Simplify mapping from relocation sections to relocated sections.

Just store the section in MCSectionELF. This avoids multiple hash lookups.

This will also be used by ARM_EXIDX.

llvm-svn: 234139

diff --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
index 848614c..d6d6c25 100644 (file)
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -336,7 +336,8 @@ namespace llvm {
 
     const MCSectionELF *createELFRelSection(StringRef Name, unsigned Type,
                                             unsigned Flags, unsigned EntrySize,
-                                            const MCSymbol *Group);
+                                            const MCSymbol *Group,
+                                            const MCSectionELF *Associated);
 
     void renameELFSection(const MCSectionELF *Section, StringRef Name);
 

diff --git a/llvm/include/llvm/MC/MCSectionELF.h b/llvm/include/llvm/MC/MCSectionELF.h
index cd15741..86855e6 100644 (file)
--- a/llvm/include/llvm/MC/MCSectionELF.h
+++ b/llvm/include/llvm/MC/MCSectionELF.h
@@ -48,13 +48,17 @@ class MCSectionELF : public MCSection {
 
   const MCSymbol *Group;
 
+  /// Depending on the type of the section this is sh_link or sh_info.
+  const MCSectionELF *Associated;
+
 private:
   friend class MCContext;
   MCSectionELF(StringRef Section, unsigned type, unsigned flags, SectionKind K,
                unsigned entrySize, const MCSymbol *group, unsigned UniqueID,
-               MCSymbol *Begin)
+               MCSymbol *Begin, const MCSectionELF *Associated)
       : MCSection(SV_ELF, K, Begin), SectionName(Section), Type(type),
-        Flags(flags), UniqueID(UniqueID), EntrySize(entrySize), Group(group) {}
+        Flags(flags), UniqueID(UniqueID), EntrySize(entrySize), Group(group),
+        Associated(Associated) {}
   ~MCSectionELF();
 
   void setSectionName(StringRef Name) { SectionName = Name; }
@@ -79,6 +83,8 @@ public:
   bool isUnique() const { return UniqueID != ~0U; }
   unsigned getUniqueID() const { return UniqueID; }
 
+  const MCSectionELF *getAssociatedSection() const { return Associated; }
+
   static bool classof(const MCSection *S) {
     return S->getVariant() == SV_ELF;
   }

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 6be37bf..174c45f 100644 (file)
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -245,8 +245,6 @@ class ELFObjectWriter : public MCObjectWriter {
     typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
     // Map from a signature symbol to the group section
     typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
-    // Map from a section to the section with the relocations
-    typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy;
     // Map from a section to its offset
     typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy;
 
@@ -261,17 +259,14 @@ class ELFObjectWriter : public MCObjectWriter {
                             const RevGroupMapTy &RevGroupMap,
                             unsigned NumRegularSections);
 
-    void computeIndexMap(MCAssembler &Asm,
-                         SectionIndexMapTy &SectionIndexMap,
-                         RelMapTy &RelMap);
+    void computeIndexMap(MCAssembler &Asm, SectionIndexMapTy &SectionIndexMap);
 
     MCSectionData *createRelocationSection(MCAssembler &Asm,
                                            const MCSectionData &SD);
 
     void CompressDebugSections(MCAssembler &Asm, MCAsmLayout &Layout);
 
-    void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
-                          const RelMapTy &RelMap);
+    void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout);
 
     void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
                                 SectionIndexMapTy &SectionIndexMap);
@@ -279,10 +274,8 @@ class ELFObjectWriter : public MCObjectWriter {
     // Create the sections that show up in the symbol table. Currently
     // those are the .note.GNU-stack section and the group sections.
     void createIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
-                               GroupMapTy &GroupMap,
-                               RevGroupMapTy &RevGroupMap,
-                               SectionIndexMapTy &SectionIndexMap,
-                               RelMapTy &RelMap);
+                               GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap,
+                               SectionIndexMapTy &SectionIndexMap);
 
     void ExecutePostLayoutBinding(MCAssembler &Asm,
                                   const MCAsmLayout &Layout) override;
@@ -290,7 +283,6 @@ class ELFObjectWriter : public MCObjectWriter {
     void writeSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
                             const MCAsmLayout &Layout,
                             const SectionIndexMapTy &SectionIndexMap,
-                            const RelMapTy &RelMap,
                             const SectionOffsetMapTy &SectionOffsetMap);
 
