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

11 files changed, 514 insertions, 199 deletions

diff --git a/include/llvm/MC/MCSection.h b/include/llvm/MC/MCSection.h
index b33e8c9..6a1f9d7 100644
--- a/include/llvm/MC/MCSection.h
+++ b/include/llvm/MC/MCSection.h
@@ -41,33 +41,6 @@ namespace llvm {
                                       raw_ostream &OS) const = 0;
   };
 
-  
-  class MCSectionELF : public MCSection {
-    std::string Name;
-    
-    /// IsDirective - This is true if the section name is a directive, not
-    /// something that should be printed with ".section".
-    ///
-    /// FIXME: This is a hack.  Switch to a semantic view of the section instead
-    /// of a syntactic one.
-    bool IsDirective;
-    
-    MCSectionELF(const StringRef &name, bool isDirective, SectionKind K)
-      : MCSection(K), Name(name), IsDirective(isDirective) {
-    }
-  public:
-    
-    static MCSectionELF *Create(const StringRef &Name, bool IsDirective, 
-                                SectionKind K, MCContext &Ctx);
-
-    const std::string &getName() const { return Name; }
-    bool isDirective() const { return IsDirective; }
-    
-    
-    virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
-                                      raw_ostream &OS) const;
-  };
-
   class MCSectionCOFF : public MCSection {
     std::string Name;
     
diff --git a/include/llvm/MC/MCSectionELF.h b/include/llvm/MC/MCSectionELF.h
new file mode 100644
index 0000000..00369f7
--- /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
diff --git a/include/llvm/Target/TargetLoweringObjectFile.h b/include/llvm/Target/TargetLoweringObjectFile.h
index 102928b..19bb02c 100644
--- a/include/llvm/Target/TargetLoweringObjectFile.h
+++ b/include/llvm/Target/TargetLoweringObjectFile.h
@@ -204,8 +204,9 @@ protected:
   const MCSection *MergeableConst16Section;
   
 protected:
-  const MCSection *getELFSection(const char *Name, bool isDirective,
-                                 SectionKind Kind) const;
+  const MCSection *getELFSection(StringRef Section, unsigned Type, 
+                                 unsigned Flags, SectionKind Kind,
+                                 bool IsExplicit = false) const;
 public:
   TargetLoweringObjectFileELF(// FIXME: REMOVE AFTER UNIQUING IS FIXED.
                               bool hasCrazyBSS = false)
diff --git a/lib/CodeGen/ELFWriter.cpp b/lib/CodeGen/ELFWriter.cpp
index ff41338..4ad2f8b 100644
--- a/lib/CodeGen/ELFWriter.cpp
+++ b/lib/CodeGen/ELFWriter.cpp
@@ -43,7 +43,7 @@
 #include "llvm/CodeGen/MachineCodeEmitter.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/MC/MCContext.h"
-#include "llvm/MC/MCSection.h"
+#include "llvm/MC/MCSectionELF.h"
 #include "llvm/Target/TargetAsmInfo.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetELFWriterInfo.h"
@@ -178,30 +178,32 @@ void ELFWriter::addExternalSymbol(const char *External) {
 
 // getCtorSection - Get the static constructor section
 ELFSection &ELFWriter::getCtorSection() {
-  const MCSection *Ctor = TLOF.getStaticCtorSection();
-  return getSection(((MCSectionELF*)Ctor)->getName(), ELFSection::SHT_PROGBITS, 
+  const MCSectionELF *Ctor = (const MCSectionELF *)TLOF.getStaticCtorSection();
+  return getSection(Ctor->getSectionName(), ELFSection::SHT_PROGBITS, 
                     getElfSectionFlags(Ctor->getKind()));
 }
 
