking version
> numbers of other dependencies (e.g. "By that logic, everything is
> imprecise, and all dependencies should be tracked in this manner,
> including glibc, binutils, etc! A bit ridiculous!"), but as you
> mention llvm is uniquely very unstable as an API, so there may be more
> value in tracking it than other kinds of deps.
> 
> As a relatively infrequent user of mesa git checkouts, I can only say
> that finding the correct llvm version to build against can be a bit of
> a pain. As mentioned, I usually have to try several different llvm
> checkouts before finding the right one. Even when I do get it working,
> I still have no idea if that's the llvm version that the author of the
> mesa commit was using (which I'd really prefer). Is this somehow not a
> regular problem for mesa developers? Wondering if I'm blowing it out
> of proportion.

If you're not developing something specific to the llvm version
currently in development, you probably don't need a git/svn checkout of
llvm, you should just use one of the llvm releases. If you encounter
build issues using a released llvm, you should report that, as they are
all supposed to work (with a minumum, currently at 3.9/4.0 depending on
what you include in your build).

> 
> Thanks.