Special case the creation of relocation sections.

These sections are never looked up and we know when have to create them. Use
that to save adding them to the regular map and avoid a symbol->string->symbol
conversion for the group symbol.

This also makes the implementation independent of the details of how unique
sections are implemented.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233539 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index ca4eae53a887bf11faf049662a926ccdec01a3bf..a17e05d87c111398c6c018aab611a881985c0934 100644 (file)
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -194,6 +194,7 @@ namespace llvm {
     StringMap<const MCSectionMachO*> MachOUniquingMap;
     std::map<ELFSectionKey, const MCSectionELF *> ELFUniquingMap;
     std::map<COFFSectionKey, const MCSectionCOFF *> COFFUniquingMap;
+    StringMap<bool> ELFRelSecNames;
 
     /// Do automatic reset in destructor
     bool AutoReset;
@@ -304,6 +305,10 @@ namespace llvm {
                                       StringRef Group, bool Unique,
                                       const char *BeginSymName = nullptr);
 
+    const MCSectionELF *createELFRelSection(StringRef Name, unsigned Type,
+                                            unsigned Flags, unsigned EntrySize,
+                                            const MCSymbol *Group);
+
     void renameELFSection(const MCSectionELF *Section, StringRef Name);
 
     const MCSectionELF *CreateELFGroupSection();

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index c99a3ee5e2601818f525b12d2c14dd9447b051b4..6be37bfd641ba7b16d2908bddb7ddbb9058f074f 100644 (file)
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -1167,15 +1167,12 @@ ELFObjectWriter::createRelocationSection(MCAssembler &Asm,
     EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
 
   unsigned Flags = 0;
-  StringRef Group = "";
-  if (Section.getFlags() & ELF::SHF_GROUP) {
+  if (Section.getFlags() & ELF::SHF_GROUP)
     Flags = ELF::SHF_GROUP;
-    Group = Section.getGroup()->getName();
-  }
 
-  const MCSectionELF *RelaSection = Ctx.getELFSection(
+  const MCSectionELF *RelaSection = Ctx.createELFRelSection(
       RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL,
-      Flags, EntrySize, Group, true);
+      Flags, EntrySize, Section.getGroup());
   return &Asm.getOrCreateSectionData(*RelaSection);
 }
 

diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index 09de4ee05e6167ab0e9b5c5f9495e090d295a04f..2afa21219fc4dbddd43e240a64fdc44ce428e9d0 100644 (file)
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -275,6 +275,18 @@ void MCContext::renameELFSection(const MCSectionELF *Section, StringRef Name) {
   const_cast<MCSectionELF*>(Section)->setSectionName(CachedName);
 }
 
+const MCSectionELF *
+MCContext::createELFRelSection(StringRef Name, unsigned Type, unsigned Flags,
+                               unsigned EntrySize, const MCSymbol *Group) {
+  StringMap<bool>::iterator I;
+  bool Inserted;
+  std::tie(I, Inserted) = ELFRelSecNames.insert(std::make_pair(Name, true));
+
+  return new (*this)
+      MCSectionELF(I->getKey(), Type, Flags, SectionKind::getReadOnly(),
+                   EntrySize, Group, true, nullptr);
+}
+
 const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
                                              unsigned Flags, unsigned EntrySize,
                                              StringRef Group, bool Unique,