 // getDtorSection - Get the static destructor section
 ELFSection &ELFWriter::getDtorSection() {
-  const MCSection *Dtor = TLOF.getStaticDtorSection();
-  return getSection(((MCSectionELF*)Dtor)->getName(), ELFSection::SHT_PROGBITS, 
+  const MCSectionELF *Dtor = (const MCSectionELF *)TLOF.getStaticDtorSection();
+  return getSection(Dtor->getSectionName(), ELFSection::SHT_PROGBITS, 
                     getElfSectionFlags(Dtor->getKind()));
 }
 
 // getTextSection - Get the text section for the specified function
 ELFSection &ELFWriter::getTextSection(Function *F) {
-  const MCSection *Text = TLOF.SectionForGlobal(F, Mang, TM);
-  return getSection(((MCSectionELF*)Text)->getName(), ELFSection::SHT_PROGBITS,
+  const MCSectionELF *Text = 
+    (const MCSectionELF *)TLOF.SectionForGlobal(F, Mang, TM);
+  return getSection(Text->getSectionName(), ELFSection::SHT_PROGBITS,
                     getElfSectionFlags(Text->getKind()));
 }
 
 // getJumpTableSection - Get a read only section for constants when 
 // emitting jump tables. TODO: add PIC support
 ELFSection &ELFWriter::getJumpTableSection() {
-  const MCSection *JT = TLOF.getSectionForConstant(SectionKind::getReadOnly());
-  return getSection(((MCSectionELF*)JT)->getName(), 
+  const MCSectionELF *JT = 
+    (const MCSectionELF *)TLOF.getSectionForConstant(SectionKind::getReadOnly());
+  return getSection(JT->getSectionName(), 
                     ELFSection::SHT_PROGBITS,
                     getElfSectionFlags(JT->getKind()), 
                     TM.getTargetData()->getPointerABIAlignment());
@@ -226,8 +228,9 @@ ELFSection &ELFWriter::getConstantPoolSection(MachineConstantPoolEntry &CPE) {
     }
   }
 
-  const MCSection *CPSect = TLOF.getSectionForConstant(Kind);
-  return getSection(((MCSectionELF*)CPSect)->getName(),
+  const MCSectionELF *CPSect = 
+    (const MCSectionELF *)TLOF.getSectionForConstant(Kind);
+  return getSection(CPSect->getSectionName(),
                     ELFSection::SHT_PROGBITS,
                     getElfSectionFlags(Kind),
                     CPE.getAlignment());
@@ -358,8 +361,9 @@ void ELFWriter::EmitGlobal(const GlobalValue *GV) {
       return;
 
     // Get the ELF section where this global belongs from TLOF
-    const MCSection *S = TLOF.SectionForGlobal(GV, Mang, TM);
-    SectionKind Kind = ((MCSectionELF*)S)->getKind();
+    const MCSectionELF *S = 
+      (const MCSectionELF *)TLOF.SectionForGlobal(GV, Mang, TM);
+    SectionKind Kind = S->getKind();
     unsigned SectionFlags = getElfSectionFlags(Kind);
 
     // The symbol align should update the section alignment if needed
@@ -370,7 +374,7 @@ void ELFWriter::EmitGlobal(const GlobalValue *GV) {
 
     if (isELFCommonSym(GVar)) {
       GblSym->SectionIdx = ELFSection::SHN_COMMON;
-      getSection(((MCSectionELF*)S)->getName(), 
+      getSection(S->getSectionName(), 
                  ELFSection::SHT_NOBITS, SectionFlags, 1);
 
       // A new linkonce section is created for each global in the
@@ -380,7 +384,7 @@ void ELFWriter::EmitGlobal(const GlobalValue *GV) {
 
     } else if (isELFBssSym(GVar, Kind)) {
       ELFSection &ES =
-        getSection(((MCSectionELF*)S)->getName(), ELFSection::SHT_NOBITS,
+        getSection(S->getSectionName(), ELFSection::SHT_NOBITS,
                    SectionFlags);
       GblSym->SectionIdx = ES.SectionIdx;
 
