Unfortunately, the .rodata section can't be stored in flash. Instead, an
explicit .progmem section should be used, which is supported in LLVM as
address space 1 but not exposed to normal programs.
Eventually a pass should be written that converts trivial const globals
of which all loads are visible to be in addrspace 1, to get the benefits
of storing those globals directly in ROM.
This can be useful to test improvements in LLVM master and to make it
possible to support LLVM 11 for the most part already before the next
release. That also allows catching LLVM bugs early to fix them upstream.
Note that tests do not yet pass for this LLVM version, but the TinyGo
compiler can be built with the binaries from apt.llvm.org (at the time
of making this commit).
Test binaries must be run in the source directory of the package to be
tested. This wasn't done, leading to a few "file not found" errors.
This commit implements this. Unfortunately, it does not allow more
packages to be tested as both affected packages (debug/macho and
debug/plan9obj) will still fail with this patch even though the "file
not found" errors are gone.
Right now this requires setting the -port parameter, but other than that
it totally works (if esptool.py is installed). It works by converting
the ELF file to the custom ESP32 image format and flashing that using
esptool.py.
Interrupts store 32 bytes on the current stack, which may be a goroutine
stack. After that the interrupt switches to the main stack pointer so
nothing more is pushed to the current stack. However, these 32 bytes
were not included in the stack size calculation.
This commit adds those 32 bytes. The code is rather verbose, but that is
intentional to make sure it is readable. This is tricky code that's hard
to get right, so I'd rather keep it well documented.
This is a big change that will determine the stack size for many
goroutines automatically. Functions that aren't recursive and don't call
function pointers can in many cases have an automatically determined
worst case stack size. This is useful, as the stack size is usually much
lower than the previous hardcoded default of 1024 bytes: somewhere
around 200-500 bytes is common.
A side effect of this change is that the default stack sizes (including
the stack size for other architectures such as AVR) can now be changed
in the config JSON file, making it tunable per application.
Currently, turning optimizations off causes compile failures.
We rely on the optimizer removing some dead symbols.
Avoid providing an option that does not work right now.
In the future once everything has been fixed we can re-enable this.
For now, this is just an extra flag that can be used to print stack
frame information, but this is intended to provide a way to determine
stack sizes for goroutines at compile time in many cases.
Stack sizes are often somewhere around 350 bytes so are in fact not all
that big usually. Once this can be determined at compile time in many
cases, it is possible to use this information when available and as a
result increase the fallback stack size if the size cannot be determined
at compile time. This should reduce stack overflows while at the same
time reducing RAM consumption in many cases.
Interesting output for testdata/channel.go:
function stack usage (in bytes)
Reset_Handler 332
.Lcommand-line-arguments.fastreceiver 220
.Lcommand-line-arguments.fastsender 192
.Lcommand-line-arguments.iterator 192
.Lcommand-line-arguments.main$1 184
.Lcommand-line-arguments.main$2 200
.Lcommand-line-arguments.main$3 200
.Lcommand-line-arguments.main$4 328
.Lcommand-line-arguments.receive 176
.Lcommand-line-arguments.selectDeadlock 72
.Lcommand-line-arguments.selectNoOp 72
.Lcommand-line-arguments.send 184
.Lcommand-line-arguments.sendComplex 192
.Lcommand-line-arguments.sender 192
.Lruntime.run$1 548
This shows that the stack size (if these numbers are correct) can in
fact be determined automatically in many cases, especially for small
goroutines. One of the great things about Go is lightweight goroutines,
and reducing stack sizes is very important to make goroutines
lightweight on microcontrollers.
This commit merges NewCompiler and Compile into one simplifying the
external interface. More importantly, it does away with the entire
Compiler object so the public API becomes a lot smaller.
The refactor is not complete: eventually, the compiler should just
compile a single package without trying to load it first (that should be
done by the builder package).
This is necessary for better CGo support on bare metal. Existing
libraries expect to be able to include parts of libc and expect to be
able to link to those symbols.
Because with this all targets have a working libc, it is now possible to
add tests to check that a libc in fact works basically.
Not all parts of picolibc are included, such as the math or stdio parts.
These should be added later, when needed.
This commit also avoids the need for the custom memcpy/memset/memcmp
symbols that are sometimes emitted by LLVM. The C library will take care
of that.
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.
Add a target for the Adafruit Circuit Playground Bluefruit, which is
based on the nRF52840. Adds the necessary code for the machine
package and the json and linker script files in the targets directory.
The machine package code is based on board_circuitplay_express.go,
with modifications made by consulting the wiring diagram on the
adafruit website here:
https://learn.adafruit.com/adafruit-circuit-playground-bluefruit/downloads
Also adds support to the uf2 conversion packacge to set the familyID
field. The Circuit Playground Bluefruit firmware rejects uf2 files
without the family id set to 0xADA52840 (and without the flag specifying
that the family id is present).
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.
