From b1237dbc5a409bd8baae5e05cc2f737d92c60983 Mon Sep 17 00:00:00 2001
From: Zoltan Herczeg <zherczeg.u-szeged@partner.samsung.com>
Date: Mon, 16 Dec 2019 13:36:26 +0100
Subject: [PATCH] Detect keyword type even if the keyword is identifier.
 (#3448)

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com
---
 jerry-core/parser/js/js-lexer.c           | 153 ++++++++--------------
 jerry-core/parser/js/js-lexer.h           |  55 +++-----
 jerry-core/parser/js/js-parser-expr.c     |  36 ++---
 jerry-core/parser/js/js-parser-internal.h |   4 +-
 jerry-core/parser/js/js-parser-module.c   |   2 +-
 jerry-core/parser/js/js-parser-statm.c    |   7 +-
 jerry-core/parser/js/js-parser-util.c     |   6 +-
 jerry-core/parser/js/js-parser.c          |   3 +-
 jerry-core/parser/js/js-scanner-util.c    |   2 +-
 jerry-core/parser/js/js-scanner.c         |   2 +-
 10 files changed, 95 insertions(+), 175 deletions(-)

diff --git a/jerry-core/parser/js/js-lexer.c b/jerry-core/parser/js/js-lexer.c
index a770c0d7f..0f51ea1db 100644
--- a/jerry-core/parser/js/js-lexer.c
+++ b/jerry-core/parser/js/js-lexer.c
@@ -469,6 +469,7 @@ static const keyword_string_t keywords_with_length_4[] =
   LEXER_KEYWORD ("case", LEXER_KEYW_CASE),
   LEXER_KEYWORD ("else", LEXER_KEYW_ELSE),
   LEXER_KEYWORD ("enum", LEXER_KEYW_ENUM),
+  LEXER_KEYWORD ("eval", LEXER_KEYW_EVAL),
   LEXER_KEYWORD ("null", LEXER_LIT_NULL),
   LEXER_KEYWORD ("this", LEXER_KEYW_THIS),
   LEXER_KEYWORD ("true", LEXER_LIT_TRUE),
@@ -537,6 +538,7 @@ static const keyword_string_t keywords_with_length_8[] =
  */
 static const keyword_string_t keywords_with_length_9[] =
 {
+  LEXER_KEYWORD ("arguments", LEXER_KEYW_ARGUMENTS),
   LEXER_KEYWORD ("interface", LEXER_KEYW_INTERFACE),
   LEXER_KEYWORD ("protected", LEXER_KEYW_PROTECTED),
 };
@@ -600,6 +602,9 @@ typedef enum
   LEXER_PARSE_CHECK_PART_AND_RETURN = (1 << 2), /**< check identifier part and return */
 } lexer_parse_options_t;
 
+JERRY_STATIC_ASSERT (LEXER_FIRST_NON_RESERVED_KEYWORD < LEXER_FIRST_FUTURE_STRICT_RESERVED_WORD,
+                     lexer_first_non_reserved_keyword_must_be_before_lexer_first_future_strict_reserved_word);
+
 /**
  * Parse identifier.
  *
@@ -749,7 +754,7 @@ lexer_parse_identifier (parser_context_t *context_p, /**< context */
   JERRY_ASSERT (length > 0);
 
   context_p->token.type = LEXER_LITERAL;
-  context_p->token.ident_is_strict_keyword = false;
+  context_p->token.keyword_type = LEXER_EOS;
   context_p->token.lit_location.type = LEXER_IDENT_LITERAL;
   context_p->token.lit_location.has_escape = has_escape;
 
@@ -792,50 +797,52 @@ lexer_parse_identifier (parser_context_t *context_p, /**< context */
 
