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llvm-project/clang/docs/ClangLinkerWrapper.rst

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[Clang] Introduce Clang Linker Wrapper Tool This patch introduces a linker wrapper tool that allows us to preprocess files before they are sent to the linker. This adds a dummy action and job to the driver stage that builds the linker command as usual and then replaces the command line with the wrapper tool. Depends on D116543 Reviewed By: JonChesterfield Differential Revision: https://reviews.llvm.org/D116544
2021-12-31 05:41:36 +08:00
====================
Clang Linker Wrapper
====================
.. contents::
:local:
.. _clang-linker-wrapper:
Introduction
============
This tool works as a wrapper over a linking job. The tool is used to create
linked device images for offloading. It scans the linker's input for embedded
device offloading data stored in sections ``.llvm.offloading.<triple>.<arch>``
and extracts it as a temporary file. The extracted device files will then be
[Clang][Docs] Add documention for new OpenMP offloading driver This patch adds more documentation for the OpenMP offloading driver. This includes a new file that describes the overall pipeline becuase that was not previously explained in full elsewhere. Reviewed By: ABataev Differential Revision: https://reviews.llvm.org/D118815
2022-02-03 02:06:55 +08:00
passed to a device linking job to create a final device image. The sections will
also be stripped and the resulting file passed back to the host linker.
[Clang] Introduce Clang Linker Wrapper Tool This patch introduces a linker wrapper tool that allows us to preprocess files before they are sent to the linker. This adds a dummy action and job to the driver stage that builds the linker command as usual and then replaces the command line with the wrapper tool. Depends on D116543 Reviewed By: JonChesterfield Differential Revision: https://reviews.llvm.org/D116544
2021-12-31 05:41:36 +08:00
Usage
=====
This tool can be used with the following options. Arguments to the host linker
being wrapper around are passed as positional arguments using the ``--`` flag to
override parsing.
.. code-block:: console
USAGE: clang-linker-wrapper [options] <options to be passed to linker>...
OPTIONS:
Generic Options:
--help - Display available options (--help-hidden for more)
--help-list - Display list of available options (--help-list-hidden for more)
--version - Display the version of this program
clang-linker-wrapper options:
[Clang][Docs] Add documention for new OpenMP offloading driver This patch adds more documentation for the OpenMP offloading driver. This includes a new file that describes the overall pipeline becuase that was not previously explained in full elsewhere. Reviewed By: ABataev Differential Revision: https://reviews.llvm.org/D118815
2022-02-03 02:06:55 +08:00
--host-triple=<string> - Triple to use for the host compilation
--linker-path=<string> - Path of linker binary
--opt-level=<string> - Optimization level for LTO
--ptxas-option=<string> - Argument to pass to the ptxas invocation
--save-temps - Save intermediary results.
--strip-sections - Strip offloading sections from the host object file.
--target-embed-bc - Embed linked bitcode instead of an executable device image
--target-feature=<string> - Target features for triple
--bitcode-library=<string> - Path for the target bitcode library
-v - Verbose output from tools
[Clang] Introduce Clang Linker Wrapper Tool This patch introduces a linker wrapper tool that allows us to preprocess files before they are sent to the linker. This adds a dummy action and job to the driver stage that builds the linker command as usual and then replaces the command line with the wrapper tool. Depends on D116543 Reviewed By: JonChesterfield Differential Revision: https://reviews.llvm.org/D116544
2021-12-31 05:41:36 +08:00
Example
=======
This tool links object files with offloading images embedded within it using the
``-fembed-offload-object`` flag in Clang. Given an input file containing the
magic section we can pass it to this tool to extract the data contained at that
section and run a device linking job on it.
.. code-block:: console
[Clang][Docs] Add documention for new OpenMP offloading driver This patch adds more documentation for the OpenMP offloading driver. This includes a new file that describes the overall pipeline becuase that was not previously explained in full elsewhere. Reviewed By: ABataev Differential Revision: https://reviews.llvm.org/D118815
2022-02-03 02:06:55 +08:00
clang-linker-wrapper -host-triple x86_64 -linker-path /usr/bin/ld -- <Args>