diff --git a/package-lock.json b/package-lock.json
index 2e8e71e1fa..ac7902a436 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -713,9 +713,9 @@
       "optional": true
     },
     "binaryen": {
-      "version": "98.0.0-nightly.20201025",
-      "resolved": "https://registry.npmjs.org/binaryen/-/binaryen-98.0.0-nightly.20201025.tgz",
-      "integrity": "sha512-jS6VMHF2mRKMBy79DhMDX+j1ph+TahHhLazkybvr90WkXBa80ydWgLTZLe3mxms1iOHJYqFv84TrKCrlFiwzjA=="
+      "version": "98.0.0-nightly.20201027",
+      "resolved": "https://registry.npmjs.org/binaryen/-/binaryen-98.0.0-nightly.20201027.tgz",
+      "integrity": "sha512-00/IHlumty/5XzJsdaMudayXofJiDb3Ytqqdn7OJBM0L9SuVg0o0xu4l93NVf+hO6jkgXNE1t+LdB0gOdeLdjA=="
     },
     "bluebird": {
       "version": "3.7.2",
diff --git a/package.json b/package.json
index 9a7e52e300..468b524a9d 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     "url": "https://github.com/AssemblyScript/assemblyscript/issues"
   },
   "dependencies": {
-    "binaryen": "98.0.0-nightly.20201025",
+    "binaryen": "98.0.0-nightly.20201027",
     "long": "^4.0.0",
     "source-map-support": "^0.5.19",
     "ts-node": "^6.2.0"
diff --git a/tests/compiler/std/string-casemapping.optimized.wat b/tests/compiler/std/string-casemapping.optimized.wat
index 2eb8aa5fd4..46bdd6444e 100644
--- a/tests/compiler/std/string-casemapping.optimized.wat
+++ b/tests/compiler/std/string-casemapping.optimized.wat
@@ -2546,8 +2546,6 @@
              i32.eq
              local.get $3
              i32.const 2
-             i32.sub
-             i32.const 0
              i32.ge_s
              i32.and
              if
@@ -3203,18 +3201,18 @@
   local.get $0
  )
  (func $start:std/string-casemapping
-  (local $0 i64)
-  (local $1 i64)
-  (local $2 i64)
-  (local $3 i64)
+  (local $0 i32)
+  (local $1 i32)
+  (local $2 i32)
+  (local $3 i32)
   (local $4 i32)
   (local $5 i32)
   (local $6 i32)
-  (local $7 i64)
-  (local $8 i32)
-  (local $9 i32)
-  (local $10 i32)
-  (local $11 i32)
+  (local $7 i32)
+  (local $8 i64)
+  (local $9 i64)
+  (local $10 i64)
+  (local $11 i64)
   (local $12 i32)
   (local $13 i32)
   (local $14 i32)
@@ -3301,10 +3299,9 @@
   (local $95 i32)
   (local $96 i32)
   (local $97 i32)
-  (local $98 i32)
   i32.const 1056
   call $~lib/string/String#toUpperCase
-  local.tee $13
+  local.tee $12
   i32.const 1056
   call $~lib/string/String.__eq
   i32.eqz
@@ -3318,7 +3315,7 @@
   end
   i32.const 1056
   call $~lib/string/String#toLowerCase
-  local.tee $14
+  local.tee $13
   i32.const 1056
   call $~lib/string/String.__eq
   i32.eqz
@@ -3332,7 +3329,7 @@
   end
   i32.const 11328
   call $~lib/string/String#toUpperCase
-  local.tee $15
+  local.tee $14
   i32.const 11376
   call $~lib/string/String.__eq
   i32.eqz
@@ -3346,7 +3343,7 @@
   end
   i32.const 11424
   call $~lib/string/String#toLowerCase
-  local.tee $16
+  local.tee $15
   i32.const 11472
   call $~lib/string/String.__eq
   i32.eqz
@@ -3360,7 +3357,7 @@
   end
   i32.const 11520
   call $~lib/string/String#toUpperCase
-  local.tee $17
+  local.tee $16
   i32.const 11616
   call $~lib/string/String.__eq
