Speculatively revert commit 127478 (jsjodin) in an attempt to fix the

llvm-gcc-i386-linux-selfhost and llvm-x86_64-linux-checks buildbots.
The original log entry:
Remove optimization emitting a reference insted of label difference, since
it can create more relocations. Removed isBaseAddressKnownZero method,
because it is no longer used.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127540 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

@@ -191,6 +191,13 @@ void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
   assert((!Label->isInSection() || &Label->getSection() == &Section) &&
          "Section offset using wrong section base for label");
   
+  // If the section in question will end up with an address of 0 anyway, we can
+  // just emit an absolute reference to save a relocation.
+  if (Section.isBaseAddressKnownZero()) {
+    OutStreamer.EmitSymbolValue(Label, 4, 0/*AddrSpace*/);
+    return;
+  }
+  
   // Otherwise, emit it as a label difference from the start of the section.
   EmitLabelDifference(Label, SectionLabel, 4);
 }