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diff --git a/lib/ubsan/ubsan_value.h b/lib/ubsan/ubsan_value.h
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+++ b/lib/ubsan/ubsan_value.h
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+//===-- ubsan_value.h -------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Representation of data which is passed from the compiler-generated calls into
+// the ubsan runtime.
+//
+//===----------------------------------------------------------------------===//
+#ifndef UBSAN_VALUE_H
+#define UBSAN_VALUE_H
+
+// For now, only support linux and darwin. Other platforms should be easy to
+// add, and probably work as-is.
+#if !defined(__linux__) && !defined(__APPLE__)
+#error "UBSan not supported for this platform!"
+#endif
+
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_common.h"
+
+// FIXME: Move this out to a config header.
+#if __SIZEOF_INT128__
+typedef __int128 s128;
+typedef unsigned __int128 u128;
+#define HAVE_INT128_T 1
+#else
+#define HAVE_INT128_T 0
+#endif
+
+
+namespace __ubsan {
+
+/// \brief Largest integer types we support.
+#if HAVE_INT128_T
+typedef s128 SIntMax;
+typedef u128 UIntMax;
+#else
+typedef s64 SIntMax;
+typedef u64 UIntMax;
+#endif
+
+/// \brief Largest floating-point type we support.
+typedef long double FloatMax;
+
+/// \brief A description of a source location. This corresponds to Clang's
+/// \c PresumedLoc type.
+class SourceLocation {
+  const char *Filename;
+  u32 Line;
+  u32 Column;
+
+public:
+  SourceLocation() : Filename(), Line(), Column() {}
+  SourceLocation(const char *Filename, unsigned Line, unsigned Column)
+    : Filename(Filename), Line(Line), Column(Column) {}
+
+  /// \brief Determine whether the source location is known.
+  bool isInvalid() const { return !Filename; }
+
+  /// \brief Atomically acquire a copy, disabling original in-place.
+  /// Exactly one call to acquire() returns a copy that isn't disabled.
+  SourceLocation acquire() {
+    u32 OldColumn = __sanitizer::atomic_exchange(
+                        (__sanitizer::atomic_uint32_t *)&Column, ~u32(0),
+                        __sanitizer::memory_order_relaxed);
+    return SourceLocation(Filename, Line, OldColumn);
+  }
+
+  /// \brief Determine if this Location has been disabled.
+  /// Disabled SourceLocations are invalid to use.
+  bool isDisabled() {
+    return Column == ~u32(0);
+  }
+
+  /// \brief Get the presumed filename for the source location.
+  const char *getFilename() const { return Filename; }
+  /// \brief Get the presumed line number.
+  unsigned getLine() const { return Line; }
+  /// \brief Get the column within the presumed line.
+  unsigned getColumn() const { return Column; }
+};
+
+
+/// \brief A description of a type.
+class TypeDescriptor {
+  /// A value from the \c Kind enumeration, specifying what flavor of type we
+  /// have.
+  u16 TypeKind;
+
+  /// A \c Type-specific value providing information which allows us to
+  /// interpret the meaning of a ValueHandle of this type.
+  u16 TypeInfo;
+
+  /// The name of the type follows, in a format suitable for including in
+  /// diagnostics.
+  char TypeName[1];
+
+public:
+  enum Kind {
+    /// An integer type. Lowest bit is 1 for a signed value, 0 for an unsigned
+    /// value. Remaining bits are log_2(bit width). The value representation is
+    /// the integer itself if it fits into a ValueHandle, and a pointer to the
+    /// integer otherwise.
+    TK_Integer = 0x0000,
+    /// A floating-point type. Low 16 bits are bit width. The value
+    /// representation is a pointer to the floating-point value.
+    TK_Float = 0x0001,
+    /// Any other type. The value representation is unspecified.
+    TK_Unknown = 0xffff
+  };
+
+  const char *getTypeName() const { return TypeName; }
+
+  Kind getKind() const {
+    return static_cast<Kind>(TypeKind);
+  }
+
+  bool isIntegerTy() const { return getKind() == TK_Integer; }
+  bool isSignedIntegerTy() const {
+    return isIntegerTy() && (TypeInfo & 1);
+  }
+  bool isUnsignedIntegerTy() const {
+    return isIntegerTy() && !(TypeInfo & 1);
+  }
+  unsigned getIntegerBitWidth() const {
+    CHECK(isIntegerTy());
+    return 1 << (TypeInfo >> 1);
+  }
+
+  bool isFloatTy() const { return getKind() == TK_Float; }
+  unsigned getFloatBitWidth() const {
+    CHECK(isFloatTy());
+    return TypeInfo;
+  }
+};
+
+/// \brief An opaque handle to a value.
+typedef uptr ValueHandle;
+
+
+/// \brief Representation of an operand value provided by the instrumented code.
+///
+/// This is a combination of a TypeDescriptor (which is emitted as constant data
+/// as an operand to a handler function) and a ValueHandle (which is passed at
+/// runtime when a check failure occurs).
+class Value {
+  /// The type of the value.
+  const TypeDescriptor &Type;
+  /// The encoded value itself.
+  ValueHandle Val;
+
+  /// Is \c Val a (zero-extended) integer?
+  bool isInlineInt() const {
+    CHECK(getType().isIntegerTy());
+    const unsigned InlineBits = sizeof(ValueHandle) * 8;
+    const unsigned Bits = getType().getIntegerBitWidth();
+    return Bits <= InlineBits;
+  }
+
+public:
+  Value(const TypeDescriptor &Type, ValueHandle Val) : Type(Type), Val(Val) {}
+
+  const TypeDescriptor &getType() const { return Type; }
+
+  /// \brief Get this value as a signed integer.
+  SIntMax getSIntValue() const;
+
+  /// \brief Get this value as an unsigned integer.
+  UIntMax getUIntValue() const;
+
+  /// \brief Decode this value, which must be a positive or unsigned integer.
+  UIntMax getPositiveIntValue() const;
+
+  /// Is this an integer with value -1?
+  bool isMinusOne() const {
+    return getType().isSignedIntegerTy() && getSIntValue() == -1;
+  }
+
+  /// Is this a negative integer?
+  bool isNegative() const {
+    return getType().isSignedIntegerTy() && getSIntValue() < 0;
+  }
+
+  /// \brief Get this value as a floating-point quantity.
+  FloatMax getFloatValue() const;
+};
+
+} // namespace __ubsan
+
+#endif // UBSAN_VALUE_H