Add support for remapping metadata kind IDs when reading in a

bitcode file, so that two bitcode files where the same metadata kind
name happens to have been assigned a different ID can still be
linked together.

Eliminate the restriction that metadata kind IDs can't be 0.

Change MD_dbg from 1 to 0, because we can now, and because it's
less mysterious that way.

llvm-svn: 108939

1 files changed, 2 insertions, 3 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index fa1b2c4bee2..985c16c783d 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -634,12 +634,11 @@ static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
   SmallVector<StringRef, 4> Names;
   M->getMDKindNames(Names);
   
-  assert(Names[0] == "" && "MDKind #0 is invalid");
-  if (Names.size() == 1) return;
+  if (Names.empty()) return;
 
   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
   
-  for (unsigned MDKindID = 1, e = Names.size(); MDKindID != e; ++MDKindID) {
+  for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
     Record.push_back(MDKindID);
     StringRef KName = Names[MDKindID];
     Record.append(KName.begin(), KName.end());