         if (compare_result == 0)
         {
-          if (JERRY_UNLIKELY (keyword_p->type >= LEXER_FIRST_FUTURE_STRICT_RESERVED_WORD))
+          context_p->token.keyword_type = (uint8_t) keyword_p->type;
+
+          if (JERRY_LIKELY (keyword_p->type < LEXER_FIRST_NON_RESERVED_KEYWORD))
           {
-#if ENABLED (JERRY_ES2015)
-            if (keyword_p->type == LEXER_KEYW_YIELD && (context_p->status_flags & PARSER_IS_GENERATOR_FUNCTION))
+            if (ident_start_p == buffer_p)
             {
-              if (ident_start_p == buffer_p)
-              {
-                parser_raise_error (context_p, PARSER_ERR_INVALID_KEYWORD);
-              }
-
-              if (context_p->status_flags & PARSER_DISALLOW_YIELD)
-              {
-                parser_raise_error (context_p, PARSER_ERR_YIELD_NOT_ALLOWED);
-              }
-
-              context_p->token.type = (uint8_t) LEXER_KEYW_YIELD;
-              break;
+              /* Escape sequences are not allowed in a keyword. */
+              parser_raise_error (context_p, PARSER_ERR_INVALID_KEYWORD);
             }
 
-            if (keyword_p->type == LEXER_KEYW_LET && !context_p->token.lit_location.has_escape)
-            {
-              if (context_p->status_flags & PARSER_IS_STRICT)
-              {
-                context_p->token.type = (uint8_t) LEXER_KEYW_LET;
-              }
-              break;
-            }
-#endif /* ENABLED (JERRY_ES2015) */
-
-            if (context_p->status_flags & PARSER_IS_STRICT)
-            {
-              parser_raise_error (context_p, PARSER_ERR_STRICT_IDENT_NOT_ALLOWED);
-            }
-
-            context_p->token.ident_is_strict_keyword = true;
+            context_p->token.type = (uint8_t) keyword_p->type;
             break;
           }
 
-          if (ident_start_p == buffer_p)
+#if ENABLED (JERRY_ES2015)
+          if (keyword_p->type == LEXER_KEYW_YIELD && (context_p->status_flags & PARSER_IS_GENERATOR_FUNCTION))
           {
-            parser_raise_error (context_p, PARSER_ERR_INVALID_KEYWORD);
+            if (ident_start_p == buffer_p)
+            {
+              parser_raise_error (context_p, PARSER_ERR_INVALID_KEYWORD);
+            }
+
+            if (context_p->status_flags & PARSER_DISALLOW_YIELD)
+            {
+              parser_raise_error (context_p, PARSER_ERR_YIELD_NOT_ALLOWED);
+            }
+
+            context_p->token.type = (uint8_t) LEXER_KEYW_YIELD;
+            break;
           }
 
-          context_p->token.type = (uint8_t) keyword_p->type;
+          if (keyword_p->type == LEXER_KEYW_LET && ident_start_p != buffer_p)
+          {
+            if (context_p->status_flags & PARSER_IS_STRICT)
+            {
+              context_p->token.type = (uint8_t) LEXER_KEYW_LET;
+            }
+            break;
+          }
+#endif /* ENABLED (JERRY_ES2015) */
+
+          if (keyword_p->type >= LEXER_FIRST_FUTURE_STRICT_RESERVED_WORD
+              && (context_p->status_flags & PARSER_IS_STRICT))
+          {
+            parser_raise_error (context_p, PARSER_ERR_STRICT_IDENT_NOT_ALLOWED);
+          }
           break;
         }
       }
@@ -1187,7 +1194,7 @@ lexer_parse_number (parser_context_t *context_p) /**< context */
   size_t length;
 
   context_p->token.type = LEXER_LITERAL;
-  context_p->token.ident_is_strict_keyword = false;
+  context_p->token.keyword_type = LEXER_EOS;
   context_p->token.extra_value = LEXER_NUMBER_DECIMAL;
   context_p->token.lit_location.char_p = source_p;
   context_p->token.lit_location.type = LEXER_NUMBER_LITERAL;
@@ -2164,25 +2171,6 @@ lexer_construct_literal_object (parser_context_t *context_p, /**< context */
                               literal_type,
                               literal_p->has_escape);
 
