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Summary: This adds a unique ID to the COFF section uniquing map, similar to the one we have for ELF. The unique id is not currently exposed via the assembler because we don't have a use case for it yet. Users generally create .pdata with the .seh_* family of directives, and the assembler internally needs to produce .pdata and .xdata sections corresponding to the code section. The association between .text sections and the assembler-created .xdata and .pdata sections is maintained as an ID field of MCSectionCOFF. The CFI-related sections are created with the given unique ID, so if more code is added to the same text section, we can find and reuse the CFI sections that were already created. Reviewers: majnemer, rafael Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D19376 llvm-svn: 268331
93 lines
3.2 KiB
C++
93 lines
3.2 KiB
C++
//===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares the MCSectionCOFF class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCSECTIONCOFF_H
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#define LLVM_MC_MCSECTIONCOFF_H
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#include "llvm/ADT/StringRef.h"
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#include "llvm/MC/MCSection.h"
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namespace llvm {
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class MCSymbol;
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/// This represents a section on Windows
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class MCSectionCOFF final : public MCSection {
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// The memory for this string is stored in the same MCContext as *this.
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StringRef SectionName;
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// FIXME: The following fields should not be mutable, but are for now so the
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// asm parser can honor the .linkonce directive.
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/// This is the Characteristics field of a section, drawn from the enums
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/// below.
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mutable unsigned Characteristics;
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/// The unique IDs used with the .pdata and .xdata sections created internally
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/// by the assembler. This ID is used to ensure that for every .text section,
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/// there is exactly one .pdata and one .xdata section, which is required by
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/// the Microsoft incremental linker. This data is mutable because this ID is
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/// not notionally part of the section.
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mutable unsigned WinCFISectionID = ~0U;
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/// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
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/// Two COMDAT sections are merged if they have the same COMDAT symbol.
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MCSymbol *COMDATSymbol;
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/// This is the Selection field for the section symbol, if it is a COMDAT
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/// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
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mutable int Selection;
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private:
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friend class MCContext;
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MCSectionCOFF(StringRef Section, unsigned Characteristics,
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MCSymbol *COMDATSymbol, int Selection, SectionKind K,
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MCSymbol *Begin)
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: MCSection(SV_COFF, K, Begin), SectionName(Section),
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Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
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Selection(Selection) {
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assert((Characteristics & 0x00F00000) == 0 &&
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"alignment must not be set upon section creation");
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}
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public:
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~MCSectionCOFF();
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/// Decides whether a '.section' directive should be printed before the
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/// section name
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bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
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StringRef getSectionName() const { return SectionName; }
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unsigned getCharacteristics() const { return Characteristics; }
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MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
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int getSelection() const { return Selection; }
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void setSelection(int Selection) const;
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void PrintSwitchToSection(const MCAsmInfo &MAI, raw_ostream &OS,
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const MCExpr *Subsection) const override;
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bool UseCodeAlign() const override;
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bool isVirtualSection() const override;
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unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
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if (WinCFISectionID == ~0U)
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WinCFISectionID = (*NextID)++;
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return WinCFISectionID;
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}
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static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
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};
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} // end namespace llvm
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#endif
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