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

llvm-svn: 274336

1 files changed, 15 insertions, 7 deletions

diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index f48ab2f8e34..47ed1ca3add 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/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;