Add support for allowing us to create uniquely identified "COMDAT" or "ELF

Group" sections while lowering. In particular, for ELF sections this is
useful for creating function-specific groups that get merged into the
same named section.

Also use const Twine& instead of StringRef for the getELF functions
while we're here.

Differential Revision: http://reviews.llvm.org/D21743

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274336 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index 98dd127c0c0baedd5fb5df38d23897ba68cf77ec..fe1377e054e8288a899b706cb87184030278e19b 100644 (file)
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -339,48 +339,56 @@ namespace llvm {
                              BeginSymName);
     }
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags) {
       return getELFSection(Section, Type, Flags, nullptr);
     }
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags, const char *BeginSymName) {
       return getELFSection(Section, Type, Flags, 0, "", BeginSymName);
     }
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags, unsigned EntrySize,
-                                StringRef Group) {
+                                const Twine &Group) {
       return getELFSection(Section, Type, Flags, EntrySize, Group, nullptr);
     }
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags, unsigned EntrySize,
-                                StringRef Group, const char *BeginSymName) {
+                                const Twine &Group, const char *BeginSymName) {
       return getELFSection(Section, Type, Flags, EntrySize, Group, ~0,
                            BeginSymName);
     }
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags, unsigned EntrySize,
-                                StringRef Group, unsigned UniqueID) {
+                                const Twine &Group, unsigned UniqueID) {
       return getELFSection(Section, Type, Flags, EntrySize, Group, UniqueID,
                            nullptr);
     }
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags, unsigned EntrySize,
-                                StringRef Group, unsigned UniqueID,
+                                const Twine &Group, unsigned UniqueID,
                                 const char *BeginSymName);
 
-    MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+    MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                 unsigned Flags, unsigned EntrySize,
                                 const MCSymbolELF *Group, unsigned UniqueID,
                                 const char *BeginSymName,
                                 const MCSectionELF *Associated);
 
-    MCSectionELF *createELFRelSection(StringRef Name, unsigned Type,
+    /// Get a section with the provided group identifier. This section is
+    /// named by concatenating \p Prefix with '.' then \p Suffix. The \p Type
+    /// describes the type of the section and \p Flags are used to further
+    /// configure this named section.
+    MCSectionELF *getELFNamedSection(const Twine &Prefix, const Twine &Suffix,
+                                     unsigned Type, unsigned Flags,
+                                     unsigned EntrySize = 0);
+
+    MCSectionELF *createELFRelSection(const Twine &Name, unsigned Type,
                                       unsigned Flags, unsigned EntrySize,
                                       const MCSymbolELF *Group,
                                       const MCSectionELF *Associated);

diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index a8e854ecbee0d481ab60de4691d9ddfce31f9109..5f814c957e92f7493638440bda6382cf323b63a7 100644 (file)
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -69,11 +69,9 @@ void TargetLoweringObjectFileELF::emitPersonalityValue(
       cast<MCSymbolELF>(getContext().getOrCreateSymbol(NameData));
   Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
   Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
-  StringRef Prefix = ".data.";
-  NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end());
   unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
-  MCSection *Sec = getContext().getELFSection(NameData, ELF::SHT_PROGBITS,
-                                              Flags, 0, Label->getName());
+  MCSection *Sec = getContext().getELFNamedSection(".data", Label->getName(),
+                                                   ELF::SHT_PROGBITS, Flags, 0);
   unsigned Size = DL.getPointerSize();
   Streamer.SwitchSection(Sec);
   Streamer.EmitValueToAlignment(DL.getPointerABIAlignment());

diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index f48ab2f8e349caeb314e640317cb9e527a824df2..47ed1ca3add5761cdaadf36f0713e8f6c2d80592 100644 (file)
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -309,32 +309,40 @@ void MCContext::renameELFSection(MCSectionELF *Section, StringRef Name) {
   const_cast<MCSectionELF *>(Section)->setSectionName(CachedName);
 }
 
-MCSectionELF *MCContext::createELFRelSection(StringRef Name, unsigned Type,
+MCSectionELF *MCContext::createELFRelSection(const Twine &Name, unsigned Type,
                                              unsigned Flags, unsigned EntrySize,
                                              const MCSymbolELF *Group,
                                              const MCSectionELF *Associated) {
   StringMap<bool>::iterator I;
   bool Inserted;
-  std::tie(I, Inserted) = ELFRelSecNames.insert(std::make_pair(Name, true));
+  std::tie(I, Inserted) =
+      ELFRelSecNames.insert(std::make_pair(Name.str(), true));
 
   return new (ELFAllocator.Allocate())
       MCSectionELF(I->getKey(), Type, Flags, SectionKind::getReadOnly(),
                    EntrySize, Group, true, nullptr, Associated);
 }
 
-MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
+MCSectionELF *MCContext::getELFNamedSection(const Twine &Prefix,
+                                            const Twine &Suffix, unsigned Type,
+                                            unsigned Flags,
+                                            unsigned EntrySize) {
+  return getELFSection(Prefix + "." + Suffix, Type, Flags, EntrySize, Suffix);
+}
+
+MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
                                        unsigned Flags, unsigned EntrySize,
-                                       StringRef Group, unsigned UniqueID,
+                                       const Twine &Group, unsigned UniqueID,
                                        const char *BeginSymName) {
   MCSymbolELF *GroupSym = nullptr;
-  if (!Group.empty())
+  if (!Group.isTriviallyEmpty() && !Group.str().empty())
     GroupSym = cast<MCSymbolELF>(getOrCreateSymbol(Group));
 
   return getELFSection(Section, Type, Flags, EntrySize, GroupSym, UniqueID,
                        BeginSymName, nullptr);
 }
 
-MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
+MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
                                        unsigned Flags, unsigned EntrySize,
                                        const MCSymbolELF *GroupSym,
                                        unsigned UniqueID,
@@ -345,7 +353,7 @@ MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
     Group = GroupSym->getName();
   // Do the lookup, if we have a hit, return it.
   auto IterBool = ELFUniquingMap.insert(
-      std::make_pair(ELFSectionKey{Section, Group, UniqueID}, nullptr));
+      std::make_pair(ELFSectionKey{Section.str(), Group, UniqueID}, nullptr));
   auto &Entry = *IterBool.first;
   if (!IterBool.second)
     return Entry.second;