r199632 - Make the Linux support for finding libc++ somewhat less braindead.
Evgeniy Stepanov
eugeni.stepanov at gmail.com
Tue Jan 21 01:12:36 PST 2014
On Tue, Jan 21, 2014 at 1:06 PM, Chandler Carruth <chandlerc at google.com> wrote:
> On Tue, Jan 21, 2014 at 12:06 AM, Evgeniy Stepanov
> <eugeni.stepanov at gmail.com> wrote:
>>
>> I don't this adding builddir/lib to linker search path would be right.
>
>
> Why not?
Because at the moment it contains a bunch of host libraries, and
libc++ we are trying to link is a target library. Of course, at the
moment it is being built with the host compiler, but it is a target
library in spirit.
>
>>
>> Would it make sense to move libc++.so to lib/clang/3.5/lib/linux/?
>
>
> This is a good question.
>
> Historically, GCC has considered libstdc++ to be "part of" the compiler or
> toolchain, and distributed them together. We lookup libstdc++ out of GCC's
> installation tree for example.
>
> Also historically, libc++ has *not* been distributed as "part of" the
> compiler or toolchain. On OS X it is actually more part of the OS than the
> toolchain. Even on Linux, some care has been taken to try to make it
> effective to use libc++ with a GCC host just as much as with a Clang host.
>
> I'm not trying to endorse either of these approaches, but that's what they
> have been historically. To my mind, that makes lib/clang/<version>
> inapropriate for libc++. If we want to switch to shipping libc++ as merely
> an implementation detail of Clang itself, then I would suggest installing
> *both* headers and libraries under lib/clang/<version>. But that would be a
> reasonably radical departure from current trends etc.
I see, lib/clang is not a good choice then.
>
>>
>>
>> On Mon, Jan 20, 2014 at 7:23 PM, Alexey Samsonov <samsonov at google.com>
>> wrote:
>> > 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 \
>> >>
>> >>
>> >> _______________________________________________
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>> >
>> >
>> >
>> > --
>> > Alexey Samsonov, MSK
>> > _______________________________________________
>> > cfe-commits mailing list
>> > cfe-commits at cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
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