IR: Stop using DIDescriptor::is*() and auto-casting

`DIDescriptor`'s subclasses allow construction from incompatible
pointers, and `DIDescriptor` defines a series of `isa<>`-like functions
(e.g., `isCompileUnit()` instead of `isa<MDCompileUnit>()`) that clients
tend to use like this:

    if (DICompileUnit(N).isCompileUnit())
      foo(DICompileUnit(N));

These construction patterns work together to make `DIDescriptor` behave
differently from normal pointers.

Instead, use built-in `isa<>`, `dyn_cast<>`, etc., and only build
`DIDescriptor`s from pointers that are valid for their type.

I've split this into a few commits for different parts of LLVM and clang
(to decrease the patch size and increase the chance of review).
Generally the changes I made were NFC, but in a few places I made things
stricter if it made sense from the surrounded code.

Eventually a follow-up commit will remove the API for the "old" way.

llvm-svn: 234255

1 files changed, 3 insertions, 7 deletions

diff --git a/llvm/tools/opt/BreakpointPrinter.cpp b/llvm/tools/opt/BreakpointPrinter.cpp
index 3cbc0ae50f1..eb89b9bca80 100644
--- a/llvm/tools/opt/BreakpointPrinter.cpp
+++ b/llvm/tools/opt/BreakpointPrinter.cpp
@@ -30,14 +30,12 @@ struct BreakpointPrinter : public ModulePass {
   BreakpointPrinter(raw_ostream &out) : ModulePass(ID), Out(out) {}
 
   void getContextName(DIDescriptor Context, std::string &N) {
-    if (Context.isNameSpace()) {
-      DINameSpace NS(Context);
+    if (DINameSpace NS = dyn_cast<MDNamespace>(Context)) {
       if (!NS.getName().empty()) {
         getContextName(NS.getContext(), N);
         N = N + NS.getName().str() + "::";
       }
-    } else if (Context.isType()) {
-      DIType TY(Context);
+    } else if (DIType TY = dyn_cast<MDType>(Context)) {
       if (!TY.getName().empty()) {
         getContextName(TY.getContext().resolve(TypeIdentifierMap), N);
         N = N + TY.getName().str() + "::";
@@ -55,9 +53,7 @@ struct BreakpointPrinter : public ModulePass {
     if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.sp"))
       for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
         std::string Name;
-        DISubprogram SP(NMD->getOperand(i));
-        assert((!SP || SP.isSubprogram()) &&
-               "A MDNode in llvm.dbg.sp should be null or a DISubprogram.");
+        DISubprogram SP = cast_or_null<MDSubprogram>(NMD->getOperand(i));
         if (!SP)
           continue;
         getContextName(SP.getContext().resolve(TypeIdentifierMap), Name);