Ayke van Laethem
734613c20e
I ran into an issue where I did a method call on a nil interface and it
resulted in a HardFault. Luckily I quickly realized what was going on so
I could fix it, but I think undefined behavior is definitely the wrong
behavior in this case. This commit therefore changes such calls to cause
a nil panic instead of introducing undefined behavior.
This does have a code size impact. It's relatively minor, much lower
than I expected. When comparing the before and after of the drivers
smoke tests (probably the most representative sample available), I found
that most did not change at all and those that did change, normally not
more than 100 bytes (16 or 32 byte changes are typical).
Right now the pattern is the following:
switch typecode {
case 1:
call method 1
case 2:
call method 2
default:
nil panic
}
I also tried the following (in the hope that it would be easier to
optimize), but it didn't really result in a code size reduction:
switch typecode {
case 1:
call method 1
case 2:
call method 2
case 0:
nil panic
default:
unreachable
}
Some code got smaller, while other code (the majority) got bigger. Maybe
this can be improved once range[1] is finally allowed[2] on function
parameters, but it'll probably take a while before that is implemented.
[1]: https://llvm.org/docs/LangRef.html#range-metadata
[2]: https://github.com/rust-lang/rust/issues/50156
TinyGo - Go compiler for small places
TinyGo is a Go compiler intended for use in small places such as microcontrollers, WebAssembly (Wasm), and command-line tools.
It reuses libraries used by the Go language tools alongside LLVM to provide an alternative way to compile programs written in the Go programming language.
Here is an example program that blinks the built-in LED when run directly on any supported board with onboard LED:
package main
import (
"machine"
"time"
)
func main() {
led := machine.LED
led.Configure(machine.PinConfig{Mode: machine.PinOutput})
for {
led.Low()
time.Sleep(time.Millisecond * 1000)
led.High()
time.Sleep(time.Millisecond * 1000)
}
}
The above program can be compiled and run without modification on an Arduino Uno, an Adafruit ItsyBitsy M0, or any of the supported boards that have a built-in LED, just by setting the correct TinyGo compiler target. For example, this compiles and flashes an Arduino Uno:
tinygo flash -target arduino examples/blinky1
Installation
See the getting started instructions for information on how to install TinyGo, as well as how to run the TinyGo compiler using our Docker container.
Supported boards/targets
You can compile TinyGo programs for microcontrollers, WebAssembly and Linux.
The following 32 microcontroller boards are currently supported:
- Adafruit Circuit Playground Bluefruit
- Adafruit Circuit Playground Express
- Adafruit CLUE Alpha
- Adafruit Feather M0
- Adafruit Feather M4
- Adafruit ItsyBitsy M0
- Adafruit ItsyBitsy M4
- Adafruit Metro M4 Express Airlift
- Adafruit PyBadge
- Adafruit PyPortal
- Adafruit Trinket M0
- Arduino Mega 2560
- Arduino Nano
- Arduino Nano33 IoT
- Arduino Uno
- BBC micro:bit
- Digispark
- Game Boy Advance
- Makerdiary nRF52840-MDK
- Nordic Semiconductor PCA10031
- Nordic Semiconductor PCA10040
- Nordic Semiconductor PCA10056
- Particle Argon
- Particle Boron
- Particle Xenon
- Phytec reel board
- PineTime DevKit
- SiFIve HiFive1
- ST Micro "Nucleo F103RB"
- ST Micro STM32F103XX "Bluepill"
- ST Micro STM32F407 "Discovery"
- X9 Pro smartwatch
For more information, see this list of boards. Pull requests for additional support are welcome!
Currently supported features:
For a description of currently supported Go language features, please see https://tinygo.org/lang-support/.
Documentation
Documentation is located on our web site at https://tinygo.org/.
You can find the web site code at https://github.com/tinygo-org/tinygo-site.
Getting help
If you're looking for a more interactive way to discuss TinyGo usage or development, we have a #TinyGo channel on the Gophers Slack.
If you need an invitation for the Gophers Slack, you can generate one here which should arrive fairly quickly (under 1 min): https://invite.slack.golangbridge.org
Contributing
Your contributions are welcome!
Please take a look at our CONTRIBUTING.md document for details.
Project Scope
Goals:
- Have very small binary sizes. Don't pay for what you don't use.
- Support for most common microcontroller boards.
- Be usable on the web using WebAssembly.
- Good CGo support, with no more overhead than a regular function call.
- Support most standard library packages and compile most Go code without modification.
Non-goals:
- Using more than one core.
- Be efficient while using zillions of goroutines. However, good goroutine support is certainly a goal.
- Be as fast as
gc. However, LLVM will probably be better at optimizing certain things so TinyGo might actually turn out to be faster for number crunching. - Be able to compile every Go program out there.
Why this project exists
We never expected Go to be an embedded language and so its got serious problems...
-- Rob Pike, GopherCon 2014 Opening Keynote
TinyGo is a project to bring Go to microcontrollers and small systems with a single processor core. It is similar to emgo but a major difference is that we want to keep the Go memory model (which implies garbage collection of some sort). Another difference is that TinyGo uses LLVM internally instead of emitting C, which hopefully leads to smaller and more efficient code and certainly leads to more flexibility.
The original reasoning was: if Python can run on microcontrollers, then certainly Go should be able to run on even lower level micros.
License
This project is licensed under the BSD 3-clause license, just like the Go project itself.
Some code has been copied from the LLVM project and is therefore licensed under a variant of the Apache 2.0 license. This has been clearly indicated in the header of these files.