   i32.eqz
@@ -3374,7 +3371,7 @@
   end
   i32.const 11616
   call $~lib/string/String#toLowerCase
-  local.tee $18
+  local.tee $17
   i32.const 11712
   call $~lib/string/String.__eq
   i32.eqz
@@ -3388,7 +3385,7 @@
   end
   i32.const 11808
   call $~lib/string/String#toUpperCase
-  local.tee $19
+  local.tee $18
   i32.const 11872
   call $~lib/string/String.__eq
   i32.eqz
@@ -3402,7 +3399,7 @@
   end
   i32.const 11872
   call $~lib/string/String#toLowerCase
-  local.tee $20
+  local.tee $19
   i32.const 11936
   call $~lib/string/String.__eq
   i32.eqz
@@ -3416,7 +3413,7 @@
   end
   i32.const 12000
   call $~lib/string/String#toUpperCase
-  local.tee $21
+  local.tee $20
   i32.const 12096
   call $~lib/string/String.__eq
   i32.eqz
@@ -3430,7 +3427,7 @@
   end
   i32.const 12096
   call $~lib/string/String#toLowerCase
-  local.tee $22
+  local.tee $21
   i32.const 12192
   call $~lib/string/String.__eq
   i32.eqz
@@ -3444,7 +3441,7 @@
   end
   i32.const 12288
   call $~lib/string/String#toUpperCase
-  local.tee $23
+  local.tee $22
   i32.const 12384
   call $~lib/string/String.__eq
   i32.eqz
@@ -3458,7 +3455,7 @@
   end
   i32.const 12384
   call $~lib/string/String#toLowerCase
-  local.tee $24
+  local.tee $23
   i32.const 12480
   call $~lib/string/String.__eq
   i32.eqz
@@ -3472,7 +3469,7 @@
   end
   i32.const 12576
   call $~lib/string/String#toUpperCase
-  local.tee $25
+  local.tee $24
   i32.const 12656
   call $~lib/string/String.__eq
   i32.eqz
@@ -3486,7 +3483,7 @@
   end
   i32.const 12736
   call $~lib/string/String#toUpperCase
-  local.tee $26
+  local.tee $25
   i32.const 12816
   call $~lib/string/String.__eq
   i32.eqz
@@ -3500,7 +3497,7 @@
   end
   i32.const 12896
   call $~lib/string/String#toUpperCase
-  local.tee $27
+  local.tee $26
   i32.const 12960
   call $~lib/string/String.__eq
   i32.eqz
@@ -3514,7 +3511,7 @@
   end
   i32.const 13024
   call $~lib/string/String#toUpperCase
-  local.tee $28
+  local.tee $27
   i32.const 13104
   call $~lib/string/String.__eq
   i32.eqz
@@ -3528,7 +3525,7 @@
   end
   i32.const 13184
   call $~lib/string/String#toUpperCase
-  local.tee $29
+  local.tee $28
   i32.const 13264
   call $~lib/string/String.__eq
   i32.eqz
@@ -3542,7 +3539,7 @@
   end
   i32.const 13344
   call $~lib/string/String#toUpperCase
-  local.tee $30
+  local.tee $29
   i32.const 13408
   call $~lib/string/String.__eq
   i32.eqz
@@ -3556,7 +3553,7 @@
   end
   i32.const 13472
   call $~lib/string/String#toUpperCase
-  local.tee $31
+  local.tee $30
   i32.const 13552
   call $~lib/string/String.__eq
   i32.eqz
@@ -3570,7 +3567,7 @@
   end
   i32.const 13632
   call $~lib/string/String#toUpperCase
-  local.tee $32
+  local.tee $31
   i32.const 13712
   call $~lib/string/String.__eq
   i32.eqz
@@ -3584,7 +3581,7 @@
   end
   i32.const 13792
   call $~lib/string/String#toUpperCase
-  local.tee $33
+  local.tee $32
   i32.const 13952
   call $~lib/string/String.__eq
   i32.eqz
@@ -3598,7 +3595,7 @@
   end
   i32.const 13792
   call $~lib/string/String#toLowerCase
-  local.tee $34
+  local.tee $33
   i32.const 14112
