[ELF] SHF_LINK_ORDER should sort based on InputSectionDescriptions

    
This change alters the sorting for OutputSections with the SHF_LINK_ORDER
flag in OutputSection::finalize() to use the InputSectionDescription
representation and not the OutputSection::Sections representation.

Differential revision: https://reviews.llvm.org/D33772

llvm-svn: 304700

lld/ELF/OutputSections.cpp

@@ -99,8 +99,20 @@ template <class ELFT> static void finalizeShtGroup(OutputSection *Sec) {
 
 template <class ELFT> void OutputSection::finalize() {
   if ((this->Flags & SHF_LINK_ORDER) && !this->Sections.empty()) {
+    OutputSectionCommand *Cmd = Script->getCmd(this);
+    // Link order may be distributed across several InputSectionDescriptions
+    // but sort must consider them all at once.
+    std::vector<InputSection **> ScriptSections;
+    std::vector<InputSection *> Sections;
+    for (BaseCommand *Base : Cmd->Commands)
+      if (auto *ISD = dyn_cast<InputSectionDescription>(Base))
+        for (InputSection *&IS : ISD->Sections) {
+          ScriptSections.push_back(&IS);
+          Sections.push_back(IS);
+        }
     std::sort(Sections.begin(), Sections.end(), compareByFilePosition);
-    assignOffsets();
+    for (int I = 0, N = Sections.size(); I < N; ++I)
+      *ScriptSections[I] = Sections[I];
 
     // We must preserve the link order dependency of sections with the
     // SHF_LINK_ORDER flag. The dependency is indicated by the sh_link field. We

lld/ELF/Writer.cpp

@@ -257,11 +257,6 @@ template <class ELFT> void Writer<ELFT>::run() {
   if (ErrorCount)
     return;
 
-  if (!Script->Opt.HasSections)
-    Script->fabricateDefaultCommands();
-  else
-    Script->synchronize();
-
   for (BaseCommand *Base : Script->Opt.Commands)
     if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base))
       OutputSectionCommands.push_back(Cmd);
@@ -1261,6 +1256,12 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
       applySynthetic({InX::MipsGot},
                      [](SyntheticSection *SS) { SS->updateAllocSize(); });
   }
+
+  if (!Script->Opt.HasSections)
+    Script->fabricateDefaultCommands();
+  else
+    Script->synchronize();
+
   // Fill other section headers. The dynamic table is finalized
   // at the end because some tags like RELSZ depend on result
   // of finalizing other sections.