1 //===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file declares the MCSectionCOFF class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_MC_MCSECTIONCOFF_H 14 #define LLVM_MC_MCSECTIONCOFF_H 15 16 #include "llvm/ADT/StringRef.h" 17 #include "llvm/MC/MCSection.h" 18 #include "llvm/MC/SectionKind.h" 19 #include <cassert> 20 21 namespace llvm { 22 23 class MCSymbol; 24 25 /// This represents a section on Windows 26 class MCSectionCOFF final : public MCSection { 27 // The memory for this string is stored in the same MCContext as *this. 28 StringRef SectionName; 29 30 // FIXME: The following fields should not be mutable, but are for now so the 31 // asm parser can honor the .linkonce directive. 32 33 /// This is the Characteristics field of a section, drawn from the enums 34 /// below. 35 mutable unsigned Characteristics; 36 37 /// The unique IDs used with the .pdata and .xdata sections created internally 38 /// by the assembler. This ID is used to ensure that for every .text section, 39 /// there is exactly one .pdata and one .xdata section, which is required by 40 /// the Microsoft incremental linker. This data is mutable because this ID is 41 /// not notionally part of the section. 42 mutable unsigned WinCFISectionID = ~0U; 43 44 /// The COMDAT symbol of this section. Only valid if this is a COMDAT section. 45 /// Two COMDAT sections are merged if they have the same COMDAT symbol. 46 MCSymbol *COMDATSymbol; 47 48 /// This is the Selection field for the section symbol, if it is a COMDAT 49 /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0 50 mutable int Selection; 51 52 private: 53 friend class MCContext; MCSectionCOFF(StringRef Section,unsigned Characteristics,MCSymbol * COMDATSymbol,int Selection,SectionKind K,MCSymbol * Begin)54 MCSectionCOFF(StringRef Section, unsigned Characteristics, 55 MCSymbol *COMDATSymbol, int Selection, SectionKind K, 56 MCSymbol *Begin) 57 : MCSection(SV_COFF, K, Begin), SectionName(Section), 58 Characteristics(Characteristics), COMDATSymbol(COMDATSymbol), 59 Selection(Selection) { 60 assert((Characteristics & 0x00F00000) == 0 && 61 "alignment must not be set upon section creation"); 62 } 63 64 public: 65 /// Decides whether a '.section' directive should be printed before the 66 /// section name 67 bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const; 68 getSectionName()69 StringRef getSectionName() const { return SectionName; } getCharacteristics()70 unsigned getCharacteristics() const { return Characteristics; } getCOMDATSymbol()71 MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; } getSelection()72 int getSelection() const { return Selection; } 73 74 void setSelection(int Selection) const; 75 76 void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T, 77 raw_ostream &OS, 78 const MCExpr *Subsection) const override; 79 bool UseCodeAlign() const override; 80 bool isVirtualSection() const override; 81 getOrAssignWinCFISectionID(unsigned * NextID)82 unsigned getOrAssignWinCFISectionID(unsigned *NextID) const { 83 if (WinCFISectionID == ~0U) 84 WinCFISectionID = (*NextID)++; 85 return WinCFISectionID; 86 } 87 isImplicitlyDiscardable(StringRef Name)88 static bool isImplicitlyDiscardable(StringRef Name) { 89 return Name.startswith(".debug"); 90 } 91 classof(const MCSection * S)92 static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; } 93 }; 94 95 } // end namespace llvm 96 97 #endif // LLVM_MC_MCSECTIONCOFF_H 98