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.

llvm-svn: 264302

1 files changed, 17 insertions, 16 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index fa63867..e92b5a9 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/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.
     //