Revert "Remove dead code."

This reverts commit r207884 which was prematurely committed by accident.

llvm-svn: 207886

8 files changed, 27 insertions, 0 deletions

diff --git a/lld/include/lld/Core/DefinedAtom.h b/lld/include/lld/Core/DefinedAtom.h
index f2bcce4d02e..3e340eb4504 100644
--- a/lld/include/lld/Core/DefinedAtom.h
+++ b/lld/include/lld/Core/DefinedAtom.h
@@ -270,6 +270,12 @@ public:
   /// is R__.
   virtual ContentPermissions permissions() const;
 
+  /// \brief means this is a zero size atom that exists to provide an alternate
+  /// name for another atom.  Alias atoms must have a special Reference to the
+  /// atom they alias which the layout engine recognizes and forces the alias
+  /// atom to layout right before the target atom.
+  virtual bool isAlias() const = 0;
+
   /// \brief returns a reference to the raw (unrelocated) bytes of this Atom's
   /// content.
   virtual ArrayRef<uint8_t> rawContent() const = 0;
diff --git a/lld/include/lld/ReaderWriter/Simple.h b/lld/include/lld/ReaderWriter/Simple.h
index c8e2b20d4bd..aff987a6c6d 100644
--- a/lld/include/lld/ReaderWriter/Simple.h
+++ b/lld/include/lld/ReaderWriter/Simple.h
@@ -140,6 +140,8 @@ public:
     return DefinedAtom::deadStripNormal;
   }
 
+  bool isAlias() const override { return false; }
+
   DefinedAtom::reference_iterator begin() const override {
     uintptr_t index = 0;
     const void *it = reinterpret_cast<const void *>(index);
diff --git a/lld/lib/ReaderWriter/CoreLinkingContext.cpp b/lld/lib/ReaderWriter/CoreLinkingContext.cpp
index 36ec7a2ed5c..0ee4b51af92 100644
--- a/lld/lib/ReaderWriter/CoreLinkingContext.cpp
+++ b/lld/lib/ReaderWriter/CoreLinkingContext.cpp
@@ -63,6 +63,8 @@ public:
     return DefinedAtom::permR_X;
   }
 
+  bool isAlias() const override { return false; }
+
   ArrayRef<uint8_t> rawContent() const override { return ArrayRef<uint8_t>(); }
 
   reference_iterator begin() const override {
@@ -126,6 +128,8 @@ public:
     return DefinedAtom::permRW_;
   }
 
+  bool isAlias() const override { return false; }
+
   ArrayRef<uint8_t> rawContent() const override { return ArrayRef<uint8_t>(); }
 
   reference_iterator begin() const override {
@@ -269,3 +273,4 @@ void CoreLinkingContext::addPasses(PassManager &pm) {
 }
 
 Writer &CoreLinkingContext::writer() const { return *_writer; }
+
diff --git a/lld/lib/ReaderWriter/ELF/Atoms.h b/lld/lib/ReaderWriter/ELF/Atoms.h
index 81d1c7ee6f3..6fec07c18e8 100644
--- a/lld/lib/ReaderWriter/ELF/Atoms.h
+++ b/lld/lib/ReaderWriter/ELF/Atoms.h
@@ -381,6 +381,9 @@ public:
     }
   }
 
+  // FIXME: Not Sure if ELF supports alias atoms. Find out more.
+  bool isAlias() const override { return false; }
+
   ArrayRef<uint8_t> rawContent() const override { return _contentData; }
 
   DefinedAtom::reference_iterator begin() const override {
@@ -484,6 +487,8 @@ public:
 
   virtual bool isThumb() const { return false; }
 
+  bool isAlias() const override { return false; }
+
   ArrayRef<uint8_t> rawContent() const override { return _contentData; }
 
   DefinedAtom::reference_iterator begin() const override {
@@ -566,6 +571,8 @@ public:
 
   ContentPermissions permissions() const override { return permRW_; }
 
+  bool isAlias() const override { return false; }
+
   ArrayRef<uint8_t> rawContent() const override { return ArrayRef<uint8_t>(); }
 
   DefinedAtom::reference_iterator begin() const override {
diff --git a/lld/lib/ReaderWriter/Native/ReaderNative.cpp b/lld/lib/ReaderWriter/Native/ReaderNative.cpp
index 9b8a749aee2..f338e81ea95 100644
--- a/lld/lib/ReaderWriter/Native/ReaderNative.cpp
+++ b/lld/lib/ReaderWriter/Native/ReaderNative.cpp
@@ -98,6 +98,10 @@ public:
      return (DefinedAtom::ContentPermissions)(attributes().permissions);
   }
 
+  bool isAlias() const override {
+     return (attributes().alias != 0);
+  }
+
   ArrayRef<uint8_t> rawContent() const override;
 
   reference_iterator begin() const override;
diff --git a/lld/lib/ReaderWriter/Native/WriterNative.cpp b/lld/lib/ReaderWriter/Native/WriterNative.cpp
index 80f50e866f4..5d56c7a295e 100644
--- a/lld/lib/ReaderWriter/Native/WriterNative.cpp
+++ b/lld/lib/ReaderWriter/Native/WriterNative.cpp
@@ -431,6 +431,7 @@ private:
     attrs.deadStrip         = atom.deadStrip();
     attrs.dynamicExport     = atom.dynamicExport();
     attrs.permissions       = atom.permissions();
+    attrs.alias             = atom.isAlias();
     return attrs;
   }
 
diff --git a/lld/lib/ReaderWriter/PECOFF/Atoms.h b/lld/lib/ReaderWriter/PECOFF/Atoms.h
index c4ae1271c0b..a7477ddffa6 100644
--- a/lld/lib/ReaderWriter/PECOFF/Atoms.h
+++ b/lld/lib/ReaderWriter/PECOFF/Atoms.h
@@ -105,6 +105,7 @@ public:
     return sectionPositionAny;
   }
   DeadStripKind deadStrip() const override { return deadStripNormal; }
+  bool isAlias() const override { return false; }
 
   Kind getKind() const { return _kind; }
 
diff --git a/lld/lib/ReaderWriter/YAML/ReaderWriterYAML.cpp b/lld/lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
index dbc50873f75..e9bfc1a8233 100644
--- a/lld/lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
+++ b/lld/lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
@@ -892,6 +892,7 @@ template <> struct MappingTraits<const lld::DefinedAtom *> {
     DeadStripKind deadStrip() const override { return _deadStrip; }
     DynamicExport dynamicExport() const override { return _dynamicExport; }
     ContentPermissions permissions() const override { return _permissions; }
+    bool isAlias() const override { return false; }
     bool isGroupChild() const { return _isGroupChild; }
     ArrayRef<uint8_t> rawContent() const override {
       if (!occupiesDiskSpace())