[llvm-dev] Should we split llvm Support and ADT?

[Zachary Turner via llvm-dev]

It's that TableGen depends on Support, so if you change one file in
support, support gets recompiled into a new static archive, which triggers
a rerun of tablegen on all the tablegen inputs, which is extremely slow.

On Fri, May 26, 2017 at 5:56 PM Hal Finkel <hfinkel at anl.gov> wrote:

>
>
> On 05/26/2017 07:47 PM, Zachary Turner via llvm-dev wrote:
>
> Changing a header file somewhere and having to spend 10 minutes waiting
> for a build leads to a lot of wasted developer time.
>
> The real culprit here is tablegen.  Can we split support and ADT into two
> - the parts that tablegen depends on and the parts that it doesn't?
>
>
> What's the actual problem here? Is it that TableGen regenerates different
> files and so we then need to rebuild all dependencies of those files? Maybe
> we should use a diff-and-update approach (I thought, however, that we
> already did that).
>
>  -Hal
>
>
> From what I can gather, Tablegen currently depends on these headers and
> all of their transitive dependencies.
>
> #include "llvm/Support/Casting.h"
> #include "llvm/Support/CommandLine.h"
> #include "llvm/Support/Compiler.h"
> #include "llvm/Support/DataTypes.h"
> #include "llvm/Support/Debug.h"
> #include "llvm/Support/Error.h"
> #include "llvm/Support/ErrorHandling.h"
> #include "llvm/Support/Format.h"
> #include "llvm/Support/FormattedStream.h"
> #include "llvm/Support/LEB128.h"
> #include "llvm/Support/LowLevelTypeImpl.h"
> #include "llvm/Support/ManagedStatic.h"
> #include "llvm/Support/MathExtras.h"
> #include "llvm/Support/MemoryBuffer.h"
> #include "llvm/Support/PrettyStackTrace.h"
> #include "llvm/Support/Regex.h"
> #include "llvm/Support/SMLoc.h"
> #include "llvm/Support/ScopedPrinter.h"
> #include "llvm/Support/Signals.h"
> #include "llvm/Support/SourceMgr.h"
> #include "llvm/Support/raw_ostream.h"
>
> #include "llvm/ADT/APInt.h"
> #include "llvm/ADT/ArrayRef.h"
> #include "llvm/ADT/BitVector.h"
> #include "llvm/ADT/CachedHashString.h"
> #include "llvm/ADT/DenseSet.h"
> #include "llvm/ADT/IndexedMap.h"
> #include "llvm/ADT/IntEqClasses.h"
> #include "llvm/ADT/MapVector.h"
> #include "llvm/ADT/Optional.h"
> #include "llvm/ADT/PointerUnion.h"
> #include "llvm/ADT/STLExtras.h"
> #include "llvm/ADT/SetVector.h"
> #include "llvm/ADT/SmallPtrSet.h"
> #include "llvm/ADT/SmallSet.h"
> #include "llvm/ADT/SmallVector.h"
> #include "llvm/ADT/SparseBitVector.h"
> #include "llvm/ADT/Statistic.h"
> #include "llvm/ADT/StringExtras.h"
> #include "llvm/ADT/StringMap.h"
> #include "llvm/ADT/StringRef.h"
> #include "llvm/ADT/StringSet.h"
> #include "llvm/ADT/StringSwitch.h"
> #include "llvm/ADT/TinyPtrVector.h"
> #include "llvm/ADT/Twine.h"
>
>
> Is this something worth putting effort into?  If so, I volunteer.
>
>
>
> _______________________________________________
> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
> --
> Hal Finkel
> Lead, Compiler Technology and Programming Languages
> Leadership Computing Facility
> Argonne National Laboratory
>
>
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