- Use compiler-rt and picolibc instead of avr-libc.
- Use ld.lld instead of avr-ld (or avr-gcc).
This makes it much easier to get started with TinyGo on AVR because
installing these extra tools (gcc-avr, avr-libc) can be a hassle.
It also opens the door for future improvements such as ThinLTO.
There is a code size increase but I think it's worth it in the long run.
The code size increase can hopefully be reduced with improvements to the
LLVM AVR backend and to compiler-rt.
This change adds support for compiler-rt, which supports float64 (unlike
libgcc for AVR). This gets a number of tests to pass that require
float64 support.
We're still using libgcc with this change, but libgcc will probably be
removed eventually once AVR support in compiler-rt is a bit more mature.
I've also pushed a fix for a small regression in our
xtensa_release_14.0.0-patched LLVM branch that has also been merged
upstream. Without it, a floating point comparison against zero always
returns true which is certainly a bug. It is necessary to correctly
print floating point values.
This commit adds support for musl-libc and uses it by default on Linux.
The main benefit of it is that binaries are always statically linked
instead of depending on the host libc, even when using CGo.
Advantages:
- The resulting binaries are always statically linked.
- No need for any tools on the host OS, like a compiler, linker, or
libc in a release build of TinyGo.
- This also simplifies cross compilation as no cross compiler is
needed (it's all built into the TinyGo release build).
Disadvantages:
- Binary size increases by 5-6 kilobytes if -no-debug is used. Binary
size increases by a much larger margin when debugging symbols are
included (the default behavior) because musl is built with debugging
symbols enabled.
- Musl does things a bit differently than glibc, and some CGo code
might rely on the glibc behavior.
- The first build takes a bit longer because musl needs to be built.
As an additional bonus, time is now obtained from the system in a way
that fixes the Y2038 problem because musl has been a bit more agressive
in switching to 64-bit time_t.
This is really just a preparatory commit for musl support. The idea is
to store not just the archive file (.a) but also an include directory.
This is optional for picolibc but required for musl, so the main purpose
of this commit is the refactor needed for this change.
The main change is in building the libraries, where -fshort-enums was
passed on RISC-V while other C files weren't compiled with this setting.
Note: the test already passed before this change, but it seems like a
good idea to explicitly test for enum size consistency.
There is also not a particular reason not to pass -fshort-enums on
RISC-V. Perhaps it's better to do it there too (on baremetal targets
that don't have to worry about binary compatibility).
This refactor makes adding a new library (such as a libc) much easier in
the future as it avoids a lot of duplicate code. Additionally, CI should
become a little bit faster (~15s) as build-builtins now uses the build
cache.
We don't need the separate submodule: compiler-rt is already included in
the llvm-project repository.
This should hopefully make CI slightly faster too.
This is a large commit that moves all code directly related to
compiling/linking into a new builder package. This has a number of
advantages:
* It cleanly separates the API between the command line and the full
compilation (with a very small API surface).
* When the compiler finally compiles one package at a time (instead of
everything at once as it does now), something will have to invoke it
once per package. This builder package will be the natural place to
do that, and also be the place where the whole process can be
parallelized.
* It allows the TinyGo compiler to be used as a package. A client can
simply import the builder package and compile code using it.
As part of this refactor, the following additional things changed:
* Exported symbols have been made unexported when they weren't needed.
* The compilation target has been moved into the compileopts.Options
struct. This is done because the target really is just another
compiler option, and the API is simplified by moving it in there.
* The moveFile function has been duplicated. It does not really belong
in the builder API but is used both by the builder and the command
line. Moving it into a separate package didn't seem useful either
for what is essentially an utility function.
* Some doc strings have been improved.
Some future changes/refactors I'd like to make after this commit:
* Clean up the API between the builder and the compiler package.
* Perhaps move the test files (in testdata/) into the builder package.
* Perhaps move the loader package into the builder package.
This makes it possible to query these environment variables from
anywhere, which might be useful. More importantly, it puts them in a
central location from where they can be queried, useful for a `go env`
subcommand.
On Debian, all LLVM commands have a version suffix (clang-8, ld.lld-8,
wasm-ld-8, etc.). However. Most other distributions only provide a
version prefix for Clang and not for all the other commands.
This commit fixes the issue by trying the command with the version
suffix first and falling back to one without if needed.
This commit avoids setting the working directory to the TinyGo root when
invocating Clang. This helps to weed out issues before we add support
for bundling Clang in a release.
The ar file format is pretty simple and can be implemented by using a Go
library. Use that instead of calling out to llvm-ar.
There are a few limitations to the used package, but that doesn't seem
to matter for our use case (linking compiler-rt for use with ld.lld):
* no index is created
* long filenames are truncated
* no support for archives bigger than 4GB
A few changes to make sure compiler-rt is correctly compiled (and
doesn't include host headers, for example).
This improves support for AVR, but it still doesn't work. Compiler-rt
itself doesn't really work for AVR either.
Ayke van Laethem