Instead of having complex logic around how to include the libc++ headers
and __config_site, handle that by defining cxx-headers as an INTERFACE
library and linking against it. After this patch, linking against cxx-headers
is sufficient to get the right __config_site include and include paths
for libc++.
Differential Revision: https://reviews.llvm.org/D82702
This allows passing parameters to the test suites without using
LLVM_LIT_ARGS. The problem is that we sometimes want to set some
Lit arguments on the CMake command line, but the Lit parameters in
a CMake cache file. If the only knob to do that is LLVM_LIT_ARGS,
the command-line entry overrides the cache one, and the parameters
set by the cache are ignored.
This fixes a current issue with the build bots that they completely
ignore the 'std' param set by Lit, because other Lit arguments are
provided via LLVM_LIT_ARGS on the CMake command-line.
Since we can always find the rest of the LLVM tree, we can always run the
tests in the standalone mode. Do it so that the default behavior is the
same in the standalone and non-standalone modes.
Since we require that libc++ is built as part of the monorepo layout, we
can assume the path of the rest of LLVM and avoid requiring that LLVM_PATH
be set explicitly.
We've decided to move away from that by requiring that libc++ is built
as part of the monorepo a while ago. This commit removes code pertaining
to that unsupported use case and produces a clear error when the user
violates that.
In fact, building outside of the monorepo will still work as long as
LLVM_PATH is pointing to the root of the LLVM project, although that
is not officially supported.
Before this patch, the __config_site header was only generated when at
least one __config_site macro needed to be defined. This lead to two
different code paths in how libc++ is configured, depending on whether
a __config_site header was generated or not. After this patch, the
__config_site is always generated, but it can be empty in case there
are no macros to define in it.
More context on why this change is important
--------------------------------------------
In addition to being confusing, this double-code-path situation lead to
broken code being checked in undetected in 2405bd6898, which introduced
the LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT CMake setting. Specifically,
the _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT <__config_site> macro was
supposed NOT to be defined unless LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT
was specified explicitly on the CMake command line. Instead, what happened
is that it was defined to 0 if it wasn't specified explicitly and a
<__config_site> header was generated. And defining that macro to 0 had
the important effect of using the non-unique RTTI comparison implementation,
which changes the ABI.
This change in behavior wasn't noticed because the <__config_site> header
is not generated by default. However, the Apple configuration does cause
a <__config_site> header to be generated, which lead to the wrong RTTI
implementation being used, and to https://llvm.org/PR45549. We came close
to an ABI break in the dylib, but were saved due to a downstream-only
change that overrode the decision of the <__config_site> for the purpose
of RTTI comparisons in libc++abi. This is an incredible luck that we should
not rely on ever again.
While the problem itself was fixed with 2464d8135e by setting
LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT explicitly in the Apple
CMake cache and then in d0fcdcd28f by making the setting less
brittle, the point still is that we should have had a single code
path from the beginning. Unlike most normal libraries, the macros
that configure libc++ are really complex, there's a lot of them and
they control important properties of the C++ runtime. There must be
a single code path for that, and it must be simple and robust.
Differential Revision: https://reviews.llvm.org/D80927
When testing libc++ for our cross-compiled CheriBSD target we specify an
explicit LIBCXX_CXX_ABI_INCLUDE_PATHS for libcxxrt. The hardcoded path
/usr/include/c++/v1 was introduced in 61e89737c5
and overrides any value passed on the CMake command line. Fix this by using
it as a fallback rather than a fixed default value.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D82095
This commit adds CMake caches for the various configurations of libc++
that are tested by our build bots.
Differential Revision: https://reviews.llvm.org/D81293
Before this patch, we tried detecting whether small atomics were available
without linking against libatomic. However, that's not really what we want
to know -- instead, we want to know what's required in order to support
atomics fully, which is to link against libatomic when it's provided.
That is both much simpler, and it doesn't suffer the problem that we would
not link against libatomic when small atomics didn't require it, which
lead to non-lockfree atomics never working.
Furthermore, because we understand that some platforms might not want to
(or be able to) ship non-lockfree atomics, we add that notion to the test
suite, independently of a potential extern library.
After this patch, we therefore:
(1) Link against libatomic when it is provided
(2) Independently detect whether non-lockfree atomics are supported in
the test suite, regardless of whether that means we're linking against
an external library or not (which is an implementation detail).
