Weird Code Generation

[willemneal]

I have a simple C file:

#include <webassembly.h>

export int contract_function(int bid) {
  return bid;
}

compiled with:

wa-compile --bare -o example.wasm example.c

Which generates:

(module
 (type $0 (func (param i32) (result i32)))
 (import "env" "memory" (memory $0 1))
 (table 0 anyfunc)
 (export "contract_function" (func $0))
 (func $0 (type $0) (param $var$0 i32) (result i32)
  (block $label$0 i32
   (i32.store offset=12
    (i32.sub
     (i32.load offset=4
      (i32.const 0)
     )
     (i32.const 16)
    )
    (get_local $var$0)
   )
   (get_local $var$0)
  )
 )
)

This generates a memory RuntimeError: memory access out of bounds when I try to load it.

However, when I compile using wasmfiddle I get:

(module
 (table 0 anyfunc)
 (memory $0 1)
 (export "memory" (memory $0))
 (export "contract_function" (func $contract_function))
 (func $contract_function (; 0 ;) (param $0 i32) (result i32)
  (get_local $0)
 )
)

Any ideas?

[xtuc]

I think it comes from LLVM, I already saw a similar error.

[willemneal]

Hmm could it be that the precompiled binaries used are over a year old?

[dcodeIO]

Yes, the binaries are quite old.