Make Verdef and Verdaux adjacent in the version definition section.

Previously, Verdefs and Verdauxs are separated in the section.
The new layout is easier to write as we do not have to maintain
two pointers and can avoid passing a reference to a pointer.

llvm-svn: 275665

diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 573c7f7..1ff94f6 100644 (file)
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -1498,39 +1498,35 @@ template <class ELFT> void VersionDefinitionSection<ELFT>::finalize() {
   this->Header.sh_info = getVerDefNum();
 }
 
-template <class Elf_Verdef, class Elf_Verdaux>
-static void writeDefinition(Elf_Verdef *&Verdef, Elf_Verdaux *&Verdaux,
-                            uint32_t Flags, uint32_t Index, StringRef Name,
-                            size_t StrTabOffset) {
+template <class ELFT>
+void VersionDefinitionSection<ELFT>::writeOne(uint8_t *Buf, uint32_t Index,
+                                              StringRef Name, size_t NameOff) {
+  auto *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
   Verdef->vd_version = 1;
   Verdef->vd_cnt = 1;
-  Verdef->vd_aux =
-      reinterpret_cast<char *>(Verdaux) - reinterpret_cast<char *>(Verdef);
-  Verdef->vd_next = sizeof(Elf_Verdef);
-
-  Verdef->vd_flags = Flags;
+  Verdef->vd_aux = sizeof(Elf_Verdef);
+  Verdef->vd_next = sizeof(Elf_Verdef) + sizeof(Elf_Verdaux);
+  Verdef->vd_flags = (Index == 1 ? VER_FLG_BASE : 0);
   Verdef->vd_ndx = Index;
   Verdef->vd_hash = hashSysv(Name);
-  ++Verdef;
 
-  Verdaux->vda_name = StrTabOffset;
+  auto *Verdaux = reinterpret_cast<Elf_Verdaux *>(Buf + sizeof(Elf_Verdef));
+  Verdaux->vda_name = NameOff;
   Verdaux->vda_next = 0;
-  ++Verdaux;
 }
 
 template <class ELFT>
 void VersionDefinitionSection<ELFT>::writeTo(uint8_t *Buf) {
-  Elf_Verdef *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
-  Elf_Verdaux *Verdaux =
-      reinterpret_cast<Elf_Verdaux *>(Verdef + getVerDefNum());
-
-  writeDefinition(Verdef, Verdaux, VER_FLG_BASE, 1, getFileDefName(),
-                  FileDefNameOff);
+  writeOne(Buf, 1, getFileDefName(), FileDefNameOff);
 
-  for (Version &V : Config->SymbolVersions)
-    writeDefinition(Verdef, Verdaux, 0, V.Id, V.Name, V.NameOff);
+  for (Version &V : Config->SymbolVersions) {
+    Buf += sizeof(Elf_Verdef) + sizeof(Elf_Verdaux);
+    writeOne(Buf, V.Id, V.Name, V.NameOff);
+  }
 
-  Verdef[-1].vd_next = 0;
+  // Need to terminate the last version definition.
+  Elf_Verdef *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
+  Verdef->vd_next = 0;
 }
 
 template <class ELFT>

diff --git a/lld/ELF/OutputSections.h b/lld/ELF/OutputSections.h
index 1f6ea1a..1dbd7d8 100644 (file)
--- a/lld/ELF/OutputSections.h
+++ b/lld/ELF/OutputSections.h
@@ -262,12 +262,15 @@ class VersionDefinitionSection final : public OutputSectionBase<ELFT> {
   typedef typename ELFT::Verdef Elf_Verdef;
   typedef typename ELFT::Verdaux Elf_Verdaux;
 
-  unsigned FileDefNameOff;
-
 public:
   VersionDefinitionSection();
   void finalize() override;
   void writeTo(uint8_t *Buf) override;
+
+private:
+  void writeOne(uint8_t *Buf, uint32_t Index, StringRef Name, size_t NameOff);
+
+  unsigned FileDefNameOff;
 };
 
 // The .gnu.version section specifies the required version of each symbol in the