Can't get this to work with LLVM 16.0.4

[TGMM]

First of all thanks for this repository. This has been pretty informative and interesting. I'm trying to replicate this repo using LLVM 16.0.4 instead of 14.0.6. I've successfully cross-compiled llc and lld. And i've got the resulting binary files. The issue arises when I try to compile the example LLVM IR, I get the following error: this.program: error: /lib/wasm32-wasi/libc.a(__main_void.o): undefined symbol: main Comparing the resulting main.o files from the 14 and 16 version respectively with wasm2wat I get the following:

14

  (type (;0;) (func (result i32)))
  (type (;1;) (func (param i32 i32) (result i32)))
  (import "env" "__linear_memory" (memory (;0;) 1))
  (import "env" "printf" (func (;0;) (type 1)))
  (import "env" "__indirect_function_table" (table (;0;) 0 funcref))
  (func $__original_main (type 0) (result i32)
    i32.const 0
    i32.const 0
    call 0
    drop
    i32.const 0)
  (func $main (type 1) (param i32 i32) (result i32)
    call $__original_main)
  (data $.L.str (i32.const 0) "Hello wasm!\0a\00"))

16

  (type (;0;) (func (result i32)))
  (type (;1;) (func (param i32 i32) (result i32)))
  (import "env" "__linear_memory" (memory (;0;) 1))
  (import "env" "printf" (func (;0;) (type 1)))
  (func $__original_main (type 0) (result i32)
    i32.const 0
    i32.const 0
    call 0
    drop
    i32.const 0)
  (func $main (type 1) (param i32 i32) (result i32)
    call $__original_main)
  (data $.L.str (i32.const 0) "Hello wasm!\0a\00"))

The only noticeable difference I can see is the lack of the (import "env" "__indirect_function_table" (table (;0;) 0 funcref)) instruction on the 16 version. But I don't know how to tell the compiler to add that instruction. Searching for an answer I found that that __original_main main should no longer be generated with the new LLVM versions (from 14 onwards), but yours is 14 and still has it, so I don't know what that means.

You can try it on my fork, here, in case you have time and want to take a look.

[soedirgo]

Hey @TGMM, thanks for checking this out!

I was able to get it to work with the existing instructions, though I also had to update emsdk (3.1.21 -> 3.1.40) and WASI (15 -> 20).

I've updated the README with the updated versions - can you try it again?

[TGMM]

Hello, thank you for your response. I forgot to mention I also updated the emsdk and WASI versions when I compiled mine. I used 3.1.39 I believe (since 3.1.40 wasn't out yet). I tried following the instructions again (which were almost exactly what I did the first time). But I continue getting the same error this.program: error: /lib/wasm32-wasi/libc.a(__main_void.o): undefined symbol: main when trying to run the demo. Is there a way you could share your resulting files so I can compare them with mine? Could there be anything in my environment that's different to yours that's causing this issue? In the meantime, I'll try to make a Docker image following your steps and see if that works.

EDIT: I forgot to mention I'm compiling this on a Windows machine using WSL2.

[soedirgo]

Hey, sorry for the late response!

So it turns out that I was also having the undefined symbol: main issue - I couldn't reproduce it previously because I didn't properly replace the llc/lld build assets.

I was able to nail down the cause to a missing symbol in the LLVM IR placeholder, so it had nothing to do with the build steps after all. Let me know if that works!