BitcodeWriter: Move abbreviation for GenericDINode; almost NFC

Simplify ValueEnumerator and WriteModuleMetadata by shifting the logic
for the METADATA_GENERIC_DEBUG abbreviation into WriteGenericDINode.
(This is just like r264302, but for GenericDINode.)

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

llvm-svn: 264303

1 files changed, 18 insertions, 17 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index e92b5a9..9977be5 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -936,11 +936,28 @@ static void WriteDILocation(const DILocation *N, const ValueEnumerator &VE,
   Record.clear();
 }
 
+static unsigned createGenericDINodeAbbrev(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_GENERIC_DEBUG));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  return Stream.EmitAbbrev(Abbv);
+}
+
 static void WriteGenericDINode(const GenericDINode *N,
                                const ValueEnumerator &VE,
                                BitstreamWriter &Stream,
                                SmallVectorImpl<uint64_t> &Record,
-                               unsigned Abbrev) {
+                               unsigned &Abbrev) {
+  if (!Abbrev)
+    Abbrev = createGenericDINodeAbbrev(Stream);
+
   Record.push_back(N->isDistinct());
   Record.push_back(N->getTag());
   Record.push_back(0); // Per-tag version field; unused for now.
@@ -1370,22 +1387,6 @@ static void WriteModuleMetadata(const Module &M,
 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
 #include "llvm/IR/Metadata.def"
 
-  if (VE.hasGenericDINode()) {
-    // Abbrev for METADATA_GENERIC_DEBUG.
-    //
-    // 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_GENERIC_DEBUG));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
-    GenericDINodeAbbrev = Stream.EmitAbbrev(Abbv);
-  }
-
   SmallVector<uint64_t, 64> Record;
   for (const Metadata *MD : MDs) {
     if (const MDNode *N = dyn_cast<MDNode>(MD)) {