Update prebuilt Clang to r416183b from Android.

https://android.googlesource.com/platform/prebuilts/clang/host/
linux-x86/+/06a71ddac05c22edb2d10b590e1769b3f8619bef

clang 12.0.5 (based on r416183b) from build 7284624.

Change-Id: I277a316abcf47307562d8b748b84870f31a72866
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/linux-x64/clang/include/llvm/Support/MathExtras.h b/linux-x64/clang/include/llvm/Support/MathExtras.h
index 85d5a5a..33b9065 100644
--- a/linux-x64/clang/include/llvm/Support/MathExtras.h
+++ b/linux-x64/clang/include/llvm/Support/MathExtras.h
@@ -14,10 +14,11 @@
 #define LLVM_SUPPORT_MATHEXTRAS_H
 
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/SwapByteOrder.h"
 #include <algorithm>
 #include <cassert>
 #include <climits>
+#include <cmath>
+#include <cstdint>
 #include <cstring>
 #include <limits>
 #include <type_traits>
@@ -39,6 +40,7 @@
 #endif
 
 namespace llvm {
+
 /// The behavior an operation has on an input of 0.
 enum ZeroBehavior {
   /// The returned value is undefined.
@@ -49,6 +51,42 @@
   ZB_Width
 };
 
+/// Mathematical constants.
+namespace numbers {
+// TODO: Track C++20 std::numbers.
+// TODO: Favor using the hexadecimal FP constants (requires C++17).
+constexpr double e          = 2.7182818284590452354, // (0x1.5bf0a8b145749P+1) https://oeis.org/A001113
+                 egamma     = .57721566490153286061, // (0x1.2788cfc6fb619P-1) https://oeis.org/A001620
+                 ln2        = .69314718055994530942, // (0x1.62e42fefa39efP-1) https://oeis.org/A002162
+                 ln10       = 2.3025850929940456840, // (0x1.24bb1bbb55516P+1) https://oeis.org/A002392
+                 log2e      = 1.4426950408889634074, // (0x1.71547652b82feP+0)
+                 log10e     = .43429448190325182765, // (0x1.bcb7b1526e50eP-2)
+                 pi         = 3.1415926535897932385, // (0x1.921fb54442d18P+1) https://oeis.org/A000796
+                 inv_pi     = .31830988618379067154, // (0x1.45f306bc9c883P-2) https://oeis.org/A049541
+                 sqrtpi     = 1.7724538509055160273, // (0x1.c5bf891b4ef6bP+0) https://oeis.org/A002161
+                 inv_sqrtpi = .56418958354775628695, // (0x1.20dd750429b6dP-1) https://oeis.org/A087197
+                 sqrt2      = 1.4142135623730950488, // (0x1.6a09e667f3bcdP+0) https://oeis.org/A00219
+                 inv_sqrt2  = .70710678118654752440, // (0x1.6a09e667f3bcdP-1)
+                 sqrt3      = 1.7320508075688772935, // (0x1.bb67ae8584caaP+0) https://oeis.org/A002194
+                 inv_sqrt3  = .57735026918962576451, // (0x1.279a74590331cP-1)
+                 phi        = 1.6180339887498948482; // (0x1.9e3779b97f4a8P+0) https://oeis.org/A001622
+constexpr float ef          = 2.71828183F, // (0x1.5bf0a8P+1) https://oeis.org/A001113
+                egammaf     = .577215665F, // (0x1.2788d0P-1) https://oeis.org/A001620
+                ln2f        = .693147181F, // (0x1.62e430P-1) https://oeis.org/A002162
+                ln10f       = 2.30258509F, // (0x1.26bb1cP+1) https://oeis.org/A002392
+                log2ef      = 1.44269504F, // (0x1.715476P+0)
+                log10ef     = .434294482F, // (0x1.bcb7b2P-2)
+                pif         = 3.14159265F, // (0x1.921fb6P+1) https://oeis.org/A000796
+                inv_pif     = .318309886F, // (0x1.45f306P-2) https://oeis.org/A049541
+                sqrtpif     = 1.77245385F, // (0x1.c5bf8aP+0) https://oeis.org/A002161
+                inv_sqrtpif = .564189584F, // (0x1.20dd76P-1) https://oeis.org/A087197
+                sqrt2f      = 1.41421356F, // (0x1.6a09e6P+0) https://oeis.org/A002193
+                inv_sqrt2f  = .707106781F, // (0x1.6a09e6P-1)
+                sqrt3f      = 1.73205081F, // (0x1.bb67aeP+0) https://oeis.org/A002194
+                inv_sqrt3f  = .577350269F, // (0x1.279a74P-1)
+                phif        = 1.61803399F; // (0x1.9e377aP+0) https://oeis.org/A001622
+} // namespace numbers
+
 namespace detail {
 template <typename T, std::size_t SizeOfT> struct TrailingZerosCounter {
   static unsigned count(T Val, ZeroBehavior) {
@@ -73,13 +111,13 @@
   }
 };
 