   call $~lib/string/String.__eq
   i32.eqz
@@ -3612,7 +3609,7 @@
   end
   i32.const 14272
   call $~lib/string/String#toUpperCase
-  local.tee $35
+  local.tee $34
   i32.const 14304
   call $~lib/string/String.__eq
   i32.eqz
@@ -3626,7 +3623,7 @@
   end
   i32.const 14336
   call $~lib/string/String#toLowerCase
-  local.tee $36
+  local.tee $35
   i32.const 14368
   call $~lib/string/String.__eq
   i32.eqz
@@ -3640,7 +3637,7 @@
   end
   i32.const 14400
   call $~lib/string/String#toUpperCase
-  local.tee $37
+  local.tee $36
   i32.const 14608
   call $~lib/string/String.__eq
   i32.eqz
@@ -3654,9 +3651,9 @@
   end
   i32.const 14272
   call $~lib/string/String#toUpperCase
-  local.tee $38
+  local.tee $37
   call $~lib/string/String#toLowerCase
-  local.tee $39
+  local.tee $38
   i32.const 14816
   call $~lib/string/String.__eq
   i32.eqz
@@ -3670,9 +3667,9 @@
   end
   i32.const 14848
   call $~lib/string/String#toUpperCase
-  local.tee $40
+  local.tee $39
   call $~lib/string/String#toLowerCase
-  local.tee $41
+  local.tee $40
   i32.const 14880
   call $~lib/string/String.__eq
   i32.eqz
@@ -3686,9 +3683,9 @@
   end
   i32.const 14912
   call $~lib/string/String#toUpperCase
-  local.tee $42
+  local.tee $41
   call $~lib/string/String#toLowerCase
-  local.tee $43
+  local.tee $42
   i32.const 14912
   call $~lib/string/String.__eq
   i32.eqz
@@ -3702,9 +3699,9 @@
   end
   i32.const 65536
   call $~lib/string/String.fromCodePoint
-  local.tee $44
+  local.tee $43
   call $~lib/string/String#toLowerCase
-  local.tee $45
+  local.tee $44
   i32.const 15168
   call $~lib/string/String.__eq
   i32.eqz
@@ -3718,9 +3715,9 @@
   end
   i32.const 65536
   call $~lib/string/String.fromCodePoint
-  local.tee $46
+  local.tee $45
   call $~lib/string/String#toUpperCase
-  local.tee $47
+  local.tee $46
   i32.const 15168
   call $~lib/string/String.__eq
   i32.eqz
@@ -3734,7 +3731,7 @@
   end
   i32.const 15200
   call $~lib/string/String#toLowerCase
-  local.tee $48
+  local.tee $47
   i32.const 15232
   call $~lib/string/String.__eq
   i32.eqz
@@ -3748,7 +3745,7 @@
   end
   i32.const 15264
   call $~lib/string/String#toLowerCase
-  local.tee $49
+  local.tee $48
   i32.const 15296
   call $~lib/string/String.__eq
   i32.eqz
@@ -3762,7 +3759,7 @@
   end
   i32.const 15328
   call $~lib/string/String#toLowerCase
-  local.tee $50
+  local.tee $49
   i32.const 15360
   call $~lib/string/String.__eq
   i32.eqz
@@ -3776,7 +3773,7 @@
   end
   i32.const 15392
   call $~lib/string/String#toLowerCase
-  local.tee $51
+  local.tee $50
   i32.const 15424
   call $~lib/string/String.__eq
   i32.eqz
@@ -3790,7 +3787,7 @@
   end
   i32.const 15456
   call $~lib/string/String#toLowerCase
-  local.tee $52
+  local.tee $51
   i32.const 15488
   call $~lib/string/String.__eq
   i32.eqz
@@ -3804,7 +3801,7 @@
   end
   i32.const 15520
   call $~lib/string/String#toLowerCase
-  local.tee $53
+  local.tee $52
   i32.const 15552
   call $~lib/string/String.__eq
   i32.eqz
@@ -3818,7 +3815,7 @@
   end
   i32.const 15584
   call $~lib/string/String#toLowerCase
-  local.tee $54
+  local.tee $53
   i32.const 15616
