[libcxx-dev] libcxx performance issue
Marshall Clow via libcxx-dev
libcxx-dev at lists.llvm.org
Mon Aug 26 15:36:43 PDT 2019
On Sat, Aug 24, 2019 at 11:28 AM Yan Yichen via libcxx-dev <
libcxx-dev at lists.llvm.org> wrote:
> Dear developers,
> Sorry to bother you, but I’ve met a wired problem using clang with
> 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.
I'm afraid I have no idea what you're comparing *with*.
If you have an old libstdc++ (say), then that will be much faster, because
it's missing lots of C++11 features.
But that's just a guess.
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