users users via llvm-dev
2021-Feb-11 22:53 UTC
[llvm-dev] Clang++: No member name 'make_unique' in namespace 'std'
Hi David, Thank you so much for your quick response! I am very inexperienced with llvm. Please bear with me if my questions look stupid: 1. Here is the output from the command ss"clang++ -v": $ clang++ -v clang version 12.0.0 (... .../llvm/llvm-project_git/clang 36263a7cccc0d98afc36dea55e7a004d08455811) Target: powerpc64le-unknown-linux-gnu Thread model: posix InstalledDir: ... .../llvm/llvm-project_git/build_12.0.0_36263a7_010421/bin Found candidate GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.2 Found candidate GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.5 Selected GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.5 Candidate multilib: .;@m64 Selected multilib: .;@m64 Before using clang++, I removed gcc modules, because I thought clang++ should not be dependent of any host compiler once it was built successfully. Or does it need to make my host compiler (such as gcc/8.2.0) available to it so that to compile my project? 2. Here are the options I used to build llvm: -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi;openmp;parallel-libs" -DCMAKE_BUILD_TYPE="Release" -DLLVM_TARGETS_TO_BUILD=PowerPC -DLLVM_ENABLE_LIBPFM=OFF -DRUN_HAVE_GNU_POSIX_REGEX=0 -DRUN_HAVE_THREAD_SAFETY_ATTRIBUTES=0 -Wno-dev ../llvm Are these correct options to use? Please advise. Thank you so much David! Best, Shelton On Thu, Feb 11, 2021 at 4:26 PM David Blaikie <dblaikie at gmail.com> wrote:> 1) clang++ -v will show you which standard library headers it's using, > it might be using an older standard library on your system that > doesn't have std::make_unique. > 2) Did you build the compiler in release mode, or in debug mode? (with > or without assertions enabled) > > On Thu, Feb 11, 2021 at 2:21 PM users users via llvm-dev > <llvm-dev at lists.llvm.org> wrote: > > > > Dear LLVM Developers: > > > > 1. Recently I built llvm/12.0 on IBM power8 using gcc/8.2.0. When I > run clang++ with an example from > https://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique: > > > > #include <iostream> > > > > #include <iomanip> > > #include <memory> > > > > struct Vec3 > > { > > int x, y, z; > > > > // following constructor is no longer needed since C++20 > > Vec3(int x = 0, int y = 0, int z = 0) noexcept : x(x), y(y), z(z) { } > > > > friend std::ostream& operator<<(std::ostream& os, const Vec3& v) { > > return os << "{ x=" << v.x << ", y=" << v.y << ", z=" << v.z << > " }"; > > } > > }; > > > > int main() > > { > > // Use the default constructor. > > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); > > // Use the constructor that matches these arguments > > std::unique_ptr<Vec3> v2 = std::make_unique<Vec3>(0,1,2); > > // Create a unique_ptr to an array of 5 elements > > std::unique_ptr<Vec3[]> v3 = std::make_unique<Vec3[]>(5); > > > > std::cout << "make_unique<Vec3>(): " << *v1 << '\n' > > << "make_unique<Vec3>(0,1,2): " << *v2 << '\n' > > << "make_unique<Vec3[]>(5): "; > > for (int i = 0; i < 5; i++) { > > std::cout << std::setw(i ? 30 : 0) << v3[i] << '\n'; > > } > > } > > > > > > It failed with the following errors: > > Error: no member named 'make_unique' in namespace 'std' > > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); > > ... ... > > > > Any idea and suggestion about what is going on? or have I missed > something? The command I used to compile the code above: > > $ clang++ a.cpp > > > > 2. Comparing this llvm with my current gcc/8.2.0 on a project (openmp > code running 1 thread), it showed that llvm is almost twice as slow as gcc > (both compile with -O3) on my IBM power8 machine. Is it suppose to be with > such slower performance than gcc? > > > > Thank you very much for any advice! > > > > Best Regards, > > Shelton > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210211/3529b9ca/attachment.html>
David Blaikie via llvm-dev
2021-Feb-11 23:08 UTC
[llvm-dev] Clang++: No member name 'make_unique' in namespace 'std'
