Revert "DebugInfo: Include .dwo file name when hashing multiple CUs in a single file"

This reverts commit r304119 and r304118. GreenDragon is broken.

llvm-svn: 304125
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
index 201030f..ff04ec7 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -380,12 +380,10 @@
 /// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
 /// with the inclusion of the full CU and all top level CU entities.
 // TODO: Initialize the type chain at 0 instead of 1 for CU signatures.
-uint64_t DIEHash::computeCUSignature(StringRef DWOName, const DIE &Die) {
+uint64_t DIEHash::computeCUSignature(const DIE &Die) {
   Numbering.clear();
   Numbering[&Die] = 1;
 
-  if (!DWOName.empty())
-    Hash.update(DWOName);
   // Hash the DIE.
   computeHash(Die);
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.h b/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
index 29337ae..e2864b1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
@@ -36,7 +36,7 @@
   DIEHash(AsmPrinter *A = nullptr) : AP(A) {}
 
   /// \brief Computes the CU signature.
-  uint64_t computeCUSignature(StringRef DWOName, const DIE &Die);
+  uint64_t computeCUSignature(const DIE &Die);
 
   /// \brief Computes the type signature.
   uint64_t computeTypeSignature(const DIE &Die);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index bf27516..06358c4 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -613,13 +613,6 @@
 
   finishVariableDefinitions();
 
-  // Include the DWO file name in the hash if there's more than one CU.
-  // This handles ThinLTO's situation where imported CUs may very easily be
-  // duplicate with the same CU partially imported into another ThinLTO unit.
-  StringRef DWOName;
-  if (CUMap.size() > 1)
-    DWOName = Asm->TM.Options.MCOptions.SplitDwarfFile;
-
   // Handle anything that needs to be done on a per-unit basis after
   // all other generation.
   for (const auto &P : CUMap) {
@@ -634,8 +627,7 @@
     auto *SkCU = TheCU.getSkeleton();
     if (useSplitDwarf()) {
       // Emit a unique identifier for this CU.
-      uint64_t ID =
-          DIEHash(Asm).computeCUSignature(DWOName, TheCU.getUnitDie());
+      uint64_t ID = DIEHash(Asm).computeCUSignature(TheCU.getUnitDie());
       TheCU.addUInt(TheCU.getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
                     dwarf::DW_FORM_data8, ID);
       SkCU->addUInt(SkCU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,