-  context_p->lit_object.type = LEXER_LITERAL_OBJECT_ANY;
-
-  if (literal_p->length == 4
-      && source_p[0] == LIT_CHAR_LOWERCASE_E
-      && source_p[3] == LIT_CHAR_LOWERCASE_L
-      && source_p[1] == LIT_CHAR_LOWERCASE_V
-      && source_p[2] == LIT_CHAR_LOWERCASE_A)
-  {
-    context_p->lit_object.type = LEXER_LITERAL_OBJECT_EVAL;
-  }
-
-  if (literal_p->length == 9
-      && source_p[0] == LIT_CHAR_LOWERCASE_A
-      && source_p[8] == LIT_CHAR_LOWERCASE_S
-      && memcmp (source_p + 1, "rgument", 7) == 0)
-  {
-    context_p->lit_object.type = LEXER_LITERAL_OBJECT_ARGUMENTS;
-  }
-
   if (destination_start_p != local_byte_array)
   {
     JERRY_ASSERT (context_p->u.allocated_buffer_p == destination_start_p);
@@ -2260,7 +2248,6 @@ lexer_construct_number_object (parser_context_t *context_p, /**< context */
     {
       context_p->lit_object.literal_p = literal_p;
       context_p->lit_object.index = (uint16_t) literal_index;
-      context_p->lit_object.type = LEXER_LITERAL_OBJECT_ANY;
       return false;
     }
 
@@ -2282,7 +2269,6 @@ lexer_construct_number_object (parser_context_t *context_p, /**< context */
 
   context_p->lit_object.literal_p = literal_p;
   context_p->lit_object.index = (uint16_t) literal_index;
-  context_p->lit_object.type = LEXER_LITERAL_OBJECT_ANY;
 
   context_p->literal_count++;
   return false;
@@ -2624,12 +2610,11 @@ lexer_construct_regexp_object (parser_context_t *context_p, /**< context */
   literal_p->u.bytecode_p = (ecma_compiled_code_t *) re_bytecode_p;
 
   context_p->token.type = LEXER_LITERAL;
-  context_p->token.ident_is_strict_keyword = false;
+  context_p->token.keyword_type = LEXER_EOS;
   context_p->token.lit_location.type = LEXER_REGEXP_LITERAL;
 
   context_p->lit_object.literal_p = literal_p;
   context_p->lit_object.index = (uint16_t) (context_p->literal_count - 1);
-  context_p->lit_object.type = LEXER_LITERAL_OBJECT_ANY;
 #else /* !ENABLED (JERRY_BUILTIN_REGEXP) */
   JERRY_UNUSED (parse_only);
   parser_raise_error (context_p, PARSER_ERR_UNSUPPORTED_REGEXP);
@@ -2664,22 +2649,16 @@ lexer_expect_identifier (parser_context_t *context_p, /**< context */
                                       literal_type);
 
       if (literal_type != LEXER_STRING_LITERAL
-          && (context_p->status_flags & PARSER_IS_STRICT)
-          && context_p->lit_object.type != LEXER_LITERAL_OBJECT_ANY)
+          && (context_p->status_flags & PARSER_IS_STRICT))
       {
-        parser_error_t error;
-
-        if (context_p->lit_object.type == LEXER_LITERAL_OBJECT_EVAL)
+        if (context_p->token.keyword_type == LEXER_KEYW_EVAL)
         {
-          error = PARSER_ERR_EVAL_NOT_ALLOWED;
+          parser_raise_error (context_p, PARSER_ERR_EVAL_NOT_ALLOWED);
         }
-        else
+        else if (context_p->token.keyword_type == LEXER_KEYW_ARGUMENTS)
         {
-          JERRY_ASSERT (context_p->lit_object.type == LEXER_LITERAL_OBJECT_ARGUMENTS);
-          error = PARSER_ERR_ARGUMENTS_NOT_ALLOWED;
+          parser_raise_error (context_p, PARSER_ERR_ARGUMENTS_NOT_ALLOWED);
         }
-
-        parser_raise_error (context_p, error);
       }
       return;
     }
@@ -2690,7 +2669,7 @@ lexer_expect_identifier (parser_context_t *context_p, /**< context */
     /* When parsing default exports for modules, it is not required by functions or classes to have identifiers.
      * In this case we use a synthetic name for them. */
     context_p->token.type = LEXER_LITERAL;
-    context_p->token.ident_is_strict_keyword = false;
+    context_p->token.keyword_type = LEXER_EOS;
     context_p->token.lit_location.type = LEXER_IDENT_LITERAL;
     context_p->token.lit_location.has_escape = false;
     lexer_construct_literal_object (context_p, &lexer_default_literal, literal_type);
@@ -3098,38 +3077,10 @@ lexer_token_is_let (parser_context_t *context_p) /**< context */
 {
   JERRY_ASSERT (context_p->token.type == LEXER_LITERAL);
 
