feat: implement unreachable instruction

Signed-off-by: Florian Hartung <florian.hartung@dlr.de>

Author: florianhartung

src/core/error.rs

@@ -30,7 +30,7 @@ pub enum RuntimeError {
     UnmetImport,
     UndefinedTableIndex,
     // "undefined element" <- as-call_indirect-last
-    // "unreachable"
+    ReachedUnreachable,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone)]
@@ -314,6 +314,9 @@ impl Display for RuntimeError {
             RuntimeError::UndefinedTableIndex => {
                 f.write_str("Indirect call: table index out of bounds")
             }
+            RuntimeError::ReachedUnreachable => {
+                f.write_str("an unreachable statement was reached, triggered a trap")
+            }
         }
     }
 }

src/execution/interpreter_loop.rs

@@ -378,6 +378,9 @@ pub(super) fn run<H: HookSet>(
                     val
                 )
             }
+            UNREACHABLE => {
+                return Err(RuntimeError::ReachedUnreachable);
+            }
             I32_LOAD => {
                 let memarg = MemArg::read_unvalidated(wasm);
                 let relative_address: u32 = stack.pop_value(ValType::NumType(NumType::I32)).into();

tests/specification/run.rs

@@ -78,6 +78,7 @@ pub fn to_wasm_testsuite_string(runtime_error: RuntimeError) -> Result<String, B
         RuntimeError::FunctionNotFound => not_represented,
         RuntimeError::StackSmash => not_represented,
         RuntimeError::BadConversionToInteger => Ok("invalid conversion to integer"),
+        RuntimeError::ReachedUnreachable => Ok("unreachable"),
 
         RuntimeError::MemoryAccessOutOfBounds => Ok("out of bounds memory access"),
         RuntimeError::TableAccessOutOfBounds => Ok("out of bounds table access"),