Rip all of the global variable lowering logic out of TargetAsmInfo. Since

it is highly specific to the object file that will be generated in the end,
this introduces a new TargetLoweringObjectFile interface that is implemented
for each of ELF/MachO/COFF/Alpha/PIC16 and XCore.

Though still is still a brutal and ugly refactoring, this is a major step
towards goodness.

This patch also:
1. fixes a bunch of dangling pointer problems in the PIC16 backend.
2. disables the TargetLowering copy ctor which PIC16 was accidentally using.
3. gets us closer to xcore having its own crazy target section flags and
   pic16 not having to shadow sections with its own objects.
4. fixes wierdness where ELF targets would set CStringSection but not
   CStringSection_.  Factor the code better.
5. fixes some bugs in string lowering on ELF targets.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77294 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 647 insertions, 0 deletions

diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
new file mode 100644
index 0000000..b1d9c9a
--- /dev/null
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -0,0 +1,647 @@
+//===-- llvm/Target/TargetLoweringObjectFile.cpp - Object File Info -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements classes used to handle lowerings specific to common
+// object file formats.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/ADT/StringExtras.h"
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//                              Generic Code
+//===----------------------------------------------------------------------===//
+
+TargetLoweringObjectFile::TargetLoweringObjectFile() {
+  TextSection = 0;
+  DataSection = 0;
+  BSSSection_ = 0;
+  ReadOnlySection = 0;
+  TLSDataSection = 0;
+  TLSBSSSection = 0;
+  CStringSection_ = 0;
+}
+
+TargetLoweringObjectFile::~TargetLoweringObjectFile() {
+}
+
+static bool isSuitableForBSS(const GlobalVariable *GV) {
+  Constant *C = GV->getInitializer();
+  
+  // Must have zero initializer.
+  if (!C->isNullValue())
+    return false;
+  
+  // Leave constant zeros in readonly constant sections, so they can be shared.
+  if (GV->isConstant())
+    return false;
+  
+  // If the global has an explicit section specified, don't put it in BSS.
+  if (!GV->getSection().empty())
+    return false;
+  
+  // If -nozero-initialized-in-bss is specified, don't ever use BSS.
+  if (NoZerosInBSS)
+    return false;
+  
+  // Otherwise, put it in BSS!
+  return true;
+}
+
+static bool isConstantString(const Constant *C) {
+  // 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())
+    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 false;
+}
+
+static SectionKind::Kind SectionKindForGlobal(const GlobalValue *GV,
+                                              const TargetMachine &TM) {
+  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::Text;
+
+  
+  // Handle thread-local data first.
+  if (GVar->isThreadLocal()) {
+    if (isSuitableForBSS(GVar))
+      return SectionKind::ThreadBSS;
+    return SectionKind::ThreadData;
+  }
+
+  // Variable can be easily put to BSS section.
+  if (isSuitableForBSS(GVar))
+    return SectionKind::BSS;
+
+  Constant *C = GVar->getInitializer();
+  
+  // If the global is marked constant, we can put it into a mergable section,
+  // a mergable string section, or general .data if it contains relocations.
+  if (GVar->isConstant()) {
+    // If the initializer for the global contains something that requires a
+    // relocation, then we may have to drop this into a wriable data section
+    // even though it is marked const.
+    switch (C->getRelocationInfo()) {
+    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::MergeableCString;
+      
+      // 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.
+      switch (TM.getTargetData()->getTypeAllocSize(C->getType())) {
+      case 4:  return SectionKind::MergeableConst4;
+      case 8:  return SectionKind::MergeableConst8;
+      case 16: return SectionKind::MergeableConst16;
+      default: return SectionKind::MergeableConst;
+      }
+      
+    case Constant::LocalRelocation:
+      // In static relocation model, the linker will resolve all addresses, so
+      // the relocation entries will actually be constants by the time the app
+      // starts up.  However, we can't put this into a mergable section, because
+      // the linker doesn't take relocations into consideration when it tries to
+      // merge entries in the section.
+      if (ReloModel == Reloc::Static)
+        return SectionKind::ReadOnly;
+              
+      // Otherwise, the dynamic linker needs to fix it up, put it in the
+      // writable data.rel.local section.