-  const uint8_t *char_p = context_p->token.lit_location.char_p;
-
-  return (!(context_p->status_flags & PARSER_IS_STRICT)
-          && context_p->token.lit_location.type == LEXER_IDENT_LITERAL
-          && context_p->token.lit_location.length == 3
-          && char_p[0] == LIT_CHAR_LOWERCASE_L
-          && char_p[1] == LIT_CHAR_LOWERCASE_E
-          && char_p[2] == LIT_CHAR_LOWERCASE_T);
+  return (context_p->token.keyword_type == LEXER_KEYW_LET
+          && !context_p->token.lit_location.has_escape);
 } /* lexer_token_is_let */
 
-/**
- * Compares the current literal object to an expected identifier
- *
- * Note:
- *   Escape sequences are allowed.
- *
- * @return true if the input identifiers are the same
- */
-bool
-lexer_literal_object_is_identifier (parser_context_t *context_p, /**< context */
-                                    const char *identifier_p, /**< identifier */
-                                    size_t identifier_length) /**< identifier length */
-{
-  JERRY_ASSERT (context_p->token.type == LEXER_LITERAL
-                && context_p->token.lit_location.type == LEXER_IDENT_LITERAL);
-
-  lexer_literal_t *literal_p = context_p->lit_object.literal_p;
-
-  return (literal_p->prop.length == identifier_length
-          && memcmp (literal_p->u.char_p, identifier_p, identifier_length) == 0);
-} /* lexer_literal_object_is_identifier */
-
 #endif /* ENABLED (JERRY_ES2015) */
 
 /**
diff --git a/jerry-core/parser/js/js-lexer.h b/jerry-core/parser/js/js-lexer.h
index 2b3f81353..00e18990b 100644
--- a/jerry-core/parser/js/js-lexer.h
+++ b/jerry-core/parser/js/js-lexer.h
@@ -144,6 +144,17 @@ typedef enum
   LEXER_KEYW_THROW,              /**< throw */
   LEXER_KEYW_TRY,                /**< try */
 
+  LEXER_KEYW_CLASS,              /**< class */
+  LEXER_KEYW_EXTENDS,            /**< extends */
+  LEXER_KEYW_SUPER,              /**< super */
+  LEXER_KEYW_CONST,              /**< const */
+  LEXER_KEYW_EXPORT,             /**< export */
+  LEXER_KEYW_IMPORT,             /**< import */
+  LEXER_KEYW_ENUM,               /**< enum */
+#if ENABLED (JERRY_ES2015)
+  LEXER_KEYW_AWAIT,              /**< await */
+#endif /* ENABLED (JERRY_ES2015) */
+
   /* These are virtual tokens. */
   LEXER_EXPRESSION_START,        /**< expression start */
   LEXER_PROPERTY_GETTER,         /**< property getter function */
@@ -153,32 +164,15 @@ typedef enum
   LEXER_CLASS_CONSTRUCTOR,       /**< special value for class constructor method */
   LEXER_INVALID_PATTERN,         /**< special value for invalid destructuring pattern */
 
-#if !ENABLED (JERRY_ES2015)
-  /* Future reserved words: these keywords
-   * must form a group after all other keywords. */
-#define LEXER_FIRST_FUTURE_RESERVED_WORD LEXER_KEYW_CLASS
-#endif /* !ENABLED (JERRY_ES2015) */
-  LEXER_KEYW_CLASS,              /**< class */
-  LEXER_KEYW_EXTENDS,            /**< extends */
-  LEXER_KEYW_SUPER,              /**< super */
-  LEXER_KEYW_CONST,              /**< const */
-  LEXER_KEYW_EXPORT,             /**< export */
-  LEXER_KEYW_IMPORT,             /**< import */
-#if ENABLED (JERRY_ES2015)
-  /* Future reserved words: these keywords
-   * must form a group after all other keywords.
-   * Note:
-   *      Tokens from LEXER_KEYW_CLASS to LEXER_KEYW_IMPORT
-   *      are no longer future reserved words in ES2015. */
-#define LEXER_FIRST_FUTURE_RESERVED_WORD LEXER_KEYW_ENUM
-#endif /* ENABLED (JERRY_ES2015) */
-  LEXER_KEYW_ENUM,               /**< enum */
-#if ENABLED (JERRY_ES2015)
-  LEXER_KEYW_AWAIT,              /**< await */
-#endif /* ENABLED (JERRY_ES2015) */
+  /* Keywords which are not keyword tokens. */
+#define LEXER_FIRST_NON_RESERVED_KEYWORD LEXER_KEYW_EVAL
+  /* Keywords which cannot be assigned in strict mode. */
+#define LEXER_FIRST_NON_STRICT_ARGUMENTS LEXER_KEYW_EVAL
+  LEXER_KEYW_EVAL,               /**< eval */
+  LEXER_KEYW_ARGUMENTS,          /**< arguments */
 
