It's a bool, so treat it like one. Fixes a MSVC warning.
[oota-llvm.git] / lib / Target / TargetLoweringObjectFile.cpp
index 7c5eaf9dbffbd498e142fadaed83d2b0ad75b6b7..b2ee95501fd8adb8dd9c8a9a9bc8827576d930da 100644 (file)
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/MC/MCContext.h"
-#include "llvm/MC/MCSection.h"
-#include "llvm/Target/TargetMachine.h"
+#include "llvm/MC/MCSectionMachO.h"
+#include "llvm/MC/MCSectionELF.h"
 #include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Mangler.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 using namespace llvm;
 
@@ -34,6 +37,23 @@ TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) {
   DataSection = 0;
   BSSSection = 0;
   ReadOnlySection = 0;
+  StaticCtorSection = 0;
+  StaticDtorSection = 0;
+  LSDASection = 0;
+  EHFrameSection = 0;
+
+  DwarfAbbrevSection = 0;
+  DwarfInfoSection = 0;
+  DwarfLineSection = 0;
+  DwarfFrameSection = 0;
+  DwarfPubNamesSection = 0;
+  DwarfPubTypesSection = 0;
+  DwarfDebugInlineSection = 0;
+  DwarfStrSection = 0;
+  DwarfLocSection = 0;
+  DwarfARangesSection = 0;
+  DwarfRangesSection = 0;
+  DwarfMacroInfoSection = 0;
 }
 
 TargetLoweringObjectFile::~TargetLoweringObjectFile() {
@@ -62,36 +82,53 @@ static bool isSuitableForBSS(const GlobalVariable *GV) {
   return true;
 }
 
-static bool isConstantString(const Constant *C) {
+/// IsNullTerminatedString - Return true if the specified constant (which is
+/// known to have a type that is an array of 1/2/4 byte elements) ends with a
+/// nul value and contains no other nuls in it.
+static bool IsNullTerminatedString(const Constant *C) {
+  const ArrayType *ATy = cast<ArrayType>(C->getType());
+  
   // First check: is we have constant array of i8 terminated with zero
-  const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
-  // Check, if initializer is a null-terminated string
-  if (CVA && CVA->isCString())
+  if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) {
+    if (ATy->getNumElements() == 0) return false;
+
+    ConstantInt *Null =
+      dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1));
+    if (Null == 0 || Null->getZExtValue() != 0)
+      return false; // Not null terminated.
+    
+    // Verify that the null doesn't occur anywhere else in the string.
+    for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i)
+      // Reject constantexpr elements etc.
+      if (!isa<ConstantInt>(CVA->getOperand(i)) ||
+          CVA->getOperand(i) == Null)
+        return false;
     return true;
+  }
 
   // Another possibility: [1 x i8] zeroinitializer
   if (isa<ConstantAggregateZero>(C))
-    if (const ArrayType *Ty = dyn_cast<ArrayType>(C->getType()))
-      return (Ty->getElementType() == Type::Int8Ty &&
-              Ty->getNumElements() == 1);
+    return ATy->getNumElements() == 1;
 
   return false;
 }
 
-/// SectionKindForGlobal - This is a top-level target-independent classifier for
+/// getKindForGlobal - This is a top-level target-independent classifier for
 /// a global variable.  Given an global variable and information from TM, it
 /// classifies the global in a variety of ways that make various target
 /// implementations simpler.  The target implementation is free to ignore this
 /// extra info of course.
-static SectionKind SectionKindForGlobal(const GlobalValue *GV,
-                                        const TargetMachine &TM) {
+SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV,
+                                                       const TargetMachine &TM){
+  assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
+         "Can only be used for global definitions");
+  
   Reloc::Model ReloModel = TM.getRelocationModel();
   
   // Early exit - functions should be always in text sections.
   const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
   if (GVar == 0)
     return SectionKind::getText();
-
   
