[ELF] - Fix "--symbol-ordering-file doesn't work with linker scripts"

This is PR33889,

Patch adds support of combination of linkerscript and
-symbol-ordering-file option.

If no sorting commands are present in script inside section declaration
and no --sort-section option specified, code uses sorting from ordering 
file if any exist.

Differential revision: https://reviews.llvm.org/D35843

llvm-svn: 310045

lld/ELF/InputSection.cpp

@@ -44,6 +44,29 @@ std::string lld::toString(const InputSectionBase *Sec) {
   return (toString(Sec->File) + ":(" + Sec->Name + ")").str();
 }
 
+template <class ELFT> DenseMap<SectionBase *, int> elf::buildSectionOrder() {
+  // Build a map from symbols to their priorities. Symbols that didn't
+  // appear in the symbol ordering file have the lowest priority 0.
+  // All explicitly mentioned symbols have negative (higher) priorities.
+  DenseMap<StringRef, int> SymbolOrder;
+  int Priority = -Config->SymbolOrderingFile.size();
+  for (StringRef S : Config->SymbolOrderingFile)
+    SymbolOrder.insert({S, Priority++});
+
+  // Build a map from sections to their priorities.
+  DenseMap<SectionBase *, int> SectionOrder;
+  for (ObjFile<ELFT> *File : ObjFile<ELFT>::Instances) {
+    for (SymbolBody *Body : File->getSymbols()) {
+      auto *D = dyn_cast<DefinedRegular>(Body);
+      if (!D || !D->Section)
+        continue;
+      int &Priority = SectionOrder[D->Section];
+      Priority = std::min(Priority, SymbolOrder.lookup(D->getName()));
+    }
+  }
+  return SectionOrder;
+}
+
 template <class ELFT>
 static ArrayRef<uint8_t> getSectionContents(ObjFile<ELFT> *File,
                                             const typename ELFT::Shdr *Hdr) {
@@ -982,6 +1005,11 @@ uint64_t MergeInputSection::getOffset(uint64_t Offset) const {
   return Piece.OutputOff + Addend;
 }
 
+template DenseMap<SectionBase *, int> elf::buildSectionOrder<ELF32LE>();
+template DenseMap<SectionBase *, int> elf::buildSectionOrder<ELF32BE>();
+template DenseMap<SectionBase *, int> elf::buildSectionOrder<ELF64LE>();
+template DenseMap<SectionBase *, int> elf::buildSectionOrder<ELF64BE>();
+
 template InputSection::InputSection(ObjFile<ELF32LE> *, const ELF32LE::Shdr *,
                                     StringRef);
 template InputSection::InputSection(ObjFile<ELF32BE> *, const ELF32BE::Shdr *,

lld/ELF/InputSection.h

@@ -331,6 +331,9 @@ private:
 // The list of all input sections.
 extern std::vector<InputSectionBase *> InputSections;
 
+// Builds section order for handling --symbol-ordering-file.
+template <class ELFT> llvm::DenseMap<SectionBase *, int> buildSectionOrder();
+
 } // namespace elf
 
 std::string toString(const elf::InputSectionBase *);

lld/ELF/LinkerScript.cpp

@@ -228,6 +228,29 @@ static void sortSections(InputSection **Begin, InputSection **End,
     std::stable_sort(Begin, End, getComparator(K));
 }
 
+static llvm::DenseMap<SectionBase *, int> getSectionOrder() {
+  switch (Config->EKind) {
+  case ELF32LEKind:
+    return buildSectionOrder<ELF32LE>();
+  case ELF32BEKind:
+    return buildSectionOrder<ELF32BE>();
+  case ELF64LEKind:
+    return buildSectionOrder<ELF64LE>();
+  case ELF64BEKind:
+    return buildSectionOrder<ELF64BE>();
+  default:
+    llvm_unreachable("unknown ELF type");
+  }
+}
+
+static void sortBySymbolOrder(InputSection **Begin, InputSection **End) {
+  if (Config->SymbolOrderingFile.empty())
+    return;
+  static llvm::DenseMap<SectionBase *, int> Order = getSectionOrder();
+  MutableArrayRef<InputSection *> In(Begin, End - Begin);
+  sortByOrder(In, [&](InputSectionBase *S) { return Order.lookup(S); });
+}
+
 // Compute and remember which sections the InputSectionDescription matches.
 std::vector<InputSection *>
 LinkerScript::computeInputSections(const InputSectionDescription *Cmd) {
@@ -273,8 +296,15 @@ LinkerScript::computeInputSections(const InputSectionDescription *Cmd) {
     //    --sort-section is handled as an inner SORT command.
     // 3. If one SORT command is given, and if it is SORT_NONE, don't sort.
     // 4. If no SORT command is given, sort according to --sort-section.
+    // 5. If no SORT commands are given and --sort-section is not specified,
+    //    apply sorting provided by --symbol-ordering-file if any exist.
     InputSection **Begin = Ret.data() + SizeBefore;
     InputSection **End = Ret.data() + Ret.size();
+    if (Pat.SortOuter == SortSectionPolicy::Default &&
+        Config->SortSection == SortSectionPolicy::Default) {
+      sortBySymbolOrder(Begin, End);
+      continue;
+    }
     if (Pat.SortOuter != SortSectionPolicy::None) {
       if (Pat.SortInner == SortSectionPolicy::Default)
         sortSections(Begin, End, Config->SortSection);

lld/ELF/OutputSections.cpp

@@ -184,6 +184,20 @@ static bool canMergeToProgbits(unsigned Type) {
          Type == SHT_NOTE;
 }
 
