[interpreter] Bytecode register optimizer.

test/cctest/interpreter/bytecode_expectations/DoExpression.golden

Index: test/cctest/interpreter/bytecode_expectations/DoExpression.golden
diff --git a/test/cctest/interpreter/bytecode_expectations/DoExpression.golden b/test/cctest/interpreter/bytecode_expectations/DoExpression.golden
index 68f264f64cd46f7d3961ecb3a0c5d341d3cbfa4d..ea50803c231eea241578a2258a01b77e95332f78 100644
--- a/test/cctest/interpreter/bytecode_expectations/DoExpression.golden
+++ b/test/cctest/interpreter/bytecode_expectations/DoExpression.golden
@@ -14,11 +14,11 @@ snippet: "
 "
 frame size: 2
 parameter count: 1
-bytecode array length: 6
+bytecode array length: 7
 bytecodes: [
   /*   30 E> */ B(StackCheck),
-  /*   42 S> */ B(Ldar), R(0),
-  /*   42 E> */ B(Star), R(1),
+  /*   42 S> */ B(Mov), R(0), R(1),
+  /*   50 S> */ B(Ldar), R(0),
   /*   60 S> */ B(Return),
 ]
 constant pool: [
@@ -32,7 +32,7 @@ snippet: "
 "
 frame size: 3
 parameter count: 1
-bytecode array length: 11
+bytecode array length: 13
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   55 S> */ B(LdaSmi), U8(100),
@@ -40,6 +40,7 @@ bytecodes: [
   /*   42 S> */ B(LdaUndefined),
                 B(Star), R(0),
   /*   42 E> */ B(Star), R(2),
+  /*   63 S> */ B(Ldar), R(2),
   /*   73 S> */ B(Return),
 ]
 constant pool: [
@@ -53,7 +54,7 @@ snippet: "
 "
 frame size: 2
 parameter count: 1
-bytecode array length: 25
+bytecode array length: 24
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   34 E> */ B(StackCheck),
@@ -62,12 +63,11 @@ bytecodes: [
   /*   69 S> */ B(Inc),
   /*   71 E> */ B(Star), R(1),
                 B(Star), R(0),
-  /*   74 S> */ B(Jump), U8(12),
-  /*   64 E> */ B(Ldar), R(0),
-  /*   62 E> */ B(Star), R(1),
+  /*   74 S> */ B(Jump), U8(11),
+  /*   62 E> */ B(Mov), R(0), R(1),
   /*   84 S> */ B(LdaSmi), U8(20),
   /*   86 E> */ B(Star), R(1),
-                B(Jump), U8(-20),
+                B(Jump), U8(-19),
                 B(LdaUndefined),
   /*   94 S> */ B(Return),
 ]