   // Handle thread-local data first.
   if (GVar->isThreadLocal()) {
@@ -116,10 +153,24 @@ static SectionKind SectionKindForGlobal(const GlobalValue *GV,
     default: llvm_unreachable("unknown relocation info kind");
     case Constant::NoRelocation:
       // If initializer is a null-terminated string, put it in a "cstring"
-      // section if the target has it.
-      if (isConstantString(C))
-        return SectionKind::getMergeableCString();
-      
+      // section of the right width.
+      if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
+        if (const IntegerType *ITy = 
+              dyn_cast<IntegerType>(ATy->getElementType())) {
+          if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 ||
+               ITy->getBitWidth() == 32) &&
+              IsNullTerminatedString(C)) {
+            if (ITy->getBitWidth() == 8)
+              return SectionKind::getMergeable1ByteCString();
+            if (ITy->getBitWidth() == 16)
+              return SectionKind::getMergeable2ByteCString();
+                                         
+            assert(ITy->getBitWidth() == 32 && "Unknown width");
+            return SectionKind::getMergeable4ByteCString();
+          }
+        }
+      }
+        
       // Otherwise, just drop it into a mergable constant section.  If we have
       // a section for this size, use it, otherwise use the arbitrary sized
       // mergable section.
@@ -181,33 +232,18 @@ static SectionKind SectionKindForGlobal(const GlobalValue *GV,
 /// the specified global variable or function definition.  This should not
 /// be passed external (or available externally) globals.
 const MCSection *TargetLoweringObjectFile::
-SectionForGlobal(const GlobalValue *GV, Mangler *Mang,
+SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang,
                  const TargetMachine &TM) const {
-  assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
-         "Can only be used for global definitions");
-  
-  SectionKind Kind = SectionKindForGlobal(GV, TM);
-  
   // Select section name.
-  if (GV->hasSection()) {
-    // If the target has special section hacks for specifically named globals,
-    // return them now.
-    if (const MCSection *TS = getSpecialCasedSectionGlobals(GV, Mang, Kind))
-      return TS;
-    
-    // If the target has magic semantics for certain section names, make sure to
-    // pick up the flags.  This allows the user to write things with attribute
-    // section and still get the appropriate section flags printed.
-    Kind = getKindForNamedSection(GV->getSection().c_str(), Kind);
-    
-    return getOrCreateSection(GV->getSection().c_str(), false, Kind);
-  }
-
+  if (GV->hasSection())
+    return getExplicitSectionGlobal(GV, Kind, Mang, TM);
+  
   
   // Use default section depending on the 'type' of global
   return SelectSectionForGlobal(GV, Kind, Mang, TM);
 }
 
+
 // Lame default implementation. Calculate the section name for global.
 const MCSection *
 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
@@ -240,66 +276,166 @@ TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
 }
 
 
-const MCSection *TargetLoweringObjectFile::
-getOrCreateSection(const char *Name, bool isDirective, SectionKind Kind) const {
-  if (MCSection *S = Ctx->GetSection(Name))
-    return S;
-  return MCSection::Create(Name, isDirective, Kind, *Ctx);
-}
-
-
 
 //===----------------------------------------------------------------------===//
 //                                  ELF
 //===----------------------------------------------------------------------===//
+typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
+
+TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
+  // If we have the section uniquing map, free it.
+  delete (ELFUniqueMapTy*)UniquingMap;
+}
+
+const MCSection *TargetLoweringObjectFileELF::
+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[Section];
+  if (Entry) return Entry;
+  
+  return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit,
+                                      getContext());
+}
 
 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
                                              const TargetMachine &TM) {
+  if (UniquingMap != 0)
+    ((ELFUniqueMapTy*)UniquingMap)->clear();
   TargetLoweringObjectFile::Initialize(Ctx, TM);
-  if (!HasCrazyBSS)
-    BSSSection = getOrCreateSection("\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 = getOrCreateSection("\t.bss", false, SectionKind::getBSS());
 
+  BSSSection = 
+    getELFSection(".bss", MCSectionELF::SHT_NOBITS,
+                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
+                  SectionKind::getBSS());
     
