Change MCSectionELF to represent a section semantically instead of

syntactically as a string, very similiar to what Chris did with MachO.
The parsing support and validation is not introduced yet.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78890 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 168 insertions, 0 deletions

diff --git a/include/llvm/MC/MCSectionELF.h b/include/llvm/MC/MCSectionELF.h
new file mode 100644
index 0000000000..00369f7d2f
--- /dev/null
+++ b/include/llvm/MC/MCSectionELF.h
@@ -0,0 +1,168 @@
+//===- MCSectionELF.h - ELF 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 MCSectionELF class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCSECTIONELF_H
+#define LLVM_MC_MCSECTIONELF_H
+
+#include "llvm/MC/MCSection.h"
+
+namespace llvm {
+  
+/// MCSectionELF - This represents a section on linux, lots of unix variants
+/// and some bare metal systems.
+class MCSectionELF : public MCSection {
+  std::string SectionName;
+  
+  /// Type - This is the sh_type field of a section, drawn from the enums below.
+  unsigned Type;
+  
+  /// Flags - This is the sh_flags field of a section, drawn from the enums.
+  /// below.
+  unsigned Flags;
+
+  /// HasCrazyBSS - PPC/Linux doesn't support the .bss directive, it 
+  /// needs .section .bss. TODO: replace this with a TAI method.
+  bool HasCrazyBSS;
+
+  /// IsExplicit - Indicates that this section comes from globals with an
+  /// explicit section specfied.
+  bool IsExplicit;
+  
+  MCSectionELF(const StringRef &Section, unsigned T, unsigned F, 
+               SectionKind K, bool hasCrazyBSS, bool isExplicit)
+    : MCSection(K), SectionName(Section.str()), Type(T), Flags(F), 
+      HasCrazyBSS(hasCrazyBSS), IsExplicit(isExplicit) {}
+public:
+  
+  static MCSectionELF *Create(const StringRef &Section, unsigned Type, 
+                              unsigned Flags, SectionKind K, 
+                              bool hasCrazyBSS, bool isExplicit, 
+                              MCContext &Ctx);
+
+  /// ShouldOmitSectionDirective - Decides whether a '.section' directive
+  /// should be printed before the section name
+  bool ShouldOmitSectionDirective(const char *Name) const;
+
+  /// ShouldPrintSectionType - Only prints the section type if supported
+  bool ShouldPrintSectionType(unsigned Ty) const;
+  
+  /// These are the section type and flags fields.  An ELF section can have
+  /// only one Type, but can have more than one of the flags specified.
+  ///
+  /// Valid section types.
+  enum {
+    // This value marks the section header as inactive.
+    SHT_NULL             = 0x00U,
+
+    // Holds information defined by the program, with custom format and meaning.
+    SHT_PROGBITS         = 0x01U,
+
+    // This section holds a symbol table.
+    SHT_SYMTAB           = 0x02U,
+
+    // The section holds a string table.
+    SHT_STRTAB           = 0x03U,
+
+    // The section holds relocation entries with explicit addends.
+    SHT_RELA             = 0x04U,
+
+    // The section holds a symbol hash table.
+    SHT_HASH             = 0x05U,
+    
+    // Information for dynamic linking.
+    SHT_DYNAMIC          = 0x06U,
+
+    // The section holds information that marks the file in some way.
+    SHT_NOTE             = 0x07U,
+
+    // A section of this type occupies no space in the file.
+    SHT_NOBITS           = 0x08U,
+
+    // The section holds relocation entries without explicit addends.
+    SHT_REL              = 0x09U,
+
+    // This section type is reserved but has unspecified semantics. 
+    SHT_SHLIB            = 0x0aU,
+
+    // This section holds a symbol table.
+    SHT_DYNSYM           = 0x0bU,
+
+    // This section contains an array of pointers to initialization functions.
+    SHT_INIT_ARRAY       = 0x0eU,
+
+    // This section contains an array of pointers to termination functions.
+    SHT_FINI_ARRAY       = 0x0fU,
+
+    // This section contains an array of pointers to functions that are invoked
+    // before all other initialization functions.
+    SHT_PREINIT_ARRAY    = 0x10U,
+
+    // A section group is a set of sections that are related and that must be
+    // treated specially by the linker.
+    SHT_GROUP            = 0x11U,
+
+    // This section is associated with a section of type SHT_SYMTAB, when the
+    // referenced symbol table contain the escape value SHN_XINDEX
+    SHT_SYMTAB_SHNDX     = 0x12U,
+
+    LAST_KNOWN_SECTION_TYPE = SHT_SYMTAB_SHNDX
+  }; 
+
+  /// Valid section flags.
+  enum {
+    // The section contains data that should be writable.
+    SHF_WRITE            = 0x1U,
+
+    // The section occupies memory during execution.
+    SHF_ALLOC            = 0x2U,
+
+    // The section contains executable machine instructions.
+    SHF_EXECINSTR        = 0x4U,
+
+    // The data in the section may be merged to eliminate duplication.
+    SHF_MERGE            = 0x10U,
+
+    // Elements in the section consist of null-terminated character strings.
+    SHF_STRINGS          = 0x20U,
+
+    // A field in this section holds a section header table index.
+    SHF_INFO_LINK        = 0x40U,
+
+    // Adds special ordering requirements for link editors.
+    SHF_LINK_ORDER       = 0x80U,
+
+    // This section requires special OS-specific processing to avoid incorrect
+    // behavior.
+    SHF_OS_NONCONFORMING = 0x100U,
+
+    // This section is a member of a section group.
+    SHF_GROUP            = 0x200U,
+
+    // This section holds Thread-Local Storage.
+    SHF_TLS              = 0x400U
+  };
+
+  StringRef getSectionName() const {
+    return StringRef(SectionName);
+  }
+  
+  unsigned getType() const { return Type; }
+  unsigned getFlags() const { return Flags; }
+  
+  virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
+                                    raw_ostream &OS) const;
+};
+
+} // end namespace llvm
+
+#endif