[interpreter] Add support for scalable operands.

src/interpreter/register-translator.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/register-translator.h"
-
-#include "src/interpreter/bytecode-array-builder.h"
-
-namespace v8 {
-namespace internal {
-namespace interpreter {
-
-RegisterTranslator::RegisterTranslator(RegisterMover* mover)
-    : mover_(mover),
-      emitting_moves_(false),
-      window_registers_count_(0),
-      output_moves_count_(0) {}
-
-void RegisterTranslator::TranslateInputRegisters(Bytecode bytecode,
-                                                 uint32_t* raw_operands,
-                                                 int raw_operand_count) {
-  DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode), raw_operand_count);
-  if (!emitting_moves_) {
-    emitting_moves_ = true;
-    DCHECK_EQ(window_registers_count_, 0);
-    int register_bitmap = Bytecodes::GetRegisterOperandBitmap(bytecode);
-    for (int i = 0; i < raw_operand_count; i++) {
-      if ((register_bitmap & (1 << i)) == 0) {
-        continue;
-      }
-      Register in_reg = Register::FromRawOperand(raw_operands[i]);
-      Register out_reg = TranslateAndMove(bytecode, i, in_reg);
-      raw_operands[i] = out_reg.ToRawOperand();
-    }
-    window_registers_count_ = 0;
-    emitting_moves_ = false;
-  } else {
-    // When the register translator is translating registers, it will
-    // cause the bytecode generator to emit moves on it's behalf. This
-    // path is reached by these moves.
-    DCHECK(bytecode == Bytecode::kMovWide && raw_operand_count == 2 &&
-           Register::FromRawOperand(raw_operands[0]).is_valid() &&
-           Register::FromRawOperand(raw_operands[1]).is_valid());
-  }
-}
-
-Register RegisterTranslator::TranslateAndMove(Bytecode bytecode,
-                                              int operand_index, Register reg) {
-  if (FitsInReg8Operand(reg)) {
-    return reg;
-  }
-
-  OperandType operand_type = Bytecodes::GetOperandType(bytecode, operand_index);
-  OperandSize operand_size = Bytecodes::SizeOfOperand(operand_type);
-  if (operand_size == OperandSize::kShort) {
-    CHECK(FitsInReg16Operand(reg));
-    return Translate(reg);
-  }
-
-  CHECK((operand_type == OperandType::kReg8 ||
-         operand_type == OperandType::kRegOut8) &&
-        RegisterIsMovableToWindow(bytecode, operand_index));
-  Register translated_reg = Translate(reg);
-  Register window_reg(kTranslationWindowStart + window_registers_count_);
-  window_registers_count_ += 1;
-  if (Bytecodes::IsRegisterInputOperandType(operand_type)) {
-    DCHECK(!Bytecodes::IsRegisterOutputOperandType(operand_type));
-    mover()->MoveRegisterUntranslated(translated_reg, window_reg);
-  } else if (Bytecodes::IsRegisterOutputOperandType(operand_type)) {
-    DCHECK_LT(output_moves_count_, kTranslationWindowLength);
-    output_moves_[output_moves_count_] =
-        std::make_pair(window_reg, translated_reg);
-    output_moves_count_ += 1;
-  } else {
-    UNREACHABLE();
-  }
-  return window_reg;
-}
-
-// static
-bool RegisterTranslator::RegisterIsMovableToWindow(Bytecode bytecode,
-                                                   int operand_index) {
-  // By design, we only support moving individual registers. There
-  // should be wide variants of such bytecodes instead to avoid the
-  // need for a large translation window.
-  OperandType operand_type = Bytecodes::GetOperandType(bytecode, operand_index);
-  if (operand_type != OperandType::kReg8 &&
-      operand_type != OperandType::kRegOut8) {
-    return false;
-  } else if (operand_index + 1 == Bytecodes::NumberOfOperands(bytecode)) {
-    return true;
-  } else {
-    OperandType next_operand_type =
-        Bytecodes::GetOperandType(bytecode, operand_index + 1);
-    return (next_operand_type != OperandType::kRegCount8 &&
-            next_operand_type != OperandType::kRegCount16);
-  }
-}
-
-void RegisterTranslator::TranslateOutputRegisters() {
-  if (!emitting_moves_) {
-    emitting_moves_ = true;
-    while (output_moves_count_ > 0) {
-      output_moves_count_ -= 1;
-      mover()->MoveRegisterUntranslated(
-          output_moves_[output_moves_count_].first,
-          output_moves_[output_moves_count_].second);
-    }
-    emitting_moves_ = false;
-  }
-}
-
-// static
-Register RegisterTranslator::Translate(Register reg) {
-  if (reg.index() >= kTranslationWindowStart) {
-    return Register(reg.index() + kTranslationWindowLength);
-  } else {
-    return reg;
-  }
-}
-
-// static
-bool RegisterTranslator::InTranslationWindow(Register reg) {
-  return (reg.index() >= kTranslationWindowStart &&
-          reg.index() <= kTranslationWindowLimit);
-}
-
-// static
-Register RegisterTranslator::UntranslateRegister(Register reg) {
-  if (reg.index() >= kTranslationWindowStart) {
-    return Register(reg.index() - kTranslationWindowLength);
-  } else {
-    return reg;
-  }
-}
-
-// static
-int RegisterTranslator::DistanceToTranslationWindow(Register reg) {
-  return kTranslationWindowStart - reg.index();
-}
-
-// static
-bool RegisterTranslator::FitsInReg8Operand(Register reg) {
-  return reg.is_byte_operand() && reg.index() < kTranslationWindowStart;
-}
-
-// static
-bool RegisterTranslator::FitsInReg16Operand(Register reg) {
-  int max_index = Register::MaxRegisterIndex() - kTranslationWindowLength + 1;
-  return reg.is_short_operand() && reg.index() < max_index;
-}
-
-// static
-int RegisterTranslator::RegisterCountAdjustment(int register_count,
-                                                int parameter_count) {
-  if (register_count > kTranslationWindowStart) {
-    return kTranslationWindowLength;
-  } else if (parameter_count > 0) {
-    Register param0 = Register::FromParameterIndex(0, parameter_count);
-    if (!param0.is_byte_operand()) {
-      // TODO(oth): Number of parameters means translation is
-      // required, but the translation window location is such that
-      // some space is wasted. Hopefully a rare corner case, but could
-      // relocate window to limit waste.
-      return kTranslationWindowLimit + 1 - register_count;
-    }
-  }
-  return 0;
-}
-
-}  // namespace interpreter
-}  // namespace internal
-}  // namespace v8