-  TextSection = getOrCreateSection("\t.text", true, SectionKind::getText());
-  DataSection = getOrCreateSection("\t.data", true, SectionKind::getDataRel());
-  ReadOnlySection =
-    getOrCreateSection("\t.rodata", false, SectionKind::getReadOnly());
-  TLSDataSection =
-    getOrCreateSection("\t.tdata", false, SectionKind::getThreadData());
-  CStringSection = getOrCreateSection("\t.rodata.str", true,
-                               SectionKind::getMergeableCString());
-
-  TLSBSSSection = getOrCreateSection("\t.tbss", false, 
-                                     SectionKind::getThreadBSS());
-
-  DataRelSection = getOrCreateSection("\t.data.rel", false,
-                                      SectionKind::getDataRel());
-  DataRelLocalSection = getOrCreateSection("\t.data.rel.local", false,
-                                   SectionKind::getDataRelLocal());
-  DataRelROSection = getOrCreateSection("\t.data.rel.ro", false,
-                                SectionKind::getReadOnlyWithRel());
-  DataRelROLocalSection =
-    getOrCreateSection("\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 = getOrCreateSection(".rodata.cst4", false,
-                                SectionKind::getMergeableConst4());
-  MergeableConst8Section = getOrCreateSection(".rodata.cst8", false,
-                                SectionKind::getMergeableConst8());
-  MergeableConst16Section = getOrCreateSection(".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", MCSectionELF::SHT_PROGBITS, 
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRel());
+
+  StaticDtorSection =
+    getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRel());
+  
+  // Exception Handling Sections.
+  
+  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
+  // it contains relocatable pointers.  In PIC mode, this is probably a big
+  // 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", MCSectionELF::SHT_PROGBITS,
+                  MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
+  EHFrameSection =
+    getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS, 
+                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
+                  SectionKind::getDataRel());
+  
+  // Debug Info Sections.
+  DwarfAbbrevSection = 
+    getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfInfoSection = 
+    getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfLineSection = 
+    getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfFrameSection = 
+    getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfPubNamesSection = 
+    getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfPubTypesSection = 
+    getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfStrSection = 
+    getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
+                  SectionKind::getMetadata());
+  DwarfLocSection = 
+    getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfARangesSection = 
+    getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfRangesSection = 
+    getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
+  DwarfMacroInfoSection = 
+    getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0, 
+                  SectionKind::getMetadata());
 }
 
 
-SectionKind TargetLoweringObjectFileELF::
-getKindForNamedSection(const char *Name, SectionKind K) const {
+static SectionKind 
+getELFKindForNamedSection(const char *Name, SectionKind K) {
   if (Name[0] != '.') return K;
   
   // Some lame default implementation based on some magic section names.
@@ -324,63 +460,67 @@ getKindForNamedSection(const char *Name, SectionKind K) const {
   return K;
 }
 
-void TargetLoweringObjectFileELF::
-getSectionFlagsAsString(SectionKind Kind, SmallVectorImpl<char> &Str) const {
-  Str.push_back(',');
-  Str.push_back('"');
+
+static unsigned
+getELFSectionType(const char *Name, SectionKind K) {
+
+  if (strcmp(Name, ".init_array") == 0)
+    return MCSectionELF::SHT_INIT_ARRAY;
+
+  if (strcmp(Name, ".fini_array") == 0)
+    return MCSectionELF::SHT_FINI_ARRAY;
+
+  if (strcmp(Name, ".preinit_array") == 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 (!Kind.isMetadata())
-    Str.push_back('a');
-  if (Kind.isText())
-    Str.push_back('x');
-  if (Kind.isWriteable())
-    Str.push_back('w');
-  if (Kind.isMergeableCString() ||
-      Kind.isMergeableConst4() ||
-      Kind.isMergeableConst8() ||
-      Kind.isMergeableConst16())
-    Str.push_back('M');
-  if (Kind.isMergeableCString())
-    Str.push_back('S');
-  if (Kind.isThreadLocal())
-    Str.push_back('T');
-  
-  Str.push_back('"');
-  Str.push_back(',');
-  
-  // If comment string is '@', e.g. as on ARM - use '%' instead
-  if (AtIsCommentChar)
-    Str.push_back('%');
-  else
-    Str.push_back('@');
-  
-  const char *KindStr;
-  if (Kind.isBSS() || Kind.isThreadBSS())
-    KindStr = "nobits";
-  else
-    KindStr = "progbits";
-  
-  Str.append(KindStr, KindStr+strlen(KindStr));
-  
-  if (Kind.isMergeableCString()) {
-    // TODO: Eventually handle multiple byte character strings.  For now, all
-    // mergable C strings are single byte.
-    Str.push_back(',');
-    Str.push_back('1');
-  } else if (Kind.isMergeableConst4()) {
-    Str.push_back(',');
-    Str.push_back('4');
-  } else if (Kind.isMergeableConst8()) {
-    Str.push_back(',');
-    Str.push_back('8');
-  } else if (Kind.isMergeableConst16()) {
-    Str.push_back(',');
-    Str.push_back('1');
-    Str.push_back('6');
-  }
+  if (K.isText())
+    Flags |= MCSectionELF::SHF_EXECINSTR;
+  
+  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(SectionName, Kind);
+  
+  return getELFSection(SectionName, 
+                       getELFSectionType(SectionName, Kind), 
+                       getELFSectionFlags(Kind), Kind, true);
+}
+
 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
   if (Kind.isText())                 return ".gnu.linkonce.t.";
   if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
@@ -407,13 +547,18 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
   if (GV->isWeakForLinker()) {
     const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
     std::string Name = Mang->makeNameProper(GV->getNameStr());
-    return getOrCreateSection((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;
   
