$8565e4c5 indexed-append-guards.js:16:1
  Registers: 11
  Blocks:    7
  Constants:
    [0] = String("use strict")
    [1] = Int32(0)
    [2] = Int32(1)
    [3] = Undefined
    [4] = String("Indexed object append mutated")
    [5] = String("length")
    [6] = Bool(false)
    [7] = Int32(2)
    [8] = String("Array length changed")
    [9] = String("Array append mutated")

block0:
  [   0] GetGlobal dst:reg6, `Object`
  [  10] GetById dst:reg7, base:reg6, `preventExtensions` (Object.preventExtensions)
  [  28] NewObject dst:reg8
  [  38] ToPrimitiveWithStringHint dst:Int32(0), value:Int32(0)
  [  48] PutByValue base:reg8, property:Int32(0), src:Int32(1), kind:Own
  [  60] Call dst:reg5, callee:reg7, this_value:reg6, Object.preventExtensions, arguments:[reg8]
  [  88] DynamicInitializeLexicalBinding `object`, src:reg5
  [  98] GetGlobal dst:reg7, `expect_type_error`
  [  a8] NewFunction dst:reg6, shared_function_data_index:0
  [  c0] Call dst:reg5, callee:reg7, this_value:Undefined, expect_type_error, arguments:[reg6]
  [  e8] GetGlobal dst:reg7, `object`
  [  f8] GetByValue dst:reg6, base:reg7, property:Int32(1) (object[Int32(1)])
  [ 110] StrictlyInequals dst:reg7, lhs:reg6, rhs:Undefined
  [ 120] Mov dst:reg6, src:Undefined
  [ 130] JumpFalse condition:reg7, target:block2

block1:
  [ 140] GetGlobal dst:reg9, `Error`
  [ 150] CallConstruct dst:reg8, callee:reg9, Error, arguments:[String("Indexed object append mutated")]
  [ 170] Throw src:reg8

block2:
  [ 178] NewPrimitiveArray dst:reg5, elements:[1, 2]
  [ 198] DynamicInitializeLexicalBinding `array`, src:reg5
  [ 1a8] GetGlobal dst:reg7, `Object`
  [ 1b8] GetById dst:reg8, base:reg7, `defineProperty` (Object.defineProperty)
  [ 1d0] GetGlobal dst:reg9, `array`
  [ 1e0] NewObject dst:reg10
  [ 1f0] InitObjectLiteralProperty object:reg10, `writable`, src:Bool(false), shape_cache_index:0, property_slot:0
  [ 208] CacheObjectShape object:reg10
  [ 218] Call dst:reg5, callee:reg8, this_value:reg7, Object.defineProperty, arguments:[reg9, String("length"), reg10]
  [ 248] GetGlobal dst:reg8, `expect_type_error`
  [ 258] NewFunction dst:reg7, shared_function_data_index:1
  [ 270] Call dst:reg6, callee:reg8, this_value:Undefined, expect_type_error, arguments:[reg7]
  [ 298] GetGlobal dst:reg5, `array`
  [ 2a8] GetLength dst:reg8, base:reg5 (array.length)
  [ 2c0] StrictlyInequals dst:reg5, lhs:reg8, rhs:Int32(2)
  [ 2d0] Mov dst:reg8, src:Undefined
  [ 2e0] JumpFalse condition:reg5, target:block4

block3:
  [ 2f0] GetGlobal dst:reg10, `Error`
  [ 300] CallConstruct dst:reg7, callee:reg10, Error, arguments:[String("Array length changed")]
  [ 320] Throw src:reg7

block4:
  [ 328] GetGlobal dst:reg6, `array`
  [ 338] GetByValue dst:reg5, base:reg6, property:Int32(2) (array[Int32(2)])
  [ 350] StrictlyInequals dst:reg6, lhs:reg5, rhs:Undefined
  [ 360] Mov dst:reg5, src:Undefined
  [ 370] JumpFalse condition:reg6, target:block6

block5:
  [ 380] GetGlobal dst:reg10, `Error`
  [ 390] CallConstruct dst:reg7, callee:reg10, Error, arguments:[String("Array append mutated")]
  [ 3b0] Throw src:reg7

block6:
  [ 3b8] End value:reg5


expect_type_error$fc915998 indexed-append-guards.js:4:5
  Registers: 9
  Blocks:    8
  Locals:    error~0, did_throw~1
  Constants:
    [0] = Bool(false)
    [1] = Bool(true)
    [2] = Undefined
    [3] = String("Expected TypeError")

block0:
  [   0] GetLexicalEnvironment dst:reg4
  [   8] Mov dst:did_throw~1, src:Bool(false)
  [  18] Jump target:block5

block1:
  [  20] Catch dst:reg5
  [  28] SetLexicalEnvironment environment:reg4
  [  30] Mov dst:error~0, src:reg5
  [  40] GetGlobal dst:reg7, `TypeError`
  [  50] InstanceOf dst:reg8, lhs:error~0, rhs:reg7
  [  60] Not dst:reg6, src:reg8
  [  70] JumpFalse condition:reg6, target:block3

block2:
  [  80] Throw src:error~0

block3:
  [  88] Mov dst:did_throw~1, src:Bool(true)

block4:
  [  98] Not dst:reg5, src:did_throw~1
  [  a8] JumpIf condition:reg5, true_target:block6, false_target:block7

block5:
  [  b8] Call dst:reg5, callee:arg0, this_value:Undefined, callback
  [  d8] Jump target:block4

block6:
  [  e0] GetGlobal dst:reg8, `Error`
  [  f0] CallConstruct dst:reg6, callee:reg8, Error, arguments:[String("Expected TypeError")]
  [ 110] Throw src:reg6

block7:
  [ 118] End value:Undefined

Exception handlers:
  [  b8 ..   e0] => handler block1


$ec717972 indexed-append-guards.js:18:5
  Registers: 6
  Blocks:    1
  Constants:
    [0] = Int32(1)
    [1] = Int32(2)
    [2] = Undefined

block0:
  [   0] GetGlobal dst:reg5, `object`
  [  10] PutByValue base:reg5, property:Int32(1), src:Int32(2), kind:Normal (object[Int32(1)])
  [  28] End value:Undefined


$01eb2052 indexed-append-guards.js:26:5
  Registers: 8
  Blocks:    1
  Constants:
    [0] = Int32(3)
    [1] = Undefined

block0:
  [   0] GetGlobal dst:reg5, `array`
  [  10] GetGlobal dst:reg6, `array`
  [  20] GetLength dst:reg7, base:reg6 (array.length)
  [  38] PutByValue base:reg5, property:reg7, src:Int32(3), kind:Normal (array[reg7])
  [  50] End value:Undefined