DebugInfo: Remove MDString-based type references

Eliminate DITypeIdentifierMap and make DITypeRef a thin wrapper around
DIType*.  It is no longer legal to refer to a DICompositeType by its
'identifier:', and DIBuilder no longer retains all types with an
'identifier:' automatically.

Aside from the bitcode upgrade, this is mainly removing logic to resolve
an MDString-based reference to an actualy DIType.  The commits leading
up to this have made the implicit type map in DICompileUnit's
'retainedTypes:' field superfluous.

This does not remove DITypeRef, DIScopeRef, DINodeRef, and
DITypeRefArray, or stop using them in DI-related metadata.  Although as
of this commit they aren't serving a useful purpose, there are patchces
under review to reuse them for CodeView support.

The tests in LLVM were updated with deref-typerefs.sh, which is attached
to the thread "[RFC] Lazy-loading of debug info metadata":

  http://lists.llvm.org/pipermail/llvm-dev/2016-April/098318.html

llvm-svn: 267296

1 files changed, 2 insertions, 6 deletions

diff --git a/llvm/tools/opt/BreakpointPrinter.cpp b/llvm/tools/opt/BreakpointPrinter.cpp
index f76ad79fbe7..33b3edcd123 100644
--- a/llvm/tools/opt/BreakpointPrinter.cpp
+++ b/llvm/tools/opt/BreakpointPrinter.cpp
@@ -25,7 +25,6 @@ namespace {
 struct BreakpointPrinter : public ModulePass {
   raw_ostream &Out;
   static char ID;
-  DITypeIdentifierMap TypeIdentifierMap;
 
   BreakpointPrinter(raw_ostream &out) : ModulePass(ID), Out(out) {}
 
@@ -37,16 +36,13 @@ struct BreakpointPrinter : public ModulePass {
       }
     } else if (auto *TY = dyn_cast<DIType>(Context)) {
       if (!TY->getName().empty()) {
-        getContextName(TY->getScope().resolve(TypeIdentifierMap), N);
+        getContextName(TY->getScope().resolve(), N);
         N = N + TY->getName().str() + "::";
       }
     }
   }
 
   bool runOnModule(Module &M) override {
-    TypeIdentifierMap.clear();
-    TypeIdentifierMap = generateDITypeIdentifierMap(M);
-
     StringSet<> Processed;
     if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.sp"))
       for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
@@ -54,7 +50,7 @@ struct BreakpointPrinter : public ModulePass {
         auto *SP = cast_or_null<DISubprogram>(NMD->getOperand(i));
         if (!SP)
           continue;
-        getContextName(SP->getScope().resolve(TypeIdentifierMap), Name);
+        getContextName(SP->getScope().resolve(), Name);
         Name = Name + SP->getDisplayName().str();
         if (!Name.empty() && Processed.insert(Name).second) {
           Out << Name << "\n";