-#if __GNUC__ >= 4 || defined(_MSC_VER)
+#if defined(__GNUC__) || defined(_MSC_VER)
 template <typename T> struct TrailingZerosCounter<T, 4> {
   static unsigned count(T Val, ZeroBehavior ZB) {
     if (ZB != ZB_Undefined && Val == 0)
       return 32;
 
-#if __has_builtin(__builtin_ctz) || LLVM_GNUC_PREREQ(4, 0, 0)
+#if __has_builtin(__builtin_ctz) || defined(__GNUC__)
     return __builtin_ctz(Val);
 #elif defined(_MSC_VER)
     unsigned long Index;
@@ -95,7 +133,7 @@
     if (ZB != ZB_Undefined && Val == 0)
       return 64;
 
-#if __has_builtin(__builtin_ctzll) || LLVM_GNUC_PREREQ(4, 0, 0)
+#if __has_builtin(__builtin_ctzll) || defined(__GNUC__)
     return __builtin_ctzll(Val);
 #elif defined(_MSC_VER)
     unsigned long Index;
@@ -142,13 +180,13 @@
   }
 };
 
-#if __GNUC__ >= 4 || defined(_MSC_VER)
+#if defined(__GNUC__) || defined(_MSC_VER)
 template <typename T> struct LeadingZerosCounter<T, 4> {
   static unsigned count(T Val, ZeroBehavior ZB) {
     if (ZB != ZB_Undefined && Val == 0)
       return 32;
 
-#if __has_builtin(__builtin_clz) || LLVM_GNUC_PREREQ(4, 0, 0)
+#if __has_builtin(__builtin_clz) || defined(__GNUC__)
     return __builtin_clz(Val);
 #elif defined(_MSC_VER)
     unsigned long Index;
@@ -164,7 +202,7 @@
     if (ZB != ZB_Undefined && Val == 0)
       return 64;
 
-#if __has_builtin(__builtin_clzll) || LLVM_GNUC_PREREQ(4, 0, 0)
+#if __has_builtin(__builtin_clzll) || defined(__GNUC__)
     return __builtin_clzll(Val);
 #elif defined(_MSC_VER)
     unsigned long Index;
@@ -275,6 +313,34 @@
   return Val;
 }
 
