[llvm-dev] TableGen: spring cleaning, new features for "functional programming"

[Nicolai Hähnle via llvm-dev]

Hi Philip,

On 14.03.2018 16:56, Philip Pfaffe wrote:
> if you're open to it, I'd like suggest another smallish cleanup in 
> libTablegen, namely doing something about the layering. Basicly what bit 
> me a few times is that there is a `Main.cpp` file. This particular file 
> adds CLI options such as -o, -d, -I. So if you build some out-of-tree 
> tool and happen to link against `all` components because you're lazy, 
> there is a high likelihood of an option clash, which are nasty to debug. 
> Can we move these options outside of the library and put them in the 
> tool instead?

No. The reason for those options being there is that any TableGen 
frontend will want them. In particular, clang-tblgen uses this 
functionality.

Cheers,
Nicolai


> 
> Cheers,
> Philip
> 
> 2018-02-19 20:26 GMT+01:00 Nicolai Hähnle via llvm-dev 
> <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>>:
> 
>     Hi all,
> 
>     While working on some features for the AMDGPU backend --
>     specifically, explicit address components for image intrinsics,
>     which involves generating both
> 
>     (a) a lot of intrinsics with different but somewhat regular
>     parameter types, and
> 
>     (b) the patterns to select instructions for those intrinsics
> 
>     -- I got fed up with a lot of the TableGen bugs and limitations and
>     set out to fix things.
> 
>     I now have an already rather long list of ~30 patches which do a
>     bunch of things in lib/TableGen/ such as:
> 
>     - better and earlier error messages
>     - cleanup type checking
>     - cleanup variable resolving
>     - cleanup record instantiation
>     - late generation of anonymous records that appear in expressions
>     - cleanup !foreach
>     - add !foldl
>     - add !isa<type>(...) and make !cast more useful
>     - add !dag builtin to generate DAG nodes from lists
>     - some other minor new built-ins like !size, !le, !lt, !ge, !gt
>     - add a defset mechanism for collecting records which can then later
>     be looped over in a foreach statement
>     - make foreach statements in multiclass work
>     - probably more...
> 
>     An earlier version of the patches is here if you already want to
>     take a look: https://cgit.freedesktop.org/~nh/llvm/log/?h=mimg
>     <https://cgit.freedesktop.org/~nh/llvm/log/?h=mimg>
> 
>     My plan is to clean those up over the next days and weeks and submit
>     them to Phabricator.
> 
>     With the exception of !foreach, which doesn't actually seem to be
>     used, all the changes should be backward compatible. In fact, most
>     of the larger changes are simply refactoring TableGen in a way that
>     makes things work that look like they should already work but don't.
> 
>     I would appreciate feedback and help in reviewing the patches when
>     they arrive!
> 
>     Thanks,
>     Nicolai
> 
>     P.S.: I'm going to document some of my findings and changes on my
>     blog, the first entry is here:
>     https://nhaehnle.blogspot.de/2018/02/tablegen-1-what-has-tablegen-ever-done.html
>     <https://nhaehnle.blogspot.de/2018/02/tablegen-1-what-has-tablegen-ever-done.html>
> 
>     -- 
>     Lerne, wie die Welt wirklich ist,
>     Aber vergiss niemals, wie sie sein sollte.
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> 
> 


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.