This uses the existing Clang driver APIs for expanding response files
and so should be pretty carefully accurate to what is needed here.
Note that this doesn't try to generalize the expansion more widely for
the interop Clang invocation, but it would be straightforward to do so
if needed at some point.
This parallelizes the compilations and dramatically reduces the time to
build runtimes.
As part of this, teach the driver infrastructure to have an option to
control the use of threads and to build the relevant thread pool and
thread it into the various APIs.
However, it requires our `ClangRunner` to become thread-safe and to
invoke Clang in a way that is thread-safe. This is somewhat challenging
as the code in `clang_main` is distinctly _not_ thread-safe.
To address this, the relevant logic of `clang_main`, especially the CC1
execution, is extracted into our runner and cleaned up to be much more
appropriate in a multithreaded context. Much of this code should
eventually be factored back into Clang, but that will be a follow-up
patch to upstream.
Last but not least, this rearranges the `ClangRunner` API to make a bit
more sense out of the different options for building runtimes, and have
a clean model for which things need to be passed in at which points.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
This layer allows runtimes to be built on-demand but cached in a
consistent and re-usable location on the system. It handles careful
filesystem operations to ensure consistency even in the face of multiple
versions and build configurations.
This addresses a number of TODOs from the initial runtimes building
on-demand, and sets the stage to scale up to more runtimes.
This doesn't switch on-demand runtimes to be on by default, I wanted to
wait and make that change as a separate step.
---------
Co-authored-by: Geoff Romer <gromer@google.com>
This is the first step to having Clang's runtime libraries fully
available for the Carbon toolchain. This PR focuses on the lowest level
runtimes, the CRT files and the builtins library.
The goal is to intercept Clang runs where it needs these
target-dependent pieces to be available, and build them on demand using
our Clang-running infrastructure. This avoids most of the subprocess
overhead, but there is still some due to missing features in Clang.
This requires exporting the sources for these runtimes from the Bazel
build, and installing them in our target-independent resource directory.
We then build a simplified "build" of these sources within the
`ClangRunner` itself to produce the specific artifacts and layout
expected by Clang.
It also required fixing our use of Clang on macOS to have a default
system root in order to successfully compile or link.
It also required cleaning up how the `ClangRunner` used target
information more generally -- instead of taking the target as
a constructor parameter, it manages its target internally and relies on
the Clang target-specifying command line flags.
I looked at whether we could split this into another layer separate from
the `ClangRunner`, but that proved frustratingly difficult to manage.
While we support building these on-demand as part of a detected link,
that doesn't seem feasible as we don't have the necessary separation
between compilation runs of Clang and link runs of Clang. However,
I have tried to factor the internals to provide as clear of separation
as I could across these.
I have also created a stand-alone subcommand to directly build the
runtimes which allows for easy testing. It also supports building them
into a specific directory, and that directory can in turn be passed to
a Clang invocation. This is designed to work both at the API level with
`ClangRunner` and at the subcommand level.
Currently, the only part of the commandline that is detected and
forwarded to the runtimes build is the target. Eventually, the plan is
to expand this so that we can build a maximally tailored set of runtimes
for a given compilation.
The other big TODO here is to actually implement caching storage of
these runtimes so they aren't built on every execution. Right now, this
uses a somewhat hack-y build of a temporary directory, but this isn't
expected to be suitable long-term. Building these runtimes on *every*
link makes those commands take approximately 15 seconds with an ASan
build like our default development build, and just over 2 seconds in an
optimized build. Because of this, I've kept all of this disabled by
default for now. The goal is that once caching and some other
improvements land, we can enable this by default.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This removes the separately built and installed LLD binary. The symlinks
used by Clang when directly invoking LLD now point back to the main
`carbon-busybox` binary and dispatch through the newly added subcommand.
With this change we're down to shipping a single busybox binary in the
toolchain, removing duplicate installed copies of LLD and all its LLVM
dependencies. =]
The LLD subcommand works a bit differently from the `clang` subcommand
because the CLI for LLD is specific to which platform flavor of linker
is being invoked.
As part of this, I've extracted some of the common functionality in the
Clang runner into a base class that can be re-used. I expect to use this
again in a follow-up change to add subcommands to run other LLVM tools.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Chandler Carruth
Thomas Köppe