Apart from bumping the toolchain Clang's and port's version, this commit
completely overhauls the way LLVM toolchain is built.
First, it gets rid of a complicated two-stage process of first compiling
clang and compiler-rt builtins and then building libunwind, libc++abi,
and libc++ -- it is possible to create a complete cross-compilation
toolchain in a single CMake invocation with a modern LLVM. Moreover, the
old method was inherently unsupported and subtly broken.
Next, it utilizes full potential of the Stubs "framework". Now we are
even able to compile Clang with -Wl,-z,defs which makes one of the
patches obsolete and the whole installation less error-prone. Note that
it comes at a cost of complicating the bootstrap process on a completely
novel architecture but this hopefully won't happen often.
Lastly, it fixes handling of the -no*lib* family of flags in the
Serenity LLVM driver and correctly uses -nostartfiles in conjunction
with stubs to make necessary CMake configure-time checks succeed.
We were previously missing `Kernel/Arch`, which gets included by
`Kernel/API`.
While at it, remove `AK` from the list of copied headers for the
toolchain, as nothing in our LibC headers should ever publicly depend on
AK.
This is needed to avoid including LibC headers in Lagom builds.
Unfortunately, we cannot rely on the build machine to provide a
fully POSIX-compatible ELF header for Lagom builds, so we have to
use our own.
The latter is problematic as it may be contained in the username (e.g.
email address-like) and thus the $SRC_ROOT path. This would cause an
invalid sed command to be created, breaking both of these scripts.
Add a patch to let llvm's InstrProfiling modules know serenity supports
all the Unix-y features required to make -fprofile-instr-generate and
-fcoverage-mapping work properly on target.
Besides a version bump, the following changes have been made to our
toolchain infrastructure:
- LLVM/Clang is now built with -march=native if the host compiler
supports it. An exception to this is CI, as the toolchain cache is
shared among many different machines there.
- The LLVM tarball is not re-extracted if the hash of the applied
patches doesn't differ.
- The patches have been split up into atomic chunks.
- Port-specific patches have been integrated into the main patches,
which will aid in the work towards self-hosting.
- <sysroot>/usr/local/lib is now appended to the linker's search path by
default.
- --pack-dyn-relocs=relr is appended to the linker command line by
default, meaning ports take advantage of RELR relocations without any
patches or additional compiler flags.
The formatting of LLVM port's package.sh has been bothering me, so I
also indented the arguments to the CMake invocation.
This commit adds support for building the SerenityOS userland with the
new [mold linker].
This is not enabled by default yet; to link using mold, run the
`Toolchain/BuildMold.sh` script to build the latest release of mold, and
set the `ENABLE_MOLD_LINKER` CMake variable to ON. This option relies on
toolchain support that has been added just recently, so you might need
to rebuild your toolchain for mold to work.
[mold linker]: https://github.com/rui314/mold
We erroneously appended ".so" after the base name for the library,
so we ended up checking for the existence of e.g. `libc.so.so`,
which obviously didn't exist, so we overwrote the existing libraries
when we rebuilt the toolchain.
Our build of LLVM's objcopy now supports the single missing feature
(--update-section) that previously forced us to use the one from GNU
Binutils. This means that there is no reason anymore to build Binutils
alongside LLVM's tools.
This commit backports the LLVM commit that adds support for the
`--update-section` flag to llvm-objcopy. We use this feature of GNU
objcopy to embed the symbol map in the kernel.
The corresponding LLVM Phabricator Differential Revision can be found
here: https://reviews.llvm.org/D112116
This patch is identical to the upstream commit, except for two hunks
that had to be changed as they didn't apply cleanly.
By setting CMAKE_MODULE_PATH in the LLVM initial cache scripts, we can
make the "SerenityOS" CMAKE_SYSTEM_NAME usable in the builds of
compiler-rt, libunwind, libcxxabi and libcxx.
This simplifies some toolchain patches and brings the cross-compiler
patches closer to the Port's patches, and closer to something
upstreamable.
This commit updates the Clang toolchain's version to 13.0.0, which comes
with better C++20 support and improved handling of new features by
clang-format. Due to the newly enabled `-Bsymbolic-functions` flag, our
Clang binaries will only be 2-4% slower than if we dynamically linked
them, but we save hundreds of megabytes of disk space.
The `BuildClang.sh` script has been reworked to build the entire
toolchain in just three steps: one for the compiler, one for GNU
binutils, and one for the runtime libraries. This reduces the complexity
of the build script, and will allow us to modify the CI configuration to
only rebuild the libraries when our libc headers change.
Most of the compile flags have been moved out to a separate CMake cache
file, similarly to how the Android and Fuchsia toolchains are
implemented within the LLVM repo. This provides a nicer interface than
the heaps of command-line arguments.
We no longer build separate toolchains for each architecture, as the
same Clang binary can compile code for multiple targets.
The horrible mess that `SERENITY_CLANG_ARCH` was, has been removed in
this commit. Clang happily accepts an `i686-pc-serenity` target triple,
which matches what our GCC toolchain accepts.
Ninja disables its fancy output mode when it's not writing to a TTY.
So don't pipe its output into something else, so that it writes to
a TTY if the invoking terminal is a TTY.
`LLVM_LLVM_BUILD_LLVM_DYLIB` does not exist, so passing this does
nothing but make CMake warn.
However, since we pass `LLVM_LINK_LLVM_DYLIB`, `LLVM_BUILD_LLVM_DYLIB`
(the correct spelling) defaults to true anyways. So let's pass fewer
flags.
No behavior change, but fixes a CMake warning.
This library is used by virtually all executables in the Clang
toolchain. By default, it is linked statically, which leads to huge
file sizes and us running out of artifact storage disk space on CI.
This contains all the bits and pieces necessary to build a Clang binary
that will correctly compile SerenityOS.
I had some trouble with getting LLVM building with a single command, so
for now, I decided to build each LLVM component in a separate command
invocation. In the future, we can also make the main llvm build step
architecture-independent, but that would come with extra work to make
library and include paths work.
The binutils build invocation and related boilerplate is duplicated
because we only use `objdump` from GNU binutils in the Clang toolchain,
so most features can be disabled.
