diff --git a/src/builtins.ts b/src/builtins.ts
index 67c2083a..227179bd 100644
--- a/src/builtins.ts
+++ b/src/builtins.ts
@@ -54,7 +54,6 @@ import {
 import {
   ElementKind,
   FunctionPrototype,
-  Class,
   Field,
   Global,
   DecoratorFlags
@@ -479,6 +478,7 @@ export namespace BuiltinSymbols {
 
   // std/runtime.ts
   export const runtime_id = "~lib/runtime/__runtime_id";
+  export const runtime_instanceof = "~lib/runtime/__runtime_instanceof";
   export const runtime_allocate = "~lib/runtime/runtime.allocate";
   export const runtime_reallocate = "~lib/runtime/runtime.reallocate";
   export const runtime_register = "~lib/runtime/runtime.register";
@@ -3652,6 +3652,20 @@ export function compileCall(
       }
       return module.createI32(classReference.ensureId());
     }
+    case BuiltinSymbols.runtime_instanceof: {
+      if (
+        checkTypeAbsent(typeArguments, reportNode, prototype) |
+        checkArgsRequired(operands, 2, reportNode, compiler)
+      ) {
+        compiler.currentType = Type.void;
+        return module.createUnreachable();
+      }
+      let arg0 = compiler.compileExpression(operands[0], Type.u32, ConversionKind.IMPLICIT, WrapMode.NONE);
+      let arg1 = compiler.compileExpression(operands[1], Type.u32, ConversionKind.IMPLICIT, WrapMode.NONE);
+      compiler.needsInstanceOf = true;
+      compiler.currentType = Type.bool;
+      return module.createCall(BuiltinSymbols.runtime_instanceof, [ arg0, arg1 ], NativeType.I32);
+    }
     case BuiltinSymbols.gc_mark_roots: {
       if (
         checkTypeAbsent(typeArguments, reportNode, prototype) |
@@ -3660,7 +3674,7 @@ export function compileCall(
         compiler.currentType = Type.void;
         return module.createUnreachable();
       }
-      compiler.needsTraverse = true;
+      compiler.needsMark = true;
       compiler.currentType = Type.void;
       return module.createCall(BuiltinSymbols.gc_mark_roots, null, NativeType.None);
     }
@@ -3674,7 +3688,7 @@ export function compileCall(
       }
       let arg0 = compiler.compileExpression(operands[0], Type.u32, ConversionKind.IMPLICIT, WrapMode.NONE);
       let arg1 = compiler.compileExpression(operands[1], compiler.options.usizeType, ConversionKind.IMPLICIT, WrapMode.NONE);
-      compiler.needsTraverse = true;
+      compiler.needsMark = true;
       compiler.currentType = Type.void;
       return module.createCall(BuiltinSymbols.gc_mark_members, [ arg0, arg1 ], NativeType.None);
     }
@@ -4061,7 +4075,7 @@ export function compileAbort(
   ]);
 }
 
-/** Compiles the mark_roots function if required. */
+/** Compiles the `__gc_mark_roots` function. */
 export function compileMarkRoots(compiler: Compiler): void {
   var module = compiler.module;
   var exprs = new Array<ExpressionRef>();
@@ -4113,6 +4127,7 @@ export function compileMarkRoots(compiler: Compiler): void {
   );
 }
 
+/** Compiles the `__gc_mark_members` function. */
 export function compileMarkMembers(compiler: Compiler): void {
   var program = compiler.program;
   var module = compiler.module;
@@ -4221,6 +4236,81 @@ export function compileMarkMembers(compiler: Compiler): void {
   module.addFunction(BuiltinSymbols.gc_mark_members, ftype, [ nativeSizeType ], current);
 }
 
+/** Compiles the `__runtime_instanceof` function. */
+export function compileInstanceOf(compiler: Compiler): void {
+  var program = compiler.program;
+  var module = compiler.module;
+  var managedClasses = program.managedClasses;
+  var ftype = compiler.ensureFunctionType([ Type.i32, Type.i32 ], Type.i32); // $0 instanceof $1 -> bool
+
+  // NOTE: There are multiple ways to model this. The one chosen here is to compute
+  // all possibilities in a branchless expression, growing linearly with the number
+  // of chained base classes.
+  //
+  // switch ($0) {
+  //   case ANIMAL_ID: {
+  //     return ($1 == ANIMAL_ID);
+  //   }
+  //   case CAT_ID: {
+  //     return ($1 == CAT_ID) | ($1 == ANIMAL_ID);
+  //   }
+  //   case BLACKCAT_ID: {
+  //     return ($1 == BLACKCAT_ID) | ($1 == CAT_ID) | ($1 == ANIMAL_ID);
+  //   }
+  // }
+  // return false;
+  //
+  // Another one would be an inner br_table, but class id distribution in larger
+  // programs in unclear, possibly leading to lots of holes in that table that
+  // could either degenerate into multiple ifs when compiling for size or to
+  // huge tables when compiling for speed.
