Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/MC/MCSectionCOFF.h b/linux-x64/clang/include/llvm/MC/MCSectionCOFF.h
new file mode 100644
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+++ b/linux-x64/clang/include/llvm/MC/MCSectionCOFF.h
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+//===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the MCSectionCOFF class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCSECTIONCOFF_H
+#define LLVM_MC_MCSECTIONCOFF_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/MC/MCSection.h"
+#include "llvm/MC/SectionKind.h"
+#include <cassert>
+
+namespace llvm {
+
+class MCSymbol;
+
+/// This represents a section on Windows
+class MCSectionCOFF final : public MCSection {
+  // The memory for this string is stored in the same MCContext as *this.
+  StringRef SectionName;
+
+  // FIXME: The following fields should not be mutable, but are for now so the
+  // asm parser can honor the .linkonce directive.
+
+  /// This is the Characteristics field of a section, drawn from the enums
+  /// below.
+  mutable unsigned Characteristics;
+
+  /// The unique IDs used with the .pdata and .xdata sections created internally
+  /// by the assembler. This ID is used to ensure that for every .text section,
+  /// there is exactly one .pdata and one .xdata section, which is required by
+  /// the Microsoft incremental linker. This data is mutable because this ID is
+  /// not notionally part of the section.
+  mutable unsigned WinCFISectionID = ~0U;
+
+  /// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
+  /// Two COMDAT sections are merged if they have the same COMDAT symbol.
+  MCSymbol *COMDATSymbol;
+
+  /// This is the Selection field for the section symbol, if it is a COMDAT
+  /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
+  mutable int Selection;
+
+private:
+  friend class MCContext;
+  MCSectionCOFF(StringRef Section, unsigned Characteristics,
+                MCSymbol *COMDATSymbol, int Selection, SectionKind K,
+                MCSymbol *Begin)
+      : MCSection(SV_COFF, K, Begin), SectionName(Section),
+        Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
+        Selection(Selection) {
+    assert((Characteristics & 0x00F00000) == 0 &&
+           "alignment must not be set upon section creation");
+  }
+
+public:
+  ~MCSectionCOFF();
+
+  /// Decides whether a '.section' directive should be printed before the
+  /// section name
+  bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
+
+  StringRef getSectionName() const { return SectionName; }
+  unsigned getCharacteristics() const { return Characteristics; }
+  MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
+  int getSelection() const { return Selection; }
+
+  void setSelection(int Selection) const;
+
+  void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
+                            raw_ostream &OS,
+                            const MCExpr *Subsection) const override;
+  bool UseCodeAlign() const override;
+  bool isVirtualSection() const override;
+
+  unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
+    if (WinCFISectionID == ~0U)
+      WinCFISectionID = (*NextID)++;
+    return WinCFISectionID;
+  }
+
+  static bool isImplicitlyDiscardable(StringRef Name) {
+    return Name.startswith(".debug");
+  }
+
+  static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_MC_MCSECTIONCOFF_H