+#if __has_builtin(__builtin_bitreverse8)
+template<>
+inline uint8_t reverseBits<uint8_t>(uint8_t Val) {
+  return __builtin_bitreverse8(Val);
+}
+#endif
+
+#if __has_builtin(__builtin_bitreverse16)
+template<>
+inline uint16_t reverseBits<uint16_t>(uint16_t Val) {
+  return __builtin_bitreverse16(Val);
+}
+#endif
+
+#if __has_builtin(__builtin_bitreverse32)
+template<>
+inline uint32_t reverseBits<uint32_t>(uint32_t Val) {
+  return __builtin_bitreverse32(Val);
+}
+#endif
+
+#if __has_builtin(__builtin_bitreverse64)
+template<>
+inline uint64_t reverseBits<uint64_t>(uint64_t Val) {
+  return __builtin_bitreverse64(Val);
+}
+#endif
+
 // NOTE: The following support functions use the _32/_64 extensions instead of
 // type overloading so that signed and unsigned integers can be used without
 // ambiguity.
@@ -327,14 +393,12 @@
 /// to keep MSVC from (incorrectly) warning on isUInt<64> that we're shifting
 /// left too many places.
 template <unsigned N>
-constexpr inline typename std::enable_if<(N < 64), bool>::type
-isUInt(uint64_t X) {
+constexpr inline std::enable_if_t<(N < 64), bool> isUInt(uint64_t X) {
   static_assert(N > 0, "isUInt<0> doesn't make sense");
   return X < (UINT64_C(1) << (N));
 }
 template <unsigned N>
-constexpr inline typename std::enable_if<N >= 64, bool>::type
-isUInt(uint64_t X) {
+constexpr inline std::enable_if_t<N >= 64, bool> isUInt(uint64_t X) {
   return true;
 }
 
@@ -376,7 +440,7 @@
 inline int64_t minIntN(int64_t N) {
   assert(N > 0 && N <= 64 && "integer width out of range");
 
-  return -(UINT64_C(1)<<(N-1));
+  return UINT64_C(1) + ~(UINT64_C(1) << (N - 1));
 }
 
 /// Gets the maximum value for a N-bit signed integer.
@@ -434,21 +498,6 @@
   return Value && !(Value & (Value - 1));
 }
 
-/// Return a byte-swapped representation of the 16-bit argument.
-inline uint16_t ByteSwap_16(uint16_t Value) {
-  return sys::SwapByteOrder_16(Value);
-}
-
-/// Return a byte-swapped representation of the 32-bit argument.
-inline uint32_t ByteSwap_32(uint32_t Value) {
-  return sys::SwapByteOrder_32(Value);
-}
-
-/// Return a byte-swapped representation of the 64-bit argument.
-inline uint64_t ByteSwap_64(uint64_t Value) {
-  return sys::SwapByteOrder_64(Value);
-}
-
 /// Count the number of ones from the most significant bit to the first
 /// zero bit.
 ///
@@ -486,7 +535,7 @@
   static unsigned count(T Value) {
     // Generic version, forward to 32 bits.
     static_assert(SizeOfT <= 4, "Not implemented!");
-#if __GNUC__ >= 4
+#if defined(__GNUC__)
     return __builtin_popcount(Value);
 #else
     uint32_t v = Value;
@@ -499,7 +548,7 @@
 
 template <typename T> struct PopulationCounter<T, 8> {
   static unsigned count(T Value) {
-#if __GNUC__ >= 4
+#if defined(__GNUC__)
     return __builtin_popcountll(Value);
 #else
     uint64_t v = Value;
@@ -523,6 +572,16 @@
   return detail::PopulationCounter<T, sizeof(T)>::count(Value);
 }
 
+/// Compile time Log2.
+/// Valid only for positive powers of two.
+template <size_t kValue> constexpr inline size_t CTLog2() {
+  static_assert(kValue > 0 && llvm::isPowerOf2_64(kValue),
+                "Value is not a valid power of 2");
+  return 1 + CTLog2<kValue / 2>();
+}
+
+template <> constexpr inline size_t CTLog2<1>() { return 0; }
+
 /// Return the log base 2 of the specified value.
 inline double Log2(double Value) {
 #if defined(__ANDROID_API__) && __ANDROID_API__ < 18
@@ -559,15 +618,20 @@
 }
 
 /// Return the greatest common divisor of the values using Euclid's algorithm.
-inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) {
+template <typename T>
+inline T greatestCommonDivisor(T A, T B) {
   while (B) {
-    uint64_t T = B;
+    T Tmp = B;
     B = A % B;
-    A = T;
+    A = Tmp;
   }
   return A;
 }
 
+inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) {
+  return greatestCommonDivisor<uint64_t>(A, B);
+}
+
 /// This function takes a 64-bit integer and returns the bit equivalent double.
 inline double BitsToDouble(uint64_t Bits) {
   double D;
@@ -615,25 +679,6 @@
   return (A | B) & (1 + ~(A | B));
 }
 
-/// Aligns \c Addr to \c Alignment bytes, rounding up.
-///
-/// Alignment should be a power of two.  This method rounds up, so
-/// alignAddr(7, 4) == 8 and alignAddr(8, 4) == 8.
-inline uintptr_t alignAddr(const void *Addr, size_t Alignment) {
-  assert(Alignment && isPowerOf2_64((uint64_t)Alignment) &&
-         "Alignment is not a power of two!");
-
-  assert((uintptr_t)Addr + Alignment - 1 >= (uintptr_t)Addr);
-
-  return (((uintptr_t)Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1));
-}
-
-/// Returns the necessary adjustment for aligning \c Ptr to \c Alignment
-/// bytes, rounding up.
-inline size_t alignmentAdjustment(const void *Ptr, size_t Alignment) {
-  return alignAddr(Ptr, Alignment) - (uintptr_t)Ptr;
-}
-
 /// 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) {
@@ -699,18 +744,10 @@
   return alignTo(Numerator, Denominator) / Denominator;
 }
 
-/// \c alignTo for contexts where a constant expression is required.
-/// \sa alignTo
-///
-/// \todo FIXME: remove when \c constexpr becomes really \c constexpr
-template <uint64_t Align>
-struct AlignTo {
-  static_assert(Align != 0u, "Align must be non-zero");
-  template <uint64_t Value>
-  struct from_value {
-    static const uint64_t value = (Value + Align - 1) / Align * Align;
-  };
-};
+/// Returns the integer nearest(Numerator / Denominator).
+inline uint64_t divideNearest(uint64_t Numerator, uint64_t Denominator) {
+  return (Numerator + (Denominator / 2)) / Denominator;
+}
 
 /// Returns the largest uint64_t less than or equal to \p Value and is
 /// \p Skew mod \p Align. \p Align must be non-zero
@@ -720,13 +757,6 @@
   return (Value - Skew) / Align * Align + Skew;
 }
 
-/// Returns the offset to the next integer (mod 2**64) that is greater than
-/// or equal to \p Value and is a multiple of \p Align. \p Align must be
-/// non-zero.
-inline uint64_t OffsetToAlignment(uint64_t Value, uint64_t Align) {
-  return alignTo(Value, Align) - Value;
-}
-
 /// Sign-extend the number in the bottom B bits of X to a 32-bit integer.
 /// Requires 0 < B <= 32.
 template <unsigned B> constexpr inline int32_t SignExtend32(uint32_t X) {
@@ -762,8 +792,7 @@
 /// Subtract two unsigned integers, X and Y, of type T and return the absolute
 /// value of the result.
 template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, T>::type
-AbsoluteDifference(T X, T Y) {
+std::enable_if_t<std::is_unsigned<T>::value, T> AbsoluteDifference(T X, T Y) {
   return std::max(X, Y) - std::min(X, Y);
 }
 
@@ -771,7 +800,7 @@
 /// maximum representable value of T on overflow.  ResultOverflowed indicates if
 /// the result is larger than the maximum representable value of type T.
 template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, T>::type
+std::enable_if_t<std::is_unsigned<T>::value, T>
 SaturatingAdd(T X, T Y, bool *ResultOverflowed = nullptr) {
   bool Dummy;
   bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
@@ -788,7 +817,7 @@
 /// maximum representable value of T on overflow.  ResultOverflowed indicates if
 /// the result is larger than the maximum representable value of type T.
 template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, T>::type
+std::enable_if_t<std::is_unsigned<T>::value, T>
 SaturatingMultiply(T X, T Y, bool *ResultOverflowed = nullptr) {
   bool Dummy;
   bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
@@ -834,7 +863,7 @@
 /// overflow. ResultOverflowed indicates if the result is larger than the
 /// maximum representable value of type T.
 template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, T>::type
+std::enable_if_t<std::is_unsigned<T>::value, T>
 SaturatingMultiplyAdd(T X, T Y, T A, bool *ResultOverflowed = nullptr) {
   bool Dummy;
   bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
@@ -848,6 +877,87 @@
 
