Error parsing WebAssembly text file:

[LiaoPeng]

Pardon again, I compiled my assemblyscript program to wasm text. Then I deploy the code on a webassembly virtual machine. It throws the below exceptions when it running.

Error parsing WebAssembly text file:
invalid stack access
(if (result i32)

(if (result i32)
      (i64.eq
       (call $token/CurrencyStats#primaryKey
        (get_local $1)
       )
       (call $token/CurrencyStats#primaryKey
        (i32.load offset=12
         (call $~lib/array/Array<DataItem<CurrencyStats>>#__get
          (i32.load offset=24
           (get_local $0)
          )
          (get_local $3)
         )
        )
       )
      )

stack was not empty at end of control structure: stack.size() > controlStack.back().outerStackSize
(block $break|0

(block $break|0
   (loop $repeat|0
    (br_if $break|0
     (i32.ge_u
      (get_local $1)
      (get_local $4)
     )
    )

I used the interface in my code. Because of the project and code is too long, so I don't paste the code. Can you give me some advice to solve this problem?

[dcodeIO]

If you append --validate to the asc command when compiling, does it also emit an error?

[LiaoPeng]

@dcodeIO I append --validate to the asc command when compiling, the compiling progress works fine. And the running progress is also emit an error. The asc options --optimize, -O Optimizes the module. Also has the usual shorthands:, what's the difference between the different optimize level?

[dcodeIO]

Which VM are you using to run the binary? This looks like an issue with either the VM or Binaryen to me, if --validate works.

The only optimization presets you'll most likely care about are either -O3 if you'd like to optimize for speed. or -Oz if you'd like to optimize for binary size. The number corresponds to optimizeLevel (speed) and the letter to shrinkLevel (size).

[LiaoPeng]

Thanks for your answer. I using the WAVM to run the binary. https://github.com/AndrewScheidecker/WAVM

[dcodeIO]

I'd suggest to create an issue at WAVM with the text format in question. Afaik they have their own text format parser and my first guess would be that it doesn't yet handle something Binaryen emits with AssemblyScript as the generator, but I might of course be wrong.

[LiaoPeng]

I really appreciate you answer with patient. I had found my issue code.

   for (; idx < len; ++idx) {
            if (newobj.primaryKey() == this._items_vector[idx]._value.primaryKey()) {
                item = this._items_vector[idx];
                break; // if removed, works find
            }
        }

I remove the break, so it works fine.

I run another test case

let arr:Array<u64> = [12];
        let idx: i32 = 0;
        for (; idx < arr.length; ++idx) {
            if (arr[idx] == owner) {
                break; // not removed
            } 
 }

It works also fine. I think the newobj.primaryKey() == this._items_vector[idx]._value.primaryKey() leaded the binary generated unusual.

[dcodeIO]

I don't think that there is anything wrong with code generation on the AssemblyScript side when --validate does not report any issues. You can also try to validate the resulting binary or text format with WABT to double-check.

[LiaoPeng]

Thank you for your advice.
I checked the wast text, a exception was threw.

My assembly script code:

	function pwr(a: i32, b: i32): i32 {
		
		if (a == b) {
			return a;
		} else  {
			return b;
		} 
	}

The wast code :

(module
 (type $iii (func (param i32 i32) (result i32)))
 (type $v (func))
 (global $~lib/internal/allocator/AL_BITS i32 (i32.const 3))
 (global $~lib/internal/allocator/AL_SIZE i32 (i32.const 8))
 (global $~lib/internal/allocator/AL_MASK i32 (i32.const 7))
 (global $~lib/internal/allocator/MAX_SIZE_32 i32 (i32.const 1073741824))
 (global $~lib/allocator/arena/startOffset (mut i32) (i32.const 0))
 (global $~lib/allocator/arena/offset (mut i32) (i32.const 0))
 (global $HEAP_BASE i32 (i32.const 8))
 (memory $0 0)
 (export "memory" (memory $0))
 (export "pwr" (func $safemath/pwr))
 (start $start)
 (func $safemath/pwr (; 0 ;) (type $iii) (param $0 i32) (param $1 i32) (result i32)
  (if
   (i32.eq
    (get_local $0)
    (get_local $1)
   )
   (return
    (get_local $0)
   )
   (return
    (get_local $1)
   )
  )
 )
 (func $start (; 1 ;) (type $v)
  (set_global $~lib/allocator/arena/startOffset
   (i32.and
    (i32.add
     (get_global $HEAP_BASE)
     (get_global $~lib/internal/allocator/AL_MASK)
    )
    (i32.xor
     (get_global $~lib/internal/allocator/AL_MASK)
     (i32.const -1)
    )
   )
  )
  (set_global $~lib/allocator/arena/offset
   (get_global $~lib/allocator/arena/startOffset)
  )
 )
)

It seem that multi-if condition with return statements compiled incorrectly.

