Add support for embedded metadata to LLVM. This introduces two new types of

Constant, MDString and MDNode which can only be used by globals with a name
that starts with "llvm." or as arguments to a function with the same naming
restriction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68420 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 58 insertions, 2 deletions

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index dd9db8f..66ccdc2 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -286,10 +286,12 @@ void BitcodeReaderValueList::ResolveConstantForwardRefs() {
                                    UserCS->getType()->isPacked());
       } else if (isa<ConstantVector>(UserC)) {
         NewC = ConstantVector::get(&NewOps[0], NewOps.size());
-      } else {
-        // Must be a constant expression.
+      } else if (isa<ConstantExpr>(UserC)) {
         NewC = cast<ConstantExpr>(UserC)->getWithOperands(&NewOps[0],
                                                           NewOps.size());
+      } else {
+        assert(isa<MDNode>(UserC) && "Must be a metadata node.");
+        NewC = MDNode::get(&NewOps[0], NewOps.size());
       }
       
       UserC->replaceAllUsesWith(NewC);
@@ -999,6 +1001,29 @@ bool BitcodeReader::ParseConstants() {
                          AsmStr, ConstrStr, HasSideEffects);
       break;
     }
+    case bitc::CST_CODE_MDSTRING: {
+      if (Record.size() < 2) return Error("Invalid MDSTRING record");
+      unsigned MDStringLength = Record.size();
+      SmallString<8> String;
+      String.resize(MDStringLength);
+      for (unsigned i = 0; i != MDStringLength; ++i)
+        String[i] = Record[i];
+      V = MDString::get(String.c_str(), String.c_str() + MDStringLength);
+      break;
+    }
+    case bitc::CST_CODE_MDNODE: {
+      if (Record.empty() || Record.size() % 2 == 1)
+        return Error("Invalid CST_MDNODE record");
+      
+      unsigned Size = Record.size();
+      SmallVector<Constant*, 8> Elts;
+      for (unsigned i = 0; i != Size; i += 2) {
+        const Type *Ty = getTypeByID(Record[i], false);
+        Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], Ty));
+      }
+      V = MDNode::get(&Elts[0], Elts.size());
+      break;
+    }
     }
     
     ValueList.AssignValue(V, NextCstNo);
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index d4d3443..c836d39 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -458,6 +458,8 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
   unsigned String8Abbrev = 0;
   unsigned CString7Abbrev = 0;
   unsigned CString6Abbrev = 0;
+  unsigned MDString8Abbrev = 0;
+  unsigned MDString6Abbrev = 0;
   // If this is a constant pool for the module, emit module-specific abbrevs.
   if (isGlobal) {
     // Abbrev for CST_CODE_AGGREGATE.
@@ -485,6 +487,19 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
     CString6Abbrev = Stream.EmitAbbrev(Abbv);
+
+    // Abbrev for CST_CODE_MDSTRING.
+    Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_MDSTRING));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
+    MDString8Abbrev = Stream.EmitAbbrev(Abbv);
+    // Abbrev for CST_CODE_MDSTRING.
+    Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_MDSTRING));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
+    MDString6Abbrev = Stream.EmitAbbrev(Abbv);
   }  
   
   SmallVector<uint64_t, 64> Record;
@@ -678,6 +693,22 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
         Record.push_back(CE->getPredicate());
         break;
       }
+    } else if (const MDString *S = dyn_cast<MDString>(C)) {
+      Code = bitc::CST_CODE_MDSTRING;
+      AbbrevToUse = MDString6Abbrev;
+      for (unsigned i = 0, e = S->size(); i != e; ++i) {
+        char V = S->begin()[i];
+        Record.push_back(V);
+
+        if (!BitCodeAbbrevOp::isChar6(V))
+          AbbrevToUse = MDString8Abbrev;
+      }
+    } else if (const MDNode *N = dyn_cast<MDNode>(C)) {
+      Code = bitc::CST_CODE_MDNODE;
+      for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
+        Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
+        Record.push_back(VE.getValueID(N->getOperand(i)));
+      }
     } else {
       assert(0 && "Unknown constant!");
     }