[PATCH] add support for LayoutAfter/LayoutBefore references

[kledzik at apple.com]

================
Comment at: include/lld/Core/Pass.h:117-146
@@ -113,11 +116,32 @@
 
-/// Pass for sorting atoms.
-class OrderPass : public Pass {
+/// Pass for atoms layout.
+class LayoutPass : public Pass {
 public:
-  OrderPass() : Pass() {}
-  
+  class CompareAtoms {
+  public:
+    CompareAtoms(const LayoutPass &pass) : _layout(pass) {}
+    bool operator()(const DefinedAtom *left, const DefinedAtom *right);
+  private:
+    const LayoutPass &_layout;
+  };
+
+  LayoutPass() : Pass(), _compareAtoms(*this) {}
+
   /// Sorts atoms in mergedFile by content type then by command line order.
   virtual void perform(MutableFile &mergedFile);
-};
 
+  virtual ~LayoutPass() {}
+
+private:
+  void buildFollowOnTable(MutableFile::DefinedAtomRange &range);
+  void buildPrecededByTable(MutableFile::DefinedAtomRange &range);
+  void buildOrdinalOverrideMap(MutableFile::DefinedAtomRange &range);
+
+  typedef std::map<const Atom *, const Atom *> AtomToAtomT;
+  typedef std::map<const Atom *, uint64_t> AtomToOrdinalT;
+  AtomToAtomT _followOnNexts;
+  AtomToAtomT _followOnRoots;
+  AtomToOrdinalT _ordinalOverrideMap;
+  CompareAtoms _compareAtoms;
+};
 
----------------
Michael Spencer wrote:
> This should really be in the Passes library.
I think what Michael means here is that Pass.h should just contain the Interface to the pass.  The implementation details should be in the pass implementation.

================
Comment at: include/lld/Core/Reference.h:38-39
@@ +37,4 @@
+  enum {
+    LayoutBefore = -1,
+    LayoutAfter = -2
+  };
----------------
The type should be encoded in these names.  These values are "kinds", so better names would be kindLayoutBefore and kindLayoutAfter.

================
Comment at: include/lld/Core/Reference.h:55-59
@@ +54,7 @@
+    case -1:
+      return "layoutbefore";
+      break;
+    case -2:
+      return "layoutafter";
+      break;
+    default:
----------------
The usual YAML style is a dash between words (e.g. layout-before).  Where else are these string used?

================
Comment at: lib/ReaderWriter/ELF/Atoms.h:78-82
@@ -80,7 +77,7 @@
 private:
-  const Atom  *_target;
-  uint64_t     _targetSymbolIndex;
-  uint64_t     _offsetInAtom;
-  Addend       _addend;
-  Kind         _kind;
+  const Atom *_target;
+  uint64_t _targetSymbolIndex;
+  uint64_t _offsetInAtom;
+  Addend _addend;
+  Kind _kind;
 };
----------------
:-(.  I find having the ivar names vertically aligned to be much more readable.  Why did you go out of your way to remove that?

================
Comment at: test/followon-test.objtxt:30
@@ +29,2 @@
+# CHKORDER:   - name:            fn2
+# CHKORDER:   - name:            fn3
----------------
Since the kind name is "layout after" seems like the test file name should match (layout-after.objtxt).


http://llvm-reviews.chandlerc.com/D373