wa-diff 0.1.0

wa-info

wa-info is a tool to inspect WebAssembly binary format wasm files.

It can show sections overview in the summary output, disassemble function(s) code, show information about dotnet AOT. It is available as dotnet tool.

wa-diff

wa-diff is a tool to compare WebAssembly binary files

wa-edit

wa-edit is a tool to modify WebAssembly binary files

Installation

To install wa-info, wa-diff and wa-edit as dotnet tool run:

dotnet tool install -g wa-info
dotnet tool install -g wa-diff
dotnet tool install -g wa-edit

to update use:

dotnet tool update -g wa-info
dotnet tool update -g wa-diff
dotnet tool update -g wa-edit

Nugets

The packaged tools can be also retrieved as nugets

https://www.nuget.org/packages/wa-info https://www.nuget.org/packages/wa-diff https://www.nuget.org/packages/wa-edit

Command line options

wa-info:

Usage: wa-info OPTIONS* file.wasm [file2.wasm ...]

Provides information about WebAssembly file(s)

Copyright 2021 Microsoft Corporation

Options:
      --aot-stats            Show stats about methods
  -a, --assembly-filter=REGEX
                             Filter assemblies and process only those matching
                               REGEX
  -d, --disassemble          Show functions(s) disassembled code
  -f, --function-filter=REGEX
                             Filter wasm functions REGEX
      --function-offset=REGEX
                             Filter wasm functions REGEX
  -h, --help, -?             Show this message and exit
  -o, --instruction-offsets  Show instruction offsets
  -t, --type-filter=REGEX    Filter types and process only those matching REGEX
  -v, --verbose              Output information about progress during the run
                               of the tool. Use multiple times to increase
                               verbosity, like -vv

wa-diff:

Usage: wa-diff OPTIONS* file1.wasm file2.wasm

Compares WebAssembly binary file(s)

Copyright 2021 Microsoft Corporation

Options:
  -d, --disassemble          Show functions(s) disassembled code
  -f, --function-filter=REGEX
                             Filter wasm functions REGEX
      --function-offset=REGEX
                             Filter wasm functions REGEX
  -h, --hide-const-loads     Hide const loads values
  -s, --function-size        Compare function code sizes
  -v, --verbose              Output information about progress during the run
                               of the tool. Use multiple times to increase
                               verbosity, like -vv

wa-edit:

Usage: wa-edit OPTIONS* source.wasm destination.wasm

Modifies WebAssembly file (source.wasm) and writes updated file (destination.
wasm)

Copyright 2022 Microsoft Corporation

Options:
  -a, --data-auto-split      Split the data segment to avoid long empty chunks
                               with zeroes
  -d, --data-section=FILE    Replace the data section with content of the FILE
  -m, --data-section-mode=MODE
                             Set the data section replacement MODE. Possible
                               values: Active, Passive
  -o, --data-offset=VALUE    Data section offset
  -h, --help, -?             Show this message and exit
  -v, --verbose              Output information about progress during the run
                               of the tool. Use multiple times to increase
                               verbosity, like -vv

Example usage

Disassemble function

> wa-info -d -f test test.wasm
(func test_simd(param i32) (result i32))
 local 1 123
 local.get $0
 i32x4.splat    [SIMD]
 local.tee $1
 local.get $1
 i16x8.avgr.u    [SIMD]
 i32x4.extract.lane    [SIMD]

Summary of the module and sections

> wa-info dotnet.wasm
Module: path: dotnet.wasm
  size: 74,502,446
  binary format version: 1
  sections: 17
    id: Type size: 5,237
    id: Import size: 4,315
    id: Function size: 163,566
    id: Table size: 9
    id: Memory size: 7
    id: Global size: 19
    id: Export size: 7,213
    id: Element size: 428,929
    id: Code size: 34,177,740
    id: Data size: 9,520,741
    id: Custom name: name size: 21,544,785
    id: Custom name: .debug_info size: 4,035,679
    id: Custom name: .debug_loc size: 1,436,083
    id: Custom name: .debug_ranges size: 140,966
    id: Custom name: .debug_abbrev size: 240,230
    id: Custom name: .debug_line size: 2,060,872
    id: Custom name: .debug_str size: 735,984

Disassemble function

note: build the app with -p:WasmNativeDebugSymbols=true -p:WasmNativeStrip=false to preserve name custom section

