r199632 - Make the Linux support for finding libc++ somewhat less braindead.

[Alexey Samsonov]

Hi Chandler,

Fixing include paths is not enough - you should also fix library
lookup paths for dynamic linker in Clang driver. Currently if the
build tree has both Clang binary and built libc++ like this:
<...>/bin/clang++
<...>/lib/libc++.so

Clang binary is not able to locate libc++.so with -stdlib=libc++
provided. Therefore the following brute-force bootstrap process
wouldn't work:
(1) configure a new build tree with default options and build Clang and libc++
(2) configure a new build tree with just-built Clang as c/c++ compiler
and specify LLVM_ENABLE_LIBCXX=ON

I'll try to take a closer look at this (and potentially fix the
driver) tomorrow, unless someone who has more understanding picks it
up from here.



On Mon, Jan 20, 2014 at 1:42 PM, Chandler Carruth <chandlerc at gmail.com> wrote:
> Author: chandlerc
> Date: Mon Jan 20 03:42:24 2014
> New Revision: 199632
>
> URL: http://llvm.org/viewvc/llvm-project?rev=199632&view=rev
> Log:
> Make the Linux support for finding libc++ somewhat less braindead.
>
> Now instead of just looking in the system root for it, we also look
> relative to the clang binary's directory. This should "just work" in
> almost all cases. I've added test cases accordingly.
>
> This is probably *very* worthwhile to backport to the 3.4 branch so that
> folks can check it out, build it, and use that as their host compiler
> going forward.
>
> Modified:
>     cfe/trunk/lib/Driver/ToolChains.cpp
>     cfe/trunk/test/Driver/linux-header-search.cpp
>
> Modified: cfe/trunk/lib/Driver/ToolChains.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.cpp?rev=199632&r1=199631&r2=199632&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Driver/ToolChains.cpp (original)
> +++ cfe/trunk/lib/Driver/ToolChains.cpp Mon Jan 20 03:42:24 2014
> @@ -2945,9 +2945,24 @@ void Linux::AddClangCXXStdlibIncludeArgs
>
>    // Check if libc++ has been enabled and provide its include paths if so.
>    if (GetCXXStdlibType(DriverArgs) == ToolChain::CST_Libcxx) {
> -    // libc++ is always installed at a fixed path on Linux currently.
> -    addSystemInclude(DriverArgs, CC1Args,
> -                     getDriver().SysRoot + "/usr/include/c++/v1");
> +    const std::string LibCXXIncludePathCandidates[] = {
> +      // The primary location is within the Clang installation.
> +      // FIXME: We shouldn't hard code 'v1' here to make Clang future proof to
> +      // newer ABI versions.
> +      getDriver().Dir + "/../include/c++/v1",
> +
> +      // We also check the system as for a long time this is the only place Clang looked.
> +      // FIXME: We should really remove this. It doesn't make any sense.
> +      getDriver().SysRoot + "/usr/include/c++/v1"
> +    };
> +    for (unsigned i = 0; i < llvm::array_lengthof(LibCXXIncludePathCandidates);
> +         ++i) {
> +      if (!llvm::sys::fs::exists(LibCXXIncludePathCandidates[i]))
> +        continue;
> +      // Add the first candidate that exists.
> +      addSystemInclude(DriverArgs, CC1Args, LibCXXIncludePathCandidates[i]);
> +      break;
> +    }
>      return;
>    }
>
> @@ -2971,7 +2986,7 @@ void Linux::AddClangCXXStdlibIncludeArgs
>                                 MIPSABIDirSuffix, DriverArgs, CC1Args))
>      return;
>
> -  const std::string IncludePathCandidates[] = {
> +  const std::string LibStdCXXIncludePathCandidates[] = {
>      // Gentoo is weird and places its headers inside the GCC install, so if the
>      // first attempt to find the headers fails, try these patterns.
>      InstallDir.str() + "/include/g++-v" + Version.MajorStr + "." +
> @@ -2984,8 +2999,9 @@ void Linux::AddClangCXXStdlibIncludeArgs
>      LibDir.str() + "/../include/c++",
>    };
>
> -  for (unsigned i = 0; i < llvm::array_lengthof(IncludePathCandidates); ++i) {
> -    if (addLibStdCXXIncludePaths(IncludePathCandidates[i],
> +  for (unsigned i = 0; i < llvm::array_lengthof(LibStdCXXIncludePathCandidates);
> +       ++i) {
> +    if (addLibStdCXXIncludePaths(LibStdCXXIncludePathCandidates[i],
>                                   TripleStr + MIPSABIDirSuffix + BiarchSuffix,
>                                   DriverArgs, CC1Args))
>        break;
>
> Modified: cfe/trunk/test/Driver/linux-header-search.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/linux-header-search.cpp?rev=199632&r1=199631&r2=199632&view=diff
> ==============================================================================
> --- cfe/trunk/test/Driver/linux-header-search.cpp (original)
> +++ cfe/trunk/test/Driver/linux-header-search.cpp Mon Jan 20 03:42:24 2014
> @@ -1,6 +1,29 @@
>  // General tests that the header search paths detected by the driver and passed
>  // to CC1 are sane.
>  //
> +// Test a simulated installation of libc++ on Linux, both through sysroot and
> +// the installation path of Clang.
> +// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
> +// RUN:     -target x86_64-unknown-linux-gnu \
> +// RUN:     -stdlib=libc++ \
> +// RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
> +// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
> +// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-SYSROOT %s
> +// CHECK-BASIC-LIBCXX-SYSROOT: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
> +// CHECK-BASIC-LIBCXX-SYSROOT: "-isysroot" "[[SYSROOT:[^"]+]]"
> +// CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
> +// CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
> +// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
> +// RUN:     -target x86_64-unknown-linux-gnu \
> +// RUN:     -stdlib=libc++ \
> +// RUN:     -ccc-install-dir %S/Inputs/basic_linux_libcxx_tree/usr/bin \
> +// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
> +// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-INSTALL %s
> +// CHECK-BASIC-LIBCXX-INSTALL: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
> +// CHECK-BASIC-LIBCXX-INSTALL: "-isysroot" "[[SYSROOT:[^"]+]]"
> +// CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/c++/v1"
> +// CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
> +//
>  // Test a very broken version of multiarch that shipped in Ubuntu 11.04.
>  // RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
>  // RUN:     -target i386-unknown-linux \
>
>
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits



-- 
Alexey Samsonov, MSK