From dbd52e451a7cdf93201fe7356eb76558154c9b8b Mon Sep 17 00:00:00 2001
From: Zoltan Herczeg <zherczeg.u-szeged@partner.samsung.com>
Date: Wed, 18 Jul 2018 03:03:25 -0700
Subject: [PATCH] Reduce with stack consumption by 1.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com
---
 jerry-core/parser/js/byte-code.h |  2 +-
 jerry-core/vm/vm-stack.c         | 25 +++++++++++++++++--------
 jerry-core/vm/vm.c               |  8 +++-----
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/jerry-core/parser/js/byte-code.h b/jerry-core/parser/js/byte-code.h
index 0ce85f38a7..e3a684854b 100644
--- a/jerry-core/parser/js/byte-code.h
+++ b/jerry-core/parser/js/byte-code.h
@@ -202,7 +202,7 @@
 /* PARSER_FOR_IN_CONTEXT_STACK_ALLOCATION must be <= 4 */
 #define PARSER_FOR_IN_CONTEXT_STACK_ALLOCATION 4
 /* PARSER_WITH_CONTEXT_STACK_ALLOCATION must be <= 4 */
-#define PARSER_WITH_CONTEXT_STACK_ALLOCATION 2
+#define PARSER_WITH_CONTEXT_STACK_ALLOCATION 1
 /* PARSER_TRY_CONTEXT_STACK_ALLOCATION must be <= 3 */
 #define PARSER_TRY_CONTEXT_STACK_ALLOCATION 2
 
diff --git a/jerry-core/vm/vm-stack.c b/jerry-core/vm/vm-stack.c
index 2de190a44c..9b8400b114 100644
--- a/jerry-core/vm/vm-stack.c
+++ b/jerry-core/vm/vm-stack.c
@@ -54,15 +54,23 @@ vm_stack_context_abort (vm_frame_ctx_t *frame_ctx_p, /**< frame context */
       break;
     }
     case VM_CONTEXT_CATCH:
-    case VM_CONTEXT_WITH:
     {
-      ecma_deref_object (frame_ctx_p->lex_env_p);
-      frame_ctx_p->lex_env_p = ecma_get_object_from_value (vm_stack_top_p[-2]);
+      JERRY_ASSERT (PARSER_TRY_CONTEXT_STACK_ALLOCATION > PARSER_WITH_CONTEXT_STACK_ALLOCATION);
 
-      JERRY_ASSERT (PARSER_TRY_CONTEXT_STACK_ALLOCATION == PARSER_WITH_CONTEXT_STACK_ALLOCATION);
+      const uint16_t size_diff = PARSER_TRY_CONTEXT_STACK_ALLOCATION - PARSER_WITH_CONTEXT_STACK_ALLOCATION;
 
-      VM_MINUS_EQUAL_U16 (frame_ctx_p->context_depth, PARSER_TRY_CONTEXT_STACK_ALLOCATION);
-      vm_stack_top_p -= PARSER_TRY_CONTEXT_STACK_ALLOCATION;
+      VM_MINUS_EQUAL_U16 (frame_ctx_p->context_depth, size_diff);
+      vm_stack_top_p -= size_diff;
+      /* FALLTHRU */
+    }
+    case VM_CONTEXT_WITH:
+    {
+      ecma_object_t *lex_env_p = frame_ctx_p->lex_env_p;
+      frame_ctx_p->lex_env_p = ecma_get_lex_env_outer_reference (lex_env_p);
+      ecma_deref_object (lex_env_p);
+
+      VM_MINUS_EQUAL_U16 (frame_ctx_p->context_depth, PARSER_WITH_CONTEXT_STACK_ALLOCATION);
+      vm_stack_top_p -= PARSER_WITH_CONTEXT_STACK_ALLOCATION;
       break;
     }
     default:
@@ -218,8 +226,9 @@ vm_stack_find_finally (vm_frame_ctx_t *frame_ctx_p, /**< frame context */
       }
       else
       {
-        ecma_deref_object (frame_ctx_p->lex_env_p);
-        frame_ctx_p->lex_env_p = ecma_get_object_from_value (vm_stack_top_p[-2]);
+        ecma_object_t *lex_env_p = frame_ctx_p->lex_env_p;
+        frame_ctx_p->lex_env_p = ecma_get_lex_env_outer_reference (lex_env_p);
+        ecma_deref_object (lex_env_p);
 
         if (byte_code_p[0] == CBC_CONTEXT_END)
         {
diff --git a/jerry-core/vm/vm.c b/jerry-core/vm/vm.c
index bb6061c808..978dd43819 100644
--- a/jerry-core/vm/vm.c
+++ b/jerry-core/vm/vm.c
@@ -2314,14 +2314,12 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
           object_p = ecma_get_object_from_value (result);
 
           with_env_p = ecma_create_object_lex_env (frame_ctx_p->lex_env_p, object_p);
-
           ecma_deref_object (object_p);
 
           VM_PLUS_EQUAL_U16 (frame_ctx_p->context_depth, PARSER_WITH_CONTEXT_STACK_ALLOCATION);
           stack_top_p += PARSER_WITH_CONTEXT_STACK_ALLOCATION;
 
           stack_top_p[-1] = VM_CREATE_CONTEXT (VM_CONTEXT_WITH, branch_offset);
-          stack_top_p[-2] = ecma_make_object_value (frame_ctx_p->lex_env_p);
 
           frame_ctx_p->lex_env_p = with_env_p;
           continue;
@@ -2468,8 +2466,9 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
 
           if (VM_GET_CONTEXT_TYPE (stack_top_p[-1]) == VM_CONTEXT_CATCH)
           {
-            ecma_deref_object (frame_ctx_p->lex_env_p);
-            frame_ctx_p->lex_env_p = ecma_get_object_from_value (stack_top_p[-2]);
+            ecma_object_t *lex_env_p = frame_ctx_p->lex_env_p;
+            frame_ctx_p->lex_env_p = ecma_get_lex_env_outer_reference (lex_env_p);
+            ecma_deref_object (lex_env_p);
           }
 
           stack_top_p[-1] = (ecma_value_t) VM_CREATE_CONTEXT (VM_CONTEXT_FINALLY_JUMP, branch_offset);
@@ -2903,7 +2902,6 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
           ecma_string_t *catch_name_p = ecma_get_string_from_value (literal_start_p[literal_index]);
           ecma_op_create_mutable_binding (catch_env_p, catch_name_p, false);
 
-          stack_top_p[-2 - 1] = ecma_make_object_value (frame_ctx_p->lex_env_p);
           frame_ctx_p->lex_env_p = catch_env_p;
         }
         else