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cmake: use CMAKE_INSTALL_RPATH_USE_LINK_PATH (#29703)

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* cmake: use CMAKE_INSTALL_RPATH_USE_LINK_PATH

Spack has a heuristic to add rpaths for packages it knows are required,
but it's really a heuristic, and it does not work when the dependencies
put their libraries in a different folder than `<prefix>/lib{64,}`.

CMake patches binaries after install with the "install rpaths", which by
default are provided by Spack and its heuristic through
`CMAKE_INSTALL_RPATH`.

CMake however knows better what libraries are effectively being linked
to, and has an option to include those in the install rpath too, through
`CMAKE_INSTALL_RPATH_USE_LINK_PATH`.

These two CMake options are complementary, repeated rpaths seem to be
filtered, and the "use link path" paths are appended to Spack's
heuristic "install rpath".

So, it seems like a good idea to enable "use link path" by default, so
that:
- `dlopen` by library name uses Spack's heuristic search paths
- linked libraries in non-standard locations within a prefix get an
rpath thanks to CMake.

* docs
This commit is contained in:
Harmen Stoppels 2022-03-29 18:24:10 +02:00 committed by GitHub
parent c0b400c422
commit 9516fa9447
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2 changed files with 80 additions and 31 deletions
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109
lib/spack/docs/build_systems/cmakepackage.rst
View File

@ -159,6 +159,85 @@ and CMake simply ignores the empty command line argument. For example the follow
will generate ``'cmake' '-DEXAMPLE=ON' ...`` when `@2.0: +example` is met, but will
result in ``'cmake' '' ...`` when the spec version is below ``2.0``.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
CMake arguments provided by Spack
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following default arguments are controlled by Spack:
``CMAKE_INSTALL_PREFIX``
------------------------
Is set to the the package's install directory.
``CMAKE_PREFIX_PATH``
---------------------
CMake finds dependencies through calls to ``find_package()``, ``find_program()``,
``find_library()``, ``find_file()``, and ``find_path()``, which use a list of search
paths from ``CMAKE_PREFIX_PATH``. Spack sets this variable to a list of prefixes of the
spec's transitive dependencies.
For troubleshooting cases where CMake fails to find a dependency, add the
``--debug-find`` flag to ``cmake_args``.
``CMAKE_BUILD_TYPE``
--------------------
Every CMake-based package accepts a ``-DCMAKE_BUILD_TYPE`` flag to
dictate which level of optimization to use. In order to ensure
uniformity across packages, the ``CMakePackage`` base class adds
a variant to control this:
.. code-block:: python
variant('build_type', default='RelWithDebInfo',
description='CMake build type',
values=('Debug', 'Release', 'RelWithDebInfo', 'MinSizeRel'))
However, not every CMake package accepts all four of these options.
Grep the ``CMakeLists.txt`` file to see if the default values are
missing or replaced. For example, the
`dealii <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/dealii/package.py>`_
package overrides the default variant with:
.. code-block:: python
variant('build_type', default='DebugRelease',
description='The build type to build',
values=('Debug', 'Release', 'DebugRelease'))
For more information on ``CMAKE_BUILD_TYPE``, see:
https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html
``CMAKE_INSTALL_RPATH`` and ``CMAKE_INSTALL_RPATH_USE_LINK_PATH=ON``
--------------------------------------------------------------------
CMake uses different RPATHs during the build and after installation, so that executables
can locate the libraries they're linked to during the build, and installed executables
do not have RPATHs to build directories. In Spack, we have to make sure that RPATHs are
set properly after installation.
Spack sets ``CMAKE_INSTALL_RPATH`` to a list of ``<prefix>/lib`` or ``<prefix>/lib64``
directories of the spec's link-type dependencies. Apart from that, it sets
``-DCMAKE_INSTALL_RPATH_USE_LINK_PATH=ON``, which should add RPATHs for directories of
linked libraries not in the directories covered by ``CMAKE_INSTALL_RPATH``.
Usually it's enough to set only ``-DCMAKE_INSTALL_RPATH_USE_LINK_PATH=ON``, but the
reason to provide both options is that packages may dynamically open shared libraries,
which CMake cannot detect. In those cases, the RPATHs from ``CMAKE_INSTALL_RPATH`` are
used as search paths.
.. note::
Some packages provide stub libraries, which contain an interface for linking without
an implementation. When using such libraries, it's best to override the option
``-DCMAKE_INSTALL_RPATH_USE_LINK_PATH=OFF`` in ``cmake_args``, so that stub libraries
are not used at runtime.
^^^^^^^^^^
Generators
@ -196,36 +275,6 @@ generators, but it should be simple to add support for alternative
generators. For more information on CMake generators, see:
https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html
^^^^^^^^^^^^^^^^
CMAKE_BUILD_TYPE
^^^^^^^^^^^^^^^^
Every CMake-based package accepts a ``-DCMAKE_BUILD_TYPE`` flag to
dictate which level of optimization to use. In order to ensure
uniformity across packages, the ``CMakePackage`` base class adds
a variant to control this:
.. code-block:: python
variant('build_type', default='RelWithDebInfo',
description='CMake build type',
values=('Debug', 'Release', 'RelWithDebInfo', 'MinSizeRel'))
However, not every CMake package accepts all four of these options.
Grep the ``CMakeLists.txt`` file to see if the default values are
missing or replaced. For example, the
`dealii <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/dealii/package.py>`_
package overrides the default variant with:
.. code-block:: python
variant('build_type', default='DebugRelease',
description='The build type to build',
values=('Debug', 'Release', 'DebugRelease'))
For more information on ``CMAKE_BUILD_TYPE``, see:
https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
CMakeLists.txt in a sub-directory
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

2
lib/spack/spack/build_systems/cmake.py
View File

@ -193,7 +193,7 @@ def _std_args(pkg):
# Set up CMake rpath
args.extend([
define('CMAKE_INSTALL_RPATH_USE_LINK_PATH', False),
define('CMAKE_INSTALL_RPATH_USE_LINK_PATH', True),
define('CMAKE_INSTALL_RPATH',
spack.build_environment.get_rpaths(pkg)),
define('CMAKE_PREFIX_PATH',