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(int32_t bit_offset) const {
+  if (!InRange(bit_offset)) {
+    return false;
+  }
+  return GetBit(bit_offset);
+}
+
+
+void BitmapBuilder::Set(int32_t bit_offset, bool value) {
+  while (!InRange(bit_offset)) {
+    int32_t new_size = size_ + kIncrementSize;
+    ASSERT(new_size > size_);
+    uint8_t* new_bit_list = reinterpret_cast<uint8_t*>(
+        Isolate::Current()->current_zone()->Allocate(new_size));
+    ASSERT(new_bit_list != NULL);
+    uint8_t* old_bit_list =
+        (size_ == kInitialSize) ? bit_list_ : bit_list_dynamic_;

[srdjan, 2012/03/14 17:31:32]

You could instead have bit_list_dynamic_ point to bit_list_ and always refer to
bit_list_dynamic_ (could also rename them to bit_list_data_ and bit_list_).

[siva, 2012/03/14 22:54:20]

Good point. Done.

On 2012/03/14 17:31:32, srdjan wrote:

+    memmove(new_bit_list, old_bit_list, size_);
+    memset((new_bit_list + size_), 0, kIncrementSize);
+    size_ = new_size;
+    bit_list_dynamic_ = new_bit_list;
+  }
+  SetBit(bit_offset, value);
+}
+
+
+// Return the bit offset of the highest bit set.
+int32_t BitmapBuilder::Maximum() const {
+  int32_t bound = BitSize();
+  for (int32_t i = bound; i >= 0; i--) {

[srdjan, 2012/03/14 17:31:32]

intptr_t

[siva, 2012/03/14 22:54:20]

Done.

+    if (Get(i)) return i;
+  }
+  return Bitmap::kNoMaximum;
+}
+
+
+// Return the bit offset of the lowest bit set.
+int32_t BitmapBuilder::Minimum() const {
+  int32_t bound = BitSize();
+  for (int32_t i = 0; i < bound; i++) {
+    if (Get(i)) return i;
+  }
+  return Bitmap::kNoMinimum;
+}
+
+
+void BitmapBuilder::SetRange(int32_t min, int32_t max, bool value) {
+  for (int32_t i = min; i <= max; i++) {
+    Set(i, value);
+  }
+}
+
+
+void BitmapBuilder::SetBits(const Bitmap& bitmap) {
+  int32_t min = bitmap.Minimum();
+  int32_t max = bitmap.Maximum();
+  if (min == Bitmap::kNoMinimum || max == Bitmap::kNoMaximum) {
+    return;
+  }
+  for (int32_t i = min; i <= max; i++) {
+    Set(i, bitmap.Get(i));
+  }

[srdjan, 2012/03/14 17:31:32]

Don't you need to clear the bits outside Minimum..Maximum range? Right now you
will clear only bits within the Minimum..Maximum.

[siva, 2012/03/14 22:54:20]

Done.

+}
+
+
+RawBitmap* BitmapBuilder::GetBitmap() const {
+  const Bitmap& bmap = Bitmap::Handle(Bitmap::New(size_));
+  int32_t bound = BitSize();
+  for (int32_t i = 0; i < bound; i++) {
+    bmap.SetBit(i, Get(i));
+  }
+  return bmap.raw();
+}
+
+
+bool BitmapBuilder::GetBit(int32_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;
+  if (size_ == kInitialSize) {
+    return ((bit_list_[byte_offset] & mask) != 0);
+  } else {
+    ASSERT(bit_list_dynamic_ != NULL);
+    return ((bit_list_dynamic_[byte_offset] & mask) != 0);
+  }
+}
+
+
+void BitmapBuilder::SetBit(int32_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;
+  if (size_ == kInitialSize) {
+    byte_addr = &(bit_list_[byte_offset]);
+  } else {
+    ASSERT(bit_list_dynamic_ != NULL);
+    byte_addr = &(bit_list_dynamic_[byte_offset]);
+  }
+  if (value) {
+    *byte_addr |= mask;
+  } else {
+    *byte_addr &= ~mask;
+  }
+}
+
+}  // namespace dart