DebugInfo: Rewrite llvm::getDISubprogram(), NFC

Simplify implementation of `llvm::getDISubprogram()`.  I might go
through and see how difficult it is to update the users, since this
function doesn't really seem necessary anymore.

llvm-svn: 233662

1 files changed, 3 insertions, 11 deletions

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index aa61283918f..d841e3ca9c6 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -461,17 +461,9 @@ DIVariable llvm::cleanseInlinedVariable(MDNode *DV, LLVMContext &VMContext) {
 }
 
 DISubprogram llvm::getDISubprogram(const MDNode *Scope) {
-  DIDescriptor D(Scope);
-  if (D.isSubprogram())
-    return DISubprogram(Scope);
-
-  if (D.isLexicalBlockFile())
-    return getDISubprogram(DILexicalBlockFile(Scope).getContext());
-
-  if (D.isLexicalBlock())
-    return getDISubprogram(DILexicalBlock(Scope).getContext());
-
-  return DISubprogram();
+  if (auto *LocalScope = dyn_cast_or_null<MDLocalScope>(Scope))
+    return LocalScope->getSubprogram();
+  return nullptr;
 }
 
 DISubprogram llvm::getDISubprogram(const Function *F) {