+      return SectionKind::ReadOnlyWithRelLocal;
+              
+    case Constant::GlobalRelocations:
+      // In static relocation model, the linker will resolve all addresses, so
+      // the relocation entries will actually be constants by the time the app
+      // starts up.  However, we can't put this into a mergable section, because
+      // the linker doesn't take relocations into consideration when it tries to
+      // merge entries in the section.
+      if (ReloModel == Reloc::Static)
+        return SectionKind::ReadOnly;
+      
+      // Otherwise, the dynamic linker needs to fix it up, put it in the
+      // writable data.rel section.
+      return SectionKind::ReadOnlyWithRel;
+    }
+  }
+
+  // Okay, this isn't a constant.  If the initializer for the global is going
+  // to require a runtime relocation by the dynamic linker, put it into a more
+  // specific section to improve startup time of the app.  This coalesces these
+  // globals together onto fewer pages, improving the locality of the dynamic
+  // linker.
+  if (ReloModel == Reloc::Static)
+    return SectionKind::DataNoRel;
+
+  switch (C->getRelocationInfo()) {
+  default: llvm_unreachable("unknown relocation info kind");
+  case Constant::NoRelocation:
+    return SectionKind::DataNoRel;
+  case Constant::LocalRelocation:
+    return SectionKind::DataRelLocal;
+  case Constant::GlobalRelocations:
+    return SectionKind::DataRel;
+  }
+}
+
+/// SectionForGlobal - This method computes the appropriate section to emit
+/// the specified global variable or function definition.  This should not
+/// be passed external (or available externally) globals.
+const Section *TargetLoweringObjectFile::
+SectionForGlobal(const GlobalValue *GV, const TargetMachine &TM) const {
+  assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
+         "Can only be used for global definitions");
+  
+  SectionKind::Kind GVKind = SectionKindForGlobal(GV, TM);
+  
+  SectionKind Kind = SectionKind::get(GVKind, GV->isWeakForLinker(),
+                                      GV->hasSection());
+
+
+  // Select section name.
+  if (GV->hasSection()) {
+    // If the target has special section hacks for specifically named globals,
+    // return them now.
+    if (const Section *TS = getSpecialCasedSectionGlobals(GV, 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.
+    GVKind = getKindForNamedSection(GV->getSection().c_str(), GVKind);
+    
+    return getOrCreateSection(GV->getSection().c_str(), false, GVKind);
+  }
+
+  
+  // Use default section depending on the 'type' of global
+  return SelectSectionForGlobal(GV, Kind, TM);
+}
+
+// Lame default implementation. Calculate the section name for global.
+const Section*
+TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
+                                                 SectionKind Kind,
+                                                 const TargetMachine &TM) const{
+  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
+  
+  if (Kind.isText())
+    return getTextSection();
+  
+  if (Kind.isBSS() && BSSSection_ != 0)
+    return BSSSection_;
+  
+  if (Kind.isReadOnly() && ReadOnlySection != 0)
+    return ReadOnlySection;
+
+  return getDataSection();
+}
+
+/// getSectionForMergableConstant - Given a mergable constant with the
+/// specified size and relocation information, return a section that it
+/// should be placed in.
+const Section *
+TargetLoweringObjectFile::
+getSectionForMergeableConstant(SectionKind Kind) const {
+  if (Kind.isReadOnly() && ReadOnlySection != 0)
+    return ReadOnlySection;
+  
+  return DataSection;
+}
+
+
+const Section *TargetLoweringObjectFile::
+getOrCreateSection(const char *Name, bool isDirective,
+                   SectionKind::Kind Kind) const {
+  Section &S = Sections[Name];
+
+  // This is newly-created section, set it up properly.