   /* Future strict reserved words: these keywords
-   * must form a group after future reserved words. */
+   * must form a group after non-reserved keywords. */
 #define LEXER_FIRST_FUTURE_STRICT_RESERVED_WORD LEXER_KEYW_IMPLEMENTS
   LEXER_KEYW_IMPLEMENTS,         /**< implements */
   LEXER_KEYW_PRIVATE,            /**< private */
@@ -246,16 +240,6 @@ typedef enum
   LEXER_SCAN_IDENT_PROPERTY = (1u << 1),         /**< scan valid property names */
 } lexer_scan_ident_opts_t;
 
-/**
- * Lexer literal object types.
- */
-typedef enum
-{
-  LEXER_LITERAL_OBJECT_ANY,                 /**< unspecified object type */
-  LEXER_LITERAL_OBJECT_EVAL,                /**< reference is equal to eval */
-  LEXER_LITERAL_OBJECT_ARGUMENTS,           /**< reference is equal to arguments */
-} lexer_literal_object_type_t;
-
 /**
  * Lexer number types.
  */
@@ -283,7 +267,7 @@ typedef struct
 typedef struct
 {
   uint8_t type;                              /**< token type */
-  uint8_t ident_is_strict_keyword;           /**< identifier is strict reserved keyword */
+  uint8_t keyword_type;                      /**< keyword type for identifiers */
   uint8_t extra_value;                       /**< helper value for different purposes */
   uint8_t flags;                             /**< flag bits for the current token */
   parser_line_counter_t line;                /**< token start line */
@@ -298,7 +282,6 @@ typedef struct
 {
   lexer_literal_t *literal_p;                /**< pointer to the literal object */
   uint16_t index;                            /**< literal index */
-  uint8_t type;                              /**< literal object type */
 } lexer_lit_object_t;
 
 /**
diff --git a/jerry-core/parser/js/js-parser-expr.c b/jerry-core/parser/js/js-parser-expr.c
index 61fe519eb..4dac20c53 100644
--- a/jerry-core/parser/js/js-parser-expr.c
+++ b/jerry-core/parser/js/js-parser-expr.c
@@ -99,22 +99,16 @@ parser_check_invalid_assign (parser_context_t *context_p) /**< context */
 {
   JERRY_ASSERT (context_p->last_cbc.literal_type == LEXER_IDENT_LITERAL);
 
-  if (JERRY_UNLIKELY ((context_p->status_flags & PARSER_IS_STRICT)
-                      && context_p->last_cbc.literal_object_type != LEXER_LITERAL_OBJECT_ANY))
+  if (JERRY_UNLIKELY (context_p->status_flags & PARSER_IS_STRICT))
   {
-    parser_error_t error;
-
-    if (context_p->last_cbc.literal_object_type == LEXER_LITERAL_OBJECT_EVAL)
+    if (context_p->last_cbc.literal_keyword_type == LEXER_KEYW_EVAL)
     {
-      error = PARSER_ERR_EVAL_CANNOT_ASSIGNED;
+      parser_raise_error (context_p, PARSER_ERR_EVAL_CANNOT_ASSIGNED);
     }
-    else
+    else if (context_p->last_cbc.literal_keyword_type == LEXER_KEYW_ARGUMENTS)
     {
-      JERRY_ASSERT (context_p->last_cbc.literal_object_type == LEXER_LITERAL_OBJECT_ARGUMENTS);
-      error = PARSER_ERR_ARGUMENTS_CANNOT_ASSIGNED;
+      parser_raise_error (context_p, PARSER_ERR_ARGUMENTS_CANNOT_ASSIGNED);
     }
-
-    parser_raise_error (context_p, error);
   }
 } /* parser_check_invalid_assign */
 