On Thu, Feb 11, 2021 at 2:53 PM users users <usertestexamples at gmail.com> wrote:> > Hi David, > > Thank you so much for your quick response! > I am very inexperienced with llvm. Please bear with me if my questions look stupid: > > 1. Here is the output from the command ss"clang++ -v": > > > $ clang++ -v > > clang version 12.0.0 (... .../llvm/llvm-project_git/clang 36263a7cccc0d98afc36dea55e7a004d08455811) > > Target: powerpc64le-unknown-linux-gnu > > Thread model: posix > > InstalledDir: ... .../llvm/llvm-project_git/build_12.0.0_36263a7_010421/bin > > Found candidate GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.2 > > Found candidate GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.5 > > Selected GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.5 > > Candidate multilib: .;@m64 > > Selected multilib: .;@m64 > > > Before using clang++, I removed gcc modules, because I thought clang++ should not be dependent of any host compiler once it was built successfully. Or does it need to make my host compiler (such as gcc/8.2.0) available to it so that to compile my project?I think you may need to pass -stdlib=libc++ to use the libc++ you built/installed, rather than the system libstdc++ which looks a bit out of date (& so doesn't have std::make_unique).> > 2. Here are the options I used to build llvm: > -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi;openmp;parallel-libs" -DCMAKE_BUILD_TYPE="Release" -DLLVM_TARGETS_TO_BUILD=PowerPC -DLLVM_ENABLE_LIBPFM=OFF -DRUN_HAVE_GNU_POSIX_REGEX=0 -DRUN_HAVE_THREAD_SAFETY_ATTRIBUTES=0 -Wno-dev ../llvm > Are these correct options to use?Mostly right except you probably want/need -DLLVM_ENABLE_ASSERTIONS=Off if you want a production-speed compiler.> > Please advise. Thank you so much David! > > Best, > Shelton > > > > On Thu, Feb 11, 2021 at 4:26 PM David Blaikie <dblaikie at gmail.com> wrote: >> >> 1) clang++ -v will show you which standard library headers it's using, >> it might be using an older standard library on your system that >> doesn't have std::make_unique. >> 2) Did you build the compiler in release mode, or in debug mode? (with >> or without assertions enabled) >> >> On Thu, Feb 11, 2021 at 2:21 PM users users via llvm-dev >> <llvm-dev at lists.llvm.org> wrote: >> > >> > Dear LLVM Developers: >> > >> > 1. Recently I built llvm/12.0 on IBM power8 using gcc/8.2.0. When I run clang++ with an example from https://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique: >> > >> > #include <iostream> >> > >> > #include <iomanip> >> > #include <memory> >> > >> > struct Vec3 >> > { >> > int x, y, z; >> > >> > // following constructor is no longer needed since C++20 >> > Vec3(int x = 0, int y = 0, int z = 0) noexcept : x(x), y(y), z(z) { } >> > >> > friend std::ostream& operator<<(std::ostream& os, const Vec3& v) { >> > return os << "{ x=" << v.x << ", y=" << v.y << ", z=" << v.z << " }"; >> > } >> > }; >> > >> > int main() >> > { >> > // Use the default constructor. >> > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); >> > // Use the constructor that matches these arguments >> > std::unique_ptr<Vec3> v2 = std::make_unique<Vec3>(0,1,2); >> > // Create a unique_ptr to an array of 5 elements >> > std::unique_ptr<Vec3[]> v3 = std::make_unique<Vec3[]>(5); >> > >> > std::cout << "make_unique<Vec3>(): " << *v1 << '\n' >> > << "make_unique<Vec3>(0,1,2): " << *v2 << '\n' >> > << "make_unique<Vec3[]>(5): "; >> > for (int i = 0; i < 5; i++) { >> > std::cout << std::setw(i ? 30 : 0) << v3[i] << '\n'; >> > } >> > } >> > >> > >> > It failed with the following errors: >> > Error: no member named 'make_unique' in namespace 'std' >> > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); >> > ... ... >> > >> > Any idea and suggestion about what is going on? or have I missed something? The command I used to compile the code above: >> > $ clang++ a.cpp >> > >> > 2. Comparing this llvm with my current gcc/8.2.0 on a project (openmp code running 1 thread), it showed that llvm is almost twice as slow as gcc (both compile with -O3) on my IBM power8 machine. Is it suppose to be with such slower performance than gcc? >> > >> > Thank you very much for any advice! >> > >> > Best Regards, >> > Shelton >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > _______________________________________________ >> > LLVM Developers mailing list >> > llvm-dev at lists.llvm.org >> > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev