DI: Add Function::getSubprogram()

Add `Function::setSubprogram()` and `Function::getSubprogram()`,
convenience methods to forward to `setMetadata()` and `getMetadata()`,
respectively, and deal in `DISubprogram` instead of `MDNode`.

Also add a verifier check to enforce that `!dbg` attachments are always
subprograms.

Originally (when I had the llvm-dev discussion back in April) I thought
I'd store a pointer directly on `llvm::Function` for these attachments
-- we frequently have debug info, and that's much cheaper than using map
in the context if there are no other function-level attachments -- but
for now I'm just using the generic infrastructure.  Let's add the extra
complexity only if this shows up in a profile.

llvm-svn: 246339

1 files changed, 13 insertions, 1 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index c8aba14e813..bcf8c0ffa1e 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -1779,8 +1779,20 @@ void Verifier::visitFunction(const Function &F) {
     }
 
     // Visit metadata attachments.
-    for (const auto &I : MDs)
+    for (const auto &I : MDs) {
+      // Verify that the attachment is legal.
+      switch (I.first) {
+      default:
+        break;
+      case LLVMContext::MD_dbg:
+        Assert(isa<DISubprogram>(I.second),
+               "function !dbg attachment must be a subprogram", &F, I.second);
+        break;
+      }
+
+      // Verify the metadata itself.
       visitMDNode(*I.second);
+    }
   }
 
   // If this function is actually an intrinsic, verify that it is only used in