[Intepreter] Extend and move Register class.

Add methods for converting parameter index to a register and vice-versa.

Move Register class into bytecodes.h.

Update Bytecodes::Decode to pretty print parameters.

BUG=v8:4280
LOG=NO

Review URL: https://codereview.chromium.org/1325983002

Cr-Commit-Position: refs/heads/master@{#30549}

src/interpreter/bytecode-array-builder.cc

@@ -37,10 +37,10 @@ void BytecodeArrayBuilder::set_parameter_count(int number_of_parameters) {
 int BytecodeArrayBuilder::parameter_count() const { return parameter_count_; }
 
 
-Register BytecodeArrayBuilder::Parameter(int param_index) {
-  DCHECK_GE(param_index, 0);
-  DCHECK_LT(param_index, parameter_count_);
-  return Register(kLastParamRegisterIndex - parameter_count_ + param_index + 1);
+Register BytecodeArrayBuilder::Parameter(int parameter_index) {
+  DCHECK_GE(parameter_index, 0);
+  DCHECK_LT(parameter_index, parameter_count_);
+  return Register::FromParameterIndex(parameter_index, parameter_count_);
 }
 
 
@@ -229,10 +229,13 @@ bool BytecodeArrayBuilder::OperandIsValid(Bytecode bytecode, int operand_index,
     case OperandType::kIdx:
       return true;
     case OperandType::kReg: {
-      int reg_index = Register::FromOperand(operand_value).index();
-      return (reg_index >= 0 && reg_index < temporary_register_next_) ||
-             (reg_index <= kLastParamRegisterIndex &&
-              reg_index > kLastParamRegisterIndex - parameter_count_);
+      Register reg = Register::FromOperand(operand_value);
+      if (reg.is_parameter()) {
+        int parameter_index = reg.ToParameterIndex(parameter_count_);
+        return parameter_index >= 0 && parameter_index < parameter_count_;
+      } else {
+        return (reg.index() >= 0 && reg.index() < temporary_register_next_);
+      }
     }
   }
   UNREACHABLE();

src/interpreter/bytecode-array-builder.h

@@ -8,7 +8,6 @@
 #include <vector>
 
 #include "src/ast.h"
-#include "src/frames.h"
 #include "src/identity-map.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/zone.h"
@@ -64,9 +63,6 @@ class BytecodeArrayBuilder {
   BytecodeArrayBuilder& Return();
 
  private:
-  static const int kLastParamRegisterIndex =
-      -InterpreterFrameConstants::kLastParamFromRegisterPointer / kPointerSize;
-
   static Bytecode BytecodeForBinaryOperation(Token::Value op);
   static bool FitsInByteOperand(int value);
   static bool FitsInByteOperand(size_t value);
@@ -100,32 +96,6 @@ class BytecodeArrayBuilder {
   DISALLOW_IMPLICIT_CONSTRUCTORS(BytecodeArrayBuilder);
 };
 
-// An interpreter register which is located in the function's register file
-// in its stack-frame.
-class Register {
- public:
-  static const int kMaxRegisterIndex = 128;
-  static const int kMinRegisterIndex = -127;
-
-  explicit Register(int index) : index_(index) {
-    DCHECK_LE(index_, kMaxRegisterIndex);
-    DCHECK_GE(index_, kMinRegisterIndex);
-  }
-
-  int index() { return index_; }
-
-  uint8_t ToOperand() { return static_cast<uint8_t>(-index_); }
-  static Register FromOperand(uint8_t operand) {
-    return Register(-static_cast<int8_t>(operand));
-  }
-
- private:
-  void* operator new(size_t size);
-  void operator delete(void* p);
-
-  int index_;
-};
-
 // A stack-allocated class than allows the instantiator to allocate
 // temporary registers that are cleaned up when scope is closed.
 class TemporaryRegisterScope {

src/interpreter/bytecodes.cc

@@ -4,7 +4,7 @@
 
 #include "src/interpreter/bytecodes.h"
 
-#include "src/interpreter/bytecode-array-builder.h"
+#include "src/frames.h"
 
 namespace v8 {
 namespace internal {
@@ -103,8 +103,8 @@ int Bytecodes::MaximumSize() { return 1 + kMaxOperands; }
 
 
 // static
-std::ostream& Bytecodes::Decode(std::ostream& os,
-                                const uint8_t* bytecode_start) {
+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]);
@@ -132,9 +132,20 @@ std::ostream& Bytecodes::Decode(std::ostream& os,
       case interpreter::OperandType::kImm8:
         os << "#" << static_cast<int>(operand);
         break;
-      case interpreter::OperandType::kReg:
-        os << "r" << Register::FromOperand(operand).index();
+      case interpreter::OperandType::kReg: {
+        Register reg = Register::FromOperand(operand);
+        if (reg.is_parameter()) {
+          int parameter_index = reg.ToParameterIndex(parameter_count);
+          if (parameter_index == 0) {
+            os << "<this>";
+          } else {
+            os << "a" << parameter_index - 1;
+          }
+        } else {
+          os << "r" << reg.index();
+        }
         break;
+      }
       case interpreter::OperandType::kNone:
         UNREACHABLE();
         break;
@@ -156,6 +167,44 @@ std::ostream& operator<<(std::ostream& os, const OperandType& operand_type) {
   return os << Bytecodes::OperandTypeToString(operand_type);
 }
 
