First step towards implementing stack map descriptions for the optimizing compiler.

vm/bitmap.cc

+// Copyright (c) 2012, 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/bitmap.h"
+
+#include "platform/assert.h"
+#include "vm/object.h"
+
+namespace dart {
+
+bool BitmapBuilder::Get(intptr_t bit_offset) const {
+  if (!InRange(bit_offset)) {
+    return false;
+  }
+  return GetBit(bit_offset);
+}
+
+
+void BitmapBuilder::Set(intptr_t bit_offset, bool value) {
+  while (!InRange(bit_offset)) {
+    intptr_t new_size = size_in_bytes_ + kIncrementSizeInBytes;
+    ASSERT(new_size > size_in_bytes_);
+    uint8_t* new_bit_list = reinterpret_cast<uint8_t*>(
+        Isolate::Current()->current_zone()->Allocate(new_size));
+    ASSERT(new_bit_list != NULL);
+    ASSERT(bit_list_ != NULL);
+    uint8_t* old_bit_list = bit_list_;
+    memmove(new_bit_list, old_bit_list, size_in_bytes_);
+    memset((new_bit_list + size_in_bytes_), 0, kIncrementSizeInBytes);
+    size_in_bytes_ = new_size;
+    bit_list_ = new_bit_list;
+  }
+  SetBit(bit_offset, value);
+}
+
+
+// Return the bit offset of the highest bit set.
+intptr_t BitmapBuilder::Maximum() const {
+  intptr_t bound = SizeInBits();
+  for (intptr_t i = (bound - 1); i >= 0; i--) {
+    if (Get(i)) return i;
+  }
+  return Stackmap::kNoMaximum;
+}
+
+
+// Return the bit offset of the lowest bit set.
+intptr_t BitmapBuilder::Minimum() const {
+  intptr_t bound = SizeInBits();
+  for (intptr_t i = 0; i < bound; i++) {
+    if (Get(i)) return i;
+  }
+  return Stackmap::kNoMinimum;
+}
+
+
+void BitmapBuilder::SetRange(intptr_t min, intptr_t max, bool value) {
+  for (intptr_t i = min; i <= max; i++) {
+    Set(i, value);
+  }
+}
+
+
+void BitmapBuilder::SetBits(const Stackmap& bitmap) {
+  intptr_t min = bitmap.Minimum();
+  intptr_t max = bitmap.Maximum();
+  if (min == Stackmap::kNoMinimum || max == Stackmap::kNoMaximum) {
+    return;
+  }
+  for (intptr_t i = 0; i < min; i++) {
+    Set(i, false);
+  }
+  for (intptr_t i = min; i <= max; i++) {
+    Set(i, bitmap.IsObject(i));
+  }
+  intptr_t bound = SizeInBits();
+  for (intptr_t i = (max + 1); i < bound; i++) {
+    Set(i, false);
+  }
+}
+
+
+bool BitmapBuilder::GetBit(intptr_t bit_offset) const {
+  ASSERT(InRange(bit_offset));
+  int byte_offset = bit_offset >> kBitsPerByteLog2;
+  int bit_remainder = bit_offset & (kBitsPerByte - 1);
+  uint8_t mask = 1U << bit_remainder;
+  ASSERT(bit_list_ != NULL);
+  return ((bit_list_[byte_offset] & mask) != 0);
+}
+
+
+void BitmapBuilder::SetBit(intptr_t bit_offset, bool value) {
+  ASSERT(InRange(bit_offset));
+  int byte_offset = bit_offset >> kBitsPerByteLog2;
+  int bit_remainder = bit_offset & (kBitsPerByte - 1);
+  uint8_t mask = 1U << bit_remainder;
+  uint8_t* byte_addr;
+  ASSERT(bit_list_ != NULL);
+  byte_addr = &(bit_list_[byte_offset]);
+  if (value) {
+    *byte_addr |= mask;
+  } else {
+    *byte_addr &= ~mask;
+  }
+}
+
+}  // namespace dart