Differential Revision: https://reviews.llvm.org/D81190
When the __config_site header is generated, but LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT
wasn't specified, _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT would be defined
to 0, which was the NonUnique RTTI comparison implementation. The intent
was to use the Unique RTTI comparison implementation in that case, which
caused https://llvm.org/PR45549.
Instead, use a proper "switch" to select the RTTI comparison implementation.
Note that 0 can't be used as a value, because that is treated the same
by CMake as a variable that is just not defined.
Differential Revision: https://reviews.llvm.org/D80037
Android doesn't have a libgcc_s and uses libgcc instead, so adjust the
build accordingly. This matches compiler-rt's build setup. libc++abi and
libunwind were already checking for libgcc but in a different context.
This change makes them search only for libgcc on Android now, but the
code to link against libgcc if it were present was already there.
Reviewed By: #libc, #libc_abi, #libunwind, rprichard, srhines
Differential Revision: https://reviews.llvm.org/D78787
The introduction of LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT changed
the default from =1 (assuming merged typeinfos) to =0 (not assuming
merged typeinfos) on all platforms where at least one other __config_site
macro is defined.
This commit explicitly enables the assumption of merged typeinfo names
on Apple platform to restore the previous behavior, at least until the
underlying issue has been fixed.
Instead of the ad-hoc #define _LIBCXX_DYNAMIC_FALLBACK, provide an option
to enable the setting when building libc++abi. Also use the occasion to
rename the option to something slightly more descriptive.
Note that in the future, it would be great to simply remove this option
altogether. However, in the meantime, it seems better to have it be an
official option than something ad-hoc.
It turns out that all this time, we've actually been building without
assertions enabled in the dylib. This commit updates the Apple CMake
cache to make it consistent with reality.
Chromium's build sets LIBCXX_CXX_ABI_SYSTEM explicitly when building
libc++, which was broken by 61e89737c5 (which stopped listening to
that option). As a workaround, this commit uses the system libc++abi
when LIBCXX_CXX_ABI_SYSTEM is used.
However, we will need to work with Chromium to standardize their build
of libc++, because LIBCXX_CXX_ABI_SYSTEM is not a public facing build
configuration for libc++, and has never been AFAICT.
The 'runtimes' build started failing because libc++ stopped using the
in-tree libc++abi when HAVE_CXXABI is set after 61e89737c. This commit
tries to bring back the old behavior when HAVE_CXXABI is set in order
to fix CIs.
However, we really need to sit down and discuss what ways of building
libc++ are supported and formalize them, because having the libc++ build
system branch on basically random variables in some CMake cache somewhere
is not a viable path forward.
In standalone builds the cxxabi_shared and cxxabi_static targets don't exist.
We need to link against the library itself.
Differential Revision: https://reviews.llvm.org/D77294
This commit removes support for building against the system libc++abi,
which was supported on Apple platforms. This is basically never what we
want to do, since libc++ and libc++abi are coupled and building a trunk
libc++ against an older libc++abi can lead to incompatibilities (and
good luck debugging them!). It might have made some sense to support
that when the monorepo did not exist, however I don't think this is
anything but a footgun nowadays.
Furthermore, based on the newly-made assumption that we're building
against the monorepo libc++abi, we can simplify the search path logic
for finding libc++abi.
This area of our build system has a lot of technical debt accumulated,
and it's surprisingly difficult to change. We've tried different things
and failed several times in the past. I did test this change on our
Docker image for the build bots and on Apple platforms, however it is
possible that this breaks some unknown configuration, in which case it
should be fine to revert this (so we can try again!).
Summary:
This is NFC. We only add additional information to the log.
Reviewers: EricWF, ldionne, mclow.lists
Reviewed By: ldionne
Subscribers: kristof.beyls, dexonsmith, danielkiss, mgorny, ldionne, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D75991
Configuring libc++abi with LIBCXX_ENABLE_STATIC=OFF is broken since
https://reviews.llvm.org/D71894, so this patch fixes the issue for
Apple platforms to unblock our CI.
These are a part of the libc so linking these explicitly isn't necessary
and embedding these as deplibs causes link time error.
This issues was introduced in a9b5fff which changed how we emit deplibs.
Differential Revision: https://reviews.llvm.org/D71135
Handle the case when libc++abi and libunwind are being built together
with libc++ in the runtimes build. This logic was used in the previous
implementation but dropped in r374116.