@@ -1054,8 +1048,7 @@ parser_parse_function_expression (parser_context_t *context_p, /**< context */
       }
 #endif /* ENABLED (JERRY_DEBUGGER) */
 
-      if (context_p->token.ident_is_strict_keyword
-          || context_p->lit_object.type != LEXER_LITERAL_OBJECT_ANY)
+      if (context_p->token.keyword_type >= LEXER_FIRST_NON_STRICT_ARGUMENTS)
       {
         status_flags |= PARSER_HAS_NON_STRICT_ARG;
       }
@@ -1113,7 +1106,7 @@ parser_parse_function_expression (parser_context_t *context_p, /**< context */
   }
 
   context_p->last_cbc.literal_type = LEXER_FUNCTION_LITERAL;
-  context_p->last_cbc.literal_object_type = LEXER_LITERAL_OBJECT_ANY;
+  context_p->last_cbc.literal_keyword_type = LEXER_EOS;
 } /* parser_parse_function_expression */
 
 #if ENABLED (JERRY_ES2015)
@@ -1176,7 +1169,7 @@ parser_parse_template_literal (parser_context_t *context_p) /**< context */
       context_p->last_cbc_opcode = CBC_ADD_TWO_LITERALS;
       context_p->last_cbc.value = context_p->lit_object.index;
       context_p->last_cbc.literal_type = context_p->token.lit_location.type;
-      context_p->last_cbc.literal_object_type = context_p->lit_object.type;
+      context_p->last_cbc.literal_keyword_type = context_p->token.keyword_type;
     }
     else
     {
@@ -1374,14 +1367,14 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
 
       cbc_opcode_t opcode = CBC_PUSH_LITERAL;
 
-      if (context_p->lit_object.type != LEXER_LITERAL_OBJECT_EVAL)
+      if (context_p->token.keyword_type != LEXER_KEYW_EVAL)
       {
         if (context_p->last_cbc_opcode == CBC_PUSH_LITERAL)
         {
           context_p->last_cbc_opcode = CBC_PUSH_TWO_LITERALS;
           context_p->last_cbc.value = context_p->lit_object.index;
           context_p->last_cbc.literal_type = context_p->token.lit_location.type;
-          context_p->last_cbc.literal_object_type = context_p->lit_object.type;
+          context_p->last_cbc.literal_keyword_type = context_p->token.keyword_type;
           break;
         }
 
@@ -1390,7 +1383,7 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
           context_p->last_cbc_opcode = CBC_PUSH_THREE_LITERALS;
           context_p->last_cbc.third_literal_index = context_p->lit_object.index;
           context_p->last_cbc.literal_type = context_p->token.lit_location.type;
-          context_p->last_cbc.literal_object_type = context_p->lit_object.type;
+          context_p->last_cbc.literal_keyword_type = context_p->token.keyword_type;
           break;
         }
 
@@ -1460,7 +1453,7 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
       }
 
       context_p->last_cbc.literal_type = LEXER_REGEXP_LITERAL;
-      context_p->last_cbc.literal_object_type = LEXER_LITERAL_OBJECT_ANY;
+      context_p->last_cbc.literal_keyword_type = LEXER_EOS;
       break;
     }
     case LEXER_KEYW_THIS:
@@ -1704,7 +1697,7 @@ parser_process_unary_expression (parser_context_t *context_p, /**< context */
         else
         {
           if (context_p->last_cbc_opcode == CBC_PUSH_LITERAL
-              && context_p->last_cbc.literal_object_type == LEXER_LITERAL_OBJECT_EVAL
+              && context_p->last_cbc.literal_keyword_type == LEXER_KEYW_EVAL
               && context_p->last_cbc.literal_type == LEXER_IDENT_LITERAL)
           {
             is_eval = true;
@@ -2460,8 +2453,7 @@ parser_pattern_process_assignment (parser_context_t *context_p, /**< context */
     lexer_construct_literal_object (context_p, &context_p->token.lit_location, LEXER_IDENT_LITERAL);
 