@@ -396,7 +400,7 @@ void ELFWriter::EmitGlobal(const GlobalValue *GV) {
 
     } else { // The symbol must go to some kind of data section
       ELFSection &ES =
-        getSection(((MCSectionELF*)S)->getName(), ELFSection::SHT_PROGBITS,
+        getSection(S->getSectionName(), ELFSection::SHT_PROGBITS,
                    SectionFlags);
       GblSym->SectionIdx = ES.SectionIdx;
 
diff --git a/lib/MC/CMakeLists.txt b/lib/MC/CMakeLists.txt
index e3cc536..ec76320 100644
--- a/lib/MC/CMakeLists.txt
+++ b/lib/MC/CMakeLists.txt
@@ -4,6 +4,7 @@ add_llvm_library(LLVMMC
   MCAsmStreamer.cpp
   MCContext.cpp
   MCSection.cpp
+  MCSectionELF.cpp
   MCSectionMachO.cpp
   MCStreamer.cpp
   TargetAsmParser.cpp
diff --git a/lib/MC/MCSection.cpp b/lib/MC/MCSection.cpp
index 8b7fcd2..3e83763 100644
--- a/lib/MC/MCSection.cpp
+++ b/lib/MC/MCSection.cpp
@@ -20,91 +20,6 @@ using namespace llvm;
 MCSection::~MCSection() {
 }
 
