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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108939 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 11 insertions, 4 deletions

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index b3f0776d29..f486b51cae 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -39,6 +39,7 @@ void BitcodeReader::FreeState() {
   std::vector<BasicBlock*>().swap(FunctionBBs);
   std::vector<Function*>().swap(FunctionsWithBodies);
   DeferredFunctionInfo.clear();
+  MDKindMap.clear();
 }
 
 //===----------------------------------------------------------------------===//
@@ -859,13 +860,12 @@ bool BitcodeReader::ParseMetadata() {
       SmallString<8> Name;
       Name.resize(RecordLength-1);
       unsigned Kind = Record[0];
-      (void) Kind;
       for (unsigned i = 1; i != RecordLength; ++i)
         Name[i-1] = Record[i];
       
       unsigned NewKind = TheModule->getMDKindID(Name.str());
-      assert(Kind == NewKind &&
-             "FIXME: Unable to handle custom metadata mismatch!");(void)NewKind;
+      if (!MDKindMap.insert(std::make_pair(Kind, NewKind)).second)
+        return Error("Conflicting METADATA_KIND records");
       break;
     }
     }
@@ -1621,8 +1621,12 @@ bool BitcodeReader::ParseMetadataAttachment() {
       Instruction *Inst = InstructionList[Record[0]];
       for (unsigned i = 1; i != RecordLength; i = i+2) {
         unsigned Kind = Record[i];
+        DenseMap<unsigned, unsigned>::iterator I =
+          MDKindMap.find(Kind);
+        if (I == MDKindMap.end())
+          return Error("Invalid metadata kind ID");
         Value *Node = MDValueList.getValueFwdRef(Record[i+1]);
-        Inst->setMetadata(Kind, cast<MDNode>(Node));
+        Inst->setMetadata(I->second, cast<MDNode>(Node));
       }
       break;
     }
diff --git a/lib/Bitcode/Reader/BitcodeReader.h b/lib/Bitcode/Reader/BitcodeReader.h
index 55c71f7c88..a5ab5d29e9 100644
--- a/lib/Bitcode/Reader/BitcodeReader.h
+++ b/lib/Bitcode/Reader/BitcodeReader.h
@@ -156,6 +156,9 @@ class BitcodeReader : public GVMaterializer {
   // stored here with their replacement function.
   typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
   UpgradedIntrinsicMap UpgradedIntrinsics;
+
+  // Map the bitcode's custom MDKind ID to the Module's MDKind ID.
+  DenseMap<unsigned, unsigned> MDKindMap;
   
   // After the module header has been read, the FunctionsWithBodies list is 
   // reversed.  This keeps track of whether we've done this yet.