-  if (Kind.isMergeableCString()) {
-   assert(CStringSection && "Should have string section prefix");
+  if (Kind.isMergeable1ByteCString() ||
+      Kind.isMergeable2ByteCString() ||
+      Kind.isMergeable4ByteCString()) {
     
     // We also need alignment here.
     // FIXME: this is getting the alignment of the character, not the
@@ -421,17 +566,29 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
     unsigned Align = 
       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
     
-    std::string Name = CStringSection->getName() + "1." + utostr(Align);
-    return getOrCreateSection(Name.c_str(), false,
-                              SectionKind::getMergeableCString());
+    const char *SizeSpec = ".rodata.str1.";
+    if (Kind.isMergeable2ByteCString())
+      SizeSpec = ".rodata.str2.";
+    else if (Kind.isMergeable4ByteCString())
+      SizeSpec = ".rodata.str4.";
+    else
+      assert(Kind.isMergeable1ByteCString() && "unknown string width");
+    
+    
+    std::string Name = SizeSpec + utostr(Align);
+    return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS, 
+                         MCSectionELF::SHF_ALLOC | 
+                         MCSectionELF::SHF_MERGE | 
+                         MCSectionELF::SHF_STRINGS, 
+                         Kind);
   }
   
   if (Kind.isMergeableConst()) {
-    if (Kind.isMergeableConst4())
+    if (Kind.isMergeableConst4() && MergeableConst4Section)
       return MergeableConst4Section;
-    if (Kind.isMergeableConst8())
+    if (Kind.isMergeableConst8() && MergeableConst8Section)
       return MergeableConst8Section;
-    if (Kind.isMergeableConst16())
+    if (Kind.isMergeableConst16() && MergeableConst16Section)
       return MergeableConst16Section;
     return ReadOnlySection;  // .const
   }
@@ -457,11 +614,11 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 /// should be placed in.
 const MCSection *TargetLoweringObjectFileELF::
 getSectionForConstant(SectionKind Kind) const {
-  if (Kind.isMergeableConst4())
+  if (Kind.isMergeableConst4() && MergeableConst4Section)
     return MergeableConst4Section;
-  if (Kind.isMergeableConst8())
+  if (Kind.isMergeableConst8() && MergeableConst8Section)
     return MergeableConst8Section;
-  if (Kind.isMergeableConst16())
+  if (Kind.isMergeableConst16() && MergeableConst16Section)
     return MergeableConst16Section;
   if (Kind.isReadOnly())
     return ReadOnlySection;
@@ -475,48 +632,208 @@ getSectionForConstant(SectionKind Kind) const {
 //                                 MachO
 //===----------------------------------------------------------------------===//
 
+typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
+
+TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
+  // If we have the MachO uniquing map, free it.
+  delete (MachOUniqueMapTy*)UniquingMap;
+}
+
+
+const MCSectionMachO *TargetLoweringObjectFileMachO::
+getMachOSection(const StringRef &Segment, const StringRef &Section,
+                unsigned TypeAndAttributes,
+                unsigned Reserved2, SectionKind Kind) const {
+  // We unique sections by their segment/section pair.  The returned section
+  // may not have the same flags as the requested section, if so this should be
+  // diagnosed by the client as an error.
+  
+  // Create the map if it doesn't already exist.
+  if (UniquingMap == 0)
+    UniquingMap = new MachOUniqueMapTy();
+  MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
+  
+  // Form the name to look up.
+  SmallString<64> Name;
+  Name += Segment;
+  Name.push_back(',');
+  Name += Section;
+  
+  // Do the lookup, if we have a hit, return it.
+  const MCSectionMachO *&Entry = Map[Name.str()];
+  if (Entry) return Entry;
+
+  // Otherwise, return a new section.
+  return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
+                                        Reserved2, Kind, getContext());
+}
+
+
 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
                                                const TargetMachine &TM) {
+  if (UniquingMap != 0)
+    ((MachOUniqueMapTy*)UniquingMap)->clear();
   TargetLoweringObjectFile::Initialize(Ctx, TM);
-  TextSection = getOrCreateSection("\t.text", true,
-                                   SectionKind::getText());
-  DataSection = getOrCreateSection("\t.data", true, 
-                                   SectionKind::getDataRel());
-  
-  CStringSection = getOrCreateSection("\t.cstring", true,
-                               SectionKind::getMergeableCString());
-  FourByteConstantSection = getOrCreateSection("\t.literal4\n", true,
-                                SectionKind::getMergeableConst4());
-  EightByteConstantSection = getOrCreateSection("\t.literal8\n", true,
-                                SectionKind::getMergeableConst8());
+  
+  TextSection // .text
+    = getMachOSection("__TEXT", "__text",
+                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
+                      SectionKind::getText());
+  DataSection // .data
+    = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
+  
+  CStringSection // .cstring
+    = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
+                      SectionKind::getMergeable1ByteCString());
+  UStringSection
+    = getMachOSection("__TEXT","__ustring", 0,
+                      SectionKind::getMergeable2ByteCString());
+  FourByteConstantSection // .literal4
+    = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
+                      SectionKind::getMergeableConst4());
+  EightByteConstantSection // .literal8
+    = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
+                      SectionKind::getMergeableConst8());
   
