[libcxx-dev] libcxx performance issue

Yan Yichen via libcxx-dev libcxx-dev at lists.llvm.org
Sat Aug 24 11:28:32 PDT 2019

Dear developers,
  Sorry to bother you, but I've met a wired problem using clang with libcxx.
  I've built clang and libcxx with clang, and trying to compile c++ program with libc++, but compilation is extremely slow when using libcxx, as below:

$ time clang++ -o /dev/null -std=c++11 -stdlib=libc++ test.cc
clang++ -o /dev/null -std=c++11 -stdlib=libc++ test.cc  4.29s user 0.06s system 97% cpu 4.476 total
$ time clang++ -o /dev/null -std=c++11 test.cc
clang++ -o /dev/null -std=c++11 test.cc  1.41s user 0.06s system 92% cpu 1.582 total

  I wonder if you have any idea where should I start to address this issue, or anything I probably configured wrong? Thanks in advanced.

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