Go 1.19 started reformatting code in a way that makes it more obvious
how it will be rendered on pkg.go.dev. It gets it almost right, but not
entirely. Therefore, I had to modify some of the comments so that they
are formatted correctly.
You can see that it works with the following command:
tinygo run -target=simavr ./testdata/recover.go
This also gets the following tests to pass again:
go test -run=Build -target=simavr -v
Adding support for AVR was a bit more compliated because it's also
necessary to save and restore the Y register.
This is a small change to make it easier to support architectures that
need to restore more than just the sp and pc registers. In particular,
it is needed for the AVR architecture that needs to restore the frame
pointer (Y register).
Previously we used to scan between _edata and _end. This is not correct:
the .data section starts *before* _edata.
Fixing this would mean changing _edata to _etext, but that didn't quite
work either. It appears that there are inaccessible pages between _etext
and _end on ARM. Therefore, a different solution was needed.
What I've implemented is similar to Windows and MacOS: namely, finding
writable segments by parsing the program header of the currently running
program. It's a lot more verbose, but it should be correct on all
architectures. It probably also reduces the globals to scan to those
that _really_ need to be scanned.
This bug didn't result in issues in CI, but did result in a bug in the
recover branch: https://github.com/tinygo-org/tinygo/pull/2331. This
patch fixes this bug.
Precise globals require a whole program optimization pass that is hard
to support when building packages separately. This patch removes support
for these globals by converting the last use (Linux) to use
linker-defined symbols instead.
For details, see: https://github.com/tinygo-org/tinygo/issues/2870
This replaces "precise" global scanning in LLVM with conservative
scanning of writable MachO segments. Eventually I'd like to get rid of
the AddGlobalsBitmap pass, and this is one step towards that goal.
Simplify the interrupt-based timer code in a few ways:
- Do not recalibrate the timer every 100ms. Instead, rely on the fact
that the machine package will calbrate the timer if necessary if it
makes changes to Timer0.
- Do not configure Timer0 and then set nanosecondsInTick based on that
value. Instead, use a fixed value.
These two changes together mean that in code that doesn't use PWM,
nanosecondsInTick will be constant which makes the TIMER0_OVF interrupt
handler a lot smaller.
Together this reduces the code size of AVR binaries by about 1200 bytes,
making it pretty close to the pre-timer code size (only about 250 bytes
larger).
It also somehow fixes a problem with
tinygo.org/x/drivers/examples/ws2812 on the Arduino Uno. I'm not quite
sure what was going wrong, but bisecting pointed towards the timer code
(https://github.com/tinygo-org/tinygo/pull/2428) and with this
simplification the bug appears to be gone.
Scan globals conservatively by reading writable sections from the PE
header.
I'd like to get rid of needing to precisely scan globals eventually, and
this brings us one step closer. It also avoids a bug with ThinLTO on
Windows.
This patch adds support for generating GOOS=darwin GOARCH=arm64
binaries. This means that it will become possible to run `go test` on
recent Macs, for example.
See the comment in the source for details.
Also see the discussion in
https://github.com/tinygo-org/tinygo/pull/2755, which originally
triggered this bug.
Somewhat surprising, this results in a slight code size decrease for ARM
targets of a few bytes.
This adds the `Version()` function of the `runtime` package which embeds
the go version that was used to build tinygo.
For programs that are compiled with tinygo the version can be overriden
via the:
`tinygo build -ldflags="-X 'runtime.buildVersion=abc'"` flag.
Otherwise it will continue to use the go version with which tinygo was
compiled.