+
+static const int kLastParamRegisterIndex =
+    -InterpreterFrameConstants::kLastParamFromRegisterPointer / kPointerSize;
+
+
+// Registers occupy range 0-127 in 8-bit value leaving 128 unused values.
+// Parameter indices are biased with the negative value kLastParamRegisterIndex
+// for ease of access in the interpreter.
+static const int kMaxParameterIndex = 128 + kLastParamRegisterIndex;
+
+
+Register Register::FromParameterIndex(int index, int parameter_count) {
+  DCHECK_GE(index, 0);
+  DCHECK_LT(index, parameter_count);
+  DCHECK_LE(parameter_count, kMaxParameterIndex + 1);
+  int register_index = kLastParamRegisterIndex - parameter_count + index + 1;
+  DCHECK_LT(register_index, 0);
+  DCHECK_GE(register_index, Register::kMinRegisterIndex);
+  return Register(register_index);
+}
+
+
+int Register::ToParameterIndex(int parameter_count) const {
+  DCHECK(is_parameter());
+  return index() - kLastParamRegisterIndex + parameter_count - 1;
+}
+
+
+int Register::MaxParameterIndex() { return kMaxParameterIndex; }
+
+
+uint8_t Register::ToOperand() const { return static_cast<uint8_t>(-index_); }
+
+
+Register Register::FromOperand(uint8_t operand) {
+  return Register(-static_cast<int8_t>(operand));
+}
+
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8

src/interpreter/bytecodes.h

@@ -80,6 +80,36 @@ enum class Bytecode : uint8_t {
 };
 
 
+// An interpreter register which is located in the function's register file
+// in its stack-frame. Register hold parameters, this, and expression values.
+class Register {
+ public:
+  static const int kMaxRegisterIndex = 127;
+  static const int kMinRegisterIndex = -128;
+
+  explicit Register(int index) : index_(index) {
+    DCHECK_LE(index_, kMaxRegisterIndex);
+    DCHECK_GE(index_, kMinRegisterIndex);
+  }
+
+  int index() const { return index_; }
+  bool is_parameter() const { return index_ < 0; }
+
+  static Register FromParameterIndex(int index, int parameter_count);
+  int ToParameterIndex(int parameter_count) const;
+  static int MaxParameterIndex();
+
+  static Register FromOperand(uint8_t operand);
+  uint8_t ToOperand() const;
+
+ private:
+  void* operator new(size_t size);
+  void operator delete(void* p);
+
+  int index_;
+};
+
+
 class Bytecodes {
  public:
   // Returns string representation of |bytecode|.
@@ -110,7 +140,8 @@ class Bytecodes {
   static int MaximumSize();
 
   // Decode a single bytecode and operands to |os|.
-  static std::ostream& Decode(std::ostream& os, const uint8_t* bytecode_start);
+  static std::ostream& Decode(std::ostream& os, const uint8_t* bytecode_start,
+                              int number_of_parameters);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Bytecodes);

src/objects.cc

@@ -11916,7 +11916,7 @@ void BytecodeArray::Disassemble(std::ostream& os) {
 
     SNPrintF(buf, "%p", bytecode_start);
     os << buf.start() << " : ";
-    interpreter::Bytecodes::Decode(os, bytecode_start);
+    interpreter::Bytecodes::Decode(os, bytecode_start, parameter_count());
     os << "\n";
   }
 

test/unittests/interpreter/bytecodes-unittest.cc

+// Copyright 2014 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 <vector>
+
+#include "src/v8.h"
+
+#include "src/interpreter/bytecodes.h"
+#include "test/unittests/test-utils.h"
+
+
+namespace v8 {
+namespace internal {
+namespace interpreter {
+
+TEST(OperandConversion, Registers) {
+  for (int i = 0; i < 128; i++) {
+    uint8_t operand_value = Register(i).ToOperand();
+    Register r = Register::FromOperand(operand_value);
+    CHECK_EQ(i, r.index());
+  }
+}
+
+
+TEST(OperandConversion, Parameters) {
+  int parameter_counts[] = {7, 13, 99};
+
+  size_t count = sizeof(parameter_counts) / sizeof(parameter_counts[0]);
+  for (size_t p = 0; p < count; p++) {
+    int parameter_count = parameter_counts[p];
+    for (int i = 0; i < parameter_count; i++) {
+      Register r = Register::FromParameterIndex(i, parameter_count);
+      uint8_t operand_value = r.ToOperand();
+      Register s = Register::FromOperand(operand_value);
+      CHECK_EQ(i, s.ToParameterIndex(parameter_count));
+    }
+  }
+}
+
+
+TEST(OperandConversion, RegistersParametersNoOverlap) {
+  std::vector<uint8_t> operand_count(256);
+
+  for (int i = 0; i <= Register::kMaxRegisterIndex; i++) {
+    Register r = Register(i);
+    uint8_t operand = r.ToOperand();
+    operand_count[operand] += 1;
+    CHECK_EQ(operand_count[operand], 1);
+  }
+
+  int parameter_count = Register::MaxParameterIndex() + 1;
+  for (int i = 0; i < parameter_count; i++) {
+    Register r = Register::FromParameterIndex(i, parameter_count);
+    uint8_t operand = r.ToOperand();
+    operand_count[operand] += 1;
+    CHECK_EQ(operand_count[operand], 1);
+  }
+}
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespace v8

test/unittests/unittests.gyp

@@ -95,6 +95,7 @@
         'compiler/value-numbering-reducer-unittest.cc',
         'compiler/zone-pool-unittest.cc',
         'counters-unittest.cc',
+        'interpreter/bytecodes-unittest.cc',
         'interpreter/bytecode-array-builder-unittest.cc',
         'libplatform/default-platform-unittest.cc',
         'libplatform/task-queue-unittest.cc',