Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/Support/CheckedArithmetic.h b/linux-x64/clang/include/llvm/Support/CheckedArithmetic.h
new file mode 100644
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+++ b/linux-x64/clang/include/llvm/Support/CheckedArithmetic.h
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+//==-- llvm/Support/CheckedArithmetic.h - Safe arithmetical operations *- 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 generic functions for operating on integers which
+// give the indication on whether the operation has overflown.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_CHECKEDARITHMETIC_H
+#define LLVM_SUPPORT_CHECKEDARITHMETIC_H
+
+#include "llvm/ADT/APInt.h"
+
+#include <type_traits>
+
+namespace {
+
+/// Utility function to apply a given method of \c APInt \p F to \p LHS and
+/// \p RHS, and write the output into \p Res.
+/// \return Whether the operation overflows.
+template <typename T, typename F>
+typename std::enable_if<std::is_integral<T>::value && sizeof(T) * 8 <= 64,
+ bool>::type
+checkedOp(T LHS, T RHS, F Op, T *Res = nullptr, bool Signed = true) {
+ llvm::APInt ALHS(/*BitSize=*/sizeof(T) * 8, LHS, Signed);
+ llvm::APInt ARHS(/*BitSize=*/sizeof(T) * 8, RHS, Signed);
+ bool Overflow;
+ llvm::APInt Out = (ALHS.*Op)(ARHS, Overflow);
+ if (Res)
+ *Res = Signed ? Out.getSExtValue() : Out.getZExtValue();
+ return Overflow;
+}
+}
+
+namespace llvm {
+
+/// Add two signed integers \p LHS and \p RHS, write into \p Res if non-null.
+/// Does not guarantee saturating arithmetic.
+/// \return Whether the result overflows.
+template <typename T>
+typename std::enable_if<std::is_signed<T>::value, bool>::type
+checkedAdd(T LHS, T RHS, T *Res = nullptr) {
+ return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov, Res);
+}
+
+/// Multiply two signed integers \p LHS and \p RHS, write into \p Res if
+/// non-null.
+/// Does not guarantee saturating arithmetic.
+/// \return Whether the result overflows.
+template <typename T>
+typename std::enable_if<std::is_signed<T>::value, bool>::type
+checkedMul(T LHS, T RHS, T *Res = nullptr) {
+ return checkedOp(LHS, RHS, &llvm::APInt::smul_ov, Res);
+}
+
+/// Add two unsigned integers \p LHS and \p RHS, write into \p Res if non-null.
+/// Does not guarantee saturating arithmetic.
+/// \return Whether the result overflows.
+template <typename T>
+typename std::enable_if<std::is_unsigned<T>::value, bool>::type
+checkedAddUnsigned(T LHS, T RHS, T *Res = nullptr) {
+ return checkedOp(LHS, RHS, &llvm::APInt::uadd_ov, Res, /*Signed=*/false);
+}
+
+/// Multiply two unsigned integers \p LHS and \p RHS, write into \p Res if
+/// non-null.
+/// Does not guarantee saturating arithmetic.
+/// \return Whether the result overflows.
+template <typename T>
+typename std::enable_if<std::is_unsigned<T>::value, bool>::type
+checkedMulUnsigned(T LHS, T RHS, T *Res = nullptr) {
+ return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, Res, /*Signed=*/false);
+}
+
+} // End llvm namespace
+
+#endif