(func $safemath/pwr (; 0 ;) (type $iii) (param $0 i32) (param $1 i32) (result i32)
  (if
   (i32.eq
    (get_local $0)
    (get_local $1)
   )
   (return
    (get_local $0)
   )
   (return
    (get_local $1)
   )
  )
 )

I use asc a.ts -t a.wast without option --optimize, it works like above.
If I compiled with option --optimize, it works fine.
The compiled result:

 (func $safemath/pwr (; 0 ;) (type $iii) (param $0 i32) (param $1 i32) (result i32)
  (select
   (get_local $0)
   (get_local $1)
   (i32.eq
    (get_local $0)
    (get_local $1)
   )
  )
 )

[MaxGraey]

That's really strange. I recreate your code in WebAssembly Studio:
https://webassembly.studio/?f=pllmt6sb6n

And got current output with -O0 (disable optimization):

  (func $main/pwr (export "pwr") (type $t0) (param $p0 i32) (param $p1 i32) (result i32)
    get_local $p0
    get_local $p1
    i32.eq
    if $I0
      get_local $p0
      return
    else
      get_local $p1
      return
    end
    unreachable)

Which looks normally.
And with default optimization:

  (func $main/pwr (export "pwr") (type $t0) (param $p0 i32) (param $p1 i32) (result i32)
    get_local $p0
    get_local $p1
    get_local $p0
    get_local $p1
    i32.eq
    select)

[dcodeIO]

Issue seems to be that a terminating unreachable must be generated if all prior branches return. Binaryen does this when optimizing, but --validate doesn't seem to catch this?

[MaxGraey]

No it seems problem in double return in code below (See $safemath/pwr function). Version in WebAssembly studio produce different (right) result.

[dcodeIO]

The output above is that of Binaryen writing a binary (where the unreachable is inserted), read back with WABT (as can be seen from the stack syntax). The issue, however, is in Binaryen writing just text, where the unreachable isn't inserted.

[MaxGraey]

Hmm, I read about some binaryen issue adressed to same problem with skipped unreachable in text format but present in binary. It was couple month ago... May be the same?

[dcodeIO]

Yeah, that came up before. I think a proper fix is to explicitly emit the unreachable in the compiler, not relying on any postprocessing.

[LiaoPeng]

@dcodeIO @MaxGraey
Pardon again. I found another case that was not passed.

function checkBreak():void{
    let item:i32;
    for (let idx:i32=0; idx < 32; ++idx) {
        if (idx == 12) { 
            item = idx + 32;
            break;
        }
    }
    assert(item == 32);
}
checkBreak();

The compile command asc break.ts -O -t break.wast --validate
The compiled wast content.

(module
 (type $v (func))
 (type $iiiiv (func (param i32 i32 i32 i32)))
 (import "env" "abort" (func $~lib/env/abort (param i32 i32 i32 i32)))
 (global $~lib/allocator/arena/startOffset (mut i32) (i32.const 0))
 (global $~lib/allocator/arena/offset (mut i32) (i32.const 0))
 (memory $0 1)
 (data (i32.const 8) "\08\00\00\00b\00r\00e\00a\00k\00.\00t\00s")
 (export "memory" (memory $0))
 (start $start)
 (func $break/checkBreak (; 1 ;) (type $v)
  (local $0 i32)
  (local $1 i32)
  (block $break|0
   (loop $repeat|0
    (br_if $break|0
     (i32.ge_s
      (get_local $0)
      (i32.const 32)
     )
    )
    (set_local $1
     (if (result i32)
      (i32.eq
       (get_local $0)
       (i32.const 12)
      )
      (i32.add
       (get_local $0)
       (i32.const 32)
      )
      (block
       (set_local $0
        (i32.add
         (get_local $0)
         (i32.const 1)
        )
       )
       (br $repeat|0)
      )
     )
    )
   )
  )
  (if
   (i32.ne
    (get_local $1)
    (i32.const 44)
   )
   (block
    (call $~lib/env/abort
     (i32.const 0)
     (i32.const 8)
     (i32.const 33)
     (i32.const 4)
    )
    (unreachable)
   )
  )
 )
 (func $start (; 2 ;) (type $v)
  (set_global $~lib/allocator/arena/startOffset
   (i32.const 32)
  )
  (set_global $~lib/allocator/arena/offset
   (get_global $~lib/allocator/arena/startOffset)
  )
  (call $break/checkBreak)
 )
)

Error: validate failed:
test.wast:39:9: error: type mismatch in if false branch, expected [i32] but got []
       (br $repeat|0)