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1e03c37b97
This is a second attempt at D101497, which landed as
9a9bc76c0eb72f0f2732c729a460abbd5239c2e3 but had to be reverted in
8cf7ddbdd4e5af966a369e170c73250f2e3920e7.
This issue was that in the case that `COMPILER_RT_INSTALL_PATH` is
empty, expressions like "${COMPILER_RT_INSTALL_PATH}/bin" evaluated to
"/bin" not "bin" as intended and as was originally.
One solution is to make `COMPILER_RT_INSTALL_PATH` always non-empty,
defaulting it to `CMAKE_INSTALL_PREFIX`. D99636 adopted that approach.
But, I think it is more ergonomic to allow those project-specific paths
to be relative the global ones. Also, making install paths absolute by
default inhibits the proper behavior of functions like
`GNUInstallDirs_get_absolute_install_dir` which make relative install
paths absolute in a more complicated way.
Given all this, I will define a function like the one asked for in
https://gitlab.kitware.com/cmake/cmake/-/issues/19568 (and needed for a
similar use-case).
---
Original message:
Instead of using `COMPILER_RT_INSTALL_PATH` through the CMake for
complier-rt, just use it to define variables for the subdirs which
themselves are used.
This preserves compatibility, but later on we might consider getting rid
of `COMPILER_RT_INSTALL_PATH` and just changing the defaults for the
subdir variables directly.
---
There was a seaming bug where the (non-Apple) per-target libdir was
`${target}` not `lib/${target}`. I suspect that has to do with the docs
on `COMPILER_RT_INSTALL_PATH` saying was the library dir when that's no
longer true, so I just went ahead and fixed it, allowing me to define
fewer and more sensible variables.
That last part should be the only behavior changes; everything else
should be a pure refactoring.
---
I added some documentation of these variables too. In particular, I
wanted to highlight the gotcha where `-DSomeCachePath=...` without the
`:PATH` will lead CMake to make the path absolute. See [1] for
discussion of the problem, and [2] for the brief official documentation
they added as a result.
[1]: https://cmake.org/pipermail/cmake/2015-March/060204.html
[2]: https://cmake.org/cmake/help/latest/manual/cmake.1.html#options
In 38b2dec37ee735d5409148e71ecba278caf0f969 the problem was somewhat
misidentified and so `:STRING` was used, but `:PATH` is better as it
sets the correct type from the get-go.
---
D99484 is the main thrust of the `GnuInstallDirs` work. Once this lands,
it should be feasible to follow both of these up with a simple patch for
compiler-rt analogous to the one for libcxx.
Reviewed By: phosek, #libc_abi, #libunwind
Differential Revision: https://reviews.llvm.org/D105765
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.. _BuildingCompilerRT:
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===============
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Building Compiler-RT
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===============
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.. contents::
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:local:
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.. _build instructions:
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The instructions on this page are aimed at vendors who ship Compiler-RT as part of an
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operating system distribution, a toolchain or similar shipping vehicules. If you
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are a user merely trying to use Compiler-RT in your program, you most likely want to
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refer to your vendor's documentation, or to the general documentation for using
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LLVM, Clang, the various santizers, etc.
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CMake Options
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=============
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Here are some of the CMake variables that are used often, along with a
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brief explanation and LLVM-specific notes. For full documentation, check the
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CMake docs or execute ``cmake --help-variable VARIABLE_NAME``.
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**CMAKE_BUILD_TYPE**:STRING
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Sets the build type for ``make`` based generators. Possible values are
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Release, Debug, RelWithDebInfo and MinSizeRel. On systems like Visual Studio
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the user sets the build type with the IDE settings.
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**CMAKE_INSTALL_PREFIX**:PATH
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Path where LLVM will be installed if "make install" is invoked or the
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"INSTALL" target is built.
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**CMAKE_CXX_COMPILER**:STRING
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The C++ compiler to use when building and testing Compiler-RT.
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.. _compiler-rt-specific options:
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Compiler-RT specific options
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-----------------------
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.. option:: COMPILER_RT_INSTALL_PATH:PATH
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**Default**: ```` (empty relative path)
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Prefix for directories where built Compiler-RT artifacts should be installed.
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Can be an absolute path, like the default empty string, in which case it is
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relative ``CMAKE_INSTALL_PREFIX``. If setting a relative path, make sure to
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include the ``:PATH`` with your ``-D``, i.e. use
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``-DCOMPILER_RT_INSTALL_PATH:PATH=...`` not
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``-DCOMPILER_RT_INSTALL_PATH=...``, otherwise CMake will convert the
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path to an absolute path.
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.. option:: COMPILER_RT_INSTALL_LIBRARY_DIR:PATH
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**Default**: ``lib``
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Path where built Compiler-RT libraries should be installed. If a relative
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path, relative to ``COMPILER_RT_INSTALL_PATH``.
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.. option:: COMPILER_RT_INSTALL_BINARY_DIR:PATH
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**Default**: ``bin``
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Path where built Compiler-RT executables should be installed. If a relative
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path, relative to ``COMPILER_RT_INSTALL_PATH``.
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.. option:: COMPILER_RT_INSTALL_INCLUDE_DIR:PATH
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**Default**: ``include``
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Path where Compiler-RT headers should be installed. If a relative
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path, relative to ``COMPILER_RT_INSTALL_PATH``.
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.. option:: COMPILER_RT_INSTALL_DATA_DIR:PATH
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**Default**: ``share``
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Path where Compiler-RT data should be installed. If a relative
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path, relative to ``COMPILER_RT_INSTALL_PATH``.
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.. _LLVM-specific variables:
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LLVM-specific options
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---------------------
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.. option:: LLVM_LIBDIR_SUFFIX:STRING
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Extra suffix to append to the directory where libraries are to be
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installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
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to install libraries to ``/usr/lib64``.
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