runtime/vm/assembler_mips.cc

// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/globals.h"
#if defined(TARGET_ARCH_MIPS)

#include "vm/assembler.h"

namespace dart {

DEFINE_FLAG(bool, print_stop_message, true, "Print stop message.");


void Assembler::InitializeMemoryWithBreakpoints(uword data, int length) {
  ASSERT(Utils::IsAligned(data, 4));
  ASSERT(Utils::IsAligned(length, 4));
  const uword end = data + length;
  while (data < end) {
    *reinterpret_cast<int32_t*>(data) = Instr::kBreakPointInstruction;
    data += 4;
  }
}


void Assembler::Bind(Label* label) {
  ASSERT(!label->IsBound());
  int bound_pc = buffer_.Size();
  while (label->IsLinked()) {
    int32_t position = label->Position();
    int32_t next = buffer_.Load<int32_t>(position);
    // Reletive destination from an instruction after the branch.
    int32_t dest = bound_pc - (position + Instr::kInstrSize);
    int32_t encoded = Assembler::EncodeBranchOffset(dest, next);
    buffer_.Store<int32_t>(position, encoded);
    label->position_ = Assembler::DecodeBranchOffset(next);
  }
  label->BindTo(bound_pc);
  delay_slot_available_ = false;
}


int32_t Assembler::EncodeBranchOffset(int32_t offset, int32_t instr) {
  ASSERT(Utils::IsAligned(offset, 4));
  ASSERT(Utils::IsInt(18, offset));

  // Properly preserve only the bits supported in the instruction.
  offset >>= 2;
  offset &= kBranchOffsetMask;
  return (instr & ~kBranchOffsetMask) | offset;
}


int Assembler::DecodeBranchOffset(int32_t instr) {
  // Sign-extend, left-shift by 2.
  return (((instr & kBranchOffsetMask) << 16) >> 14);
}

}  // namespace dart

#endif  // defined TARGET_ARCH_MIPS