interpreter: fix integer Eq instruction (#638)

Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>

internal/engine/interpreter/interpreter.go

@@ -1058,7 +1058,10 @@ func (ce *callEngine) callNativeFunc(ctx context.Context, callCtx *wasm.CallCont
 		case wazeroir.OperationKindEq:
 			var b bool
 			switch wazeroir.UnsignedType(op.b1) {
-			case wazeroir.UnsignedTypeI32, wazeroir.UnsignedTypeI64:
+			case wazeroir.UnsignedTypeI32:
+				v2, v1 := ce.popValue(), ce.popValue()
+				b = uint32(v1) == uint32(v2)
+			case wazeroir.UnsignedTypeI64:
 				v2, v1 := ce.popValue(), ce.popValue()
 				b = v1 == v2
 			case wazeroir.UnsignedTypeF32:

internal/integration_test/engine/adhoc_test.go

@@ -45,6 +45,7 @@ var tests = map[string]func(t *testing.T, r wazero.Runtime){
 	"multiple instantiation from same source":           testMultipleInstantiation,
 	"exported function that grows memory":               testMemOps,
 	"import functions with reference type in signature": testReftypeImports,
+	"overflow integer addition":                         testOverflow,
 }
 
 func TestEngineCompiler(t *testing.T) {
@@ -79,6 +80,8 @@ var (
 	hugestackWasm []byte
 	//go:embed testdata/reftype_imports.wasm
 	reftypeImportsWasm []byte
+	//go:embed testdata/overflow.wasm
+	overflowWasm []byte
 )
 
 func testReftypeImports(t *testing.T, r wazero.Runtime) {
@@ -120,6 +123,24 @@ func testHugeStack(t *testing.T, r wazero.Runtime) {
 	require.NoError(t, err)
 }
 
+// testOverflow ensures that adding one into the maximum integer results in the
+// minimum one. See #636.
+func testOverflow(t *testing.T, r wazero.Runtime) {
+	module, err := r.InstantiateModuleFromBinary(testCtx, overflowWasm)
+	require.NoError(t, err)
+	defer module.Close(testCtx)
+
+	for _, name := range []string{"i32", "i64"} {
+		i32 := module.ExportedFunction(name)
+		require.NotNil(t, i32)
+
+		res, err := i32.Call(testCtx)
+		require.NoError(t, err)
+
+		require.Equal(t, uint64(1), res[0])
+	}
+}
+
 func testUnreachable(t *testing.T, r wazero.Runtime) {
 	callUnreachable := func(nil api.Module) {
 		panic("panic in host function")

internal/integration_test/engine/testdata/overflow.wat

@@ -0,0 +1,18 @@
+(module
+    (global $i32g i32 (i32.const -2147483648)) ;; min of 32-bit signed integer
+    (global $i64g i64 (i64.const -9223372036854775808)) ;; min of 64-bit signed integer
+    (func $i32 (export "i32") (result i32)
+        i32.const 2147483647 ;; max of 32-bit signed integer
+        i32.const 1
+        i32.add
+        global.get $i32g
+        i32.eq
+    )
+    (func $i64 (export "i64") (result i32)
+        i64.const 9223372036854775807  ;; max of 64-bit signed integer
+        i64.const 1
+        i64.add
+        global.get $i64g
+        i64.eq
+    )
+)