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38d8be1ad8
COFF lacks a feature that other object file formats support: mergeable sections. To work around this, MSVC sticks constant pool entries in special COMDAT sections so that each constant is in it's own section. This permits unused constants to be dropped and it also allows duplicate constants in different translation units to get merged together. This fixes PR20262. Differential Revision: http://reviews.llvm.org/D4482 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213006 91177308-0d34-0410-b5e6-96231b3b80d8
88 lines
3.0 KiB
C++
88 lines
3.0 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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#include "llvm/Support/COFF.h"
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namespace llvm {
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class MCSymbol;
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/// MCSectionCOFF - This represents a section on Windows
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class MCSectionCOFF : 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
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// the asm parser can honor the .linkonce directive.
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/// Characteristics - This is the Characteristics field of a section,
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/// drawn from the enums below.
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mutable unsigned Characteristics;
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/// The COMDAT symbol of this section. Only valid if this is a COMDAT
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/// section. Two COMDAT sections are merged if they have the same
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/// COMDAT symbol.
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MCSymbol *COMDATSymbol;
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/// Selection - This is the Selection field for the section symbol, if
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/// it is a COMDAT 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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: MCSection(SV_COFF, K), 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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~MCSectionCOFF();
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public:
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/// ShouldOmitSectionDirective - Decides whether a '.section' directive
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/// should be printed before the 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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std::string getLabelBeginName() const override {
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return SectionName.str() + "_begin";
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}
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std::string getLabelEndName() const override {
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return SectionName.str() + "_end";
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}
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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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static bool classof(const MCSection *S) {
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return S->getVariant() == SV_COFF;
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}
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};
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} // end namespace llvm
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#endif
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