[interpreter] Bytecode register optimizer.

test/cctest/interpreter/bytecode_expectations/BreakableBlocks.golden

Index: test/cctest/interpreter/bytecode_expectations/BreakableBlocks.golden
diff --git a/test/cctest/interpreter/bytecode_expectations/BreakableBlocks.golden b/test/cctest/interpreter/bytecode_expectations/BreakableBlocks.golden
index b2af73c5c7f272e0c6c2e408f7267764a5505864..72ed9d977a7ab588d79599924a06a451d0cdd156 100644
--- a/test/cctest/interpreter/bytecode_expectations/BreakableBlocks.golden
+++ b/test/cctest/interpreter/bytecode_expectations/BreakableBlocks.golden
@@ -17,16 +17,15 @@ snippet: "
   }
   return x;
 "
-frame size: 2
+frame size: 1
 parameter count: 1
-bytecode array length: 17
+bytecode array length: 15
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaZero),
                 B(Star), R(0),
-  /*   56 S> */ B(Star), R(1),
-                B(LdaSmi), U8(1),
-                B(Add), R(1),
+  /*   56 S> */ B(LdaSmi), U8(1),
+                B(Add), R(0),
                 B(Star), R(0),
   /*   69 S> */ B(Jump), U8(2),
   /*   97 S> */ B(Ldar), R(0),
@@ -52,34 +51,29 @@ snippet: "
 "
 frame size: 5
 parameter count: 1
-bytecode array length: 72
+bytecode array length: 61
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   44 S> */ B(LdaZero),
                 B(Star), R(0),
   /*   71 S> */ B(LdaZero),
   /*   71 E> */ B(Star), R(1),
-  /*   76 S> */ B(Ldar), R(1),
-                B(Star), R(3),
-                B(LdaSmi), U8(10),
-  /*   76 E> */ B(TestLessThan), R(3),
-                B(JumpIfFalse), U8(54),
+  /*   76 S> */ B(LdaSmi), U8(10),
+  /*   76 E> */ B(TestLessThan), R(1),
+                B(JumpIfFalse), U8(47),
   /*   58 E> */ B(StackCheck),
   /*  106 S> */ B(LdaZero),
   /*  106 E> */ B(Star), R(2),
-  /*  111 S> */ B(Ldar), R(2),
-                B(Star), R(3),
-                B(LdaSmi), U8(3),
-  /*  111 E> */ B(TestLessThan), R(3),
-                B(JumpIfFalse), U8(33),
+  /*  111 S> */ B(LdaSmi), U8(3),
+  /*  111 E> */ B(TestLessThan), R(2),
+                B(JumpIfFalse), U8(30),
   /*   93 E> */ B(StackCheck),
   /*  129 S> */ B(Ldar), R(0),
                 B(Inc),
                 B(Star), R(0),
-  /*  142 S> */ B(Ldar), R(1),
-                B(Star), R(3),
+  /*  142 S> */ B(Nop),
   /*  150 E> */ B(Ldar), R(2),
-                B(Add), R(3),
+                B(Add), R(1),
                 B(Star), R(4),
                 B(LdaSmi), U8(12),
   /*  152 E> */ B(TestEqual), R(4),
@@ -88,11 +82,11 @@ bytecodes: [
   /*  118 S> */ B(Ldar), R(2),
                 B(Inc),
   /*  118 E> */ B(Star), R(2),
-                B(Jump), U8(-39),
+                B(Jump), U8(-32),
   /*   84 S> */ B(Ldar), R(1),
                 B(Inc),
   /*   84 E> */ B(Star), R(1),
-                B(Jump), U8(-60),
+                B(Jump), U8(-49),
   /*  188 S> */ B(Ldar), R(0),
   /*  200 S> */ B(Return),
 ]
@@ -111,13 +105,12 @@ snippet: "
 "
 frame size: 5
 parameter count: 1
-bytecode array length: 51
+bytecode array length: 50
 bytecodes: [
   /*   30 E> */ B(StackCheck),
                 B(LdaConstant), U8(0),
                 B(Star), R(3),
-                B(Ldar), R(closure),
-                B(Star), R(4),
+                B(Mov), R(closure), R(4),
                 B(CallRuntime), U16(Runtime::kPushBlockContext), R(3), U8(2),
                 B(PushContext), R(2),
                 B(LdaTheHole),
@@ -160,7 +153,7 @@ snippet: "
 "
 frame size: 6
 parameter count: 1
-bytecode array length: 131
+bytecode array length: 130
 bytecodes: [
                 B(CallRuntime), U16(Runtime::kNewFunctionContext), R(closure), U8(1),
                 B(PushContext), R(2),
@@ -171,8 +164,7 @@ bytecodes: [
   /*   42 E> */ B(StaContextSlot), R(context), U8(4),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
-                B(Ldar), R(closure),
-                B(Star), R(5),
+                B(Mov), R(closure), R(5),
                 B(CallRuntime), U16(Runtime::kPushBlockContext), R(4), U8(2),
                 B(PushContext), R(3),
                 B(LdaTheHole),