-
-//===----------------------------------------------------------------------===//
-// MCSectionELF
-//===----------------------------------------------------------------------===//
-
-MCSectionELF *MCSectionELF::
-Create(const StringRef &Name, bool IsDirective, SectionKind K, MCContext &Ctx) {
-  return new (Ctx) MCSectionELF(Name, IsDirective, K);
-}
-
-void MCSectionELF::PrintSwitchToSection(const TargetAsmInfo &TAI,
-                                        raw_ostream &OS) const {
-  if (isDirective()) {
-    OS << getName() << '\n';
-    return;
-  }
-
-  OS << "\t.section\t" << getName();
-  
-  // Handle the weird solaris syntax if desired.
-  if (TAI.usesSunStyleELFSectionSwitchSyntax() &&
-      !getKind().isMergeableConst() && !getKind().isMergeableCString()) {
-    if (!getKind().isMetadata())
-      OS << ",#alloc";
-    if (getKind().isText())
-      OS << ",#execinstr";
-    if (getKind().isWriteable())
-      OS << ",#write";
-    if (getKind().isThreadLocal())
-      OS << ",#tls";
-  } else {
-    OS << ",\"";
-  
-    if (!getKind().isMetadata())
-      OS << 'a';
-    if (getKind().isText())
-      OS << 'x';
-    if (getKind().isWriteable())
-      OS << 'w';
-    if (getKind().isMergeable1ByteCString() ||
-        getKind().isMergeable2ByteCString() ||
-        getKind().isMergeable4ByteCString() ||
-        getKind().isMergeableConst4() ||
-        getKind().isMergeableConst8() ||
-        getKind().isMergeableConst16())
-      OS << 'M';
-    if (getKind().isMergeable1ByteCString() ||
-        getKind().isMergeable2ByteCString() ||
-        getKind().isMergeable4ByteCString())
-      OS << 'S';
-    if (getKind().isThreadLocal())
-      OS << 'T';
-    
-    OS << "\",";
-    
-    // If comment string is '@', e.g. as on ARM - use '%' instead
-    if (TAI.getCommentString()[0] == '@')
-      OS << '%';
-    else
-      OS << '@';
-    
-    if (getKind().isBSS() || getKind().isThreadBSS())
-      OS << "nobits";
-    else
-      OS << "progbits";
-    
-    if (getKind().isMergeable1ByteCString()) {
-      OS << ",1";
-    } else if (getKind().isMergeable2ByteCString()) {
-      OS << ",2";
-    } else if (getKind().isMergeable4ByteCString()) {
-      OS << ",4";
-    } else if (getKind().isMergeableConst4()) {
-      OS << ",4";
-    } else if (getKind().isMergeableConst8()) {
-      OS << ",8";
-    } else if (getKind().isMergeableConst16()) {
-      OS << ",16";
-    }
-  }
-  
-  OS << '\n';
-}
-
-
 //===----------------------------------------------------------------------===//
 // MCSectionCOFF
 //===----------------------------------------------------------------------===//
diff --git a/lib/MC/MCSectionELF.cpp b/lib/MC/MCSectionELF.cpp
new file mode 100644
index 0000000..d172a9c
--- /dev/null
+++ b/lib/MC/MCSectionELF.cpp
@@ -0,0 +1,123 @@
+//===- lib/MC/MCSectionELF.cpp - ELF Code Section Representation ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetAsmInfo.h"
+
+using namespace llvm;
+
+MCSectionELF *MCSectionELF::
+Create(const StringRef &Section, unsigned Type, unsigned Flags,
+       SectionKind K, bool hasCrazyBSS, bool isExplicit, MCContext &Ctx) {
+  return new 
+    (Ctx) MCSectionELF(Section, Type, Flags, K, hasCrazyBSS, isExplicit);
+}
+
+// ShouldOmitSectionDirective - Decides whether a '.section' directive
+// should be printed before the section name
+bool MCSectionELF::ShouldOmitSectionDirective(const char *Name) const {
+  
+  // PPC/Linux doesn't support the .bss directive, it needs .section .bss.
+  // FIXME: Does .section .bss/.data/.text work everywhere??
+  if ((!HasCrazyBSS && strncmp(Name, ".bss", 4) == 0) || 
+      strncmp(Name, ".text", 5) == 0 || 
+      strncmp(Name, ".data", 5) == 0)
+    return true;
+
+  return false;
+}
+
+// ShouldPrintSectionType - Only prints the section type if supported
+bool MCSectionELF::ShouldPrintSectionType(unsigned Ty) const {
+  
+  if (IsExplicit && !(Ty == SHT_NOBITS || Ty == SHT_PROGBITS))
+    return false;
+
+  return true;
+}
+
+void MCSectionELF::PrintSwitchToSection(const TargetAsmInfo &TAI,
+                                        raw_ostream &OS) const {
+  
+  if (ShouldOmitSectionDirective(SectionName.c_str())) {
+    OS << '\t' << getSectionName() << '\n';
+    return;
+  }
+
+  OS << "\t.section\t" << getSectionName();
+  
+  // Handle the weird solaris syntax if desired.
+  if (TAI.usesSunStyleELFSectionSwitchSyntax() && 
+      !(Flags & MCSectionELF::SHF_MERGE)) {
+    if (Flags & MCSectionELF::SHF_ALLOC)
+      OS << ",#alloc";
+    if (Flags & MCSectionELF::SHF_EXECINSTR)
+      OS << ",#execinstr";
+    if (Flags & MCSectionELF::SHF_WRITE)
+      OS << ",#write";
+    if (Flags & MCSectionELF::SHF_TLS)
+      OS << ",#tls";
+  } else {
+    OS << ",\"";
+  
+    if (Flags & MCSectionELF::SHF_ALLOC)
+      OS << 'a';
+    if (Flags & MCSectionELF::SHF_EXECINSTR)
+      OS << 'x';
+    if (Flags & MCSectionELF::SHF_WRITE)
+      OS << 'w';
+    if (Flags & MCSectionELF::SHF_MERGE)
+      OS << 'M';
+    if (Flags & MCSectionELF::SHF_STRINGS)
+      OS << 'S';
+    if (Flags & MCSectionELF::SHF_TLS)
+      OS << 'T';
+   
+    OS << '"';
+
+    if (ShouldPrintSectionType(Type)) {
+      OS << ',';
+   
+      // If comment string is '@', e.g. as on ARM - use '%' instead
+      if (TAI.getCommentString()[0] == '@')
+        OS << '%';
+      else
+        OS << '@';
+    
+      if (Type == MCSectionELF::SHT_INIT_ARRAY)
+        OS << "init_array";
+      else if (Type == MCSectionELF::SHT_FINI_ARRAY)
+        OS << "fini_array";
+      else if (Type == MCSectionELF::SHT_PREINIT_ARRAY)
+        OS << "preinit_array";
+      else if (Type == MCSectionELF::SHT_NOBITS)
+        OS << "nobits";
+      else if (Type == MCSectionELF::SHT_PROGBITS)
+        OS << "progbits";
+    
+      if (getKind().isMergeable1ByteCString()) {
+        OS << ",1";
+      } else if (getKind().isMergeable2ByteCString()) {
+        OS << ",2";
+      } else if (getKind().isMergeable4ByteCString() || 
+                 getKind().isMergeableConst4()) {
+        OS << ",4";
+      } else if (getKind().isMergeableConst8()) {
+        OS << ",8";
+      } else if (getKind().isMergeableConst16()) {
+        OS << ",16";
+      }
+    }
+  }
+  
+  OS << '\n';
+}
+
diff --git a/lib/Target/ARM/ARMTargetObjectFile.h b/lib/Target/ARM/ARMTargetObjectFile.h
index 13fa7e2..9703403 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.h
+++ b/lib/Target/ARM/ARMTargetObjectFile.h
@@ -11,6 +11,7 @@
 #define LLVM_TARGET_ARM_TARGETOBJECTFILE_H
 
