Andrew Ng
cf20a2685e
Add DTLTO linker option `--thinlto-remote-compiler-prepend-arg` to enable support for the multi-call LLVM driver that requires an additional option to specify the subcommand, e.g. "llvm clang ...". Fixes https://github.com/llvm/llvm-project/issues/159125.
84 lines
3.3 KiB
ReStructuredText
84 lines
3.3 KiB
ReStructuredText
Integrated Distributed ThinLTO (DTLTO)
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======================================
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Integrated Distributed ThinLTO (DTLTO) enables the distribution of backend
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ThinLTO compilations via external distribution systems, such as Incredibuild,
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during the traditional link step.
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The implementation is documented here: https://llvm.org/docs/DTLTO.html.
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Currently, DTLTO is only supported in ELF and COFF LLD.
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ELF LLD
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-------
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The command-line interface is as follows:
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- ``--thinlto-distributor=<path>``
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Specifies the file to execute as the distributor process. If specified,
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ThinLTO backend compilations will be distributed.
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- ``--thinlto-remote-compiler=<path>``
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Specifies the path to the compiler that the distributor process will use for
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backend compilations. The compiler invoked must match the version of LLD.
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- ``--thinlto-distributor-arg=<arg>``
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Specifies ``<arg>`` on the command line when invoking the distributor.
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Can be specified multiple times.
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- ``--thinlto-remote-compiler-prepend-arg=<arg>``
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Prepends ``<arg>`` to the remote compiler's command line.
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Can be specified multiple times.
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- ``--thinlto-remote-compiler-arg=<arg>``
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Appends ``<arg>`` to the remote compiler's command line.
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Can be specified multiple times.
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Options that introduce extra input/output files may cause miscompilation if
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the distribution system does not automatically handle pushing/fetching them to
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remote nodes. In such cases, configure the distributor - possibly using
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``--thinlto-distributor-arg=`` - to manage these dependencies. See the
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distributor documentation for details.
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Some LLD LTO options (e.g., ``--lto-sample-profile=<file>``) are supported.
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Currently, other options are silently accepted but do not have the intended
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effect. Support for such options will be expanded in the future.
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COFF LLD
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--------
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The command-line interface is as follows:
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- ``/thinlto-distributor:<path>``
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Specifies the file to execute as the distributor process. If specified,
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ThinLTO backend compilations will be distributed.
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- ``/thinlto-remote-compiler:<path>``
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Specifies the path to the compiler that the distributor process will use for
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backend compilations. The compiler invoked must match the version of LLD.
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- ``/thinlto-distributor-arg:<arg>``
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Specifies ``<arg>`` on the command line when invoking the distributor.
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Can be specified multiple times.
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- ``/thinlto-remote-compiler-prepend-arg:<arg>``
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Prepends ``<arg>`` to the remote compiler's command line.
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Can be specified multiple times.
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- ``/thinlto-remote-compiler-arg:<arg>``
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Appends ``<arg>`` to the remote compiler's command line.
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Can be specified multiple times.
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Options that introduce extra input/output files may cause miscompilation if
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the distribution system does not automatically handle pushing/fetching them to
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remote nodes. In such cases, configure the distributor - possibly using
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``/thinlto-distributor-arg:`` - to manage these dependencies. See the
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distributor documentation for details.
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Some LLD LTO options (e.g., ``/lto-sample-profile:<file>``) are supported.
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Currently, other options are silently accepted but do not have the intended
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effect. Support for such options could be expanded in the future.
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Currently, there is no DTLTO command line interface supplied for ``clang-cl``,
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as users are expected to invoke LLD directly.
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