   call $~lib/string/String.__eq
   i32.eqz
@@ -3832,7 +3829,7 @@
   end
   i32.const 15648
   call $~lib/string/String#toLowerCase
-  local.tee $55
+  local.tee $54
   i32.const 15680
   call $~lib/string/String.__eq
   i32.eqz
@@ -3846,7 +3843,7 @@
   end
   i32.const 15712
   call $~lib/string/String#toLowerCase
-  local.tee $56
+  local.tee $55
   i32.const 15744
   call $~lib/string/String.__eq
   i32.eqz
@@ -3860,7 +3857,7 @@
   end
   i32.const 15776
   call $~lib/string/String#toLowerCase
-  local.tee $57
+  local.tee $56
   i32.const 15808
   call $~lib/string/String.__eq
   i32.eqz
@@ -3874,7 +3871,7 @@
   end
   i32.const 15840
   call $~lib/string/String#toLowerCase
-  local.tee $58
+  local.tee $57
   i32.const 15872
   call $~lib/string/String.__eq
   i32.eqz
@@ -3888,7 +3885,7 @@
   end
   i32.const 15904
   call $~lib/string/String#toLowerCase
-  local.tee $59
+  local.tee $58
   i32.const 15936
   call $~lib/string/String.__eq
   i32.eqz
@@ -3902,7 +3899,7 @@
   end
   i32.const 15968
   call $~lib/string/String#toLowerCase
-  local.tee $60
+  local.tee $59
   i32.const 16000
   call $~lib/string/String.__eq
   i32.eqz
@@ -3916,7 +3913,7 @@
   end
   i32.const 16032
   call $~lib/string/String#toLowerCase
-  local.tee $61
+  local.tee $60
   i32.const 16064
   call $~lib/string/String.__eq
   i32.eqz
@@ -3930,7 +3927,7 @@
   end
   i32.const 16096
   call $~lib/string/String#toLowerCase
-  local.tee $62
+  local.tee $61
   i32.const 16128
   call $~lib/string/String.__eq
   i32.eqz
@@ -3944,7 +3941,7 @@
   end
   i32.const 16160
   call $~lib/string/String#toLowerCase
-  local.tee $63
+  local.tee $62
   i32.const 16192
   call $~lib/string/String.__eq
   i32.eqz
@@ -3958,7 +3955,7 @@
   end
   i32.const 16224
   call $~lib/string/String#toLowerCase
-  local.tee $64
+  local.tee $63
   i32.const 16256
   call $~lib/string/String.__eq
   i32.eqz
@@ -3972,7 +3969,7 @@
   end
   i32.const 16288
   call $~lib/string/String#toLowerCase
-  local.tee $65
+  local.tee $64
   i32.const 16320
   call $~lib/string/String.__eq
   i32.eqz
@@ -3986,7 +3983,7 @@
   end
   i32.const 16352
   call $~lib/string/String#toLowerCase
-  local.tee $66
+  local.tee $65
   i32.const 16384
   call $~lib/string/String.__eq
   i32.eqz
@@ -4000,7 +3997,7 @@
   end
   i32.const 16416
   call $~lib/string/String#toLowerCase
-  local.tee $67
+  local.tee $66
   i32.const 16448
   call $~lib/string/String.__eq
   i32.eqz
@@ -4014,7 +4011,7 @@
   end
   i32.const 16480
   call $~lib/string/String#toLowerCase
-  local.tee $68
+  local.tee $67
   i32.const 16512
   call $~lib/string/String.__eq
   i32.eqz
@@ -4028,7 +4025,7 @@
   end
   i32.const 16544
   call $~lib/string/String#toLowerCase
-  local.tee $69
+  local.tee $68
   i32.const 16576
   call $~lib/string/String.__eq
   i32.eqz
@@ -4042,7 +4039,7 @@
   end
   i32.const 16608
   call $~lib/string/String#toLowerCase
-  local.tee $70
+  local.tee $69
   i32.const 16640
   call $~lib/string/String.__eq
   i32.eqz
@@ -4056,7 +4053,7 @@
   end
   i32.const 16672
   call $~lib/string/String#toLowerCase
-  local.tee $71
+  local.tee $70
   i32.const 16704
   call $~lib/string/String.__eq
   i32.eqz
@@ -4070,7 +4067,7 @@
   end
   i32.const 16736
   call $~lib/string/String#toLowerCase
-  local.tee $72
+  local.tee $71
   i32.const 16768
   call $~lib/string/String.__eq
   i32.eqz
@@ -4084,7 +4081,7 @@
   end
   i32.const 16800
   call $~lib/string/String#toLowerCase
-  local.tee $73
+  local.tee $72
   i32.const 15872
   call $~lib/string/String.__eq
   i32.eqz
@@ -4098,7 +4095,7 @@
   end
   i32.const 16832
   call $~lib/string/String#toLowerCase
-  local.tee $74
+  local.tee $73
   i32.const 16864
   call $~lib/string/String.__eq
   i32.eqz
@@ -4112,7 +4109,7 @@
   end
   i32.const 16896
   call $~lib/string/String#toLowerCase
-  local.tee $75
+  local.tee $74
   i32.const 16928
   call $~lib/string/String.__eq
   i32.eqz
@@ -4126,7 +4123,7 @@
   end
   i32.const 16960
   call $~lib/string/String#toLowerCase
-  local.tee $76
+  local.tee $75
   i32.const 16992
   call $~lib/string/String.__eq
   i32.eqz
@@ -4140,7 +4137,7 @@
   end
   i32.const 17024
   call $~lib/string/String#toLowerCase
-  local.tee $77
+  local.tee $76
   i32.const 17056
   call $~lib/string/String.__eq
   i32.eqz
@@ -4154,7 +4151,7 @@
   end
   i32.const 17088
   call $~lib/string/String#toLowerCase
-  local.tee $78
+  local.tee $77
   i32.const 17120
   call $~lib/string/String.__eq
   i32.eqz
@@ -4168,7 +4165,7 @@
   end
   i32.const 17152
   call $~lib/string/String#toLowerCase
-  local.tee $79
+  local.tee $78
   i32.const 17184
   call $~lib/string/String.__eq
   i32.eqz
@@ -4182,7 +4179,7 @@
   end
   i32.const 17216
   call $~lib/string/String#toLowerCase
-  local.tee $80
+  local.tee $79
   i32.const 17248
   call $~lib/string/String.__eq
   i32.eqz
@@ -4196,7 +4193,7 @@
   end
   i32.const 17280
   call $~lib/string/String#toLowerCase
-  local.tee $81
+  local.tee $80
   i32.const 17312
   call $~lib/string/String.__eq
   i32.eqz
@@ -4210,7 +4207,7 @@
   end
   i32.const 17344
   call $~lib/string/String#toLowerCase
-  local.tee $82
+  local.tee $81
   i32.const 17376
   call $~lib/string/String.__eq
   i32.eqz
@@ -4224,7 +4221,7 @@
   end
   i32.const 17408
   call $~lib/string/String#toLowerCase
-  local.tee $83
+  local.tee $82
   i32.const 17440
   call $~lib/string/String.__eq
   i32.eqz
@@ -4238,7 +4235,7 @@
   end
   i32.const 17472
   call $~lib/string/String#toLowerCase
-  local.tee $84
+  local.tee $83
   i32.const 17504
   call $~lib/string/String.__eq
   i32.eqz
@@ -4252,7 +4249,7 @@
   end
   i32.const 17536
   call $~lib/string/String#toLowerCase
-  local.tee $85
+  local.tee $84
   i32.const 17568
   call $~lib/string/String.__eq
   i32.eqz
@@ -4266,7 +4263,7 @@
   end
   i32.const 17600
   call $~lib/string/String#toUpperCase
-  local.tee $86
+  local.tee $85
   i32.const 17632
   call $~lib/string/String.__eq
   i32.eqz
@@ -4280,7 +4277,7 @@
   end
   i32.const 14848
   call $~lib/string/String#toUpperCase
-  local.tee $87
+  local.tee $86
   i32.const 17664
   call $~lib/string/String.__eq
   i32.eqz
@@ -4294,7 +4291,7 @@
   end
   i32.const 17696
   call $~lib/string/String#toUpperCase
-  local.tee $88
+  local.tee $87
   i32.const 17728
   call $~lib/string/String.__eq
   i32.eqz
@@ -4308,7 +4305,7 @@
   end
   i32.const 17760
   call $~lib/string/String#toUpperCase
-  local.tee $89
+  local.tee $88
   i32.const 17792
   call $~lib/string/String.__eq
   i32.eqz
@@ -4322,7 +4319,7 @@
   end
   i32.const 17824
   call $~lib/string/String#toUpperCase
-  local.tee $90
+  local.tee $89
   i32.const 17856
   call $~lib/string/String.__eq
   i32.eqz
@@ -4336,7 +4333,7 @@
   end
   i32.const 17888
   call $~lib/string/String#toUpperCase
-  local.tee $91
+  local.tee $90
   i32.const 17920
   call $~lib/string/String.__eq
   i32.eqz
@@ -4350,7 +4347,7 @@
   end
   i32.const 17952
   call $~lib/string/String#toUpperCase
-  local.tee $92
+  local.tee $91
   i32.const 17920
   call $~lib/string/String.__eq
   i32.eqz
@@ -4364,7 +4361,7 @@
   end
   i32.const 17984
   call $~lib/string/String#toUpperCase
-  local.tee $93
+  local.tee $92
   i32.const 18016
   call $~lib/string/String.__eq
   i32.eqz
@@ -4378,7 +4375,7 @@
   end
   i32.const 18048
   call $~lib/string/String#toUpperCase
-  local.tee $94
+  local.tee $93
   i32.const 18080
   call $~lib/string/String.__eq
   i32.eqz
@@ -4392,7 +4389,7 @@
   end
   i32.const 18112
   call $~lib/string/String#toUpperCase
-  local.tee $95
+  local.tee $94
   i32.const 18144
   call $~lib/string/String.__eq
   i32.eqz
@@ -4406,7 +4403,7 @@
   end
   i32.const 18176
   call $~lib/string/String#toUpperCase
-  local.tee $96
+  local.tee $95
   i32.const 18208
   call $~lib/string/String.__eq
   i32.eqz
@@ -4420,7 +4417,7 @@
   end
   i32.const 18240
   call $~lib/string/String#toUpperCase
-  local.tee $97
+  local.tee $96
   i32.const 18272
   call $~lib/string/String.__eq
   i32.eqz
@@ -4434,7 +4431,7 @@
   end
   i32.const 18304
   call $~lib/string/String#toUpperCase
-  local.tee $98
+  local.tee $97
   i32.const 18336
   call $~lib/string/String.__eq
   i32.eqz
@@ -4447,165 +4444,101 @@
    unreachable
   end
   loop $for-loop|0
-   local.get $4
+   local.get $0
    i32.const 1114111
    i32.le_s
    if
-    local.get $4
+    local.get $0
     call $~lib/string/String.fromCodePoint
-    local.tee $12
+    local.tee $7
     call $~lib/string/String#toLowerCase
-    local.set $5
-    local.get $12
+    local.set $1
+    local.get $7
     call $~lib/string/String#toUpperCase
-    local.set $6
-    local.get $5
+    local.set $2
+    local.get $1
     i32.const 0
     call $~lib/string/String#codePointAt
     i64.extend_i32_s
-    local.set $3
-    local.get $5
+    local.get $1
     i32.const 1
     call $~lib/string/String#codePointAt
     i64.extend_i32_s
-    local.tee $0
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $3
-     local.get $0
-     i64.const 16
-     i64.shl
-     i64.add
-     local.set $3
-    end
-    local.get $5
+    i64.const 16
+    i64.shl
+    i64.add
+    local.get $1
     i32.const 2
     call $~lib/string/String#codePointAt
     i64.extend_i32_s
-    local.tee $0
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $3
-     local.get $0
-     i64.const 32
-     i64.shl
-     i64.add
-     local.set $3
-    end
-    local.get $6
+    i64.const 32
+    i64.shl
+    i64.add
+    local.set $8
+    local.get $2
     i32.const 0
     call $~lib/string/String#codePointAt
     i64.extend_i32_s
-    local.set $0
-    local.get $6
+    local.get $2
     i32.const 1
     call $~lib/string/String#codePointAt
     i64.extend_i32_s
-    local.tee $1
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $0
-     local.get $1
-     i64.const 16
-     i64.shl
-     i64.add
-     local.set $0
-    end
-    local.get $6
+    i64.const 16
+    i64.shl
+    i64.add
+    local.get $2
     i32.const 2
     call $~lib/string/String#codePointAt
     i64.extend_i32_s
-    local.tee $1
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $0
-     local.get $1
-     i64.const 32
-     i64.shl
-     i64.add
-     local.set $0
-    end
-    local.get $4
+    i64.const 32
+    i64.shl
+    i64.add
+    local.set $9
+    local.get $0
     i32.const 0
     call $std/string-casemapping/toLowerCaseFromIndex
     i64.extend_i32_s
-    local.set $1
-    local.get $4
+    local.get $0
     i32.const 1
     call $std/string-casemapping/toLowerCaseFromIndex
     i64.extend_i32_s
-    local.tee $2
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $1
-     local.get $2
-     i64.const 16
-     i64.shl
-     i64.add
-     local.set $1
-    end
-    local.get $4
+    i64.const 16
+    i64.shl
+    i64.add
+    local.get $0
     i32.const 2
     call $std/string-casemapping/toLowerCaseFromIndex
     i64.extend_i32_s
-    local.tee $2
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $1
-     local.get $2
-     i64.const 32
-     i64.shl
-     i64.add
-     local.set $1
-    end
-    local.get $4
+    i64.const 32
+    i64.shl
+    i64.add
+    local.set $10
+    local.get $0
     i32.const 0
     call $std/string-casemapping/toUpperCaseFromIndex
     i64.extend_i32_s
-    local.set $2
-    local.get $4
+    local.get $0
     i32.const 1
     call $std/string-casemapping/toUpperCaseFromIndex
     i64.extend_i32_s
-    local.tee $7
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $2
-     local.get $7
-     i64.const 16
-     i64.shl
-     i64.add
-     local.set $2
-    end
-    local.get $4
+    i64.const 16
+    i64.shl
+    i64.add
+    local.get $0
     i32.const 2
     call $std/string-casemapping/toUpperCaseFromIndex
     i64.extend_i32_s
-    local.tee $7
-    i64.const 0
-    i64.ge_u
-    if
-     local.get $2
-     local.get $7
-     i64.const 32
-     i64.shl
-     i64.add
-     local.set $2
-    end
-    local.get $1
-    local.get $3
+    i64.const 32
+    i64.shl
+    i64.add
+    local.set $11
+    local.get $8
+    local.get $10
     i64.ne
     if
      i32.const 18368
      i32.const 1
-     local.get $4
+     local.get $0
      f64.convert_i32_s
      f64.const 0
      f64.const 0
@@ -4613,11 +4546,11 @@
      f64.const 0
      call $~lib/builtins/trace
      i32.const 18464
-     local.get $3
+     local.get $8
      call $~lib/util/number/utoa64
-     local.tee $8
+     local.tee $3
      call $~lib/string/String.__concat
-     local.tee $9
+     local.tee $4
      i32.const 0
      f64.const 0
      f64.const 0
