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List: cfe-commits
Subject: Re: r199632 - Make the Linux support for finding libc++ somewhat less braindead.
From: Alexey Samsonov <samsonov () google ! com>
Date: 2014-01-20 15:23:13
Message-ID: CAGSYnCP-qWSiAv2yH=iMCgZZ_cTUyf+c6EnReEM273NEoTjWhA () mail ! gmail ! com
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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@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@cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
--
Alexey Samsonov, MSK
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