+void elf::sortByOrder(MutableArrayRef<InputSection *> In,
+                      std::function<int(InputSectionBase *S)> Order) {
+  typedef std::pair<int, InputSection *> Pair;
+  auto Comp = [](const Pair &A, const Pair &B) { return A.first < B.first; };
+
+  std::vector<Pair> V;
+  for (InputSection *S : In)
+    V.push_back({Order(S), S});
+  std::stable_sort(V.begin(), V.end(), Comp);
+
+  for (size_t I = 0; I < V.size(); ++I)
+    In[I] = V[I].second;
+}
+
 void elf::reportDiscarded(InputSectionBase *IS) {
   if (!Config->PrintGcSections)
     return;
@@ -291,18 +305,8 @@ bool OutputSection::classof(const BaseCommand *C) {
 }
 
 void OutputSection::sort(std::function<int(InputSectionBase *S)> Order) {
-  typedef std::pair<int, InputSection *> Pair;
-  auto Comp = [](const Pair &A, const Pair &B) { return A.first < B.first; };
-
-  std::vector<Pair> V;
   assert(Commands.size() == 1);
-  auto *ISD = cast<InputSectionDescription>(Commands[0]);
-  for (InputSection *S : ISD->Sections)
-    V.push_back({Order(S), S});
-  std::stable_sort(V.begin(), V.end(), Comp);
-  ISD->Sections.clear();
-  for (Pair &P : V)
-    ISD->Sections.push_back(P.second);
+  sortByOrder(cast<InputSectionDescription>(Commands[0])->Sections, Order);
 }
 
 // Fill [Buf, Buf + Size) with Filler.

lld/ELF/OutputSections.h

@@ -170,6 +170,8 @@ private:
 
 uint64_t getHeaderSize();
 void reportDiscarded(InputSectionBase *IS);
+void sortByOrder(llvm::MutableArrayRef<InputSection *> In,
+                 std::function<int(InputSectionBase *S)> Order);
 
 extern std::vector<OutputSection *> OutputSections;
 } // namespace elf

lld/ELF/Writer.cpp

@@ -872,27 +872,8 @@ template <class ELFT> static void sortBySymbolsOrder() {
   if (Config->SymbolOrderingFile.empty())
     return;
 
-  // Build a map from symbols to their priorities. Symbols that didn't
-  // appear in the symbol ordering file have the lowest priority 0.
-  // All explicitly mentioned symbols have negative (higher) priorities.
-  DenseMap<StringRef, int> SymbolOrder;
-  int Priority = -Config->SymbolOrderingFile.size();
-  for (StringRef S : Config->SymbolOrderingFile)
-    SymbolOrder.insert({S, Priority++});
-
-  // Build a map from sections to their priorities.
-  DenseMap<SectionBase *, int> SectionOrder;
-  for (ObjFile<ELFT> *File : ObjFile<ELFT>::Instances) {
-    for (SymbolBody *Body : File->getSymbols()) {
-      auto *D = dyn_cast<DefinedRegular>(Body);
-      if (!D || !D->Section)
-        continue;
-      int &Priority = SectionOrder[D->Section];
-      Priority = std::min(Priority, SymbolOrder.lookup(D->getName()));
-    }
-  }
-
   // Sort sections by priority.
+  DenseMap<SectionBase *, int> SectionOrder = buildSectionOrder<ELFT>();
   for (BaseCommand *Base : Script->Opt.Commands)
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       Sec->sort([&](InputSectionBase *S) { return SectionOrder.lookup(S); });

lld/test/ELF/linkerscript/symbol-ordering-file.s

@@ -0,0 +1,23 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: echo "SECTIONS { .foo : { *(.foo) } }" > %t.script
+
+# RUN: ld.lld %t.o --script %t.script -o %t.out
+# RUN: llvm-objdump -s %t.out| FileCheck %s --check-prefix=BEFORE
+# BEFORE:      Contents of section .foo:
+# BEFORE-NEXT: 1122 
+
+# RUN: echo "_foo2" > %t.ord
+# RUN: echo "_foo1" >> %t.ord
+# RUN: ld.lld --symbol-ordering-file %t.ord %t.o --script %t.script -o %t2.out
+# RUN: llvm-objdump -s %t2.out| FileCheck %s --check-prefix=AFTER
+# AFTER:      Contents of section .foo:
+# AFTER-NEXT: 2211
+
+.section .foo,"ax",@progbits,unique,1
+_foo1:
+ .byte 0x11
+
+.section .foo,"ax",@progbits,unique,2
+_foo2:
+ .byte 0x22