 #include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/MC/MCSectionELF.h"
 
 namespace llvm {
 
@@ -21,14 +22,14 @@ namespace llvm {
     void Initialize(MCContext &Ctx, const TargetMachine &TM) {
       TargetLoweringObjectFileELF::Initialize(Ctx, TM);
 
-      // FIXME: Add new attribute/flag to MCSection for init_array/fini_array.
-      // That will allow not treating these as "directives".
       if (TM.getSubtarget<ARMSubtarget>().isAAPCS_ABI()) {
         StaticCtorSection =
-          getELFSection("\t.section .init_array,\"aw\",%init_array", true,
+          getELFSection(".init_array", MCSectionELF::SHT_INIT_ARRAY, 
+                        MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
                         SectionKind::getDataRel());
         StaticDtorSection =
-          getELFSection("\t.section .fini_array,\"aw\",%fini_array", true,
+          getELFSection(".fini_array", MCSectionELF::SHT_FINI_ARRAY,
+                        MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
                         SectionKind::getDataRel());
       }
     }
diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
index 00f4ffe..edc9ed3 100644
--- a/lib/Target/TargetLoweringObjectFile.cpp
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -19,7 +19,7 @@
 #include "llvm/GlobalVariable.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCSectionMachO.h"
-#include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/MC/MCSectionELF.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
@@ -288,64 +288,98 @@ TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
 }
 
 const MCSection *TargetLoweringObjectFileELF::
-getELFSection(const char *Name, bool isDirective, SectionKind Kind) const {
-  // Create the map if it doesn't already exist.
+getELFSection(StringRef Section, unsigned Type, unsigned Flags,
+              SectionKind Kind, bool IsExplicit) const {
   if (UniquingMap == 0)
     UniquingMap = new ELFUniqueMapTy();
   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap;
   
   // Do the lookup, if we have a hit, return it.
-  const MCSectionELF *&Entry = Map[Name];
+  const MCSectionELF *&Entry = Map[Section];
   if (Entry) return Entry;
   
-  return Entry = MCSectionELF::Create(Name, isDirective, Kind, getContext());
+  return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, HasCrazyBSS, 
+                                      IsExplicit, getContext());
 }
 
