tinygo_longjmp ended with a j instruction, which reaches only 128 KB. picolibc puts longjmp in the plain .text group of the linker script, while all TinyGo code goes into the .text.* group after it. In a large program the two are more than 128 KB apart and the link stops with an out of range R_XTENSA_SLOT0_OP relocation. Small programs link correctly, thus the smoke tests do not find this. Load the address of longjmp from a literal and jump to it with jx. The literal carries an R_XTENSA_32 relocation, which has no range limit. Place the literal by hand in the same section as the code. Automatic literals go into a separate section, which this tree already records as a cause of bad l32r offsets with LLVM 22 and lld. See the comments in src/device/esp/esp32.S and src/device/esp/esp32s3.S. Keep the jump instead of a call. tinygo_longjmp has no entry instruction and runs in the register window of its caller. A call would rotate the window a second time and give longjmp bad arguments. a8 is free in both ABIs. In the windowed ABI it becomes a0 of longjmp, which longjmp overwrites at once from the jmp_buf. In the call0 ABI it is a scratch register and longjmp reads only a2 and a3. The recover test passes on ESP32 in QEMU and on ESP32-S3 hardware.
TinyGo - Go compiler for small places
TinyGo is a Go compiler intended for use in small places such as microcontrollers, WebAssembly (wasm/wasi), 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.
Important
You can help TinyGo with a financial contribution using OpenCollective. Please see https://opencollective.com/tinygo for more information. Thank you!
Embedded
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 Circuit Playground Express, a Seeed Studio XIAO-ESP32S3 or any of the many 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-uno examples/blinky1
WebAssembly
TinyGo is very useful for compiling programs both for use in browsers (WASM) as well as for use on servers and other edge devices (WASI).
TinyGo programs can run in Fastly Compute, Fermyon Spin, wazero and many other WebAssembly runtimes.
Here is a small TinyGo program for use by a WASI host application:
package main
//go:wasmexport add
func add(x, y uint32) uint32 {
return x + y
}
This compiles the above TinyGo program for use on any WASI Preview 1 runtime:
tinygo build -buildmode=c-shared -o add.wasm -target=wasip1 add.go
You can also use the same syntax as Go 1.24+:
GOOS=wasip1 GOARCH=wasm tinygo build -buildmode=c-shared -o add.wasm add.go
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 targets
Embedded
You can compile TinyGo programs for over 150 different microcontroller boards.
For more information, please see https://tinygo.org/docs/reference/microcontrollers/
WebAssembly
TinyGo programs can be compiled for both WASM and WASI targets.
For more information, see https://tinygo.org/docs/guides/webassembly/
Operating Systems
You can also compile programs for Linux, macOS, and Windows targets.
For more information:
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 page on our web site 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:
- 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 it’s 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.
Some code has been copied and/or ported from Paul Stoffregen's Teensy libraries and is therefore licensed under PJRC's license. This has been clearly indicated in the header of these files.