e7c71c344d
Teach rustc to generate object files instead of a linked executable for binary and shared library crates. This lets us skip the lengthy Rust compilation phase when only the C++ dependencies of these crates have changed. This works using a Python script that replaces the linker invoked by rustc and converts the linker command line into a rspfile that can be used during the link phase. The script makes certain assumptions about how rustc invokes the linker, but since we control the version of Rust we use, we can update the script if those assumptions ever break. I've asked the Rust developers about adding an official way to do this so hopefully we won't need to rely on this hack in the future. The rustc rule for Kythe has been altered to pass linker=true, somewhat consistent with the main rustc rule, which now doesn't invoke the actual linker either. `m xref_rust` still succeeds, but hopefully we can find someone who knows more about the rest of the Kythe pipeline who can let us know whether it should still work. Otherwise, let's use this CL as an opportunity to find out whether the rest of the pipeline is happy with linker=true, since otherwise we will find it hard to maintain the Kythe rule in the future. Change-Id: Ifb9c8689c1bd78c0afcf6fdfd111140d20377536
79 lines
2.2 KiB
Python
Executable file
79 lines
2.2 KiB
Python
Executable file
#!/usr/bin/env python3
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#
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# Copyright (C) 2023 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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"""
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This script is used as a replacement for the Rust linker. It converts a linker
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command line into a rspfile that can be used during the link phase.
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"""
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import os
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import shutil
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import subprocess
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import sys
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def create_archive(out, objects, archives):
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mricmd = f'create {out}\n'
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for o in objects:
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mricmd += f'addmod {o}\n'
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for a in archives:
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mricmd += f'addlib {a}\n'
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mricmd += 'save\nend\n'
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subprocess.run([os.getenv('AR'), '-M'], encoding='utf-8', input=mricmd, check=True)
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objects = []
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archives = []
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linkdirs = []
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libs = []
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temp_archives = []
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version_script = None
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for i, arg in enumerate(sys.argv):
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if arg == '-o':
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out = sys.argv[i+1]
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if arg == '-L':
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linkdirs.append(sys.argv[i+1])
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if arg.startswith('-l') or arg == '-shared':
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libs.append(arg)
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if arg.startswith('-Wl,--version-script='):
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version_script = arg[21:]
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if arg[0] == '-':
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continue
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if arg.endswith('.o') or arg.endswith('.rmeta'):
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objects.append(arg)
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if arg.endswith('.rlib'):
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if arg.startswith(os.getenv('TMPDIR')):
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temp_archives.append(arg)
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else:
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archives.append(arg)
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create_archive(f'{out}.whole.a', objects, [])
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create_archive(f'{out}.a', [], temp_archives)
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with open(out, 'w') as f:
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print(f'-Wl,--whole-archive', file=f)
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print(f'{out}.whole.a', file=f)
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print(f'-Wl,--no-whole-archive', file=f)
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print(f'{out}.a', file=f)
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for a in archives:
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print(a, file=f)
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for linkdir in linkdirs:
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print(f'-L{linkdir}', file=f)
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for l in libs:
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print(l, file=f)
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if version_script:
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shutil.copyfile(version_script, f'{out}.version_script')
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print(f'-Wl,--version-script={out}.version_script', file=f)
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