 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
                                              const TargetMachine &TM) {
   TargetLoweringObjectFile::Initialize(Ctx, TM);
-  if (!HasCrazyBSS)
-    BSSSection = getELFSection("\t.bss", true, SectionKind::getBSS());
-  else
-    // PPC/Linux doesn't support the .bss directive, it needs .section .bss.
-    // FIXME: Does .section .bss work everywhere??
-    // FIXME2: this should just be handle by the section printer.  We should get
-    // away from syntactic view of the sections and MCSection should just be a
-    // semantic view.
-    BSSSection = getELFSection("\t.bss", false, SectionKind::getBSS());
 
+  BSSSection = 
+    getELFSection(".bss", MCSectionELF::SHT_NOBITS,
+                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
+                  SectionKind::getBSS());
     
-  TextSection = getELFSection("\t.text", true, SectionKind::getText());
-  DataSection = getELFSection("\t.data", true, SectionKind::getDataRel());
-  ReadOnlySection =
-    getELFSection("\t.rodata", false, SectionKind::getReadOnly());
-  TLSDataSection =
-    getELFSection("\t.tdata", false, SectionKind::getThreadData());
-  
-  TLSBSSSection = getELFSection("\t.tbss", false, 
-                                     SectionKind::getThreadBSS());
-
-  DataRelSection = getELFSection("\t.data.rel", false,
-                                      SectionKind::getDataRel());
-  DataRelLocalSection = getELFSection("\t.data.rel.local", false,
-                                   SectionKind::getDataRelLocal());
-  DataRelROSection = getELFSection("\t.data.rel.ro", false,
-                                SectionKind::getReadOnlyWithRel());
-  DataRelROLocalSection =
-    getELFSection("\t.data.rel.ro.local", false,
-                       SectionKind::getReadOnlyWithRelLocal());
+  TextSection = 
+    getELFSection(".text", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
+                  SectionKind::getText());
+
+  DataSection = 
+    getELFSection(".data", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
+                  SectionKind::getDataRel());
+
+  ReadOnlySection = 
+    getELFSection(".rodata", MCSectionELF::SHT_PROGBITS, 
+                  MCSectionELF::SHF_ALLOC, 
+                  SectionKind::getReadOnly());
+
+  TLSDataSection = 
+    getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 
+                  MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
+  
+  TLSBSSSection = 
+    getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
+                  MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
+
+  DataRelSection = 
+    getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRel());
+
+  DataRelLocalSection = 
+    getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRelLocal());
+
+  DataRelROSection = 
+    getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getReadOnlyWithRel());
+
+  DataRelROLocalSection = 
+    getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getReadOnlyWithRelLocal());
     
-  MergeableConst4Section = getELFSection(".rodata.cst4", false,
-                                SectionKind::getMergeableConst4());
-  MergeableConst8Section = getELFSection(".rodata.cst8", false,
-                                SectionKind::getMergeableConst8());
-  MergeableConst16Section = getELFSection(".rodata.cst16", false,
-                               SectionKind::getMergeableConst16());
+  MergeableConst4Section = 
+    getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
+                  SectionKind::getMergeableConst4());
+
+  MergeableConst8Section = 
+    getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
+                  SectionKind::getMergeableConst8());
+
+  MergeableConst16Section = 
+    getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
+                  SectionKind::getMergeableConst16());
 
   StaticCtorSection =
-    getELFSection(".ctors", false, SectionKind::getDataRel());
+    getELFSection(".ctors", MCSectionELF::SHT_PROGBITS, 
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRel());
+
   StaticDtorSection =
-    getELFSection(".dtors", false, SectionKind::getDataRel());
+    getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRel());
   
   // Exception Handling Sections.
   
