[llvm-dev] Tablegen ridiculously slow when compiling for Debug

Florian Hahn via llvm-dev
Sat, 29 Jun 2019 17:37:46 -0000

Hi,

> On Jun 29, 2019, at 18:26, Joan Lluch via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>
> Hi all,
>
> On LLVM version 7.0.1, incremental builds are very fast for both Release
and Debug. I’m compiling with Xcode
>
> I recently downloaded LLVM 9.0 from the LLVM-mirror Github repository and
found that Incremental "Debug” builds take a ridiculously long time due to
Tablegen taking ages (literally more than 10 minutes) to generate files. This
makes it totally unusable for debug purposes. However, incremental ‘Release’
builds only take a few seconds.
>
> Why is that?. Any suggestions?.



You could give setting LLVM_OPTIMIZED_TABLEGEN a try
(https://llvm.org/docs/CMake.html).

Cheers,
Florian