From 3af0079a0eb4bf149d7e7c5acd3c95dfd049f622 Mon Sep 17 00:00:00 2001
From: Robert Fancsik <frobert@inf.u-szeged.hu>
Date: Mon, 26 Aug 2019 15:59:27 +0200
Subject: [PATCH] Introduce CBC_MOV_IDENT opcode to improve performance (#3020)

After this patch CBC_ASSIGN_SET_IDENT is transformed to CBC_MOV_IDENT if the opcode has register stored literal argument.

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu
---
 jerry-core/parser/js/byte-code.h |  2 ++
 jerry-core/parser/js/js-parser.c | 16 +++++++++++-----
 jerry-core/vm/vm.c               | 13 +++++++++++++
 jerry-core/vm/vm.h               |  1 +
 4 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/jerry-core/parser/js/byte-code.h b/jerry-core/parser/js/byte-code.h
index 6ddf3c1fd..77685d918 100644
--- a/jerry-core/parser/js/byte-code.h
+++ b/jerry-core/parser/js/byte-code.h
@@ -472,6 +472,8 @@
               VM_OC_ASSIGN_PROP_THIS | VM_OC_GET_LITERAL | VM_OC_PUT_REFERENCE | VM_OC_PUT_STACK) \
   CBC_OPCODE (CBC_ASSIGN_PROP_THIS_LITERAL_BLOCK, CBC_HAS_LITERAL_ARG, -1, \
               VM_OC_ASSIGN_PROP_THIS | VM_OC_GET_LITERAL | VM_OC_PUT_REFERENCE | VM_OC_PUT_BLOCK) \
+  CBC_OPCODE (CBC_MOV_IDENT, CBC_HAS_LITERAL_ARG, -1, \
+              VM_OC_MOV_IDENT | VM_OC_GET_STACK | VM_OC_PUT_IDENT) \
   \
   /* Last opcode (not a real opcode). */ \
   CBC_OPCODE (CBC_END, CBC_NO_FLAG, 0, \
diff --git a/jerry-core/parser/js/js-parser.c b/jerry-core/parser/js/js-parser.c
index bfa088050..06fc9d80b 100644
--- a/jerry-core/parser/js/js-parser.c
+++ b/jerry-core/parser/js/js-parser.c
@@ -1863,6 +1863,8 @@ parser_post_processing (parser_context_t *context_p) /**< context */
   page_p = context_p->byte_code.first_p;
   offset = 0;
   real_offset = 0;
+  uint8_t last_register_index = (uint8_t) JERRY_MIN (context_p->register_count,
+                                                     (PARSER_MAXIMUM_NUMBER_OF_REGISTERS - 1));
 
   while (page_p != last_page_p || offset < last_position)
   {
@@ -1943,11 +1945,6 @@ parser_post_processing (parser_context_t *context_p) /**< context */
 #endif /* ENABLED (JERRY_LINE_INFO) */
     }
 
-    if (flags & CBC_HAS_BRANCH_ARG)
-    {
-      *branch_mark_p |= CBC_HIGHEST_BIT_MASK;
-    }
-
     /* Only literal and call arguments can be combined. */
     JERRY_ASSERT (!(flags & CBC_HAS_BRANCH_ARG)
                    || !(flags & (CBC_HAS_BYTE_ARG | CBC_HAS_LITERAL_ARG)));
@@ -1956,6 +1953,7 @@ parser_post_processing (parser_context_t *context_p) /**< context */
     {
       uint8_t first_byte = page_p->bytes[offset];
 
+      uint8_t *opcode_pos_p = dst_p - 1;
       *dst_p++ = first_byte;
       real_offset++;
       PARSER_NEXT_BYTE_UPDATE (page_p, offset, real_offset);
@@ -1980,6 +1978,11 @@ parser_post_processing (parser_context_t *context_p) /**< context */
       }
       else
       {
+        if (opcode == CBC_ASSIGN_SET_IDENT && JERRY_LIKELY (first_byte < last_register_index))
+        {
+          *opcode_pos_p = CBC_MOV_IDENT;
+        }
+
         break;
       }
     }
@@ -1990,10 +1993,12 @@ parser_post_processing (parser_context_t *context_p) /**< context */
       *dst_p++ = page_p->bytes[offset];
       real_offset++;
       PARSER_NEXT_BYTE_UPDATE (page_p, offset, real_offset);
+      continue;
     }
 
     if (flags & CBC_HAS_BRANCH_ARG)
     {
+      *branch_mark_p |= CBC_HIGHEST_BIT_MASK;
       bool prefix_zero = true;
 
       /* The leading zeroes are dropped from the stream. */
@@ -2020,6 +2025,7 @@ parser_post_processing (parser_context_t *context_p) /**< context */
       *dst_p++ = page_p->bytes[offset];
       real_offset++;
       PARSER_NEXT_BYTE_UPDATE (page_p, offset, real_offset);
+      continue;
     }
   }
 
diff --git a/jerry-core/vm/vm.c b/jerry-core/vm/vm.c
index 28949b771..d816f065c 100644
--- a/jerry-core/vm/vm.c
+++ b/jerry-core/vm/vm.c
@@ -1941,6 +1941,19 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
           left_value = ECMA_VALUE_UNDEFINED;
           break;
         }
+        case VM_OC_MOV_IDENT:
+        {
+          uint16_t literal_index;
+
+          READ_LITERAL_INDEX (literal_index);
+
+          JERRY_ASSERT (literal_index < register_end);
+          JERRY_ASSERT (!(opcode_data & (VM_OC_PUT_STACK | VM_OC_PUT_BLOCK)));
+
+          ecma_fast_free_value (frame_ctx_p->registers_p[literal_index]);
+          frame_ctx_p->registers_p[literal_index] = left_value;
+          continue;
+        }
         case VM_OC_ASSIGN_PROP:
         {
           result = stack_top_p[-1];
diff --git a/jerry-core/vm/vm.h b/jerry-core/vm/vm.h
index b42535158..b2a2f25d2 100644
--- a/jerry-core/vm/vm.h
+++ b/jerry-core/vm/vm.h
@@ -148,6 +148,7 @@ typedef enum
   VM_OC_PROP_DELETE,             /**< delete property */
   VM_OC_DELETE,                  /**< delete */
 
+  VM_OC_MOV_IDENT,               /**< move identifier register reference */
   VM_OC_ASSIGN,                  /**< assign */
   VM_OC_ASSIGN_PROP,             /**< assign property */
   VM_OC_ASSIGN_PROP_THIS,        /**< assign prop this */