> wa-info -d -f ves_icall_RuntimeFieldInfo_GetValueInternal$ dotnet.wasm
(func ves_icall_RuntimeFieldInfo_GetValueInternal(param i32 i32 i32) (result i32))
 local.get $0
 i32.load align:2
 i32.load offset:12 align:2
 local.tee $0
 local.get $1
 if
  local.get $1
  i32.load align:2
 else
  i32.const 0

 local.tee $1
 local.get $2
 call mono_field_get_value_object_checked
 i32.const 11201820
 i32.load align:2
 call mono_handle_new

Get AOT stats

> wa-info --aot-stats dotnet.wasm
AOT stats: 5005 function(s) call(s) interpreter, 2.96% of 169215 functions

Compare functions

> wa-diff -d -f corlib_System_RuntimeType_IsDelegate dotnet1.wasm dotnet2.wasm
(func corlib_System_RuntimeType_IsDelegate(param i32 i32) (result i32))
...
   local.tee $2
   global.set $__stack_pointer
-  i32.const 1573600
+  i32.const 1573760
   i32.load8.u
   i32.eqz
...
    i32.const 25177
    call aot_wrapper_pinvoke_corlib__Interop_sl_Sys___le_PosixFAdvise_gt_g____PInvoke___verbar_83_0_pinvoke_i4_iii8i8cl1a_Interop_2fSys_2fFileAdvice_i4_iii8i8cl1a_Interop_2fSys_2fFileAdvice_
-   i32.const 1573600
+   i32.const 1573760
    i32.const 1
    i32.store8
...
   i32.store offset:12 align:2
   local.get $2
-  i32.const 1516792
+  i32.const 1516952
   i32.load align:2
   local.tee $3

Hide load consts, this helps to reduce "noise" when checking the code changes. Output with -h

> wa-diff -h -d -f corlib.*Vector128_1_long_GetHashCode 1.wasm 2.wasm
(func corlib_System_Runtime_Intrinsics_Vector128_1_long_GetHashCode(param i32, i32) (result i32))
...
    i64.load align:3
    local.get $1
-   call corlib_System_HashCode_Add_T_ULONG_T_ULONG
+   call corlib_System_HashCode_Add_T_LONG_T_LONG
    local.get $0
    i32.const
...
    i64.load offset:8 align:3
    local.get $1
-   call corlib_System_HashCode_Add_T_ULONG_T_ULONG
+   call corlib_System_HashCode_Add_T_LONG_T_LONG
    local.get $1
    local.get $1

and standard output:

> wa-diff -d -f corlib.*Vector128_1_long_GetHashCode 1.wasm 2.wasm
(func corlib_System_Runtime_Intrinsics_Vector128_1_long_GetHashCode(param i32, i32) (result i32))
...
   local.tee $1
   global.set $global:0
-  i32.const 4411468
+  i32.const 4900240
   i32.load8.u
   i32.eqz
   if
-   i32.const 869872
+   i32.const 1032336
    call mono_aot_corlib_init_method
-   i32.const 4411468
+   i32.const 4900240
    i32.const 1
    i32.store8
...
    i64.load align:3
    local.get $1
-   call corlib_System_HashCode_Add_T_ULONG_T_ULONG
+   call corlib_System_HashCode_Add_T_LONG_T_LONG
    local.get $0
    i32.const -1
...
    i64.load offset:8 align:3
    local.get $1
-   call corlib_System_HashCode_Add_T_ULONG_T_ULONG
+   call corlib_System_HashCode_Add_T_LONG_T_LONG
    local.get $1
    local.get $1

Replace Data section

> wa-edit -v dotnet.wasm d4.wasm -a -o 0 -d memory.dat
Reading wasm file: dotnet.wasm
Writing wasm file: d4.wasm
WebAssembly binary format version: 1
Reading section:      Type size:         1632
Reading section:    Import size:         3104
Reading section:  Function size:        17745
Reading section:     Table size:            5
Reading section:    Memory size:            7
Reading section:    Global size:         2394
Reading section:    Export size:         4227
Reading section:   Element size:         8702
Reading section:      Code size:      6282132
Reading section:      Data size:       649676    segments detected: 29,539 zero bytes stripped: 48,137,494
Reading section:    Custom size:       880619
Reading section:    Custom size:      3388054
Reading section:    Custom size:       360611
Reading section:    Custom size:       134358
Reading section:    Custom size:       211464
Reading section:    Custom size:      3645378
Reading section:    Custom size:       706701