1380642 - Hide ordinals in wasm debugging

Status: NEW

(DevTools :: Debugger, enhancement, P5)

Description

[Jukka Jylänki]

STR:

Take a look at http://clbri.com/dump/wasm_debug/wasm_debug.html in wasm debugger.

The debugger shows the _main function of the wasm module as

(export "_main" $func22)

(func $func22 (result i32)
  (local $var0 i32) (local $var1 i32) (local $var2 i32) (local $var3 i32) 
  block
    get_global $global12
    set_local $var3
    get_global $global12
    i32.const 16
    i32.add
    set_global $global12
    get_global $global12
    get_global $global13
    i32.ge_s
    if
      i32.const 16
      call $import3
    end
    get_local $var3
    set_local $var1
    get_local $var3
    i32.const 4
    i32.add
    set_local $var0
    get_local $var0
    i32.const 1400
    i64.load align=1
    i64.store align=1
    get_local $var0
    i32.const 8
    i32.add
    i32.const 1400
    i32.const 8
    i32.add
    i32.load16_s align=1
    i32.store16 align=1
    get_local $var1
    get_local $var0
    i32.store
    i32.const 1410
    get_local $var1
    call $func68
    drop
    get_local $var3
    set_global $global12
    i32.const 0
    return
    unreachable
  end 
  unreachable
)

The decompiled .wast file is at

http://clbri.com/dump/wasm_debug/wasm_debug.wast

which reads

 (import "env" "STACKTOP" (global $import$3 i32))
 (export "_main" (func $_main))

 (func $_main (type $2) (result i32)
  (local $var$0 i32)
  (local $var$1 i32)
  (local $var$2 i32)
  (local $var$3 i32)
  (block $label$0
   (set_local $var$3
    (get_global $global$3)
   )
   (set_global $global$3
    (i32.add
     (get_global $global$3)
     (i32.const 16)
    )
   )
   (if
    (i32.ge_s
     (get_global $global$3)
     (get_global $global$4)
    )
    (block $label$1
     (call $import$10
      (i32.const 16)
     )
    )
   )
   (set_local $var$1
    (get_local $var$3)
   )
   (set_local $var$0
    (i32.add
     (get_local $var$3)
     (i32.const 4)
    )
   )
   (i64.store align=1
    (get_local $var$0)
    (i64.load align=1
     (i32.const 1400)
    )
   )
   (i32.store16 align=1
    (i32.add
     (get_local $var$0)
     (i32.const 8)
    )
    (i32.load16_s align=1
     (i32.add
      (i32.const 1400)
      (i32.const 8)
     )
    )
   )
   (i32.store
    (get_local $var$1)
    (get_local $var$0)
   )
   (drop
    (call $_printf
     (i32.const 1410)
     (get_local $var$1)
    )
   )
   (set_global $global$3
    (get_local $var$3)
   )
   (return
    (i32.const 0)
   )
   (unreachable)
  )
  (unreachable)
 )


It would be good to remove the indirection on the ordinals, and directly print out the symbol names in question. That is, could the debugger show

> (func "_main" (result i32)

instead of 

> (func $func22 (result i32)

and 

> get_global "STACKTOP"

for 

> (import "env" "STACKTOP" (global $import$3 i32))
> (global $global$3 (mut i32) (get_global $import$3))
> (get_global $global$3)

and

> call "abortStackOverflow"

instead of

> call $import3

Perhaps the ordinal numbers could be shown in parentheses after the name? such as call "abortStackOverflow" ($import3) ?

Comment 1

[Luke Wagner [:luke]]

I think it'd be good if our output (by default) was valid according to the official text format:
  https://webassembly.github.io/spec/text/instructions.html#expressions
Fortunately, the text format has the following abbreviation:
  (func $func22 (export "_main") ...)
  (global $glob1 (export "STACKTOP") ...)
for definitions (with the $ name optional if it isn't used).

For uses (get_global) there is no such abbreviation, so I'd recommend putting it in a (* comment *).

Comment 2

[Luke Wagner [:luke]]

Actually, probably the better option for uses is to have the name section or export name be used as the $ name, instead of an auto-generated $ name, when present.