✔ too many locals: locals exceed maximum · general

Stream: general

Topic: ✔ too many locals: locals exceed maximum

Andrew Kelley (Jun 28 2022 at 00:19):

Hello, I have received this error from wasmtime 0.37.0:

Error: failed to run main module `../lib/std/zig-cache/o/e844be59deeadc476c0e3b7eecd89e75/test.wasm`

Caused by:
    0: WebAssembly translation error
    1: Invalid input WebAssembly code at offset 17178321: too many locals: locals exceed maximum

what can I do to find out what symbol is the one that has too many locals?

Alex Crichton (Jun 28 2022 at 00:47):

unfortunately it's not easy (and we should improve this error), but with the wasm-tools CLI you can:

first translate the offset to hex
run wasm-tools dump yourfile.wasm
search the output for the hex address
a few lines up should indicate which function

Andrew Kelley (Jun 28 2022 at 00:49):

thanks for the tip!

Peter Huene (Jun 28 2022 at 00:53):

For context, 50000 is the maximum number of locals supported by the parser (that's a lot of locals...)

Andrew Kelley (Jun 28 2022 at 00:54):

yep there is a good chance the generated code here is shall we say... less than ideal :)

Andrew Kelley (Jun 28 2022 at 00:55):

first step to fixing the compiler is to find out where the bad code is!

Peter Huene (Jun 28 2022 at 00:57):

I'm happy to help find the offending function if you run into trouble

Andrew Kelley (Jun 28 2022 at 01:00):

hmm no wasm-tools in nixos yet it looks like. I'll grab a build from upstream

Andrew Kelley (Jun 28 2022 at 01:07):

hmm I'm a bit stuck on trying to get wasm-tools installed: https://clbin.com/vygfV

Alex Crichton (Jun 28 2022 at 01:08):

ah that's a rustc-too-old issue

Alex Crichton (Jun 28 2022 at 01:08):

you may be able to check out an older release and get it to work

Andrew Kelley (Jun 28 2022 at 01:09):

so that's git checkout <older tag> in the wasm-tools repo, then cargo install ?

Alex Crichton (Jun 28 2022 at 01:09):

yeah that should work

Alex Crichton (Jun 28 2022 at 01:09):

you'd want the wasm-tools-* tags I think

Andrew Kelley (Jun 28 2022 at 01:15):

alright I was able to get wasm-tools-1.0.3 built with cargo 1.56.0

Andrew Kelley (Jun 28 2022 at 01:20):

alright so I found the function that has a crap ton of locals but unfortunately no symbol name:

============== func 13896 ====================
0x105ae98 | d3 ef 27    | size of function
0x105ae9b | cb 73       | 14795 local blocks
0x105ae9d | 05 7f       | 5 locals of type I32
0x105ae9f | 01 7e       | 1 locals of type I64