     if (flags & PARSER_PATTERN_LEXICAL
-        && !(context_p->status_flags & PARSER_IS_STRICT)
-        && lexer_literal_object_is_identifier (context_p, "let", 3))
+        && context_p->token.keyword_type == LEXER_KEYW_LET)
     {
       parser_raise_error (context_p, PARSER_ERR_LEXICAL_LET_BINDING);
     }
diff --git a/jerry-core/parser/js/js-parser-internal.h b/jerry-core/parser/js/js-parser-internal.h
index 84ef10d21..2cce1f5f7 100644
--- a/jerry-core/parser/js/js-parser-internal.h
+++ b/jerry-core/parser/js/js-parser-internal.h
@@ -207,7 +207,7 @@ typedef struct
   uint16_t value;                             /**< other argument (second literal or byte). */
   uint16_t third_literal_index;               /**< literal index argument */
   uint8_t literal_type;                       /**< last literal type */
-  uint8_t literal_object_type;                /**< last literal object type */
+  uint8_t literal_keyword_type;               /**< last literal keyword type */
 } cbc_argument_t;
 
 /* Useful parser macros. */
@@ -653,8 +653,6 @@ bool lexer_current_is_literal (parser_context_t *context_p, const lexer_lit_loca
 bool lexer_token_is_identifier (parser_context_t *context_p, const char *identifier_p,
                                 size_t identifier_length);
 bool lexer_token_is_let (parser_context_t *context_p);
-bool lexer_literal_object_is_identifier (parser_context_t *context_p, const char *identifier_p,
-                                         size_t identifier_length);
 #endif /* ENABLED (JERRY_ES2015) */
 bool lexer_compare_literal_to_string (parser_context_t *context_p, const char *string_p, size_t string_length);
 uint8_t lexer_convert_binary_lvalue_token_to_binary (uint8_t token);
diff --git a/jerry-core/parser/js/js-parser-module.c b/jerry-core/parser/js/js-parser-module.c
index 3541d21ca..4d5334eee 100644
--- a/jerry-core/parser/js/js-parser-module.c
+++ b/jerry-core/parser/js/js-parser-module.c
@@ -367,7 +367,7 @@ parser_module_parse_export_clause (parser_context_t *context_p) /**< parser cont
     /* 15.2.3.1 The referenced binding cannot be a reserved word. */
     if (context_p->token.type != LEXER_LITERAL
         || context_p->token.lit_location.type != LEXER_IDENT_LITERAL
-        || context_p->token.ident_is_strict_keyword)
+        || context_p->token.keyword_type >= LEXER_FIRST_FUTURE_STRICT_RESERVED_WORD)
     {
       parser_raise_error (context_p, PARSER_ERR_IDENTIFIER_EXPECTED);
     }
diff --git a/jerry-core/parser/js/js-parser-statm.c b/jerry-core/parser/js/js-parser-statm.c
index 5eaa3ec8a..daaac713b 100644
--- a/jerry-core/parser/js/js-parser-statm.c
+++ b/jerry-core/parser/js/js-parser-statm.c
@@ -543,8 +543,7 @@ parser_parse_var_statement (parser_context_t *context_p) /**< context */
 
 #if ENABLED (JERRY_ES2015)
       if (declaration_type != LEXER_KEYW_VAR
-          && !(context_p->status_flags & PARSER_IS_STRICT)
-          && lexer_literal_object_is_identifier (context_p, "let", 3))
+          && context_p->token.keyword_type == LEXER_KEYW_LET)
       {
         parser_raise_error (context_p, PARSER_ERR_LEXICAL_LET_BINDING);
       }
@@ -679,10 +678,8 @@ parser_parse_function_statement (parser_context_t *context_p) /**< context */
 
   uint32_t status_flags = PARSER_FUNCTION_CLOSURE;
 
-  if (context_p->lit_object.type != LEXER_LITERAL_OBJECT_ANY)
+  if (context_p->token.keyword_type >= LEXER_FIRST_NON_STRICT_ARGUMENTS)
   {
-    JERRY_ASSERT (context_p->lit_object.type == LEXER_LITERAL_OBJECT_EVAL
-                  || context_p->lit_object.type == LEXER_LITERAL_OBJECT_ARGUMENTS);
     status_flags |= PARSER_HAS_NON_STRICT_ARG;
   }
 
diff --git a/jerry-core/parser/js/js-parser-util.c b/jerry-core/parser/js/js-parser-util.c
index 1036d5138..a146d6a28 100644
--- a/jerry-core/parser/js/js-parser-util.c
+++ b/jerry-core/parser/js/js-parser-util.c
@@ -308,7 +308,7 @@ parser_emit_cbc_literal (parser_context_t *context_p, /**< context */
   context_p->last_cbc_opcode = opcode;
   context_p->last_cbc.literal_index = literal_index;
   context_p->last_cbc.literal_type = LEXER_UNUSED_LITERAL;
-  context_p->last_cbc.literal_object_type = LEXER_LITERAL_OBJECT_ANY;
+  context_p->last_cbc.literal_keyword_type = LEXER_EOS;
 } /* parser_emit_cbc_literal */
 