     void ComputeSectionOrder(MCAssembler &Asm,
@@ -317,7 +309,6 @@ class ELFObjectWriter : public MCObjectWriter {
     void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
     void writeSection(MCAssembler &Asm,
                       const SectionIndexMapTy &SectionIndexMap,
-                      const RelMapTy &RelMap,
                       uint32_t GroupSymbolIndex,
                       uint64_t Offset, uint64_t Size, uint64_t Alignment,
                       const MCSectionELF &Section);
@@ -969,8 +960,7 @@ bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isUsedInReloc) {
 }
 
 void ELFObjectWriter::computeIndexMap(MCAssembler &Asm,
-                                      SectionIndexMapTy &SectionIndexMap,
-                                      RelMapTy &RelMap) {
+                                      SectionIndexMapTy &SectionIndexMap) {
   unsigned Index = 1;
   for (MCAssembler::iterator it = Asm.begin(),
          ie = Asm.end(); it != ie; ++it) {
@@ -994,7 +984,6 @@ void ELFObjectWriter::computeIndexMap(MCAssembler &Asm,
     if (MCSectionData *RelSD = createRelocationSection(Asm, SD)) {
       const MCSectionELF *RelSection =
           static_cast<const MCSectionELF *>(&RelSD->getSection());
-      RelMap[RelSection] = &Section;
       SectionIndexMap[RelSection] = Index++;
     }
   }
@@ -1172,7 +1161,7 @@ ELFObjectWriter::createRelocationSection(MCAssembler &Asm,
 
   const MCSectionELF *RelaSection = Ctx.createELFRelSection(
       RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL,
-      Flags, EntrySize, Section.getGroup());
+      Flags, EntrySize, Section.getGroup(), &Section);
   return &Asm.getOrCreateSectionData(*RelaSection);
 }
 
@@ -1321,8 +1310,7 @@ void ELFObjectWriter::CompressDebugSections(MCAssembler &Asm,
   }
 }
 
-void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
-                                       const RelMapTy &RelMap) {
+void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) {
   for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
     MCSectionData &RelSD = *it;
     const MCSectionELF &RelSection =
@@ -1332,7 +1320,7 @@ void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
     if (Type != ELF::SHT_REL && Type != ELF::SHT_RELA)
       continue;
 
-    const MCSectionELF *Section = RelMap.lookup(&RelSection);
+    const MCSectionELF *Section = RelSection.getAssociatedSection();
     MCSectionData &SD = Asm.getOrCreateSectionData(*Section);
     RelSD.setAlignment(is64Bit() ? 8 : 4);
 
@@ -1470,12 +1458,9 @@ void ELFObjectWriter::CreateMetadataSections(
                           ShStrTabBuilder.data().end());
 }
 
-void ELFObjectWriter::createIndexedSections(MCAssembler &Asm,
-                                            MCAsmLayout &Layout,
-                                            GroupMapTy &GroupMap,
-                                            RevGroupMapTy &RevGroupMap,
-                                            SectionIndexMapTy &SectionIndexMap,
-                                            RelMapTy &RelMap) {
+void ELFObjectWriter::createIndexedSections(
+    MCAssembler &Asm, MCAsmLayout &Layout, GroupMapTy &GroupMap,
+    RevGroupMapTy &RevGroupMap, SectionIndexMapTy &SectionIndexMap) {
   MCContext &Ctx = Asm.getContext();
 
   // Build the groups
@@ -1499,7 +1484,7 @@ void ELFObjectWriter::createIndexedSections(MCAssembler &Asm,
     GroupMap[Group] = SignatureSymbol;
   }
 
-  computeIndexMap(Asm, SectionIndexMap, RelMap);
+  computeIndexMap(Asm, SectionIndexMap);
 