+  //
+  // Maybe a combination of both could be utilized, like statically analyzing the
+  // ids and make a decision based on profiling experience?
+
+  var names: string[] = [ "nope" ];
+  var blocks = new Array<ExpressionRef[]>();
+  for (let [id, instance] of managedClasses) {
+    names.push(instance.internalName);
+    let condition = module.createBinary(BinaryOp.EqI32,
+      module.createGetLocal(1, NativeType.I32),
+      module.createI32(id)
+    );
+    let base = instance.base;
+    while (base) {
+      condition = module.createBinary(BinaryOp.OrI32,
+        condition,
+        module.createBinary(BinaryOp.EqI32,
+          module.createGetLocal(1, NativeType.I32),
+          module.createI32(base.ensureId())
+        )
+      );
+      base = base.base;
+    }
+    blocks.push([
+      module.createReturn(condition)
+    ]);
+  }
+
+  var current: ExpressionRef;
+  if (blocks.length) {
+    current = module.createBlock(names[1], [
+      module.createSwitch(names, "nope", module.createGetLocal(0, NativeType.I32))
+    ]);
+    for (let i = 0, k = blocks.length; i < k; ++i) {
+      blocks[i].unshift(current);
+      current = module.createBlock(i == k - 1 ? "nope" : names[i + 2], blocks[i]);
+    }
+    current = module.createBlock(null, [
+      current,
+      module.createReturn(module.createI32(0))
+    ]);
+  } else {
+    current = module.createReturn(module.createI32(0));
+  }
+  module.addFunction(BuiltinSymbols.runtime_instanceof, ftype, null, current);
+}
+
 // Helpers
 
 /** Evaluates the constant type of a type argument *or* expression. */
diff --git a/src/compiler.ts b/src/compiler.ts
index 0355aa67..154b7006 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -8,6 +8,7 @@ import {
   compileAbort,
   compileMarkRoots,
   compileMarkMembers,
+  compileInstanceOf,
   BuiltinSymbols
 } from "./builtins";
 
@@ -310,8 +311,10 @@ export class Compiler extends DiagnosticEmitter {
   argcVar: GlobalRef = 0;
   /** Argument count helper setter. */
   argcSet: FunctionRef = 0;
-  /** Indicates whether the traverseRoots function must be generated. */
-  needsTraverse: bool = false;
+  /** Indicates whether the __gc_mark_* functions must be generated. */
+  needsMark: bool = false;
+  /** Indicates whether the __runtime_instanceof function must be generated. */
+  needsInstanceOf: bool = false;
 
   /** Compiles a {@link Program} to a {@link Module} using the specified options. */
   static compile(program: Program, options: Options | null = null): Module {
@@ -393,12 +396,17 @@ export class Compiler extends DiagnosticEmitter {
       if (!explicitStartFunction) module.setStart(funcRef);
     }
 
-    // compile gc integration if necessary
-    if (this.needsTraverse) {
+    // compile gc features if utilized
+    if (this.needsMark) {
       compileMarkRoots(this);
       compileMarkMembers(this);
     }
 
+    // compile runtime features if utilized
+    if (this.needsInstanceOf) {
+      compileInstanceOf(this);
+    }
+
     // update the heap base pointer
     var memoryOffset = this.memoryOffset;
     memoryOffset = i64_align(memoryOffset, options.usizeType.byteSize);
diff --git a/src/flow.ts b/src/flow.ts
index 56839b08..7bbe99a1 100644
--- a/src/flow.ts
+++ b/src/flow.ts
@@ -812,11 +812,16 @@ export class Flow {
       // overflows if the call does not return a wrapped value or the conversion does
       case ExpressionId.Call: {
         let program = this.parentFunction.program;
-        let instance = assert(program.instancesByName.get(assert(getCallTarget(expr))));
-        assert(instance.kind == ElementKind.FUNCTION);
-        let returnType = (<Function>instance).signature.returnType;
-        return !(<Function>instance).flow.is(FlowFlags.RETURNS_WRAPPED)
-            || canConversionOverflow(returnType, type);
+        let instancesByName = program.instancesByName;
+        let instanceName = assert(getCallTarget(expr));
+        if (instancesByName.has(instanceName)) {
+          let instance = instancesByName.get(instanceName)!;
+          assert(instance.kind == ElementKind.FUNCTION);
+          let returnType = (<Function>instance).signature.returnType;
+          return !(<Function>instance).flow.is(FlowFlags.RETURNS_WRAPPED)
+              || canConversionOverflow(returnType, type);
+        }
+        return false; // assume no overflow for builtins
       }
 
       // doesn't technically overflow
diff --git a/std/assembly/runtime.ts b/std/assembly/runtime.ts
index 1e0fcd04..bbdbf54f 100644
--- a/std/assembly/runtime.ts
+++ b/std/assembly/runtime.ts
@@ -10,6 +10,11 @@ import { ArrayBufferView } from "./arraybuffer";
 @unsafe @builtin
 export declare function __runtime_id<T>(): u32;
 
+/** Tests if a managed class is the same as or a superclass of another. */
+// @ts-ignore: decorator
+@unsafe @builtin
+export declare function __runtime_instanceof(id: u32, superId: u32): bool;
+
 /** Runtime implementation. */
 export namespace runtime {
 
diff --git a/tests/compiler/call-super.optimized.wat b/tests/compiler/call-super.optimized.wat
index b6d70658..0b64d237 100644
--- a/tests/compiler/call-super.optimized.wat