 /**
@@ -330,7 +330,7 @@ parser_emit_cbc_literal_value (parser_context_t *context_p, /**< context */
   context_p->last_cbc_opcode = opcode;
   context_p->last_cbc.literal_index = literal_index;
   context_p->last_cbc.literal_type = LEXER_UNUSED_LITERAL;
-  context_p->last_cbc.literal_object_type = LEXER_LITERAL_OBJECT_ANY;
+  context_p->last_cbc.literal_keyword_type = LEXER_EOS;
   context_p->last_cbc.value = value;
 } /* parser_emit_cbc_literal_value */
 
@@ -351,7 +351,7 @@ parser_emit_cbc_literal_from_token (parser_context_t *context_p, /**< context */
   context_p->last_cbc_opcode = opcode;
   context_p->last_cbc.literal_index = context_p->lit_object.index;
   context_p->last_cbc.literal_type = context_p->token.lit_location.type;
-  context_p->last_cbc.literal_object_type = context_p->lit_object.type;
+  context_p->last_cbc.literal_keyword_type = context_p->token.keyword_type;
 } /* parser_emit_cbc_literal_from_token */
 
 /**
diff --git a/jerry-core/parser/js/js-parser.c b/jerry-core/parser/js/js-parser.c
index 1ecd49953..b98b52d1a 100644
--- a/jerry-core/parser/js/js-parser.c
+++ b/jerry-core/parser/js/js-parser.c
@@ -1729,8 +1729,7 @@ parser_parse_function_arguments (parser_context_t *context_p, /**< context */
                                     &context_p->token.lit_location,
                                     LEXER_IDENT_LITERAL);
 
-    if (context_p->token.ident_is_strict_keyword
-        || context_p->lit_object.type != LEXER_LITERAL_OBJECT_ANY)
+    if (context_p->token.keyword_type >= LEXER_FIRST_NON_STRICT_ARGUMENTS)
     {
       context_p->status_flags |= PARSER_HAS_NON_STRICT_ARG;
     }
diff --git a/jerry-core/parser/js/js-scanner-util.c b/jerry-core/parser/js/js-scanner-util.c
index 9573e6ac6..c85af9ad1 100644
--- a/jerry-core/parser/js/js-scanner-util.c
+++ b/jerry-core/parser/js/js-scanner-util.c
@@ -1116,7 +1116,7 @@ void
 scanner_detect_eval_call (parser_context_t *context_p, /**< context */
                           scanner_context_t *scanner_context_p) /**< scanner context */
 {
-  if (lexer_compare_identifier_to_string (&context_p->token.lit_location, (const uint8_t *) "eval", 4)
+  if (context_p->token.keyword_type == LEXER_KEYW_EVAL
       && lexer_check_next_character (context_p, LIT_CHAR_LEFT_PAREN))
   {
     scanner_context_p->active_literal_pool_p->status_flags |= SCANNER_LITERAL_POOL_NO_REG;
diff --git a/jerry-core/parser/js/js-scanner.c b/jerry-core/parser/js/js-scanner.c
index 2b1b40e38..fc721a4a2 100644
--- a/jerry-core/parser/js/js-scanner.c
+++ b/jerry-core/parser/js/js-scanner.c
@@ -376,7 +376,7 @@ scanner_handle_bracket (parser_context_t *context_p, /**< context */
         arrow_source_p = NULL;
 #endif /* ENABLED (JERRY_ES2015) */
 
-        if (lexer_compare_identifier_to_string (&context_p->token.lit_location, (const uint8_t *) "eval", 4))
+        if (context_p->token.keyword_type == LEXER_KEYW_EVAL)
         {
           scanner_context_p->active_literal_pool_p->status_flags |= SCANNER_LITERAL_POOL_NO_REG;
         }