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Clang nvlink Wrapper
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.. _clang-nvlink-wrapper:
Introduction
============
This tools works as a wrapper around the NVIDIA ``nvlink`` linker. The purpose
of this wrapper is to provide an interface similar to the ``ld.lld`` linker
while still relying on NVIDIA's proprietary linker to produce the final output.
``nvlink`` has a number of known quirks that make it difficult to use in a
unified offloading setting. For example, it does not accept ``.o`` files as they
must be named ``.cubin``. Static archives do not work, so passing a ``.a`` will
provide a linker error. ``nvlink`` also does not support link time optimization
and ignores many standard linker arguments. This tool works around these issues.
Usage
=====
This tool can be used with the following options. Any arguments not intended
only for the linker wrapper will be forwarded to ``nvlink``.
.. code-block:: console
OVERVIEW: A utility that wraps around the NVIDIA 'nvlink' linker.
This enables static linking and LTO handling for NVPTX targets.
USAGE: clang-nvlink-wrapper [options] <options to passed to nvlink>
OPTIONS:
--arch <value> Specify the 'sm_' name of the target architecture.
--cuda-path=<dir> Set the system CUDA path
--dry-run Print generated commands without running.
--feature <value> Specify the '+ptx' freature to use for LTO.
-g Specify that this was a debug compile.
-help-hidden Display all available options
-help Display available options (--help-hidden for more)
-L <dir> Add <dir> to the library search path
-l <libname> Search for library <libname>
-mllvm <arg> Arguments passed to LLVM, including Clang invocations,
for which the '-mllvm' prefix is preserved. Use '-mllvm
--help' for a list of options.
-o <path> Path to file to write output
--plugin-opt=jobs=<value>
Number of LTO codegen partitions
--plugin-opt=lto-partitions=<value>
Number of LTO codegen partitions
--plugin-opt=O<O0, O1, O2, or O3>
Optimization level for LTO
--plugin-opt=thinlto<value>
Enable the thin-lto backend
--plugin-opt=<value> Arguments passed to LLVM, including Clang invocations,
for which the '-mllvm' prefix is preserved. Use '-mllvm
--help' for a list of options.
--save-temps Save intermediate results
--version Display the version number and exit
-v Print verbose information
Example
=======
This tool is intended to be invoked when targeting the NVPTX toolchain directly
as a cross-compiling target. This can be used to create standalone GPU
executables with normal linking semantics similar to standard compilation.
.. code-block:: console
clang --target=nvptx64-nvidia-cuda -march=native -flto=full input.c
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