Line data    Source code

       1             : //===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This file declares the MCSectionCOFF class.
      11             : //
      12             : //===----------------------------------------------------------------------===//
      13             : 
      14             : #ifndef LLVM_MC_MCSECTIONCOFF_H
      15             : #define LLVM_MC_MCSECTIONCOFF_H
      16             : 
      17             : #include "llvm/ADT/StringRef.h"
      18             : #include "llvm/MC/MCSection.h"
      19             : #include "llvm/MC/SectionKind.h"
      20             : #include <cassert>
      21             : 
      22             : namespace llvm {
      23             : 
      24             : class MCSymbol;
      25             : 
      26             : /// This represents a section on Windows
      27       50223 : class MCSectionCOFF final : public MCSection {
      28             :   // The memory for this string is stored in the same MCContext as *this.
      29             :   StringRef SectionName;
      30             : 
      31             :   // FIXME: The following fields should not be mutable, but are for now so the
      32             :   // asm parser can honor the .linkonce directive.
      33             : 
      34             :   /// This is the Characteristics field of a section, drawn from the enums
      35             :   /// below.
      36             :   mutable unsigned Characteristics;
      37             : 
      38             :   /// The unique IDs used with the .pdata and .xdata sections created internally
      39             :   /// by the assembler. This ID is used to ensure that for every .text section,
      40             :   /// there is exactly one .pdata and one .xdata section, which is required by
      41             :   /// the Microsoft incremental linker. This data is mutable because this ID is
      42             :   /// not notionally part of the section.
      43             :   mutable unsigned WinCFISectionID = ~0U;
      44             : 
      45             :   /// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
      46             :   /// Two COMDAT sections are merged if they have the same COMDAT symbol.
      47             :   MCSymbol *COMDATSymbol;
      48             : 
      49             :   /// This is the Selection field for the section symbol, if it is a COMDAT
      50             :   /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
      51             :   mutable int Selection;
      52             : 
      53             : private:
      54             :   friend class MCContext;
      55             :   MCSectionCOFF(StringRef Section, unsigned Characteristics,
      56             :                 MCSymbol *COMDATSymbol, int Selection, SectionKind K,
      57             :                 MCSymbol *Begin)
      58       50555 :       : MCSection(SV_COFF, K, Begin), SectionName(Section),
      59             :         Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
      60       50555 :         Selection(Selection) {
      61             :     assert((Characteristics & 0x00F00000) == 0 &&
      62             :            "alignment must not be set upon section creation");
      63             :   }
      64             : 
      65             : public:
      66             :   ~MCSectionCOFF();
      67             : 
      68             :   /// Decides whether a '.section' directive should be printed before the
      69             :   /// section name
      70             :   bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
      71             : 
      72           0 :   StringRef getSectionName() const { return SectionName; }
      73           0 :   unsigned getCharacteristics() const { return Characteristics; }
      74           0 :   MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
      75           0 :   int getSelection() const { return Selection; }
      76             : 
      77             :   void setSelection(int Selection) const;
      78             : 
      79             :   void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
      80             :                             raw_ostream &OS,
      81             :                             const MCExpr *Subsection) const override;
      82             :   bool UseCodeAlign() const override;
      83             :   bool isVirtualSection() const override;
      84             : 
      85           0 :   unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
      86         116 :     if (WinCFISectionID == ~0U)
      87          42 :       WinCFISectionID = (*NextID)++;
      88         116 :     return WinCFISectionID;
      89             :   }
      90             : 
      91             :   static bool isImplicitlyDiscardable(StringRef Name) {
      92             :     return Name.startswith(".debug");
      93             :   }
      94             : 
      95         403 :   static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
      96             : };
      97             : 
      98             : } // end namespace llvm
      99             : 
     100             : #endif // LLVM_MC_MCSECTIONCOFF_H