weiwang added a comment. In D70172#2964118 <https://reviews.llvm.org/D70172#2964118>, @sugak wrote:
> Hi @yaxunl! I'm working on upgrading a large codebase from LLVM-9 to LLVM-12. > I noticed on average 10% compilation speed regression that seems to be caused > this change. We use Clang modules and historically provide `-fopenmp` > compiler flag by default. The problem seems to be that compiling and > importing modules is now slower, with the generated modules size increased by > 2X. llvm-bcanalyzer tool shows that it's dominated by > `DECLS_TO_CHECK_FOR_DEFERRED_DIAGS`. If I understand it right, your change > is only relevant when target offloading is used. I inspected all of `#pragma > omp` directives and can confirm that we don't use it. > > I see that most of this code is gated by OpenMP flag. I wonder if there is a > finer grain way to enable openmp parallel code generation without target > offloading? Would it make sense to extend this code to check if > `-fopenom-targets` is set before recording > `DECLS_TO_CHECK_FOR_DEFERRED_DIAGS`? > > Note, this was measured with @weiwang's https://reviews.llvm.org/D101793. We did an internal measurement by not adding decls into deferred diags, and that resolves the build regression. Wonder if we can have a special case for emitting diag as they are encountered when everything is on host side. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D70172/new/ https://reviews.llvm.org/D70172 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
