Use llvm.dbg.cu named metadata to collect compile units.

llvm-svn: 130756

llvm/docs/SourceLevelDebugging.html

@@ -342,7 +342,9 @@ height="369">
    that produced it.</p>
 
 <p>Compile unit descriptors provide the root context for objects declared in a
-   specific compilation unit. File descriptors are defined using this context.</p>
+   specific compilation unit. File descriptors are defined using this context.
+   These descriptors are collected by a named metadata 
+   <tt>!llvm.dbg.cu</tt>.
 
 </div>
 

llvm/lib/Analysis/DIBuilder.cpp

@@ -51,6 +51,10 @@ void DIBuilder::createCompileUnit(unsigned Lang, StringRef Filename,
     ConstantInt::get(Type::getInt32Ty(VMContext), RunTimeVer)
   };
   TheCU = DICompileUnit(MDNode::get(VMContext, Elts));
+
+  // Create a named metadata so that it is easier to find cu in a module.
+  NamedMDNode *NMD = M.getOrInsertNamedMetadata("llvm.dbg.cu");
+  NMD->addOperand(TheCU);
 }
 
 /// createFile - Create a file descriptor to hold debugging information