 /// Use this rather than HUGE_VALF; the latter causes warnings on MSVC.
 extern const float huge_valf;
+
+
+/// Add two signed integers, computing the two's complement truncated result,
+/// returning true if overflow occured.
+template <typename T>
+std::enable_if_t<std::is_signed<T>::value, T> AddOverflow(T X, T Y, T &Result) {
+#if __has_builtin(__builtin_add_overflow)
+  return __builtin_add_overflow(X, Y, &Result);
+#else
+  // Perform the unsigned addition.
+  using U = std::make_unsigned_t<T>;
+  const U UX = static_cast<U>(X);
+  const U UY = static_cast<U>(Y);
+  const U UResult = UX + UY;
+
+  // Convert to signed.
+  Result = static_cast<T>(UResult);
+
+  // Adding two positive numbers should result in a positive number.
+  if (X > 0 && Y > 0)
+    return Result <= 0;
+  // Adding two negatives should result in a negative number.
+  if (X < 0 && Y < 0)
+    return Result >= 0;
+  return false;
+#endif
+}
+
+/// Subtract two signed integers, computing the two's complement truncated
+/// result, returning true if an overflow ocurred.
+template <typename T>
+std::enable_if_t<std::is_signed<T>::value, T> SubOverflow(T X, T Y, T &Result) {
+#if __has_builtin(__builtin_sub_overflow)
+  return __builtin_sub_overflow(X, Y, &Result);
+#else
+  // Perform the unsigned addition.
+  using U = std::make_unsigned_t<T>;
+  const U UX = static_cast<U>(X);
+  const U UY = static_cast<U>(Y);
+  const U UResult = UX - UY;
+
+  // Convert to signed.
+  Result = static_cast<T>(UResult);
+
+  // Subtracting a positive number from a negative results in a negative number.
+  if (X <= 0 && Y > 0)
+    return Result >= 0;
+  // Subtracting a negative number from a positive results in a positive number.
+  if (X >= 0 && Y < 0)
+    return Result <= 0;
+  return false;
+#endif
+}
+
+/// Multiply two signed integers, computing the two's complement truncated
+/// result, returning true if an overflow ocurred.
+template <typename T>
+std::enable_if_t<std::is_signed<T>::value, T> MulOverflow(T X, T Y, T &Result) {
+  // Perform the unsigned multiplication on absolute values.
+  using U = std::make_unsigned_t<T>;
+  const U UX = X < 0 ? (0 - static_cast<U>(X)) : static_cast<U>(X);
+  const U UY = Y < 0 ? (0 - static_cast<U>(Y)) : static_cast<U>(Y);
+  const U UResult = UX * UY;
+
+  // Convert to signed.
+  const bool IsNegative = (X < 0) ^ (Y < 0);
+  Result = IsNegative ? (0 - UResult) : UResult;
+
+  // If any of the args was 0, result is 0 and no overflow occurs.
+  if (UX == 0 || UY == 0)
+    return false;
+
+  // UX and UY are in [1, 2^n], where n is the number of digits.
+  // Check how the max allowed absolute value (2^n for negative, 2^(n-1) for
+  // positive) divided by an argument compares to the other.
+  if (IsNegative)
+    return UX > (static_cast<U>(std::numeric_limits<T>::max()) + U(1)) / UY;
+  else
+    return UX > (static_cast<U>(std::numeric_limits<T>::max())) / UY;
+}
+
 } // End llvm namespace
 
 #endif