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//===- subzero/src/IceUtils.h - Utility functions ---------------*- C++ -*-===//
//
// The Subzero Code Generator
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file declares some utility functions.
///
//===----------------------------------------------------------------------===//
#ifndef SUBZERO_SRC_ICEUTILS_H
#define SUBZERO_SRC_ICEUTILS_H
#include <climits>
namespace Ice {
/// Similar to bit_cast, but allows copying from types of unrelated
/// sizes. This method was introduced to enable the strict aliasing
/// optimizations of GCC 4.4. Basically, GCC mindlessly relies on
/// obscure details in the C++ standard that make reinterpret_cast
/// virtually useless.
template <class D, class S> inline D bit_copy(const S &source) {
D destination;
// This use of memcpy is safe: source and destination cannot overlap.
memcpy(&destination, reinterpret_cast<const void *>(&source),
sizeof(destination));
return destination;
}
class Utils {
Utils() = delete;
Utils(const Utils &) = delete;
Utils &operator=(const Utils &) = delete;
public:
/// Check whether an N-bit two's-complement representation can hold value.
template <typename T> static inline bool IsInt(int N, T value) {
assert((0 < N) &&
(static_cast<unsigned int>(N) < (CHAR_BIT * sizeof(value))));
T limit = static_cast<T>(1) << (N - 1);
return (-limit <= value) && (value < limit);
}
template <typename T> static inline bool IsUint(int N, T value) {
assert((0 < N) &&
(static_cast<unsigned int>(N) < (CHAR_BIT * sizeof(value))));
T limit = static_cast<T>(1) << N;
return (0 <= value) && (value < limit);
}
/// Check whether the magnitude of value fits in N bits, i.e., whether an
/// (N+1)-bit sign-magnitude representation can hold value.
template <typename T> static inline bool IsAbsoluteUint(int N, T Value) {
assert((0 < N) &&
(static_cast<unsigned int>(N) < (CHAR_BIT * sizeof(Value))));
if (Value < 0)
Value = -Value;
return IsUint(N, Value);
}
/// Return true if the addition X + Y will cause integer overflow for
/// integers of type T.
template <typename T> static inline bool WouldOverflowAdd(T X, T Y) {
return ((X > 0 && Y > 0 && (X > std::numeric_limits<T>::max() - Y)) ||
(X < 0 && Y < 0 && (X < std::numeric_limits<T>::min() - Y)));
}
/// Return true if X is already aligned by N, where N is a power of 2.
template <typename T> static inline bool IsAligned(T X, intptr_t N) {
assert(llvm::isPowerOf2_64(N));
return (X & (N - 1)) == 0;
}
/// Return Value adjusted to the next highest multiple of Alignment.
static inline uint32_t applyAlignment(uint32_t Value, uint32_t Alignment) {
assert(llvm::isPowerOf2_32(Alignment));
return (Value + Alignment - 1) & -Alignment;
}
/// Return amount which must be added to adjust Pos to the next highest
/// multiple of Align.
static inline uint64_t OffsetToAlignment(uint64_t Pos, uint64_t Align) {
assert(llvm::isPowerOf2_64(Align));
uint64_t Mod = Pos & (Align - 1);
if (Mod == 0)
return 0;
return Align - Mod;
}
/// Rotate the value bit pattern to the left by shift bits.
/// Precondition: 0 <= shift < 32
static inline uint32_t rotateLeft32(uint32_t value, uint32_t shift) {
if (shift == 0)
return value;
return (value << shift) | (value >> (32 - shift));
}
/// Rotate the value bit pattern to the right by shift bits.
static inline uint32_t rotateRight32(uint32_t value, uint32_t shift) {
if (shift == 0)
return value;
return (value >> shift) | (value << (32 - shift));
}
};
} // end of namespace Ice
#endif // SUBZERO_SRC_ICEUTILS_H