Squashed 'third_party/ntcore_2016/' content from commit d8de5e4
Change-Id: Id4839f41b6a620d8bae58dcf1710016671cc4992
git-subtree-dir: third_party/ntcore_2016
git-subtree-split: d8de5e4f19e612e7102172c0dbf152ce82d3d63a
diff --git a/include/llvm/MathExtras.h b/include/llvm/MathExtras.h
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+++ b/include/llvm/MathExtras.h
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+//===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains some functions that are useful for math stuff.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_MATHEXTRAS_H
+#define LLVM_SUPPORT_MATHEXTRAS_H
+
+#include "llvm/Compiler.h"
+#include <cstdint>
+#include <limits>
+
+namespace llvm {
+/// \brief The behavior an operation has on an input of 0.
+enum ZeroBehavior {
+ /// \brief The returned value is undefined.
+ ZB_Undefined,
+ /// \brief The returned value is numeric_limits<T>::max()
+ ZB_Max,
+ /// \brief The returned value is numeric_limits<T>::digits
+ ZB_Width
+};
+
+namespace detail {
+template <typename T, std::size_t SizeOfT> struct LeadingZerosCounter {
+ static std::size_t count(T Val, ZeroBehavior) {
+ if (!Val)
+ return std::numeric_limits<T>::digits;
+
+ // Bisection method.
+ std::size_t ZeroBits = 0;
+ for (T Shift = std::numeric_limits<T>::digits >> 1; Shift; Shift >>= 1) {
+ T Tmp = Val >> Shift;
+ if (Tmp)
+ Val = Tmp;
+ else
+ ZeroBits |= Shift;
+ }
+ return ZeroBits;
+ }
+};
+
+#if __GNUC__ >= 4 || _MSC_VER
+template <typename T> struct LeadingZerosCounter<T, 4> {
+ static std::size_t count(T Val, ZeroBehavior ZB) {
+ if (ZB != ZB_Undefined && Val == 0)
+ return 32;
+
+#if __has_builtin(__builtin_clz) || LLVM_GNUC_PREREQ(4, 0, 0)
+ return __builtin_clz(Val);
+#elif _MSC_VER
+ unsigned long Index;
+ _BitScanReverse(&Index, Val);
+ return Index ^ 31;
+#endif
+ }
+};
+
+#if !defined(_MSC_VER) || defined(_M_X64)
+template <typename T> struct LeadingZerosCounter<T, 8> {
+ static std::size_t count(T Val, ZeroBehavior ZB) {
+ if (ZB != ZB_Undefined && Val == 0)
+ return 64;
+
+#if __has_builtin(__builtin_clzll) || LLVM_GNUC_PREREQ(4, 0, 0)
+ return __builtin_clzll(Val);
+#elif _MSC_VER
+ unsigned long Index;
+ _BitScanReverse64(&Index, Val);
+ return Index ^ 63;
+#endif
+ }
+};
+#endif
+#endif
+} // namespace detail
+
+/// \brief Count number of 0's from the most significant bit to the least
+/// stopping at the first 1.
+///
+/// Only unsigned integral types are allowed.
+///
+/// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are
+/// valid arguments.
+template <typename T>
+std::size_t countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
+ static_assert(std::numeric_limits<T>::is_integer &&
+ !std::numeric_limits<T>::is_signed,
+ "Only unsigned integral types are allowed.");
+ return detail::LeadingZerosCounter<T, sizeof(T)>::count(Val, ZB);
+}
+
+/// Log2_32 - This function returns the floor log base 2 of the specified value,
+/// -1 if the value is zero. (32 bit edition.)
+/// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
+inline unsigned Log2_32(uint32_t Value) {
+ return 31 - countLeadingZeros(Value);
+}
+
+/// Log2_64 - This function returns the floor log base 2 of the specified value,
+/// -1 if the value is zero. (64 bit edition.)
+inline unsigned Log2_64(uint64_t Value) {
+ return 63 - countLeadingZeros(Value);
+}
+
+/// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
+/// value, 32 if the value is zero. (32 bit edition).
+/// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
+inline unsigned Log2_32_Ceil(uint32_t Value) {
+ return 32 - countLeadingZeros(Value - 1);
+}
+
+/// Log2_64_Ceil - This function returns the ceil log base 2 of the specified
+/// value, 64 if the value is zero. (64 bit edition.)
+inline unsigned Log2_64_Ceil(uint64_t Value) {
+ return 64 - countLeadingZeros(Value - 1);
+}
+
+/// BitsToDouble - This function takes a 64-bit integer and returns the bit
+/// equivalent double.
+inline double BitsToDouble(uint64_t Bits) {
+ union {
+ uint64_t L;
+ double D;
+ } T;
+ T.L = Bits;
+ return T.D;
+}
+
+/// BitsToFloat - This function takes a 32-bit integer and returns the bit
+/// equivalent float.
+inline float BitsToFloat(uint32_t Bits) {
+ union {
+ uint32_t I;
+ float F;
+ } T;
+ T.I = Bits;
+ return T.F;
+}
+
+/// DoubleToBits - This function takes a double and returns the bit
+/// equivalent 64-bit integer. Note that copying doubles around
+/// changes the bits of NaNs on some hosts, notably x86, so this
+/// routine cannot be used if these bits are needed.
+inline uint64_t DoubleToBits(double Double) {
+ union {
+ uint64_t L;
+ double D;
+ } T;
+ T.D = Double;
+ return T.L;
+}
+
+/// FloatToBits - This function takes a float and returns the bit
+/// equivalent 32-bit integer. Note that copying floats around
+/// changes the bits of NaNs on some hosts, notably x86, so this
+/// routine cannot be used if these bits are needed.
+inline uint32_t FloatToBits(float Float) {
+ union {
+ uint32_t I;
+ float F;
+ } T;
+ T.F = Float;
+ return T.I;
+}
+
+/// NextPowerOf2 - Returns the next power of two (in 64-bits)
+/// that is strictly greater than A. Returns zero on overflow.
+inline uint64_t NextPowerOf2(uint64_t A) {
+ A |= (A >> 1);
+ A |= (A >> 2);
+ A |= (A >> 4);
+ A |= (A >> 8);
+ A |= (A >> 16);
+ A |= (A >> 32);
+ return A + 1;
+}
+
+} // namespace llvm
+
+#endif