@@ -354,33 +388,46 @@ void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
   // adjusted or this should be a data section.
   LSDASection =
-    getELFSection(".gcc_except_table", false, SectionKind::getReadOnly());
+    getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
   EHFrameSection =
-    getELFSection(".eh_frame", false, SectionKind::getDataRel());
+    getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS, 
+                  MCSectionELF::SHF_ALLOC, SectionKind::getDataRel());
   
   // Debug Info Sections.
   DwarfAbbrevSection = 
-    getELFSection(".debug_abbrev", false, SectionKind::getMetadata());
+    getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfInfoSection = 
-    getELFSection(".debug_info", false, SectionKind::getMetadata());
+    getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfLineSection = 
-    getELFSection(".debug_line", false, SectionKind::getMetadata());
+    getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfFrameSection = 
-    getELFSection(".debug_frame", false, SectionKind::getMetadata());
+    getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfPubNamesSection = 
-    getELFSection(".debug_pubnames", false, SectionKind::getMetadata());
+    getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfPubTypesSection = 
-    getELFSection(".debug_pubtypes", false, SectionKind::getMetadata());
+    getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfStrSection = 
-    getELFSection(".debug_str", false, SectionKind::getMetadata());
+    getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
+                  SectionKind::getMetadata());
   DwarfLocSection = 
-    getELFSection(".debug_loc", false, SectionKind::getMetadata());
+    getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfARangesSection = 
-    getELFSection(".debug_aranges", false, SectionKind::getMetadata());
+    getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfRangesSection = 
-    getELFSection(".debug_ranges", false, SectionKind::getMetadata());
+    getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
   DwarfMacroInfoSection = 
-    getELFSection(".debug_macinfo", false, SectionKind::getMetadata());
+    getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
 }
 
 
@@ -410,13 +457,62 @@ getELFKindForNamedSection(const char *Name, SectionKind K) {
   return K;
 }
 
+
+static unsigned
+getELFSectionType(const char *Name, SectionKind K) {
+
+  if (strncmp(Name, ".init_array", 11) == 0)
+    return MCSectionELF::SHT_INIT_ARRAY;
+
+  if (strncmp(Name, ".fini_array", 11) == 0)
+    return MCSectionELF::SHT_FINI_ARRAY;
+
+  if (strncmp(Name, ".preinit_array", 14) == 0)
+    return MCSectionELF::SHT_PREINIT_ARRAY;
+
+  if (K.isBSS() || K.isThreadBSS())
+    return MCSectionELF::SHT_NOBITS;
+
+  return MCSectionELF::SHT_PROGBITS;
+}
+
+
+static unsigned
+getELFSectionFlags(SectionKind K) {
+  unsigned Flags = 0;
+
+  if (!K.isMetadata())
+    Flags |= MCSectionELF::SHF_ALLOC;
+  
+  if (K.isWriteable())
+    Flags |= MCSectionELF::SHF_WRITE;
+  
+  if (K.isThreadLocal())
+    Flags |= MCSectionELF::SHF_TLS;
+  
+  // K.isMergeableConst() is left out to honour PR4650
+  if (K.isMergeableCString() || K.isMergeableConst4() ||
+      K.isMergeableConst8() || K.isMergeableConst16())
+    Flags |= MCSectionELF::SHF_MERGE;
+
+  if (K.isMergeableCString())
+    Flags |= MCSectionELF::SHF_STRINGS;
+
+  return Flags;
+}
+
+
 const MCSection *TargetLoweringObjectFileELF::
 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 
                          Mangler *Mang, const TargetMachine &TM) const {
+  const char *SectionName = GV->getSection().c_str();
+
   // Infer section flags from the section name if we can.
-  Kind = getELFKindForNamedSection(GV->getSection().c_str(), Kind);
+  Kind = getELFKindForNamedSection(SectionName, Kind);
   
-  return getELFSection(GV->getSection().c_str(), false, Kind);
+  return getELFSection(SectionName, 
+                       getELFSectionType(SectionName, Kind), 
+                       getELFSectionFlags(Kind), Kind, true);
 }
 
