[lld] r219959 - [mach-o] update __eh_frame handling for Nick's suggestions

[Tim Northover]

Author: tnorthover
Date: Thu Oct 16 15:52:18 2014
New Revision: 219959

URL: http://llvm.org/viewvc/llvm-project?rev=219959&view=rev
Log:
[mach-o] update __eh_frame handling for Nick's suggestions

First, add a comment to support more variation in FDE formats. Second, refactor
fde -> function handling into a separate function living in the ArchHandler.

Modified:
    lld/trunk/lib/ReaderWriter/MachO/ArchHandler.cpp
    lld/trunk/lib/ReaderWriter/MachO/ArchHandler.h
    lld/trunk/lib/ReaderWriter/MachO/CompactUnwindPass.cpp
    lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp

Modified: lld/trunk/lib/ReaderWriter/MachO/ArchHandler.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/ArchHandler.cpp?rev=219959&r1=219958&r2=219959&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/ArchHandler.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/ArchHandler.cpp Thu Oct 16 15:52:18 2014
@@ -153,6 +153,18 @@ bool ArchHandler::isDwarfCIE(bool swap,
   return read32(swap, *(uint32_t *)(atom->rawContent().data() + idOffset)) == 0;
 }
 
+const Atom *ArchHandler::fdeTargetFunction(const DefinedAtom *fde) {
+  for (auto ref : *fde) {
+    if (ref->kindNamespace() == Reference::KindNamespace::mach_o &&
+        ref->kindValue() == unwindRefToFunctionKind()) {
+      assert(ref->kindArch() == kindArch() && "unexpected Reference arch");
+      return ref->target();
+    }
+  }
+
+  return nullptr;
+}
+
 } // namespace mach_o
 } // namespace lld
 

Modified: lld/trunk/lib/ReaderWriter/MachO/ArchHandler.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/ArchHandler.h?rev=219959&r1=219958&r2=219959&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/ArchHandler.h (original)
+++ lld/trunk/lib/ReaderWriter/MachO/ArchHandler.h Thu Oct 16 15:52:18 2014
@@ -88,6 +88,8 @@ public:
   /// __eh_frame.
   virtual Reference::KindValue unwindRefToEhFrameKind() = 0;
 
+  virtual const Atom *fdeTargetFunction(const DefinedAtom *fde);
+
   /// Used by normalizedFromAtoms() to know where to generated rebasing and 
   /// binding info in final executables.
   virtual bool isPointer(const Reference &) = 0;

Modified: lld/trunk/lib/ReaderWriter/MachO/CompactUnwindPass.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/CompactUnwindPass.cpp?rev=219959&r1=219958&r2=219959&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/CompactUnwindPass.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/CompactUnwindPass.cpp Thu Oct 16 15:52:18 2014
@@ -411,18 +411,13 @@ private:
   collectDwarfFrameEntries(std::unique_ptr<MutableFile> &mergedFile,
                            std::map<const Atom *, const Atom *> &dwarfFrames) {
     for (const DefinedAtom *ehFrameAtom : mergedFile->defined()) {
-      if (ehFrameAtom->contentType() != DefinedAtom::typeCFI ||
-          ArchHandler::isDwarfCIE(_swap, ehFrameAtom))
+      if (ehFrameAtom->contentType() != DefinedAtom::typeCFI)
+        continue;
+      if (ArchHandler::isDwarfCIE(_swap, ehFrameAtom))
         continue;
 
-      DefinedAtom::reference_iterator ref = ehFrameAtom->begin();
-      for (; ref != ehFrameAtom->end(); ++ref)
-        if (ref->kindNamespace() == Reference::KindNamespace::mach_o &&
-            ref->kindArch() == _archHandler.kindArch() &&
-            ref->kindValue() == _archHandler.unwindRefToFunctionKind()) {
-          dwarfFrames.insert(std::make_pair(ref->target(), ehFrameAtom));
-          break;
-        }
+      if (const Atom *function = _archHandler.fdeTargetFunction(ehFrameAtom))
+        dwarfFrames[function] = ehFrameAtom;
     }
   }
 

Modified: lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp?rev=219959&r1=219958&r2=219959&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileToAtoms.cpp Thu Oct 16 15:52:18 2014
@@ -677,7 +677,9 @@ std::error_code addEHFrameReferences(con
                        addend, handler.kindArch());
 
     // Linker needs to fixup reference from the FDE to the function it's
-    // describing.
+    // describing. FIXME: there are actually different ways to do this, and the
+    // particular method used is specified in the CIE's augmentation fields
+    // (hopefully)
     uint64_t rangeFieldInFDE = cieFieldInFDE + sizeof(uint32_t);
 
     int64_t functionFromFDE = readSPtr(is64, swap, frameData + rangeFieldInFDE);