+  if (S.Name.empty()) {
+    S.Kind = SectionKind::get(Kind, false /*weak*/, !isDirective);
+    S.Name = Name;
+  }
+
+  return &S;
+}
+
+
+
+//===----------------------------------------------------------------------===//
+//                                  ELF
+//===----------------------------------------------------------------------===//
+
+TargetLoweringObjectFileELF::TargetLoweringObjectFileELF(bool atIsCommentChar,
+                                                         bool HasCrazyBSS)
+  : AtIsCommentChar(atIsCommentChar) {
+    
+  if (!HasCrazyBSS)
+    BSSSection_ = getOrCreateSection("\t.bss", true, SectionKind::BSS);
+  else
+    // PPC/Linux doesn't support the .bss directive, it needs .section .bss.
+    // FIXME: Does .section .bss work everywhere??
+    BSSSection_ = getOrCreateSection("\t.bss", false, SectionKind::BSS);
+
+    
+  TextSection = getOrCreateSection("\t.text", true, SectionKind::Text);
+  DataSection = getOrCreateSection("\t.data", true, SectionKind::DataRel);
+  ReadOnlySection =
+    getOrCreateSection("\t.rodata", false, SectionKind::ReadOnly);
+  TLSDataSection =
+    getOrCreateSection("\t.tdata", false, SectionKind::ThreadData);
+  CStringSection_ = getOrCreateSection("\t.rodata.str", true,
+                                       SectionKind::MergeableCString);
+
+  TLSBSSSection = getOrCreateSection("\t.tbss", false, SectionKind::ThreadBSS);
+
+  DataRelSection = getOrCreateSection("\t.data.rel", false,
+                                      SectionKind::DataRel);
+  DataRelLocalSection = getOrCreateSection("\t.data.rel.local", false,
+                                           SectionKind::DataRelLocal);
+  DataRelROSection = getOrCreateSection("\t.data.rel.ro", false,
+                                        SectionKind::ReadOnlyWithRel);
+  DataRelROLocalSection =
+    getOrCreateSection("\t.data.rel.ro.local", false,
+                       SectionKind::ReadOnlyWithRelLocal);
+    
+  MergeableConst4Section = getOrCreateSection(".rodata.cst4", false,
+                                              SectionKind::MergeableConst4);
+  MergeableConst8Section = getOrCreateSection(".rodata.cst8", false,
+                                              SectionKind::MergeableConst8);
+  MergeableConst16Section = getOrCreateSection(".rodata.cst16", false,
+                                               SectionKind::MergeableConst16);
+}
+
+
+SectionKind::Kind TargetLoweringObjectFileELF::
+getKindForNamedSection(const char *Name, SectionKind::Kind K) const {
+  if (Name[0] != '.') return K;
+  
+  // Some lame default implementation based on some magic section names.
+  if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
+      strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
+      strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
+      strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
+    return SectionKind::BSS;
+  
+  if (strcmp(Name, ".tdata") == 0 ||
+      strncmp(Name, ".tdata.", 7) == 0 ||
+      strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
+      strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
+    return SectionKind::ThreadData;
+  
+  if (strcmp(Name, ".tbss") == 0 ||
+      strncmp(Name, ".tbss.", 6) == 0 ||
+      strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
+      strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
+    return SectionKind::ThreadBSS;
+  
+  return K;
+}
+
+void TargetLoweringObjectFileELF::
+getSectionFlagsAsString(SectionKind Kind, SmallVectorImpl<char> &Str) const {
+  Str.push_back(',');
+  Str.push_back('"');
+  
+  if (!Kind.isMetadata())
+    Str.push_back('a');
+  if (Kind.isText())
+    Str.push_back('x');
+  if (Kind.isWriteable())
+    Str.push_back('w');
+  if (Kind.isMergeableConst() || Kind.isMergeableCString())
+    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())
+    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');
+  }
+}
+
+
+static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
+  if (Kind.isText())                 return ".gnu.linkonce.t.";
+  if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
+  
+  if (Kind.isThreadData())           return ".gnu.linkonce.td.";
+  if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
+  
+  if (Kind.isBSS())                  return ".gnu.linkonce.b.";
+  if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
+  if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
+  if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
+  if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
+  
+  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
+  return ".gnu.linkonce.d.rel.ro.";
+}
+
+const Section *TargetLoweringObjectFileELF::
+SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
+                       const TargetMachine &TM) const {
+  
+  // If this global is linkonce/weak and the target handles this by emitting it
+  // into a 'uniqued' section name, create and return the section now.