@@ -4626,11 +4559,11 @@
      f64.const 0
      call $~lib/builtins/trace
      i32.const 18880
-     local.get $1
+     local.get $10
      call $~lib/util/number/utoa64
-     local.tee $10
+     local.tee $5
      call $~lib/string/String.__concat
-     local.tee $11
+     local.tee $6
      i32.const 0
      f64.const 0
      f64.const 0
@@ -4638,22 +4571,22 @@
      f64.const 0
      f64.const 0
      call $~lib/builtins/trace
-     local.get $8
+     local.get $3
      call $~lib/rt/pure/__release
-     local.get $9
+     local.get $4
      call $~lib/rt/pure/__release
-     local.get $10
+     local.get $5
      call $~lib/rt/pure/__release
-     local.get $11
+     local.get $6
      call $~lib/rt/pure/__release
     end
-    local.get $0
-    local.get $2
+    local.get $9
+    local.get $11
     i64.ne
     if
      i32.const 18944
      i32.const 1
-     local.get $4
+     local.get $0
      f64.convert_i32_s
      f64.const 0
      f64.const 0
@@ -4661,11 +4594,11 @@
      f64.const 0
      call $~lib/builtins/trace
      i32.const 19040
-     local.get $0
+     local.get $9
      call $~lib/util/number/utoa64
-     local.tee $8
+     local.tee $3
      call $~lib/string/String.__concat
-     local.tee $9
+     local.tee $4
      i32.const 0
      f64.const 0
      f64.const 0
@@ -4674,11 +4607,11 @@
      f64.const 0
      call $~lib/builtins/trace
      i32.const 19104
-     local.get $2
+     local.get $11
      call $~lib/util/number/utoa64
-     local.tee $10
+     local.tee $5
      call $~lib/string/String.__concat
-     local.tee $11
+     local.tee $6
      i32.const 0
      f64.const 0
      f64.const 0
@@ -4686,28 +4619,30 @@
      f64.const 0
      f64.const 0
      call $~lib/builtins/trace
-     local.get $8
+     local.get $3
      call $~lib/rt/pure/__release
-     local.get $9
+     local.get $4
      call $~lib/rt/pure/__release
-     local.get $10
+     local.get $5
      call $~lib/rt/pure/__release
-     local.get $11
+     local.get $6
      call $~lib/rt/pure/__release
     end
-    local.get $12
+    local.get $7
     call $~lib/rt/pure/__release
-    local.get $5
+    local.get $1
     call $~lib/rt/pure/__release
-    local.get $6
+    local.get $2
     call $~lib/rt/pure/__release
-    local.get $4
+    local.get $0
     i32.const 1
     i32.add
-    local.set $4
+    local.set $0
     br $for-loop|0
    end
   end
+  local.get $12
+  call $~lib/rt/pure/__release
   local.get $13
   call $~lib/rt/pure/__release
   local.get $14
@@ -4878,8 +4813,6 @@
   call $~lib/rt/pure/__release
   local.get $97
   call $~lib/rt/pure/__release
-  local.get $98
-  call $~lib/rt/pure/__release
  )
  (func $~start
   call $start:std/string-casemapping
diff --git a/tests/compiler/std/string.optimized.wat b/tests/compiler/std/string.optimized.wat
index dbc2953dcc..681a102851 100644
--- a/tests/compiler/std/string.optimized.wat
+++ b/tests/compiler/std/string.optimized.wat
@@ -3659,10 +3659,9 @@
    i32.const 46
    i32.eq
    if
-    local.get $2
     local.get $0
-    i32.sub
-    i32.eqz
+    local.get $2
+    i32.eq
     local.set $2
     local.get $0
     i32.const 2