[Intepreter] Extend and move Register class.

src/interpreter/bytecodes.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecodes.h"
 
-#include "src/interpreter/bytecode-array-builder.h"
+#include "src/frames.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
 // Maximum number of operands a bytecode may have.
 static const int kMaxOperands = 3;
 
 // kBytecodeTable relies on kNone being the same as zero to detect length.
 STATIC_ASSERT(static_cast<int>(OperandType::kNone) == 0);
@@ skipping 78 matching lines @@
 
 // static
 int Bytecodes::MaximumNumberOfOperands() { return kMaxOperands; }
 
 
 // static
 int Bytecodes::MaximumSize() { return 1 + kMaxOperands; }
 
 
 // static
-std::ostream& Bytecodes::Decode(std::ostream& os,
-                                const uint8_t* bytecode_start) {
+uint8_t Bytecodes::RegisterIndexToOperand(int index) {
+  return static_cast<uint8_t>(-index);
+}
+
+
+// static
+int Bytecodes::RegisterIndexFromOperand(uint8_t operand) {
+  int8_t index = -static_cast<int8_t>(operand);
+  return index;
+}
+
+
+static const int kLastParamRegisterIndex =
+    -InterpreterFrameConstants::kLastParamFromRegisterPointer / kPointerSize;
+
+
+// static
+uint8_t Bytecodes::ParameterIndexToOperand(int index, int parameter_count) {

[rmcilroy, 2015/09/02 11:42:42]

Could we make this a Register::FromParameterIndex() instead (and then can use
Register::ToOperand if we need the operand)? This is assuming we can move
Register class over to bytecodes.h as in my earlier comment.

[oth, 2015/09/02 14:02:20]

Done.

+  // Parameters share the same space as registers
+  DCHECK_LE(parameter_count, MaximumNumberOfParameters());
+  DCHECK_GE(index, 0);

[rmcilroy, 2015/09/02 11:42:41]

nit - DCHECK_LT(index, parameter_count)

[oth, 2015/09/02 14:02:20]

Done.

+  int register_index = kLastParamRegisterIndex - parameter_count + index + 1;
+  DCHECK_LT(register_index, 0);
+  return RegisterIndexToOperand(register_index);
+}
+
+
+// static
+int Bytecodes::ParameterIndexFromOperand(uint8_t operand, int parameter_count) {
+  // Parameters share the same space as registers
+  DCHECK_LE(parameter_count, MaximumNumberOfParameters());
+  int register_index = RegisterIndexFromOperand(operand);
+  return register_index - kLastParamRegisterIndex + parameter_count - 1;
+}
+
+
+// static
+int Bytecodes::MaximumNumberOfParameters() {
+  return 128 + kLastParamRegisterIndex;

[rmcilroy, 2015/09/02 11:42:41]

This is a bit confusing. Could you use kMinRegisterIndex with the -1 adjustment
(from count to index) and mention that kLastParamRegisterIndex is negative.

[oth, 2015/09/02 14:02:20]

Comment added.

+}
+
+
+// static
+std::ostream& Bytecodes::Decode(std::ostream& os, const uint8_t* bytecode_start,
+                                int parameter_count) {
   Vector<char> buf = Vector<char>::New(50);
 
   Bytecode bytecode = Bytecodes::FromByte(bytecode_start[0]);
   int bytecode_size = Bytecodes::Size(bytecode);
 
   for (int i = 0; i < bytecode_size; i++) {
     SNPrintF(buf, "%02x ", bytecode_start[i]);
     os << buf.start();
   }
   for (int i = bytecode_size; i < Bytecodes::MaximumSize(); i++) {
     os << "   ";
   }
 
   os << bytecode << " ";
 
   const uint8_t* operands_start = bytecode_start + 1;
   int operands_size = bytecode_size - 1;
   for (int i = 0; i < operands_size; i++) {
     OperandType op_type = GetOperandType(bytecode, i);
     uint8_t operand = operands_start[i];
     switch (op_type) {
       case interpreter::OperandType::kIdx:
         os << "[" << static_cast<unsigned int>(operand) << "]";
         break;
       case interpreter::OperandType::kImm8:
         os << "#" << static_cast<int>(operand);
         break;
-      case interpreter::OperandType::kReg:
-        os << "r" << Register::FromOperand(operand).index();
+      case interpreter::OperandType::kReg: {
+        int register_index = RegisterIndexFromOperand(operand);
+        if (register_index >= 0) {
+          os << "r" << register_index;
+        } else {
+          int parameter_index =
+              ParameterIndexFromOperand(operand, parameter_count);
+          if (parameter_index == 0) {
+            os << "this";

[rmcilroy, 2015/09/02 11:42:42]

nit - could we make it "<this>" or "|this|" or something to make it clear this
is a parameter? Maybe do the same with "<a0>" or "|a0|"as well?

[oth, 2015/09/02 14:02:20]

Done <this>.

Prefer current consistency of r0, r1, r2, ...a0, a1, etc.

+          } else {
+            os << "a" << parameter_index - 1;
+          }
+        }
         break;
+      }
       case interpreter::OperandType::kNone:
         UNREACHABLE();
         break;
     }
     if (i != operands_size - 1) {
       os << ", ";
     }
   }
   return os;
 }
 
 
 std::ostream& operator<<(std::ostream& os, const Bytecode& bytecode) {
   return os << Bytecodes::ToString(bytecode);
 }
 
 
 std::ostream& operator<<(std::ostream& os, const OperandType& operand_type) {
   return os << Bytecodes::OperandTypeToString(operand_type);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8