[llvm] a41bfea - [MC] Simplify ELFObjectWriter. NFC

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2024-03-27T22:10:11-07:00
New Revision: a41bfea5c049737e9c51e8d9a5769f72fbc55f59

URL: https://github.com/llvm/llvm-project/commit/a41bfea5c049737e9c51e8d9a5769f72fbc55f59
DIFF: https://github.com/llvm/llvm-project/commit/a41bfea5c049737e9c51e8d9a5769f72fbc55f59.diff

LOG: [MC] Simplify ELFObjectWriter. NFC

And fix `if (hasRelocationAddend())` to `usesRela` to properly treat
SHT_LLVM_CALL_GRAPH_PROFILE as SHT_REL. The incorrect does not cause a
problem because the synthesized SHT_LLVM_CALL_GRAPH_PROFILE has zero
addends.

Added: 
    

Modified: 
    llvm/lib/MC/ELFObjectWriter.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index f4c6cbc8dd4442..005521bad6e014 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -141,7 +141,6 @@ struct ELFWriter {
 
   // TargetObjectWriter wrappers.
   bool is64Bit() const;
-  bool usesRela(const MCSectionELF &Sec) const;
 
   uint64_t align(Align Alignment);
 
@@ -260,6 +259,7 @@ class ELFObjectWriter : public MCObjectWriter {
   void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                         const MCFragment *Fragment, const MCFixup &Fixup,
                         MCValue Target, uint64_t &FixedValue) override;
+  bool usesRela(const MCSectionELF &Sec) const;
 
   void executePostLayoutBinding(MCAssembler &Asm,
                                 const MCAsmLayout &Layout) override;
@@ -394,11 +394,6 @@ bool ELFWriter::is64Bit() const {
   return OWriter.TargetObjectWriter->is64Bit();
 }
 
-bool ELFWriter::usesRela(const MCSectionELF &Sec) const {
-  return OWriter.hasRelocationAddend() &&
-         Sec.getType() != ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
-}
-
 // Emit the ELF header.
 void ELFWriter::writeHeader(const MCAssembler &Asm) {
   // ELF Header
@@ -825,24 +820,22 @@ MCSectionELF *ELFWriter::createRelocationSection(MCContext &Ctx,
   if (OWriter.Relocations[&Sec].empty())
     return nullptr;
 
-  const StringRef SectionName = Sec.getName();
-  bool Rela = usesRela(Sec);
-  std::string RelaSectionName = Rela ? ".rela" : ".rel";
-  RelaSectionName += SectionName;
+  unsigned Flags = ELF::SHF_INFO_LINK;
+  if (Sec.getFlags() & ELF::SHF_GROUP)
+    Flags = ELF::SHF_GROUP;
 
+  const StringRef SectionName = Sec.getName();
+  const bool Rela = OWriter.usesRela(Sec);
   unsigned EntrySize;
   if (Rela)
     EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
   else
     EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
 
-  unsigned Flags = ELF::SHF_INFO_LINK;
-  if (Sec.getFlags() & ELF::SHF_GROUP)
-    Flags = ELF::SHF_GROUP;
-
-  MCSectionELF *RelaSection = Ctx.createELFRelSection(
-      RelaSectionName, Rela ? ELF::SHT_RELA : ELF::SHT_REL, Flags, EntrySize,
-      Sec.getGroup(), &Sec);
+  MCSectionELF *RelaSection =
+      Ctx.createELFRelSection(((Rela ? ".rela" : ".rel") + SectionName),
+                              Rela ? ELF::SHT_RELA : ELF::SHT_REL, Flags,
+                              EntrySize, Sec.getGroup(), &Sec);
   RelaSection->setAlignment(is64Bit() ? Align(8) : Align(4));
   return RelaSection;
 }
@@ -938,11 +931,11 @@ void ELFWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
 void ELFWriter::writeRelocations(const MCAssembler &Asm,
                                        const MCSectionELF &Sec) {
   std::vector<ELFRelocationEntry> &Relocs = OWriter.Relocations[&Sec];
+  const bool Rela = OWriter.usesRela(Sec);
 
   // Sort the relocation entries. MIPS needs this.
   OWriter.TargetObjectWriter->sortRelocs(Asm, Relocs);
 
-  const bool Rela = usesRela(Sec);
   if (OWriter.TargetObjectWriter->getEMachine() == ELF::EM_MIPS) {
     for (const ELFRelocationEntry &Entry : Relocs) {
       uint32_t Symidx = Entry.Symbol ? Entry.Symbol->getIndex() : 0;
@@ -1499,7 +1492,7 @@ void ELFObjectWriter::recordRelocation(MCAssembler &Asm,
   FixedValue = !RelocateWithSymbol && SymA && !SymA->isUndefined()
                    ? C + Layout.getSymbolOffset(*SymA)
                    : C;
-  if (hasRelocationAddend()) {
+  if (usesRela(FixupSection)) {
     Addend = FixedValue;
     FixedValue = 0;
   }
@@ -1528,6 +1521,11 @@ void ELFObjectWriter::recordRelocation(MCAssembler &Asm,
   Relocations[&FixupSection].push_back(Rec);
 }
 
+bool ELFObjectWriter::usesRela(const MCSectionELF &Sec) const {
+  return hasRelocationAddend() &&
+         Sec.getType() != ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
+}
+
 bool ELFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
     const MCAssembler &Asm, const MCSymbol &SA, const MCFragment &FB,
     bool InSet, bool IsPCRel) const {