 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
@@ -445,7 +541,11 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
   if (GV->isWeakForLinker()) {
     const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
     std::string Name = Mang->makeNameProper(GV->getNameStr());
-    return getELFSection((Prefix+Name).c_str(), false, Kind);
+
+    return getELFSection((Prefix+Name).c_str(), 
+                         getELFSectionType((Prefix+Name).c_str(), Kind), 
+                         getELFSectionFlags(Kind), 
+                         Kind);
   }
   
   if (Kind.isText()) return TextSection;
@@ -470,7 +570,11 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
     
     
     std::string Name = SizeSpec + utostr(Align);
-    return getELFSection(Name.c_str(), false, Kind);
+    return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS, 
+                         MCSectionELF::SHF_ALLOC | 
+                         MCSectionELF::SHF_MERGE | 
+                         MCSectionELF::SHF_STRINGS, 
+                         Kind);
   }
   
   if (Kind.isMergeableConst()) {
diff --git a/lib/Target/XCore/XCoreTargetObjectFile.cpp b/lib/Target/XCore/XCoreTargetObjectFile.cpp
index 4e2dca1..9415f51 100644
--- a/lib/Target/XCore/XCoreTargetObjectFile.cpp
+++ b/lib/Target/XCore/XCoreTargetObjectFile.cpp
@@ -9,6 +9,7 @@
 
 #include "XCoreTargetObjectFile.h"
 #include "XCoreSubtarget.h"
+#include "llvm/MC/MCSectionELF.h"
 #include "llvm/Target/TargetMachine.h"
 using namespace llvm;
 
@@ -16,9 +17,12 @@ using namespace llvm;
 void XCoreTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
 
-  TextSection = getELFSection("\t.text", true,  SectionKind::getText());
-  DataSection = getELFSection("\t.dp.data", false, SectionKind::getDataRel());
-  BSSSection = getELFSection("\t.dp.bss", false, SectionKind::getBSS());
+  DataSection = getELFSection(".dp.data", MCSectionELF::SHT_PROGBITS, 
+                              MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                              SectionKind::getDataRel());
+  BSSSection = getELFSection(".dp.bss", MCSectionELF::SHT_NOBITS,
+                              MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                              SectionKind::getBSS());
   
   // TLS globals are lowered in the backend to arrays indexed by the current
   // thread id. After lowering they require no special handling by the linker
@@ -28,9 +32,12 @@ void XCoreTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
   
   if (TM.getSubtarget<XCoreSubtarget>().isXS1A())
     // FIXME: Why is this writable ("datarel")???
-    ReadOnlySection = getELFSection("\t.dp.rodata", false,
-                                    SectionKind::getDataRel());
+    ReadOnlySection = 
+      getELFSection(".dp.rodata", MCSectionELF::SHT_PROGBITS,
+                    MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                    SectionKind::getDataRel());
   else
-    ReadOnlySection = getELFSection("\t.cp.rodata", false,
-                                    SectionKind::getReadOnly());
+    ReadOnlySection = 
+      getELFSection(".cp.rodata", MCSectionELF::SHT_PROGBITS, 
+                    MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
 }
diff --git a/test/CodeGen/X86/attribute-sections.ll b/test/CodeGen/X86/attribute-sections.ll
new file mode 100644
index 0000000..0dba6e6
--- /dev/null
+++ b/test/CodeGen/X86/attribute-sections.ll
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | llc -mtriple=i386-unknown-linux-gnu | FileCheck %s -check-prefix=LINUX
+
+declare i32 @foo()
+@G0 = global i32 ()* @foo, section ".init_array"
+
+; LINUX:  .section  .init_array,"aw"
+; LINUX:  .globl G0
+
+@G1 = global i32 ()* @foo, section ".fini_array"
+
+; LINUX:  .section  .fini_array,"aw"
+; LINUX:  .globl G1
+
+@G2 = global i32 ()* @foo, section ".preinit_array"
+
+; LINUX:  .section .preinit_array,"aw"
+; LINUX:  .globl G2
+