8cbf020fdc
Summary: Currently on most platforms you have to manually link the c++ abi library used with libc++ whenever you use libc++. So your typical libc++ command like invocation might look like: ``` clang++ -stdlib=libc++ foo.cpp -lc++abi ``` Having to manually link `libc++abi.so` makes it harder for libc++ to be used generically. This patch fixes that by generating a linker script for `libc++.so` that correctly links the ABI library. On linux the linker script for libc++abi would look like: ``` # libc++.so INPUT(libc++.so.1 -lc++abi) ``` With the linker script you can now use libc++ using only `-stdlib=libc++`. This is the technique that is used on FreeBSD in ordered to link cxxrt and I think it's the best approach to make our users lives simpler. The CMake option used to enable this is `LIBCXX_ENABLE_ABI_LINKER_SCRIPT`. In future I would like to enable this by default on all platforms except for Darwin. Reviewers: mclow.lists, danalbert, rsmith, jroelofs, EricWF Subscribers: cfe-commits Differential Revision: http://reviews.llvm.org/D12508 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@250319 91177308-0d34-0410-b5e6-96231b3b80d8
80 lines
2.5 KiB
Python
Executable File
80 lines
2.5 KiB
Python
Executable File
#!/usr/bin/env python
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import os
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import sys
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def print_and_exit(msg):
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sys.stderr.write(msg + '\n')
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sys.exit(1)
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def usage_and_exit():
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print_and_exit("Usage: ./gen_link_script.py [--help] [--dryrun] <path/to/libcxx.so> <abi_libname>")
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def help_and_exit():
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help_msg = \
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"""Usage
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gen_link_script.py [--help] [--dryrun] <path/to/libcxx.so> <abi_libname>
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Generate a linker script that links libc++ to the proper ABI library.
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The script replaces the specified libc++ symlink.
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An example script for c++abi would look like "INPUT(libc++.so.1 -lc++abi)".
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Arguments
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<path/to/libcxx.so> - The top level symlink to the versioned libc++ shared
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library. This file is replaced with a linker script.
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<abi_libname> - The name of the ABI library to use in the linker script.
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The name must be one of [c++abi, stdc++, supc++, cxxrt].
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Exit Status:
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0 if OK,
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1 if the action failed.
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"""
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print_and_exit(help_msg)
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def parse_args():
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args = list(sys.argv)
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del args[0]
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if len(args) == 0:
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usage_and_exit()
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if args[0] == '--help':
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help_and_exit()
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dryrun = '--dryrun' == args[0]
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if dryrun:
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del args[0]
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if len(args) != 2:
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usage_and_exit()
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symlink_file = args[0]
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abi_libname = args[1]
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return dryrun, symlink_file, abi_libname
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def main():
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dryrun, symlink_file, abi_libname = parse_args()
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# Check that the given libc++.so file is a valid symlink.
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if not os.path.islink(symlink_file):
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print_and_exit("symlink file %s is not a symlink" % symlink_file)
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# Read the symlink so we know what libc++ to link to in the linker script.
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linked_libcxx = os.readlink(symlink_file)
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# Check that the abi_libname is one of the supported values.
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supported_abi_list = ['c++abi', 'stdc++', 'supc++', 'cxxrt']
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if abi_libname not in supported_abi_list:
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print_and_exit("abi name '%s' is not supported: Use one of %r" %
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(abi_libname, supported_abi_list))
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# Generate the linker script contents and print the script and destination
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# information.
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contents = "INPUT(%s -l%s)" % (linked_libcxx, abi_libname)
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print("GENERATING SCRIPT: '%s' as file %s" % (contents, symlink_file))
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# Remove the existing libc++ symlink and replace it with the script.
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if not dryrun:
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os.unlink(symlink_file)
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with open(symlink_file, 'w') as f:
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f.write(contents + "\n")
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if __name__ == '__main__':
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main()
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