+  if (Kind.isWeak()) {
+    const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
+    // FIXME: Use mangler interface (PR4584).
+    std::string Name = Prefix+GV->getNameStr();
+    return getOrCreateSection(Name.c_str(), false, Kind.getKind());
+  }
+  
+  if (Kind.isText()) return TextSection;
+  if (Kind.isMergeableCString()) {
+    Constant *C = cast<GlobalVariable>(GV)->getInitializer();
+    
+    // FIXME: This is completely wrong.  Why is it comparing the size of the
+    // character type to 1?
+    /// cast<ArrayType>(C->getType())->getNumElements();
+    uint64_t Size = 1;
+    if (Size <= 16) {
+      assert(CStringSection_ && "Should have string section prefix");
+      
+      // We also need alignment here.
+      // FIXME: this is getting the alignment of the character, not the
+      // alignment of the global!
+      unsigned Align = 
+        TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
+      
+      std::string Name = CStringSection_->getName() + utostr(Size) + '.' +
+      utostr(Align);
+      return getOrCreateSection(Name.c_str(), false,
+                                SectionKind::MergeableCString);
+    }
+    
+    return ReadOnlySection;
+  }
+  
+  if (Kind.isMergeableConst()) {
+    if (Kind.isMergeableConst4())
+      return MergeableConst4Section;
+    if (Kind.isMergeableConst8())
+      return MergeableConst8Section;
+    if (Kind.isMergeableConst16())
+      return MergeableConst16Section;
+    return ReadOnlySection;  // .const
+  }
+  
+  if (Kind.isReadOnly())             return ReadOnlySection;
+  
+  if (Kind.isThreadData())           return TLSDataSection;
+  if (Kind.isThreadBSS())            return TLSBSSSection;
+  
+  if (Kind.isBSS())                  return BSSSection_;
+  
+  if (Kind.isDataNoRel())            return DataSection;
+  if (Kind.isDataRelLocal())         return DataRelLocalSection;
+  if (Kind.isDataRel())              return DataRelSection;
+  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
+  
+  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
+  return DataRelROSection;
+}
+
+/// getSectionForMergeableConstant - Given a mergeable constant with the
+/// specified size and relocation information, return a section that it
+/// should be placed in.
+const Section *TargetLoweringObjectFileELF::
+getSectionForMergeableConstant(SectionKind Kind) const {
+  if (Kind.isMergeableConst4())
+    return MergeableConst4Section;
+  if (Kind.isMergeableConst8())
+    return MergeableConst8Section;
+  if (Kind.isMergeableConst16())
+    return MergeableConst16Section;
+  if (Kind.isReadOnly())
+    return ReadOnlySection;
+  
+  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
+  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
+  return DataRelROSection;
+}
+
+//===----------------------------------------------------------------------===//
+//                                 MachO
+//===----------------------------------------------------------------------===//
+
+TargetLoweringObjectFileMachO::
+TargetLoweringObjectFileMachO() {
+  TextSection = getOrCreateSection("\t.text", true, SectionKind::Text);
+  DataSection = getOrCreateSection("\t.data", true, SectionKind::DataRel);
+  
+  CStringSection_ = getOrCreateSection("\t.cstring", true,
+                                       SectionKind::MergeableCString);
+  FourByteConstantSection = getOrCreateSection("\t.literal4\n", true,
+                                               SectionKind::MergeableConst4);
+  EightByteConstantSection = getOrCreateSection("\t.literal8\n", true,
+                                                SectionKind::MergeableConst8);
+  SixteenByteConstantSection = 
+  getOrCreateSection("\t.literal16\n", true, SectionKind::MergeableConst16);
+  
+  ReadOnlySection = getOrCreateSection("\t.const", true, SectionKind::ReadOnly);
+  
+  TextCoalSection =
+  getOrCreateSection("\t__TEXT,__textcoal_nt,coalesced,pure_instructions",
+                     false, SectionKind::Text);
+  ConstTextCoalSection = getOrCreateSection("\t__TEXT,__const_coal,coalesced",
+                                            false, SectionKind::Text);
+  ConstDataCoalSection = getOrCreateSection("\t__DATA,__const_coal,coalesced",
+                                            false, SectionKind::Text);
+  ConstDataSection = getOrCreateSection("\t.const_data", true,
+                                        SectionKind::ReadOnlyWithRel);
+  DataCoalSection = getOrCreateSection("\t__DATA,__datacoal_nt,coalesced",
+                                       false, SectionKind::DataRel);
+}
+
+const Section *
+TargetLoweringObjectFileMachO::SelectSectionForGlobal(const GlobalValue *GV,
+                                                      SectionKind Kind,
+                                                const TargetMachine &TM) const {
+  assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
+  
+  if (Kind.isText())
+    return Kind.isWeak() ? TextCoalSection : TextSection;
+  
+  // If this is weak/linkonce, put this in a coalescable section, either in text
+  // or data depending on if it is writable.
