BitcodeWriter: Move abbreviation for DILocation; almost NFC

Simplify ValueEnumerator and WriteModuleMetadata by shifting the logic
for the METADATA_LOCATION abbreviation into WriteDILocation.

The only change is that the abbreviation is emitted later in the
bitcode, just before the first `DILocation` record.  This shouldn't be
observable though.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264302 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -906,10 +906,26 @@ static void WriteMDTuple(const MDTuple *N, const ValueEnumerator &VE,
   Record.clear();
 }
 
+static unsigned createDILocationAbbrev(BitstreamWriter &Stream) {
+  // Assume the column is usually under 128, and always output the inlined-at
+  // location (it's never more expensive than building an array size 1).
+  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  return Stream.EmitAbbrev(Abbv);
+}
+
 static void WriteDILocation(const DILocation *N, const ValueEnumerator &VE,
                             BitstreamWriter &Stream,
                             SmallVectorImpl<uint64_t> &Record,
-                            unsigned Abbrev) {
+                            unsigned &Abbrev) {
+  if (!Abbrev)
+    Abbrev = createDILocationAbbrev(Stream);
+
   Record.push_back(N->isDistinct());
   Record.push_back(N->getLine());
   Record.push_back(N->getColumn());
@@ -1354,21 +1370,6 @@ static void WriteModuleMetadata(const Module &M,
 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
 #include "llvm/IR/Metadata.def"
 
-  if (VE.hasDILocation()) {
-    // Abbrev for METADATA_LOCATION.
-    //
-    // Assume the column is usually under 128, and always output the inlined-at
-    // location (it's never more expensive than building an array size 1).
-    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
-    Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
-    DILocationAbbrev = Stream.EmitAbbrev(Abbv);
-  }
-
   if (VE.hasGenericDINode()) {
     // Abbrev for METADATA_GENERIC_DEBUG.
     //

lib/Bitcode/Writer/ValueEnumerator.cpp

@@ -280,7 +280,7 @@ static bool isIntOrIntVectorValue(const std::pair<const Value*, unsigned> &V) {
 
 ValueEnumerator::ValueEnumerator(const Module &M,
                                  bool ShouldPreserveUseListOrder)
-    : HasMDString(false), HasDILocation(false), HasGenericDINode(false),
+    : HasMDString(false), HasGenericDINode(false),
       ShouldPreserveUseListOrder(ShouldPreserveUseListOrder) {
   if (ShouldPreserveUseListOrder)
     UseListOrders = predictUseListOrder(M);
@@ -532,7 +532,6 @@ void ValueEnumerator::EnumerateMetadata(const Metadata *MD) {
     EnumerateValue(C->getValue());
 
   HasMDString |= isa<MDString>(MD);
-  HasDILocation |= isa<DILocation>(MD);
   HasGenericDINode |= isa<GenericDINode>(MD);
 
   // Replace the dummy ID inserted above with the correct one.  MetadataMap may

lib/Bitcode/Writer/ValueEnumerator.h

@@ -67,7 +67,6 @@ class ValueEnumerator {
   typedef DenseMap<const Metadata *, unsigned> MetadataMapType;
   MetadataMapType MetadataMap;
   bool HasMDString;
-  bool HasDILocation;
   bool HasGenericDINode;
   bool ShouldPreserveUseListOrder;
 
@@ -124,7 +123,6 @@ class ValueEnumerator {
   unsigned numMDs() const { return MDs.size(); }
 
   bool hasMDString() const { return HasMDString; }
-  bool hasDILocation() const { return HasDILocation; }
   bool hasGenericDINode() const { return HasGenericDINode; }
 
   bool shouldPreserveUseListOrder() const { return ShouldPreserveUseListOrder; }