Support for RV32IM

[puma314]

Is it possible to compile TinyGo to a RV32IM (RISC-V 32 bit) backend? I tried running

tinygo build -o main.elf -target=riscv32 main.go

But got the following error on this very simple program:

package main


func main() {
	a := 1
	b := 1
	c := a + b
	_ = c
}

$ tinygo build -o main.elf -target=riscv32 main.go
# runtime
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:30:21: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:84:42: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/time.go:11:33: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/baremetal.go:59:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/baremetal.go:64:2: undefined: exit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/panic.go:52:2: undefined: abort
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/panic.go:71:2: undefined: abort
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:14:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:26:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:35:4: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:69:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:90:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:96:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:184:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:264:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:269:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:276:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:283:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:288:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:290:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:336:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:338:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:340:3: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:351:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:359:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:360:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:364:4: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:366:4: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:381:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:383:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/print.go:385:2: undefined: putchar
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/runtime.go:70:9: undefined: ticksToNanoseconds
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/runtime.go:70:28: undefined: ticks
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:92:9: undefined: ticks
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:162:10: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:167:10: undefined: ticks
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:172:53: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:175:26: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:203:17: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:205:16: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:217:39: undefined: timeUnit
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler.go:223:4: undefined: sleepTicks
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/scheduler_any.go:15:31: undefined: nanosecondsToTicks
/opt/homebrew/Cellar/tinygo/0.31.2/src/runtime/time.go:12:9: undefined: nanosecondsToTicks

[aykevl]

What is the board/chip you want to target? TinyGo needs a lot more than just the instruction set architecture.

[puma314]

It's is a bit of an unusual use-case--our team is building a zero-knowledge VM (zkVM) that proves the execution of the RISC-V32im instruction set: https://github.com/succinctlabs/sp1.

We use ecalls to do stdin and stdout into the zkVM environment, but other than that usually we just have pure golang code that is proving some sort of computation.

[aykevl]

In that case, the zkVM would be the target. Especially since you say this:

We use ecalls to do stdin and stdout into the zkVM environment, [...]

This means that functions like putchar would call those kinds of syscalls. The runtime needs to know about these sorts of details, for example to print panic messages or to correctly schedule goroutines.

Also, the linker will need to know details like at which address it can be linked and which memory area it can use for the heap.

[jharveyb]

Relevant PR from another zkVM project:

risc0#1

Relevant discussion:

risc0/risc0#1222