   // Add sections to the groups
   for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
@@ -1519,7 +1504,6 @@ void ELFObjectWriter::createIndexedSections(MCAssembler &Asm,
 
 void ELFObjectWriter::writeSection(MCAssembler &Asm,
                                    const SectionIndexMapTy &SectionIndexMap,
-                                   const RelMapTy &RelMap,
                                    uint32_t GroupSymbolIndex,
                                    uint64_t Offset, uint64_t Size,
                                    uint64_t Alignment,
@@ -1537,7 +1521,7 @@ void ELFObjectWriter::writeSection(MCAssembler &Asm,
   case ELF::SHT_RELA: {
     sh_link = SymbolTableIndex;
     assert(sh_link && ".symtab not found");
-    const MCSectionELF *InfoSection = RelMap.find(&Section)->second;
+    const MCSectionELF *InfoSection = Section.getAssociatedSection();
     sh_info = SectionIndexMap.lookup(InfoSection);
     break;
   }
@@ -1650,7 +1634,7 @@ void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
 
 void ELFObjectWriter::writeSectionHeader(
     MCAssembler &Asm, const GroupMapTy &GroupMap, const MCAsmLayout &Layout,
-    const SectionIndexMapTy &SectionIndexMap, const RelMapTy &RelMap,
+    const SectionIndexMapTy &SectionIndexMap,
     const SectionOffsetMapTy &SectionOffsetMap) {
   const unsigned NumSections = Asm.size() + 1;
 
@@ -1682,9 +1666,9 @@ void ELFObjectWriter::writeSectionHeader(
 
     uint64_t Size = GetSectionAddressSize(Layout, SD);
 
-    writeSection(Asm, SectionIndexMap, RelMap, GroupSymbolIndex,
-                 SectionOffsetMap.lookup(&Section), Size,
-                 SD.getAlignment(), Section);
+    writeSection(Asm, SectionIndexMap, GroupSymbolIndex,
+                 SectionOffsetMap.lookup(&Section), Size, SD.getAlignment(),
+                 Section);
   }
 }
 
@@ -1728,10 +1712,9 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
 
   CompressDebugSections(Asm, const_cast<MCAsmLayout &>(Layout));
 
-  DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
   const unsigned NumUserAndRelocSections = Asm.size();
-  createIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
-                        RevGroupMap, SectionIndexMap, RelMap);
+  createIndexedSections(Asm, const_cast<MCAsmLayout &>(Layout), GroupMap,
+                        RevGroupMap, SectionIndexMap);
   const unsigned AllSections = Asm.size();
   const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
 
@@ -1741,7 +1724,7 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
   computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap,
                      NumRegularSections);
 
-  WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
+  WriteRelocations(Asm, const_cast<MCAsmLayout &>(Layout));
 
   CreateMetadataSections(const_cast<MCAssembler&>(Asm),
                          const_cast<MCAsmLayout&>(Layout),
@@ -1802,8 +1785,7 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
   WriteZeros(Padding);
 
   // ... then the section header table ...
-  writeSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, RelMap,
-                     SectionOffsetMap);
+  writeSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, SectionOffsetMap);
 
   // ... and then the remaining sections ...
   for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)

diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index 34932cc..211f164 100644 (file)
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -279,14 +279,15 @@ void MCContext::renameELFSection(const MCSectionELF *Section, StringRef Name) {
 
 const MCSectionELF *
 MCContext::createELFRelSection(StringRef Name, unsigned Type, unsigned Flags,
-                               unsigned EntrySize, const MCSymbol *Group) {
+                               unsigned EntrySize, const MCSymbol *Group,
+                               const MCSectionELF *Associated) {
   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);
+                   EntrySize, Group, true, nullptr, Associated);
 }
 
 const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
@@ -318,8 +319,9 @@ const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
   if (BeginSymName)
     Begin = createTempSymbol(BeginSymName, false);
 
-  MCSectionELF *Result = new (*this) MCSectionELF(
-      CachedName, Type, Flags, Kind, EntrySize, GroupSym, UniqueID, Begin);
+  MCSectionELF *Result =
+      new (*this) MCSectionELF(CachedName, Type, Flags, Kind, EntrySize,
+                               GroupSym, UniqueID, Begin, nullptr);
   Entry.second = Result;
   return Result;
 }
@@ -327,7 +329,7 @@ const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
 const MCSectionELF *MCContext::CreateELFGroupSection() {
   MCSectionELF *Result = new (*this)
       MCSectionELF(".group", ELF::SHT_GROUP, 0, SectionKind::getReadOnly(), 4,
-                   nullptr, ~0, nullptr);
+                   nullptr, ~0, nullptr, nullptr);
   return Result;
 }