Differential Revision: https://reviews.llvm.org/D68791
llvm-svn: 374510
Summary:
This allows the linker script generation to query CMake properties
(specifically the dependencies of libc++.so) instead of having to
carry these dependencies around manually in global variables. Notice
the removal of the LIBCXX_INTERFACE_LIBRARIES global variable.
Reviewers: phosek, EricWF
Subscribers: mgorny, christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D68343
llvm-svn: 374116
This also reverts "[libc++] Remove temporary hack for D63883".
Clearly, I don't understand how the Linux build bots are configured.
Differential Revision: https://reviews.llvm.org/D63883
llvm-svn: 368238
Summary:
Otherwise, when libcxxabi is not an enabled project in the monorepo, we
get a link error because we try to link against non-existent cxxabi_shared.
More generally, we shouldn't change the behavior of the build based on
implicit things like whether a file happens to be at a specific path or
not.
This is a re-application of r365222 that had been reverted in r365233
and then r365359 because it broke the build bots. The build bots
should now specify explicitly what ABI library they want to use
(libc++abi), so this commit should now be OK to merge. It takes a while
for build bots to pick up configuration changes, which is why this failed
the last time around.
Differential Revision: https://reviews.llvm.org/D63883
llvm-svn: 368213
Summary:
Otherwise, when libcxxabi is not an enabled project in the monorepo, we
get a link error because we try to link against non-existent cxxabi_shared.
More generally, we shouldn't change the behavior of the build based on
implicit things like whether a file happens to be at a specific path or
not.
This is a re-application of r365222 that had been reverted in r365233
because it broke the build bots. However, the build bots now specify
explicitly what ABI library they want to use (libc++abi), so this
commit should now be OK to merge.
Differential Revision: https://reviews.llvm.org/D63883
llvm-svn: 365326
Summary:
Otherwise, when libcxxabi is not an enabled project in the monorepo, we
get a link error because we try to link against non-existent cxxabi_shared.
More generally, we shouldn't change the behavior of the build based on
implicit things like whether a file happens to be at a specific path or
not.
Reviewers: EricWF
Subscribers: mgorny, christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D63883
llvm-svn: 365222
These seemed to have been used in the past but were since removed
by the add_compile_flags_if_supported functions that combine these
these checks and adding the flag, but the original checks were never
removed.
Differential Revision: https://reviews.llvm.org/D62566
llvm-svn: 362058
This fixes the issue introduced by r362048 where we always use
pragma comment(lib, ...) for dependent libraries when the compiler
is Clang, but older Clang versions don't support this pragma so
we need to check first if it's supported before using it.
llvm-svn: 362055
Instead of manually linking against libm/librt/libpthread, we should be
linking against libSystem on Apple platforms, and only that. libm and
libpthread are symlinks to libSystem anyway.
llvm-svn: 359808
Summary:
Instead of populating the global LIBCXX_LIBRARIES, we use the link-time
dependency management built into CMake to propagate link flags. This
leads to a cleaner and easier-to-follow build.
Reviewers: phosek, smeenai, EricWF
Subscribers: mgorny, christof, jkorous, dexonsmith, jfb, mstorsjo, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D60969
llvm-svn: 359571
Some linker libraries are only needed for shared libc++, some only
for static libc++, combining these together in LIBCXX_LIBRARIES and
LIBCXX_INTERFACE_LIBRARIES can introduce unnecessary dependencies.
This changes splits those up into LIBCXX_SHARED_LIBRARIES and
LIBCXX_STATIC_LIBRARIES matching what libc++abi already does.
Differential Revision: https://reviews.llvm.org/D57872
llvm-svn: 358614
This addresses the issue introduced in r354212 which broke the case when
static libc++abi is merged into static libc++, but shared libc++ is
linked against shared libc++. There are 4 different possible
combinations which is difficult to capture using a single variable. This
change splits LIBCXX_CXX_ABI_LIBRARY into two:
LIBCXX_CXX_SHARED_ABI_LIBRARY and LIBCXX_CXX_STATIC_ABI_LIBRARY to
handle the shared and static cases. This in turn allows simplification
of some of the logic around merging of static archives.
Differential Revision: https://reviews.llvm.org/D60114
llvm-svn: 357556
Summary:
This change allows specifying the version of libc++abi's ABI to re-export
when configuring CMake. It also clearly identifies which ABI version of
libc++abi each export file contains.
