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

Praveen Velliengiri via llvm-dev
Sun, 30 Jun 2019 05:32:07 -0000

Maybe try building llvm as a shared objects..

On Jun 30, 2019 1:30 AM, "Joan Lluch via llvm-dev" <llvm-dev at
lists.llvm.org>
wrote:

> Hi Florian,
>
> Ok, I ran this:
>
> cmake -S LLVM -DCMAKE_INSTALL_PREFIX=INSTALL -DLLVM_OPTIMIZED_TABLEGEN=On
> -G Xcode
>
> Compiled it again from clean, and the situation is worse than before.
> Incremental builds take an incredible amount of time stuck in running
> Tablegen scripts for all targets. Now this happens both in Release and
> Debug configurations. Just before this, at least Release compiled fine, but
> that’s no longer the case.
>
> Any other suggestions?  What could actually cause this?
>
> Thanks
> John
>
>
>
> On 29 Jun 2019, at 19:37, Florian Hahn <florian_hahn at apple.com>
wrote:
>
> 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
>
>
>
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