[lld] r316893 - [ELF] - Stop sorting input sections in createSections().

[George Rimar via llvm-commits]

Author: grimar
Date: Mon Oct 30 03:12:49 2017
New Revision: 316893

URL: http://llvm.org/viewvc/llvm-project?rev=316893&view=rev
Log:
[ELF] - Stop sorting input sections in createSections().

It does not seem that createSections() is a good place for
applying sorting. Patch changes code to do that inside
sortSections(), which looks more appropriate place.

Differential revision: https://reviews.llvm.org/D39371

Modified:
    lld/trunk/ELF/OutputSections.cpp
    lld/trunk/ELF/Writer.cpp

Modified: lld/trunk/ELF/OutputSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=316893&r1=316892&r2=316893&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.cpp (original)
+++ lld/trunk/ELF/OutputSections.cpp Mon Oct 30 03:12:49 2017
@@ -296,6 +296,7 @@ bool OutputSection::classof(const BaseCo
 }
 
 void OutputSection::sort(std::function<int(InputSectionBase *S)> Order) {
+  assert(Live);
   assert(SectionCommands.size() == 1);
   sortByOrder(cast<InputSectionDescription>(SectionCommands[0])->Sections,
               Order);

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=316893&r1=316892&r2=316893&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Mon Oct 30 03:12:49 2017
@@ -52,6 +52,7 @@ private:
   void createSections();
   void forEachRelSec(std::function<void(InputSectionBase &)> Fn);
   void sortSections();
+  void sortInputSections();
   void finalizeSections();
   void addPredefinedSections();
   void setReservedSymbolSections();
@@ -837,31 +838,6 @@ template <class ELFT> void Writer<ELFT>:
   ElfSym::Edata2 = Add("_edata", -1);
 }
 
-// Sort input sections by section name suffixes for
-// __attribute__((init_priority(N))).
-static void sortInitFini(OutputSection *Cmd) {
-  if (Cmd)
-    Cmd->sortInitFini();
-}
-
-// Sort input sections by the special rule for .ctors and .dtors.
-static void sortCtorsDtors(OutputSection *Cmd) {
-  if (Cmd)
-    Cmd->sortCtorsDtors();
-}
-
-// Sort input sections using the list provided by --symbol-ordering-file.
-static void sortBySymbolsOrder() {
-  if (Config->SymbolOrderingFile.empty())
-    return;
-
-  // Sort sections by priority.
-  DenseMap<SectionBase *, int> SectionOrder = buildSectionOrder();
-  for (BaseCommand *Base : Script->SectionCommands)
-    if (auto *Sec = dyn_cast<OutputSection>(Base))
-      Sec->sort([&](InputSectionBase *S) { return SectionOrder.lookup(S); });
-}
-
 template <class ELFT>
 void Writer<ELFT>::forEachRelSec(std::function<void(InputSectionBase &)> Fn) {
   // Scan all relocations. Each relocation goes through a series
@@ -888,11 +864,6 @@ template <class ELFT> void Writer<ELFT>:
                                  Vec.end());
 
   Script->fabricateDefaultCommands();
-  sortBySymbolsOrder();
-  sortInitFini(findSection(".init_array"));
-  sortInitFini(findSection(".fini_array"));
-  sortCtorsDtors(findSection(".ctors"));
-  sortCtorsDtors(findSection(".dtors"));
 }
 
 // This function generates assignments for predefined symbols (e.g. _end or
@@ -1050,6 +1021,34 @@ findOrphanPos(std::vector<BaseCommand *>
   return I;
 }
 
+// If no layout was provided by linker script, we want to apply default
+// sorting for special input sections and handle --symbol-ordering-file.
+template <class ELFT> void Writer<ELFT>::sortInputSections() {
+  assert(!Script->HasSectionsCommand);
+
+  // Sort input sections by priority using the list provided
+  // by --symbol-ordering-file.
+  DenseMap<SectionBase *, int> Order = buildSectionOrder();
+  if (!Order.empty())
+    for (BaseCommand *Base : Script->SectionCommands)
+      if (auto *Sec = dyn_cast<OutputSection>(Base))
+        if (Sec->Live)
+          Sec->sort([&](InputSectionBase *S) { return Order.lookup(S); });
+
+  // Sort input sections by section name suffixes for
+  // __attribute__((init_priority(N))).
+  if (OutputSection *Sec = findSection(".init_array"))
+    Sec->sortInitFini();
+  if (OutputSection *Sec = findSection(".fini_array"))
+    Sec->sortInitFini();
+
+  // Sort input sections by the special rule for .ctors and .dtors.
+  if (OutputSection *Sec = findSection(".ctors"))
+    Sec->sortCtorsDtors();
+  if (OutputSection *Sec = findSection(".dtors"))
+    Sec->sortCtorsDtors();
+}
+
 template <class ELFT> void Writer<ELFT>::sortSections() {
   Script->adjustSectionsBeforeSorting();
 
@@ -1063,8 +1062,9 @@ template <class ELFT> void Writer<ELFT>:
       Sec->SortRank = getSectionRank(Sec);
 
   if (!Script->HasSectionsCommand) {
-    // We know that all the OutputSections are contiguous in
-    // this case.
+    sortInputSections();
+
+    // We know that all the OutputSections are contiguous in this case.
     auto E = Script->SectionCommands.end();
     auto I = Script->SectionCommands.begin();
     auto IsSection = [](BaseCommand *Base) { return isa<OutputSection>(Base); };