+++ b/tests/compiler/call-super.optimized.wat
@@ -106,7 +106,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -121,7 +121,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/call-super.untouched.wat b/tests/compiler/call-super.untouched.wat
index b047896f..3c731b05 100644
--- a/tests/compiler/call-super.untouched.wat
+++ b/tests/compiler/call-super.untouched.wat
@@ -139,7 +139,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -156,7 +156,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/constructor.optimized.wat b/tests/compiler/constructor.optimized.wat
index a7e48281..c2fc78b3 100644
--- a/tests/compiler/constructor.optimized.wat
+++ b/tests/compiler/constructor.optimized.wat
@@ -1283,7 +1283,7 @@
   if
    i32.const 0
    i32.const 88
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -1298,7 +1298,7 @@
   if
    i32.const 0
    i32.const 88
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/constructor.untouched.wat b/tests/compiler/constructor.untouched.wat
index e3ffc963..625eee92 100644
--- a/tests/compiler/constructor.untouched.wat
+++ b/tests/compiler/constructor.untouched.wat
@@ -1563,7 +1563,7 @@
   if
    i32.const 0
    i32.const 88
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -1580,7 +1580,7 @@
   if
    i32.const 0
    i32.const 88
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/exports.optimized.wat b/tests/compiler/exports.optimized.wat
index 05a44692..a1374ad9 100644
--- a/tests/compiler/exports.optimized.wat
+++ b/tests/compiler/exports.optimized.wat
@@ -146,7 +146,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -161,7 +161,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/exports.untouched.wat b/tests/compiler/exports.untouched.wat
index 0796ee96..46ea1b49 100644
--- a/tests/compiler/exports.untouched.wat
+++ b/tests/compiler/exports.untouched.wat
@@ -192,7 +192,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -209,7 +209,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc.optimized.wat b/tests/compiler/gc.optimized.wat
index 97439e5f..14d0a109 100644
--- a/tests/compiler/gc.optimized.wat
+++ b/tests/compiler/gc.optimized.wat
@@ -184,7 +184,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -199,7 +199,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2250,7 +2250,7 @@
      if
       i32.const 0
       i32.const 24
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -2285,7 +2285,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2299,7 +2299,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc.untouched.wat b/tests/compiler/gc.untouched.wat
index 2a592269..80ab5637 100644
--- a/tests/compiler/gc.untouched.wat
+++ b/tests/compiler/gc.untouched.wat
@@ -203,7 +203,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -220,7 +220,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2841,7 +2841,7 @@
      if
       i32.const 0
       i32.const 24
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -2883,7 +2883,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2900,7 +2900,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/global-assign.optimized.wat b/tests/compiler/gc/global-assign.optimized.wat
index c0e9fb76..27618b5a 100644
--- a/tests/compiler/gc/global-assign.optimized.wat
+++ b/tests/compiler/gc/global-assign.optimized.wat
@@ -137,7 +137,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -152,7 +152,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/global-assign.untouched.wat b/tests/compiler/gc/global-assign.untouched.wat
index aaf0be00..6c22ff95 100644
--- a/tests/compiler/gc/global-assign.untouched.wat
+++ b/tests/compiler/gc/global-assign.untouched.wat
@@ -182,7 +182,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -199,7 +199,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/global-init.optimized.wat b/tests/compiler/gc/global-init.optimized.wat
index 2f8eccff..e030d7d8 100644
--- a/tests/compiler/gc/global-init.optimized.wat
+++ b/tests/compiler/gc/global-init.optimized.wat
@@ -136,7 +136,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -151,7 +151,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/global-init.untouched.wat b/tests/compiler/gc/global-init.untouched.wat
index 6530db3e..d48ee91e 100644
--- a/tests/compiler/gc/global-init.untouched.wat
+++ b/tests/compiler/gc/global-init.untouched.wat
@@ -181,7 +181,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -198,7 +198,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/itcm/trace.optimized.wat b/tests/compiler/gc/itcm/trace.optimized.wat
index 3e6056ac..872384f2 100644
--- a/tests/compiler/gc/itcm/trace.optimized.wat
+++ b/tests/compiler/gc/itcm/trace.optimized.wat
@@ -341,7 +341,7 @@
   if
    i32.const 0
    i32.const 128
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -356,7 +356,7 @@
   if
    i32.const 0
    i32.const 128
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -1859,7 +1859,7 @@
      if
       i32.const 0
       i32.const 128
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
diff --git a/tests/compiler/gc/itcm/trace.untouched.wat b/tests/compiler/gc/itcm/trace.untouched.wat
index abd37127..5bf72e9b 100644
--- a/tests/compiler/gc/itcm/trace.untouched.wat
+++ b/tests/compiler/gc/itcm/trace.untouched.wat
@@ -390,7 +390,7 @@
   if
    i32.const 0
    i32.const 128
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -407,7 +407,7 @@
   if
    i32.const 0
    i32.const 128
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2466,7 +2466,7 @@
      if
       i32.const 0
       i32.const 128
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
diff --git a/tests/compiler/gc/rc/global-assign.optimized.wat b/tests/compiler/gc/rc/global-assign.optimized.wat
index 83f49926..2a87c612 100644
--- a/tests/compiler/gc/rc/global-assign.optimized.wat
+++ b/tests/compiler/gc/rc/global-assign.optimized.wat
@@ -143,7 +143,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -158,7 +158,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/rc/global-assign.untouched.wat b/tests/compiler/gc/rc/global-assign.untouched.wat
index 7648165a..f704186e 100644
--- a/tests/compiler/gc/rc/global-assign.untouched.wat
+++ b/tests/compiler/gc/rc/global-assign.untouched.wat
@@ -180,7 +180,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -197,7 +197,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/rc/global-init.optimized.wat b/tests/compiler/gc/rc/global-init.optimized.wat
index c73a497d..48415596 100644
--- a/tests/compiler/gc/rc/global-init.optimized.wat
+++ b/tests/compiler/gc/rc/global-init.optimized.wat
@@ -139,7 +139,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -154,7 +154,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/gc/rc/global-init.untouched.wat b/tests/compiler/gc/rc/global-init.untouched.wat
index a94853ad..9bf25602 100644
--- a/tests/compiler/gc/rc/global-init.untouched.wat
+++ b/tests/compiler/gc/rc/global-init.untouched.wat
@@ -178,7 +178,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -195,7 +195,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/getter-call.optimized.wat b/tests/compiler/getter-call.optimized.wat
index 20c0d5b4..891e19ed 100644
--- a/tests/compiler/getter-call.optimized.wat
+++ b/tests/compiler/getter-call.optimized.wat
@@ -85,7 +85,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -100,7 +100,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/getter-call.untouched.wat b/tests/compiler/getter-call.untouched.wat
index 06c38856..f0b0fc02 100644
--- a/tests/compiler/getter-call.untouched.wat
+++ b/tests/compiler/getter-call.untouched.wat
@@ -141,7 +141,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -158,7 +158,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/inlining.optimized.wat b/tests/compiler/inlining.optimized.wat
index 8c080e3f..b67dcff3 100644
--- a/tests/compiler/inlining.optimized.wat
+++ b/tests/compiler/inlining.optimized.wat
@@ -131,7 +131,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -146,7 +146,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/inlining.untouched.wat b/tests/compiler/inlining.untouched.wat
index b057ac92..40a2ec4e 100644
--- a/tests/compiler/inlining.untouched.wat
+++ b/tests/compiler/inlining.untouched.wat
@@ -405,7 +405,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -422,7 +422,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/number.optimized.wat b/tests/compiler/number.optimized.wat
index 2bae3b10..23bf9184 100644
--- a/tests/compiler/number.optimized.wat
+++ b/tests/compiler/number.optimized.wat
@@ -303,7 +303,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -318,7 +318,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2451,7 +2451,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2465,7 +2465,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/number.untouched.wat b/tests/compiler/number.untouched.wat
index 07505064..792bee7b 100644
--- a/tests/compiler/number.untouched.wat
+++ b/tests/compiler/number.untouched.wat
@@ -399,7 +399,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -416,7 +416,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3534,7 +3534,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3551,7 +3551,7 @@
   if
    i32.const 0
    i32.const 464
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/optional-typeparameters.optimized.wat b/tests/compiler/optional-typeparameters.optimized.wat
index 64c6484a..80fb2f3c 100644
--- a/tests/compiler/optional-typeparameters.optimized.wat
+++ b/tests/compiler/optional-typeparameters.optimized.wat
@@ -100,7 +100,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -115,7 +115,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/optional-typeparameters.untouched.wat b/tests/compiler/optional-typeparameters.untouched.wat
index 95ba0e84..ea2f4ea8 100644
--- a/tests/compiler/optional-typeparameters.untouched.wat
+++ b/tests/compiler/optional-typeparameters.untouched.wat
@@ -148,7 +148,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -165,7 +165,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/runtime/instanceof.json b/tests/compiler/runtime/instanceof.json
new file mode 100644
index 00000000..85b9ce0f
--- /dev/null
+++ b/tests/compiler/runtime/instanceof.json
@@ -0,0 +1,5 @@
+{
+  "asc_flags": [
+    "--runtime arena"
+  ]
+}
\ No newline at end of file
diff --git a/tests/compiler/runtime/instanceof.optimized.wat b/tests/compiler/runtime/instanceof.optimized.wat
new file mode 100644
index 00000000..c3ece108
--- /dev/null
+++ b/tests/compiler/runtime/instanceof.optimized.wat
@@ -0,0 +1,159 @@
+(module
+ (type $FUNCSIG$viiii (func (param i32 i32 i32 i32)))
+ (type $FUNCSIG$v (func))
+ (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
+ (import "env" "abort" (func $~lib/env/abort (param i32 i32 i32 i32)))
+ (memory $0 1)
+ (data (i32.const 8) "\02\00\00\00*\00\00\00r\00u\00n\00t\00i\00m\00e\00/\00i\00n\00s\00t\00a\00n\00c\00e\00o\00f\00.\00t\00s")
+ (table $0 1 funcref)
+ (elem (i32.const 0) $null)
+ (export "memory" (memory $0))
+ (export "table" (table $0))
+ (start $start)
+ (func $start:runtime/instanceof (; 1 ;) (type $FUNCSIG$v)
+  i32.const 1
+  i32.const 1
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 7
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 3
+  i32.const 1
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 14
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 4
+  i32.const 1
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 21
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 3
+  i32.const 3
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 28
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 4
+  i32.const 3
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 35
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 1
+  i32.const 3
+  call $~lib/runtime/__runtime_instanceof
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 42
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 1
+  i32.const 4
+  call $~lib/runtime/__runtime_instanceof
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 49
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 3
+  i32.const 4
+  call $~lib/runtime/__runtime_instanceof
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 56
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+ )
+ (func $start (; 2 ;) (type $FUNCSIG$v)
+  call $start:runtime/instanceof
+ )
+ (func $~lib/runtime/__runtime_instanceof (; 3 ;) (type $FUNCSIG$iii) (param $0 i32) (param $1 i32) (result i32)
+  block $nope
+   block $runtime/instanceof/BlackCat
+    block $runtime/instanceof/Cat
+     block $~lib/string/String
+      block $runtime/instanceof/Animal
+       local.get $0
+       i32.const 1
+       i32.sub
+       br_table $runtime/instanceof/Animal $~lib/string/String $runtime/instanceof/Cat $runtime/instanceof/BlackCat $nope
+      end
+      local.get $1
+      i32.const 1
+      i32.eq
+      return
+     end
+     local.get $1
+     i32.const 2
+     i32.eq
+     return
+    end
+    local.get $1
+    i32.const 3
+    i32.eq
+    local.get $1
+    i32.const 1
+    i32.eq
+    i32.or
+    return
+   end
+   local.get $1
+   i32.const 4
+   i32.eq
+   local.get $1
+   i32.const 3
+   i32.eq
+   i32.or
+   local.get $1
+   i32.const 1
+   i32.eq
+   i32.or
+   return
+  end
+  i32.const 0
+ )
+ (func $null (; 4 ;) (type $FUNCSIG$v)
+  nop
+ )
+)
diff --git a/tests/compiler/runtime/instanceof.ts b/tests/compiler/runtime/instanceof.ts
new file mode 100644
index 00000000..542d60a2
--- /dev/null
+++ b/tests/compiler/runtime/instanceof.ts
@@ -0,0 +1,61 @@
+import { __runtime_id, __runtime_instanceof } from "runtime";
+
+class Animal {}
+class Cat extends Animal {}
+class BlackCat extends Cat {}
+
+assert( // Animal is an Animal
+  __runtime_instanceof(
+    __runtime_id<Animal>(),
+    __runtime_id<Animal>()
+  )
+);
+
+assert( // Cat is an Animal
+  __runtime_instanceof(
+    __runtime_id<Cat>(),
+    __runtime_id<Animal>()
+  )
+);
+
+assert( // BlackCat is an Animal
+  __runtime_instanceof(
+    __runtime_id<BlackCat>(),
+    __runtime_id<Animal>()
+  )
+);
+
+assert( // Cat is a Cat
+  __runtime_instanceof(
+    __runtime_id<Cat>(),
+    __runtime_id<Cat>()
+  )
+);
+
+assert( // BlackCat is a Cat
+  __runtime_instanceof(
+    __runtime_id<BlackCat>(),
+    __runtime_id<Cat>()
+  )
+);
+
+assert(! // Animal isn't necessarily a Cat
+  __runtime_instanceof(
+    __runtime_id<Animal>(),
+    __runtime_id<Cat>()
+  )
+);
+
+assert(! // Animal isn't necessarily a BlackCat
+  __runtime_instanceof(
+    __runtime_id<Animal>(),
+    __runtime_id<BlackCat>()
+  )
+);
+
+assert(! // Cat isn't necessarily a BlackCat
+  __runtime_instanceof(
+    __runtime_id<Cat>(),
+    __runtime_id<BlackCat>()
+  )
+);
diff --git a/tests/compiler/runtime/instanceof.untouched.wat b/tests/compiler/runtime/instanceof.untouched.wat
new file mode 100644
index 00000000..38cf3701
--- /dev/null
+++ b/tests/compiler/runtime/instanceof.untouched.wat
@@ -0,0 +1,164 @@
+(module
+ (type $FUNCSIG$viiii (func (param i32 i32 i32 i32)))
+ (type $FUNCSIG$v (func))
+ (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
+ (import "env" "abort" (func $~lib/env/abort (param i32 i32 i32 i32)))
+ (memory $0 1)
+ (data (i32.const 8) "\02\00\00\00*\00\00\00r\00u\00n\00t\00i\00m\00e\00/\00i\00n\00s\00t\00a\00n\00c\00e\00o\00f\00.\00t\00s\00")
+ (table $0 1 funcref)
+ (elem (i32.const 0) $null)
+ (global $~lib/memory/HEAP_BASE i32 (i32.const 60))
+ (export "memory" (memory $0))
+ (export "table" (table $0))
+ (start $start)
+ (func $start:runtime/instanceof (; 1 ;) (type $FUNCSIG$v)
+  i32.const 1
+  i32.const 1
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 7
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 3
+  i32.const 1
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 14
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 4
+  i32.const 1
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 21
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 3
+  i32.const 3
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 28
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 4
+  i32.const 3
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 35
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 1
+  i32.const 3
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 42
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 1
+  i32.const 4
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 49
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+  i32.const 3
+  i32.const 4
+  call $~lib/runtime/__runtime_instanceof
+  i32.eqz
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 16
+   i32.const 56
+   i32.const 0
+   call $~lib/env/abort
+   unreachable
+  end
+ )
+ (func $start (; 2 ;) (type $FUNCSIG$v)
+  call $start:runtime/instanceof
+ )
+ (func $~lib/runtime/__runtime_instanceof (; 3 ;) (type $FUNCSIG$iii) (param $0 i32) (param $1 i32) (result i32)
+  block $nope
+   block $runtime/instanceof/BlackCat
+    block $runtime/instanceof/Cat
+     block $~lib/string/String
+      block $runtime/instanceof/Animal
+       local.get $0
+       br_table $nope $runtime/instanceof/Animal $~lib/string/String $runtime/instanceof/Cat $runtime/instanceof/BlackCat $nope
+      end
+      local.get $1
+      i32.const 1
+      i32.eq
+      return
+     end
+     local.get $1
+     i32.const 2
+     i32.eq
+     return
+    end
+    local.get $1
+    i32.const 3
+    i32.eq
+    local.get $1
+    i32.const 1
+    i32.eq
+    i32.or
+    return
+   end
+   local.get $1
+   i32.const 4
+   i32.eq
+   local.get $1
+   i32.const 3
+   i32.eq
+   i32.or
+   local.get $1
+   i32.const 1
+   i32.eq
+   i32.or
+   return
+  end
+  i32.const 0
+  return
+ )
+ (func $null (; 4 ;) (type $FUNCSIG$v)
+ )
+)
diff --git a/tests/compiler/std/array-literal.optimized.wat b/tests/compiler/std/array-literal.optimized.wat
index 2bf5784f..a646be8b 100644
--- a/tests/compiler/std/array-literal.optimized.wat
+++ b/tests/compiler/std/array-literal.optimized.wat
@@ -177,7 +177,7 @@
   if
    i32.const 0
    i32.const 296
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -192,7 +192,7 @@
   if
    i32.const 0
    i32.const 296
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/array-literal.untouched.wat b/tests/compiler/std/array-literal.untouched.wat
index 16899f67..414c8d2a 100644
--- a/tests/compiler/std/array-literal.untouched.wat
+++ b/tests/compiler/std/array-literal.untouched.wat
@@ -233,7 +233,7 @@
   if
    i32.const 0
    i32.const 296
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -250,7 +250,7 @@
   if
    i32.const 0
    i32.const 296
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/array.optimized.wat b/tests/compiler/std/array.optimized.wat
index 46fc3e65..f8cc1348 100644
--- a/tests/compiler/std/array.optimized.wat
+++ b/tests/compiler/std/array.optimized.wat
@@ -787,7 +787,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -802,7 +802,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2340,7 +2340,7 @@
      if
       i32.const 0
       i32.const 80
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -6323,7 +6323,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -6337,7 +6337,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/array.untouched.wat b/tests/compiler/std/array.untouched.wat
index 0648266e..c2a9e471 100644
--- a/tests/compiler/std/array.untouched.wat
+++ b/tests/compiler/std/array.untouched.wat
@@ -684,7 +684,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -701,7 +701,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2859,7 +2859,7 @@
      if
       i32.const 0
       i32.const 80
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -9604,7 +9604,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -9621,7 +9621,7 @@
   if
    i32.const 0
    i32.const 80
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/arraybuffer.optimized.wat b/tests/compiler/std/arraybuffer.optimized.wat
index 68b2419e..8d392aaa 100644
--- a/tests/compiler/std/arraybuffer.optimized.wat
+++ b/tests/compiler/std/arraybuffer.optimized.wat
@@ -327,7 +327,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -342,7 +342,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/arraybuffer.untouched.wat b/tests/compiler/std/arraybuffer.untouched.wat
index 3b3718db..63a50c33 100644
--- a/tests/compiler/std/arraybuffer.untouched.wat
+++ b/tests/compiler/std/arraybuffer.untouched.wat
@@ -407,7 +407,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -424,7 +424,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/dataview.optimized.wat b/tests/compiler/std/dataview.optimized.wat
index 86170443..a194761b 100644
--- a/tests/compiler/std/dataview.optimized.wat
