[PATCH] [lld][ELF] Order segments properly

[Shankar Kalpathi Easwaran]

Hi Bigcheese,

Order the segments by their types

http://llvm-reviews.chandlerc.com/D458

Files:
  SegmentChunks.h

Index: SegmentChunks.h
===================================================================
--- SegmentChunks.h
+++ SegmentChunks.h
@@ -112,6 +112,20 @@
           const Layout::SegmentType type);
 
   enum SegmentOrder {
+    NULLT,
+    PHDR,
+    INTERP,
+    LOAD,
+    DYNAMIC,
+    NOTE,
+    TLS,
+    EH_FRAME,
+    GNU_STACK,
+    GNU_RELRO,
+    UNKNOWN
+  };
+
+  enum LoadSegmentOrder {
     permUnknown,
     permRWX,
     permRX,
@@ -181,6 +195,9 @@
 
   inline int rawflags() const { return _atomflags; }
 
+  /// \brief Convert atomflags to secondary segment order for segments
+  /// that have the same segment type. The segments are sorted by 
+  /// their permisions
   inline int64_t atomflags() const {
     switch (_atomflags) {
 
@@ -208,6 +225,34 @@
     }
   }
 
+  /// \brief convert the segment type to enumeration for sorting secgments
+  inline int64_t segmentOrder() const {
+    switch (_segmentType) {
+    case llvm::ELF::PT_NULL:
+      return NULLT;
+    case llvm::ELF::PT_PHDR:
+      return PHDR;
+    case llvm::ELF::PT_LOAD:
+      return LOAD;
+    case llvm::ELF::PT_DYNAMIC:
+      return DYNAMIC;
+    case llvm::ELF::PT_INTERP:
+      return INTERP;
+    case llvm::ELF::PT_NOTE:
+      return NOTE;
+    case llvm::ELF::PT_TLS:
+      return TLS;
+    case llvm::ELF::PT_GNU_EH_FRAME:
+      return EH_FRAME;
+    case llvm::ELF::PT_GNU_STACK:
+      return GNU_STACK;
+    case llvm::ELF::PT_GNU_RELRO:
+      return GNU_RELRO;
+    default:
+      llvm_unreachable("unknown segment type");
+    }
+  }
+
   inline int64_t numSlices() const { return _segmentSlices.size(); }
 
   inline range<SliceIter> slices() { return _segmentSlices; }
@@ -270,7 +315,9 @@
 
 template <class ELFT>
 bool Segment<ELFT>::compareSegments(Segment<ELFT> *sega, Segment<ELFT> *segb) {
-  return sega->atomflags() < segb->atomflags();
+  if (sega->segmentOrder() == segb->segmentOrder()) 
+    return sega->atomflags() < segb->atomflags();
+  return sega->segmentOrder() < segb->segmentOrder();
 }
 
 template <class ELFT> void Segment<ELFT>::assignOffsets(uint64_t startOffset) {
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