[clang] NFC: change more places to use Type::getAsTagDecl and friends (#155313)

This changes a bunch of places which use getAs<TagType>, including
derived types, just to obtain the tag definition.

This is preparation for #155028, offloading all the changes that PR used
to introduce which don't depend on any new helpers.

1 files changed, 5 insertions, 14 deletions

diff --git a/clang/lib/CIR/CodeGen/CIRGenFunction.cpp b/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
index 706c14a..deabb94 100644
--- a/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
@@ -356,12 +356,8 @@ static bool mayDropFunctionReturn(const ASTContext &astContext,
                                   QualType returnType) {
   // We can't just discard the return value for a record type with a complex
   // destructor or a non-trivially copyable type.
-  if (const RecordType *recordType =
-          returnType.getCanonicalType()->getAs<RecordType>()) {
-    if (const auto *classDecl = dyn_cast<CXXRecordDecl>(
-            recordType->getOriginalDecl()->getDefinitionOrSelf()))
-      return classDecl->hasTrivialDestructor();
-  }
+  if (const auto *classDecl = returnType->getAsCXXRecordDecl())
+    return classDecl->hasTrivialDestructor();
   return returnType.isTriviallyCopyableType(astContext);
 }
 
@@ -829,14 +825,9 @@ std::string CIRGenFunction::getCounterAggTmpAsString() {
 void CIRGenFunction::emitNullInitialization(mlir::Location loc, Address destPtr,
                                             QualType ty) {
   // Ignore empty classes in C++.
-  if (getLangOpts().CPlusPlus) {
-    if (const RecordType *rt = ty->getAs<RecordType>()) {
-      if (cast<CXXRecordDecl>(rt->getOriginalDecl())
-              ->getDefinitionOrSelf()
-              ->isEmpty())
-        return;
-    }
-  }
+  if (getLangOpts().CPlusPlus)
+    if (const auto *rd = ty->getAsCXXRecordDecl(); rd && rd->isEmpty())
+      return;
 
   // Cast the dest ptr to the appropriate i8 pointer type.
   if (builder.isInt8Ty(destPtr.getElementType())) {