+  if (Kind.isWeak()) {
+    if (Kind.isReadOnly())
+      return ConstTextCoalSection;
+    return DataCoalSection;
+  }
+  
+  // 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)
+        return CStringSection_;
+    }
+    
+    return ReadOnlySection;
+  }
+  
+  if (Kind.isMergeableConst()) {
+    if (Kind.isMergeableConst4())
+      return FourByteConstantSection;
+    if (Kind.isMergeableConst8())
+      return EightByteConstantSection;
+    if (Kind.isMergeableConst16())
+      return SixteenByteConstantSection;
+    return ReadOnlySection;  // .const
+  }
+  
+  // FIXME: ROData -> const in -static mode that is relocatable but they happen
+  // by the static linker.  Why not mergeable?
+  if (Kind.isReadOnly())
+    return ReadOnlySection;
+
+  // If this is marked const, put it into a const section.  But if the dynamic
+  // linker needs to write to it, put it in the data segment.
+  if (Kind.isReadOnlyWithRel())
+    return ConstDataSection;
+  
+  // Otherwise, just drop the variable in the normal data section.
+  return DataSection;
+}
+
+const Section *
+TargetLoweringObjectFileMachO::
+getSectionForMergeableConstant(SectionKind Kind) const {
+  // If this constant requires a relocation, we have to put it in the data
+  // segment, not in the text segment.
+  if (Kind.isDataRel())
+    return ConstDataSection;
+  
+  if (Kind.isMergeableConst4())
+    return FourByteConstantSection;
+  if (Kind.isMergeableConst8())
+    return EightByteConstantSection;
+  if (Kind.isMergeableConst16())
+    return SixteenByteConstantSection;
+  return ReadOnlySection;  // .const
+}
+
+//===----------------------------------------------------------------------===//
+//                                  COFF
+//===----------------------------------------------------------------------===//
+
+TargetLoweringObjectFileCOFF::TargetLoweringObjectFileCOFF() {
+  TextSection = getOrCreateSection("_text", true, SectionKind::Text);
+  DataSection = getOrCreateSection("_data", true, SectionKind::DataRel);
+}
+
+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());
+}
+
+static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
+  if (Kind.isText())
+    return ".text$linkonce";
+  if (Kind.isWriteable())
+    return ".data$linkonce";
+  return ".rdata$linkonce";
+}
+
+
+const Section *TargetLoweringObjectFileCOFF::
+SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
+                       const TargetMachine &TM) const {
+  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
+  
+  // If this global is linkonce/weak and the target handles this by emitting it
+  // into a 'uniqued' section name, create and return the section now.
+  if (Kind.isWeak()) {
+    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
+    // FIXME: Use mangler interface (PR4584).
+    std::string Name = Prefix+GV->getNameStr();
+    return getOrCreateSection(Name.c_str(), false, Kind.getKind());
+  }
+  
+  if (Kind.isText())
+    return getTextSection();
+  
+  if (Kind.isBSS())
+    if (const Section *S = BSSSection_)
+      return S;
+  
+  if (Kind.isReadOnly() && ReadOnlySection != 0)
+    return ReadOnlySection;
+  
+  return getDataSection();
+}
+