   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
   // to using it in -static mode.
+  SixteenByteConstantSection = 0;
   if (TM.getRelocationModel() != Reloc::Static &&
       TM.getTargetData()->getPointerSize() == 32)
-    SixteenByteConstantSection = 
-      getOrCreateSection("\t.literal16\n", true, 
-                         SectionKind::getMergeableConst16());
-  else
-    SixteenByteConstantSection = 0;
-  
-  ReadOnlySection = getOrCreateSection("\t.const", true, 
-                                       SectionKind::getReadOnly());
-  
-  TextCoalSection =
-  getOrCreateSection("\t__TEXT,__textcoal_nt,coalesced,pure_instructions",
-                     false, SectionKind::getText());
-  ConstTextCoalSection = getOrCreateSection("\t__TEXT,__const_coal,coalesced",
-                                            false,
-                                           SectionKind::getText());
-  ConstDataCoalSection = getOrCreateSection("\t__DATA,__const_coal,coalesced",
-                                            false, 
-                                          SectionKind::getText());
-  ConstDataSection = getOrCreateSection("\t.const_data", true,
-                                SectionKind::getReadOnlyWithRel());
-  DataCoalSection = getOrCreateSection("\t__DATA,__datacoal_nt,coalesced",
-                                       false,
-                                       SectionKind::getDataRel());
+    SixteenByteConstantSection =   // .literal16
+      getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
+                      SectionKind::getMergeableConst16());
+  
+  ReadOnlySection  // .const
+    = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
+  
+  TextCoalSection
+    = getMachOSection("__TEXT", "__textcoal_nt",
+                      MCSectionMachO::S_COALESCED |
+                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
+                      SectionKind::getText());
+  ConstTextCoalSection
+    = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
+                      SectionKind::getText());
+  ConstDataCoalSection
+    = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
+                      SectionKind::getText());
+  ConstDataSection  // .const_data
+    = getMachOSection("__DATA", "__const", 0,
+                      SectionKind::getReadOnlyWithRel());
+  DataCoalSection
+    = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
+                      SectionKind::getDataRel());
+
+  
+  LazySymbolPointerSection
+    = getMachOSection("__DATA", "__la_symbol_ptr",
+                      MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
+                      SectionKind::getMetadata());
+  NonLazySymbolPointerSection
+    = getMachOSection("__DATA", "__nl_symbol_ptr",
+                      MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
+                      SectionKind::getMetadata());
+  
+  if (TM.getRelocationModel() == Reloc::Static) {
+    StaticCtorSection
+      = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
+    StaticDtorSection
+      = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
+  } else {
+    StaticCtorSection
+      = getMachOSection("__DATA", "__mod_init_func",
+                        MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
+                        SectionKind::getDataRel());
+    StaticDtorSection
+      = getMachOSection("__DATA", "__mod_term_func", 
+                        MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
+                        SectionKind::getDataRel());
+  }
+  
+  // Exception Handling.
+  LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
+                                SectionKind::getDataRel());
+  EHFrameSection =
+    getMachOSection("__TEXT", "__eh_frame",
+                    MCSectionMachO::S_COALESCED |
+                    MCSectionMachO::S_ATTR_NO_TOC |
+                    MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
+                    MCSectionMachO::S_ATTR_LIVE_SUPPORT,
+                    SectionKind::getReadOnly());
+
+  // Debug Information.
+  DwarfAbbrevSection = 
+    getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfInfoSection =  
+    getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfLineSection =  
+    getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfFrameSection =  
+    getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfPubNamesSection =  
+    getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfPubTypesSection =  
+    getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfStrSection =  
+    getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfLocSection =  
+    getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfARangesSection =  
+    getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfRangesSection =  
+    getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfMacroInfoSection =  
+    getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+  DwarfDebugInlineSection = 
+    getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
+                    SectionKind::getMetadata());
+}
+
+const MCSection *TargetLoweringObjectFileMachO::
+getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 
+                         Mangler *Mang, const TargetMachine &TM) const {
+  // Parse the section specifier and create it if valid.
+  StringRef Segment, Section;
+  unsigned TAA, StubSize;
+  std::string ErrorCode =
+    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
+                                          TAA, StubSize);
+  if (!ErrorCode.empty()) {
+    // If invalid, report the error with llvm_report_error.
+    llvm_report_error("Global variable '" + GV->getNameStr() +
+                      "' has an invalid section specifier '" + GV->getSection()+
+                      "': " + ErrorCode + ".");
+    // Fall back to dropping it into the data section.
+    return DataSection;
+  }
+  
+  // Get the section.
+  const MCSectionMachO *S =
+    getMachOSection(Segment, Section, TAA, StubSize, Kind);
+  
+  // Okay, now that we got the section, verify that the TAA & StubSize agree.
+  // If the user declared multiple globals with different section flags, we need
+  // to reject it here.
+  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
+    // If invalid, report the error with llvm_report_error.
+    llvm_report_error("Global variable '" + GV->getNameStr() +
+                      "' section type or attributes does not match previous"
+                      " section specifier");
+  }
+  
+  return S;
 }
 
 const MCSection *TargetLoweringObjectFileMachO::
@@ -536,18 +853,15 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
   }
   
   // FIXME: Alignment check should be handled by section classifier.
-  if (Kind.isMergeableCString()) {
-    Constant *C = cast<GlobalVariable>(GV)->getInitializer();
-    const Type *Ty = cast<ArrayType>(C->getType())->getElementType();
-    const TargetData &TD = *TM.getTargetData();
-    unsigned Size = TD.getTypeAllocSize(Ty);
-    if (Size) {
-      unsigned Align = TD.getPreferredAlignment(cast<GlobalVariable>(GV));
-      if (Align <= 32)
+  if (Kind.isMergeable1ByteCString() ||
+      Kind.isMergeable2ByteCString()) {
+    if (TM.getTargetData()->getPreferredAlignment(
+                                              cast<GlobalVariable>(GV)) < 32) {
+      if (Kind.isMergeable1ByteCString())
         return CStringSection;
+      assert(Kind.isMergeable2ByteCString());
+      return UStringSection;
     }
-    
-    return ReadOnlySection;
   }
   
