ART: Clean up arm64 kNumberOfXRegisters usage.

Avoid undefined behavior for arm64 stemming from 1u << 32 in
loops with upper bound kNumberOfXRegisters.

Create iterators for enumerating bits in an integer either
from high to low or from low to high and use them for
<arch>Context::FillCalleeSaves() on all architectures.

Refactor runtime/utils.{h,cc} by moving all bit-fiddling
functions to runtime/base/bit_utils.{h,cc} (together with
the new bit iterators) and all time-related functions to
runtime/base/time_utils.{h,cc}. Improve test coverage and
fix some corner cases for the bit-fiddling functions.

Bug: 13925192
Change-Id: I704884dab15b41ecf7a1c47d397ab1c3fc7ee0f7

1 files changed, 47 insertions, 0 deletions

diff --git a/runtime/base/iteration_range.h b/runtime/base/iteration_range.h
new file mode 100644
index 0000000000..5a46376237
--- /dev/null
+++ b/runtime/base/iteration_range.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_BASE_ITERATION_RANGE_H_
+#define ART_RUNTIME_BASE_ITERATION_RANGE_H_
+
+namespace art {
+
+// Helper class that acts as a container for range-based loops, given an iteration
+// range [first, last) defined by two iterators.
+template <typename Iter>
+class IterationRange {
+ public:
+  typedef Iter iterator;
+  typedef typename std::iterator_traits<Iter>::difference_type difference_type;
+  typedef typename std::iterator_traits<Iter>::value_type value_type;
+  typedef typename std::iterator_traits<Iter>::pointer pointer;
+  typedef typename std::iterator_traits<Iter>::reference reference;
+
+  IterationRange(iterator first, iterator last) : first_(first), last_(last) { }
+
+  iterator begin() const { return first_; }
+  iterator end() const { return last_; }
+  iterator cbegin() const { return first_; }
+  iterator cend() const { return last_; }
+
+ private:
+  iterator first_;
+  iterator last_;
+};
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_BASE_ITERATION_RANGE_H_