[Mesa-dev] GLSL IR & TGSI on-disk shader cache

[Timothy Arceri]

On Tue, 7 Feb 2017 15:50:28 +0900
Michel Dänzer <michel at daenzer.net> wrote:

> On 07/02/17 12:42 PM, Timothy Arceri wrote:
> > 
> > This series does not include the patch that adds cache support
> > to the radeonsi backend, the main reason for this is that llvm
> > currently doesn't allow the version to be queried at runtime
> > (as far as I'm aware) although it seems like other are interested
> > in this feature [1] so I will follow up on that.
> > 
> > The reason we don't just use the build time like radv is that we
> > will want something consistent accross distros to enable 
> > distribution of precompiled shaders.
> 
> I'm not sure that's realistic. Consider e.g.
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=99078
> 
> which is a regression in LLVM 3.9.1 caused by backporting a fix from
> trunk. Since there are no plans for an LLVM 3.9.2 release, distros
> have to revert the change in their 3.9.1 packages. Mesa can't tell the
> difference from the version number, but the generated code can be very
> different depending on whether the change in question is present or
> not.

I wonder how problematic that really is, it just means the bug will be
in the cached version and it won't get replaced. It looks like other
users of llvm might be looking to rely on the version number so maybe
distros will need to bump the version themselves if llvm won't do a
release, not sure what to do about this.