+++ b/tests/compiler/std/dataview.optimized.wat
@@ -165,7 +165,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -180,7 +180,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/dataview.untouched.wat b/tests/compiler/std/dataview.untouched.wat
index 6fc5c830..ad420ca8 100644
--- a/tests/compiler/std/dataview.untouched.wat
+++ b/tests/compiler/std/dataview.untouched.wat
@@ -413,7 +413,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -430,7 +430,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/date.optimized.wat b/tests/compiler/std/date.optimized.wat
index 120ffe2d..6c655d30 100644
--- a/tests/compiler/std/date.optimized.wat
+++ b/tests/compiler/std/date.optimized.wat
@@ -89,7 +89,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -104,7 +104,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/date.untouched.wat b/tests/compiler/std/date.untouched.wat
index 48cd0512..67b2f1f7 100644
--- a/tests/compiler/std/date.untouched.wat
+++ b/tests/compiler/std/date.untouched.wat
@@ -148,7 +148,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -165,7 +165,7 @@
   if
    i32.const 0
    i32.const 48
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/map.optimized.wat b/tests/compiler/std/map.optimized.wat
index c3e7a6fb..04d1628d 100644
--- a/tests/compiler/std/map.optimized.wat
+++ b/tests/compiler/std/map.optimized.wat
@@ -135,7 +135,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -150,7 +150,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/map.untouched.wat b/tests/compiler/std/map.untouched.wat
index c6641440..bfb23208 100644
--- a/tests/compiler/std/map.untouched.wat
+++ b/tests/compiler/std/map.untouched.wat
@@ -166,7 +166,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -183,7 +183,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/new.optimized.wat b/tests/compiler/std/new.optimized.wat
index e04f158d..65a4c2f1 100644
--- a/tests/compiler/std/new.optimized.wat
+++ b/tests/compiler/std/new.optimized.wat
@@ -84,7 +84,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -99,7 +99,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/new.untouched.wat b/tests/compiler/std/new.untouched.wat
index 9b9714d5..3f797389 100644
--- a/tests/compiler/std/new.untouched.wat
+++ b/tests/compiler/std/new.untouched.wat
@@ -141,7 +141,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -158,7 +158,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/object-literal.optimized.wat b/tests/compiler/std/object-literal.optimized.wat
index 7fdc3211..0a163f0d 100644
--- a/tests/compiler/std/object-literal.optimized.wat
+++ b/tests/compiler/std/object-literal.optimized.wat
@@ -118,7 +118,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -133,7 +133,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/object-literal.untouched.wat b/tests/compiler/std/object-literal.untouched.wat
index e0609359..c1224708 100644
--- a/tests/compiler/std/object-literal.untouched.wat
+++ b/tests/compiler/std/object-literal.untouched.wat
@@ -153,7 +153,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -170,7 +170,7 @@
   if
    i32.const 0
    i32.const 64
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/operator-overloading.optimized.wat b/tests/compiler/std/operator-overloading.optimized.wat
index f8110834..a23ab054 100644
--- a/tests/compiler/std/operator-overloading.optimized.wat
+++ b/tests/compiler/std/operator-overloading.optimized.wat
@@ -167,7 +167,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -182,7 +182,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/operator-overloading.untouched.wat b/tests/compiler/std/operator-overloading.untouched.wat
index 4bd6db47..58f6db40 100644
--- a/tests/compiler/std/operator-overloading.untouched.wat
+++ b/tests/compiler/std/operator-overloading.untouched.wat
@@ -209,7 +209,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -226,7 +226,7 @@
   if
    i32.const 0
    i32.const 16
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/runtime.optimized.wat b/tests/compiler/std/runtime.optimized.wat
index 7b3867b2..7f225581 100644
--- a/tests/compiler/std/runtime.optimized.wat
+++ b/tests/compiler/std/runtime.optimized.wat
@@ -2560,7 +2560,7 @@
      if
       i32.const 0
       i32.const 232
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -2597,7 +2597,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2612,7 +2612,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2628,7 +2628,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -2643,7 +2643,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/runtime.untouched.wat b/tests/compiler/std/runtime.untouched.wat
index d90c40d0..0bbaf534 100644
--- a/tests/compiler/std/runtime.untouched.wat
+++ b/tests/compiler/std/runtime.untouched.wat
@@ -3288,7 +3288,7 @@
      if
       i32.const 0
       i32.const 232
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -3330,7 +3330,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3347,7 +3347,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3364,7 +3364,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3381,7 +3381,7 @@
   if
    i32.const 0
    i32.const 232
