ELF: Don't add .dynamic strings to .dynstr early.

[pcc]

Summary

This does not appear to be necessary because StringTableSection does not
need to be finalized, which also means that we can remove the call to
finalizeSynthetic on .dynstr.

[grimar]

I think I have no objections, but please wait for Rui accept too.

[ruiu]

LGTM

lld/ELF/SyntheticSections.cpp

DynamicSection<ELFT>::DynamicSection()
   this->Entsize = ELFT::Is64Bits ? 16 : 8;
 
   // .dynamic section is not writable on MIPS and on Fuchsia OS
   // which passes -z rodynamic.
   // See "Special Section" in Chapter 4 in the following document:
   // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
   if (Config->EMachine == EM_MIPS || Config->ZRodynamic)
     this->Flags = SHF_ALLOC;
-
-  // Add strings to .dynstr early so that .dynstr's size will be
-  // fixed early.
-  for (StringRef S : Config->FilterList)
-    addInt(DT_FILTER, In.DynStrTab->addString(S));
-  for (StringRef S : Config->AuxiliaryList)
-    addInt(DT_AUXILIARY, In.DynStrTab->addString(S));
-
-  if (!Config->Rpath.empty())
-    addInt(Config->EnableNewDtags ? DT_RUNPATH : DT_RPATH,
-           In.DynStrTab->addString(Config->Rpath));
-
-  for (InputFile *File : SharedFiles) {
-    SharedFile<ELFT> *F = cast<SharedFile<ELFT>>(File);
-    if (F->IsNeeded)
-      addInt(DT_NEEDED, In.DynStrTab->addString(F->SoName));
-  }
-  if (!Config->SoName.empty())
-    addInt(DT_SONAME, In.DynStrTab->addString(Config->SoName));
 }
 
 template <class ELFT>
 void DynamicSection<ELFT>::add(int32_t Tag, std::function<uint64_t()> Fn) {
   Entries.push_back({Tag, Fn});
 }
 
 template <class ELFT>
static uint64_t addPltRelSz() {
   if (In.RelaIplt->getParent() == In.RelaPlt->getParent() &&
       In.RelaIplt->Name == In.RelaPlt->Name)
     Size += In.RelaIplt->getSize();
   return Size;
 }
 
 // Add remaining entries to complete .dynamic contents.
 template <class ELFT> void DynamicSection<ELFT>::finalizeContents() {
+  for (StringRef S : Config->FilterList)
+    addInt(DT_FILTER, In.DynStrTab->addString(S));
+  for (StringRef S : Config->AuxiliaryList)
+    addInt(DT_AUXILIARY, In.DynStrTab->addString(S));
+
+  if (!Config->Rpath.empty())
+    addInt(Config->EnableNewDtags ? DT_RUNPATH : DT_RPATH,
+           In.DynStrTab->addString(Config->Rpath));
+
+  for (InputFile *File : SharedFiles) {
+    SharedFile<ELFT> *F = cast<SharedFile<ELFT>>(File);
+    if (F->IsNeeded)
+      addInt(DT_NEEDED, In.DynStrTab->addString(F->SoName));
+  }
+  if (!Config->SoName.empty())
+    addInt(DT_SONAME, In.DynStrTab->addString(Config->SoName));
+
   // Set DT_FLAGS and DT_FLAGS_1.
   uint32_t DtFlags = 0;
   uint32_t DtFlags1 = 0;
   if (Config->Bsymbolic)
     DtFlags |= DF_SYMBOLIC;
   if (Config->ZGlobal)
     DtFlags1 |= DF_1_GLOBAL;
   if (Config->ZInitfirst)

lld/ELF/Writer.cpp

template <class ELFT> void Writer<ELFT>::finalizeSections() {
   finalizeSynthetic(In.Bss);
   finalizeSynthetic(In.BssRelRo);
   finalizeSynthetic(In.GnuHashTab);
   finalizeSynthetic(In.HashTab);
   finalizeSynthetic(In.SymTabShndx);
   finalizeSynthetic(In.ShStrTab);
   finalizeSynthetic(In.StrTab);
   finalizeSynthetic(In.VerDef);
-  finalizeSynthetic(In.DynStrTab);
   finalizeSynthetic(In.Got);
   finalizeSynthetic(In.MipsGot);
   finalizeSynthetic(In.IgotPlt);
   finalizeSynthetic(In.GotPlt);
   finalizeSynthetic(In.RelaDyn);
   finalizeSynthetic(In.RelrDyn);
   finalizeSynthetic(In.RelaIplt);
   finalizeSynthetic(In.RelaPlt);

lld/test/ELF/verneed.s

 # CHECK-NEXT:     Address: 0x2002A8
 # CHECK-NEXT:     Offset: 0x2A8
 # CHECK-NEXT:     Size: 47
 # CHECK-NEXT:     Link: 0
 # CHECK-NEXT:     Info: 0
 # CHECK-NEXT:     AddressAlignment: 1
 # CHECK-NEXT:     EntrySize: 0
 # CHECK-NEXT:     SectionData (
-# CHECK-NEXT:       0000: 00766572 6E656564 312E736F 2E300076  |.verneed1.so.0.v|
-# CHECK-NEXT:       0010: 65726E65 6564322E 736F2E30 00663100  |erneed2.so.0.f1.|
-# CHECK-NEXT:       0020: 76330066 32007632 00673100 763100    |v3.f2.v2.g1.v1.|
+# CHECK-NEXT:       0000: 00663100 7665726E 65656431 2E736F2E  |.f1.verneed1.so.|
+# CHECK-NEXT:       0010: 30007633 00663200 76320067 31007665  |0.v3.f2.v2.g1.ve|
+# CHECK-NEXT:       0020: 726E6565 64322E73 6F2E3000 763100    |rneed2.so.0.v1.|
 # CHECK-NEXT:     )
 # CHECK-NEXT:   }
 
 # CHECK:      DynamicSymbols [
 # CHECK-NEXT:   Symbol {
 # CHECK-NEXT:     Name:
 # CHECK-NEXT:     Value: 0x0
 # CHECK-NEXT:     Size: 0