X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FMC%2FMachObjectWriter.cpp;h=61df5bb35c761b234c6d31628bf97bb9deee5a80;hb=cecbc3d28277ff4916326311cbf87335ed05d106;hp=689aabc333df71f4ac6152826612686ec7055b92;hpb=a8c02c3bdd68e65d14fb6b0d56989663754059b0;p=oota-llvm.git

diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp
index 689aabc333d..61df5bb35c7 100644
--- a/lib/MC/MachObjectWriter.cpp
+++ b/lib/MC/MachObjectWriter.cpp
@@ -616,22 +616,32 @@ public:
       if (IsPCRel)
         report_fatal_error("unsupported pc-relative relocation of difference");
 
-      // We don't currently support any situation where one or both of the
-      // symbols would require a local relocation. This is almost certainly
-      // unused and may not be possible to encode correctly.
-      if (!A_Base || !B_Base)
-        report_fatal_error("unsupported local relocations in difference");
+      // The support for the situation where one or both of the symbols would
+      // require a local relocation is handled just like if the symbols were
+      // external.  This is certainly used in the case of debug sections where
+      // the section has only temporary symbols and thus the symbols don't have
+      // base symbols.  This is encoded using the section ordinal and
+      // non-extern relocation entries.
 
       // Darwin 'as' doesn't emit correct relocations for this (it ends up with
-      // a single SIGNED relocation); reject it for now.
-      if (A_Base == B_Base)
+      // a single SIGNED relocation); reject it for now.  Except the case where
+      // both symbols don't have a base, equal but both NULL.
+      if (A_Base == B_Base && A_Base)
         report_fatal_error("unsupported relocation with identical base");
 
-      Value += Layout.getSymbolAddress(&A_SD) - Layout.getSymbolAddress(A_Base);
-      Value -= Layout.getSymbolAddress(&B_SD) - Layout.getSymbolAddress(B_Base);
+      Value += Layout.getSymbolAddress(&A_SD) - 
+               (A_Base == NULL ? 0 : Layout.getSymbolAddress(A_Base));
+      Value -= Layout.getSymbolAddress(&B_SD) -
+               (B_Base == NULL ? 0 : Layout.getSymbolAddress(B_Base));
 
-      Index = A_Base->getIndex();
-      IsExtern = 1;
+      if (A_Base) {
+        Index = A_Base->getIndex();
+        IsExtern = 1;
+      }
+      else {
+        Index = A_SD.getFragment()->getParent()->getOrdinal() + 1;
+        IsExtern = 0;
+      }
       Type = RIT_X86_64_Unsigned;
 
       MachRelocationEntry MRE;
@@ -643,8 +653,14 @@ public:
                    (Type      << 28));
       Relocations[Fragment->getParent()].push_back(MRE);
 
-      Index = B_Base->getIndex();
-      IsExtern = 1;
+      if (B_Base) {
+        Index = B_Base->getIndex();
+        IsExtern = 1;
+      }
+      else {
+        Index = B_SD.getFragment()->getParent()->getOrdinal() + 1;
+        IsExtern = 0;
+      }
       Type = RIT_X86_64_Subtractor;
     } else {
       const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
@@ -1344,7 +1360,7 @@ bool MachObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
                                                               IsPCRel, DF);
 }
 
-void MachObjectWriter::WriteObject(const MCAssembler &Asm,
+void MachObjectWriter::WriteObject(MCAssembler &Asm,
                                    const MCAsmLayout &Layout) {
   ((MachObjectWriterImpl*) Impl)->WriteObject(Asm, Layout);
 }