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/set.optimized.wat b/tests/compiler/std/set.optimized.wat
index 6dde9b44..64fbf743 100644
--- a/tests/compiler/std/set.optimized.wat
+++ b/tests/compiler/std/set.optimized.wat
@@ -131,7 +131,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -146,7 +146,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/set.untouched.wat b/tests/compiler/std/set.untouched.wat
index fc2d6458..7eba4061 100644
--- a/tests/compiler/std/set.untouched.wat
+++ b/tests/compiler/std/set.untouched.wat
@@ -166,7 +166,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -183,7 +183,7 @@
   if
    i32.const 0
    i32.const 24
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/static-array.optimized.wat b/tests/compiler/std/static-array.optimized.wat
index d9c5b8ac..39a7e425 100644
--- a/tests/compiler/std/static-array.optimized.wat
+++ b/tests/compiler/std/static-array.optimized.wat
@@ -1437,7 +1437,7 @@
      if
       i32.const 0
       i32.const 280
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
diff --git a/tests/compiler/std/static-array.untouched.wat b/tests/compiler/std/static-array.untouched.wat
index caa7baaa..6714c00c 100644
--- a/tests/compiler/std/static-array.untouched.wat
+++ b/tests/compiler/std/static-array.untouched.wat
@@ -1928,7 +1928,7 @@
      if
       i32.const 0
       i32.const 280
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
diff --git a/tests/compiler/std/string-utf8.optimized.wat b/tests/compiler/std/string-utf8.optimized.wat
index a09df18d..bddf32e4 100644
--- a/tests/compiler/std/string-utf8.optimized.wat
+++ b/tests/compiler/std/string-utf8.optimized.wat
@@ -1464,7 +1464,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -1479,7 +1479,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/string-utf8.untouched.wat b/tests/compiler/std/string-utf8.untouched.wat
index 0797cdd4..6e4071eb 100644
--- a/tests/compiler/std/string-utf8.untouched.wat
+++ b/tests/compiler/std/string-utf8.untouched.wat
@@ -1929,7 +1929,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -1946,7 +1946,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/string.optimized.wat b/tests/compiler/std/string.optimized.wat
index ba3a97a1..6700b06b 100644
--- a/tests/compiler/std/string.optimized.wat
+++ b/tests/compiler/std/string.optimized.wat
@@ -444,7 +444,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -459,7 +459,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3235,7 +3235,7 @@
      if
       i32.const 0
       i32.const 184
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -5177,7 +5177,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -5191,7 +5191,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/string.untouched.wat b/tests/compiler/std/string.untouched.wat
index 32cca640..3a1416c1 100644
--- a/tests/compiler/std/string.untouched.wat
+++ b/tests/compiler/std/string.untouched.wat
@@ -379,7 +379,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -396,7 +396,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -3850,7 +3850,7 @@
      if
       i32.const 0
       i32.const 184
-      i32.const 64
+      i32.const 69
       i32.const 10
       call $~lib/env/abort
       unreachable
@@ -6549,7 +6549,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 89
+   i32.const 94
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -6566,7 +6566,7 @@
   if
    i32.const 0
    i32.const 184
-   i32.const 91
+   i32.const 96
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/symbol.optimized.wat b/tests/compiler/std/symbol.optimized.wat
index 980cd5df..b9654c31 100644
--- a/tests/compiler/std/symbol.optimized.wat
+++ b/tests/compiler/std/symbol.optimized.wat
@@ -144,7 +144,7 @@
   if
    i32.const 0
    i32.const 72
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -159,7 +159,7 @@
   if
    i32.const 0
    i32.const 72
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/symbol.untouched.wat b/tests/compiler/std/symbol.untouched.wat
index 68a2928e..410fbd1c 100644
--- a/tests/compiler/std/symbol.untouched.wat
+++ b/tests/compiler/std/symbol.untouched.wat
@@ -200,7 +200,7 @@
   if
    i32.const 0
    i32.const 72
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -217,7 +217,7 @@
   if
    i32.const 0
    i32.const 72
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/typedarray.optimized.wat b/tests/compiler/std/typedarray.optimized.wat
index d296ffda..00e74641 100644
--- a/tests/compiler/std/typedarray.optimized.wat
+++ b/tests/compiler/std/typedarray.optimized.wat
@@ -439,7 +439,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -454,7 +454,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable
diff --git a/tests/compiler/std/typedarray.untouched.wat b/tests/compiler/std/typedarray.untouched.wat
index da69b7b8..a20d42bd 100644
--- a/tests/compiler/std/typedarray.untouched.wat
+++ b/tests/compiler/std/typedarray.untouched.wat
@@ -497,7 +497,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 102
+   i32.const 107
    i32.const 6
    call $~lib/env/abort
    unreachable
@@ -514,7 +514,7 @@
   if
    i32.const 0
    i32.const 136
-   i32.const 104
+   i32.const 109
    i32.const 6
    call $~lib/env/abort
    unreachable