   if (Kind.isMergeableConst()) {
@@ -557,11 +871,10 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
       return EightByteConstantSection;
     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
       return SixteenByteConstantSection;
-    return ReadOnlySection;  // .const
   }
-  
-  // FIXME: ROData -> const in -static mode that is relocatable but they happen
-  // by the static linker.  Why not mergeable?
+
+  // Otherwise, if it is readonly, but not something we can specially optimize,
+  // just drop it in .const.
   if (Kind.isReadOnly())
     return ReadOnlySection;
 
@@ -617,26 +930,89 @@ shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 //                                  COFF
 //===----------------------------------------------------------------------===//
 
+typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
+
+TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
+  delete (COFFUniqueMapTy*)UniquingMap;
+}
+
+
+const MCSection *TargetLoweringObjectFileCOFF::
+getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const {
+  // Create the map if it doesn't already exist.
+  if (UniquingMap == 0)
+    UniquingMap = new MachOUniqueMapTy();
+  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
+  
+  // Do the lookup, if we have a hit, return it.
+  const MCSectionCOFF *&Entry = Map[Name];
+  if (Entry) return Entry;
+  
+  return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
+}
+
 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
                                               const TargetMachine &TM) {
+  if (UniquingMap != 0)
+    ((COFFUniqueMapTy*)UniquingMap)->clear();
   TargetLoweringObjectFile::Initialize(Ctx, TM);
-  TextSection = getOrCreateSection("\t.text", true,
-                                   SectionKind::getText());
-  DataSection = getOrCreateSection("\t.data", true,
-                                   SectionKind::getDataRel());
+  TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
+  DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
+  StaticCtorSection =
+    getCOFFSection(".ctors", false, SectionKind::getDataRel());
+  StaticDtorSection =
+    getCOFFSection(".dtors", false, SectionKind::getDataRel());
+  
+  // FIXME: We're emitting LSDA info into a readonly section on COFF, even
+  // though it contains relocatable pointers.  In PIC mode, this is probably a
+  // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
+  // adjusted or this should be a data section.
+  LSDASection =
+    getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
+  EHFrameSection =
+    getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
+  
+  // Debug info.
+  // FIXME: Don't use 'directive' mode here.
+  DwarfAbbrevSection =  
+    getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfInfoSection =    
+    getCOFFSection("\t.section\t.debug_info,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfLineSection =    
+    getCOFFSection("\t.section\t.debug_line,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfFrameSection =   
+    getCOFFSection("\t.section\t.debug_frame,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfPubNamesSection =
+    getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfPubTypesSection =
+    getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfStrSection =     
+    getCOFFSection("\t.section\t.debug_str,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfLocSection =     
+    getCOFFSection("\t.section\t.debug_loc,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfARangesSection = 
+    getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfRangesSection =  
+    getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
+                   true, SectionKind::getMetadata());
+  DwarfMacroInfoSection = 
+    getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
+                   true, SectionKind::getMetadata());
 }
 
-void TargetLoweringObjectFileCOFF::
-getSectionFlagsAsString(SectionKind Kind, SmallVectorImpl<char> &Str) const {
-  // FIXME: Inefficient.
-  std::string Res = ",\"";
-  if (Kind.isText())
-    Res += 'x';
-  if (Kind.isWriteable())
-    Res += 'w';
-  Res += "\"";
-  
-  Str.append(Res.begin(), Res.end());
+const MCSection *TargetLoweringObjectFileCOFF::
+getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 
+                         Mangler *Mang, const TargetMachine &TM) const {
+  return getCOFFSection(GV->getSection().c_str(), false, Kind);
 }
 
 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
@@ -658,7 +1034,7 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
   if (GV->isWeakForLinker()) {
     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
     std::string Name = Mang->makeNameProper(GV->getNameStr());
-    return getOrCreateSection((Prefix+Name).c_str(), false, Kind);
+    return getCOFFSection((Prefix+Name).c_str(), false, Kind);
   }
   
   if (Kind.isText())