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

Florian Hahn via llvm-dev llvm-dev at lists.llvm.org
Sat Jun 29 10:37:46 PDT 2019


> 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).


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