Finally, it removes hardcoded knowledge about the 10.9 SDK for MacOS,
since that knowledge is not relevant anymore. Indeed, libc++ can't be
built with the toolchain that came with the 10.9 SDK anyway because
the version of Clang it includes is too old (for example if you want
to build a working libc++.dylib, you need bugfixes to visibility
attributes that are only in recent Clangs).
Reviewers: dexonsmith, EricWF
Subscribers: mgorny, christof, jkorous, arphaman, libcxx-commits
Differential Revision: https://reviews.llvm.org/D59489
llvm-svn: 356587
This changes add_custom_libcxx to also build libcxxabi and merges
the two into a static and hermetic library.
There are multiple advantages:
1) The resulting libFuzzer doesn't expose C++ internals and looks
like a plain C library.
2) We don't have to manually link in libstdc++ to provide cxxabi.
3) The sanitizer tests cannot interfere with an installed version
of libc++.so in LD_LIBRARY_PATH.
Differential Revision: https://reviews.llvm.org/D58013
llvm-svn: 354212
Summary:
Freestanding is *weird*. The standard allows it to differ in a bunch of odd
manners from regular C++, and the committee would like to improve that
situation. I'd like to make libc++ behave better with what freestanding should
be, so that it can be a tool we use in improving the standard. To do that we
need to try stuff out, both with "freestanding the language mode" and
"freestanding the library subset".
Let's start with the super basic: run the libc++ tests in freestanding, using
clang as the compiler, and see what works. The easiest hack to do this:
In utils/libcxx/test/config.py add:
self.cxx.compile_flags += ['-ffreestanding']
Run the tests and they all fail.
Why? Because in freestanding `main` isn't special. This "not special" property
has two effects: main doesn't get mangled, and main isn't allowed to omit its
`return` statement. The first means main gets mangled and the linker can't
create a valid executable for us to test. The second means we spew out warnings
(ew) and the compiler doesn't insert the `return` we omitted, and main just
falls of the end and does whatever undefined behavior (if you're luck, ud2
leading to non-zero return code).
Let's start my work with the basics. This patch changes all libc++ tests to
declare `main` as `int main(int, char**` so it mangles consistently (enabling us
to declare another `extern "C"` main for freestanding which calls the mangled
one), and adds `return 0;` to all places where it was missing. This touches 6124
files, and I apologize.
The former was done with The Magic Of Sed.
The later was done with a (not quite correct but decent) clang tool:
https://gist.github.com/jfbastien/793819ff360baa845483dde81170feed
This works for most tests, though I did have to adjust a few places when e.g.
the test runs with `-x c`, macros are used for main (such as for the filesystem
tests), etc.
Once this is in we can create a freestanding bot which will prevent further
regressions. After that, we can start the real work of supporting C++
freestanding fairly well in libc++.
<rdar://problem/47754795>
Reviewers: ldionne, mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, arphaman, miyuki, libcxx-commits
Differential Revision: https://reviews.llvm.org/D57624
llvm-svn: 353086
Refactor the get_llvm_lit_path() logic to respect LLVM_EXTERNAL_LIT,
and require the fallback to be defined explicitly
as LLVM_DEFAULT_EXTERNAL_LIT. This fixes building libcxx standalone
after r346888.
The old logic was using LLVM_EXTERNAL_LIT both as user-defined cache
variable and an optional pre-definition of default value from caller
(e.g. libcxx). It included a hack to make this work by assigning
the value back and forth but it was fragile and stopped working
in libcxx.
The new logic is simpler and more transparent. Default value is
provided in a separate variable, and used only when user-specified
variable is empty (i.e. not overriden).
Differential Revision: https://reviews.llvm.org/D57282
llvm-svn: 352374
The check_library_exists CMake uses a custom symbol definition. This
is a problem when checking for C library symbols because Clang
recognizes many of them as builtins, and returns the
-Wbuiltin-requires-header (or -Wincompatible-library-redeclaration)
error. When building with -Werror which is the default, this causes
the check_library_exists check fail making the build think that C
library isn't available.
To avoid this issue, we should use a symbol that isn't recognized by
Clang and wouldn't cause the same issue. __libc_start_main seems like
reasonable choice that fits the bill.
Differential Revision: https://reviews.llvm.org/D57142
llvm-svn: 352341
Louis Dionne