Support parsing async modifiers for functions. (#3460)

Only parsing is implemented, so the async functions currently behave
like normal function except they return with a resolved Promise object
when the function is terminated correctly.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/vm/opcodes.c

@@ -26,6 +26,7 @@
 #include "ecma-iterator-object.h"
 #include "ecma-lex-env.h"
 #include "ecma-objects.h"
+#include "ecma-promise-object.h"
 #include "ecma-try-catch-macro.h"
 #include "jcontext.h"
 #include "opcodes.h"
@@ -706,6 +707,21 @@ opfunc_resume_executable_object (vm_executable_object_t *executable_object_p, /*
   return result;
 } /* opfunc_resume_executable_object */
 
+/**
+ * Create a Promise object if needed and resolve it with a value
+ *
+ * @return Promise object
+ */
+ecma_value_t
+opfunc_return_promise (ecma_value_t value) /**< value */
+{
+  ecma_value_t promise = ecma_make_object_value (ecma_builtin_get (ECMA_BUILTIN_ID_PROMISE));
+  ecma_value_t result = ecma_promise_reject_or_resolve (promise, value, true);
+
+  ecma_free_value (value);
+  return result;
+} /* opfunc_return_promise */
+
 #endif /* ENABLED (JERRY_ES2015) */
 
 /**

jerry-core/vm/opcodes.h

@@ -115,6 +115,9 @@ opfunc_create_executable_object (vm_frame_ctx_t *frame_ctx_p);
 
 ecma_value_t
 opfunc_resume_executable_object (vm_executable_object_t *executable_object_p, ecma_value_t value);
+
+ecma_value_t
+opfunc_return_promise (ecma_value_t value);
 #endif /* ENABLED (JERRY_ES2015) */
 
 /**

jerry-core/vm/vm.c

@@ -2098,6 +2098,12 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
 
           goto error;
         }
+        case VM_OC_RETURN_PROMISE:
+        {
+          result = opfunc_return_promise (left_value);
+          left_value = ECMA_VALUE_UNDEFINED;
+          goto error;
+        }
         case VM_OC_STRING_CONCAT:
         {
           ecma_string_t *left_str_p = ecma_op_to_string (left_value);
@@ -2131,7 +2137,7 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
           *stack_top_p++ = ecma_copy_value (collection_p->buffer_p[tagged_idx]);
           continue;
         }
- #endif /* ENABLED (JERRY_ES2015) */
+#endif /* ENABLED (JERRY_ES2015) */
         case VM_OC_PUSH_ELISON:
         {
           *stack_top_p++ = ECMA_VALUE_ARRAY_HOLE;

jerry-core/vm/vm.h

@@ -258,6 +258,7 @@ typedef enum
   VM_OC_CREATE_GENERATOR,        /**< create a generator object */
   VM_OC_YIELD,                   /**< yield operation */
   VM_OC_EXT_RETURN,              /**< return which also clears the stack */
+  VM_OC_RETURN_PROMISE,          /**< return from an async function */
   VM_OC_STRING_CONCAT,           /**< string concatenation */
   VM_OC_GET_TEMPLATE_OBJECT,     /**< GetTemplateObject operation */
 #endif /* ENABLED (JERRY_ES2015) */
@@ -313,6 +314,7 @@ typedef enum
   VM_OC_CREATE_GENERATOR = VM_OC_NONE,        /**< create a generator object */
   VM_OC_YIELD = VM_OC_NONE,                   /**< yield operation */
   VM_OC_EXT_RETURN = VM_OC_NONE,              /**< return which also clears the stack */
+  VM_OC_RETURN_PROMISE = VM_OC_NONE,          /**< return from an async function */
   VM_OC_STRING_CONCAT = VM_OC_NONE,           /**< string concatenation */
   VM_OC_GET_TEMPLATE_OBJECT = VM_OC_NONE,     /**< GetTemplateObject operation */
 #endif /* !ENABLED (JERRY_ES2015) */