[CIR][NFC] Cleanup MissingFeature asserts in RecordLayoutBuilder (#161605)

This change cleans up some cir::MissingFeature asserts in
CIRGenRecordLayoutBuilder.cpp. In a couple of cases the asserts were
stale markers that we failed to remove when the correspond support was
implemented.

In one case, a cir::MissingFeature::bitfields() assert was ambiguous in
meaning and has been replaced by a comment and something more specific.
The missing feature in this case is just a bit of debug code to verify
certain bitfield-related conditions. This check should be added, but it
is not functionally required.

Author: andykaylor

clang/include/clang/CIR/MissingFeatures.h

@@ -133,7 +133,6 @@ struct MissingFeatures {
   // RecordType
   static bool skippedLayout() { return false; }
   static bool astRecordDeclAttr() { return false; }
-  static bool recordZeroInit() { return false; }
   static bool recordZeroInitPadding() { return false; }
   static bool zeroSizeRecordMembers() { return false; }
 
@@ -192,6 +191,7 @@ struct MissingFeatures {
   static bool builtinCheckKind() { return false; }
   static bool cgCapturedStmtInfo() { return false; }
   static bool cgFPOptionsRAII() { return false; }
+  static bool checkBitfieldClipping() { return false; }
   static bool cirgenABIInfo() { return false; }
   static bool cleanupAfterErrorDiags() { return false; }
   static bool cleanupsToDeactivate() { return false; }

clang/lib/CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp

@@ -296,9 +296,8 @@ void CIRRecordLowering::lower(bool nonVirtualBaseType) {
   }
 
   llvm::stable_sort(members);
-  // TODO: implement clipTailPadding once bitfields are implemented
-  assert(!cir::MissingFeatures::bitfields());
-  assert(!cir::MissingFeatures::recordZeroInit());
+  // TODO: Verify bitfield clipping
+  assert(!cir::MissingFeatures::checkBitfieldClipping());
 
   members.push_back(makeStorageInfo(size, getUIntNType(8)));
   determinePacked(nonVirtualBaseType);
@@ -319,9 +318,11 @@ void CIRRecordLowering::fillOutputFields() {
         fieldIdxMap[member.fieldDecl->getCanonicalDecl()] =
             fieldTypes.size() - 1;
       // A field without storage must be a bitfield.
-      assert(!cir::MissingFeatures::bitfields());
-      if (!member.data)
+      if (!member.data) {
+        assert(member.fieldDecl &&
+               "member.data is a nullptr so member.fieldDecl should not be");
         setBitFieldInfo(member.fieldDecl, member.offset, fieldTypes.back());
+      }
     } else if (member.kind == MemberInfo::InfoKind::Base) {
       nonVirtualBases[member.cxxRecordDecl] = fieldTypes.size() - 1;
     } else if (member.kind == MemberInfo::InfoKind::VBase) {
@@ -697,13 +698,9 @@ CIRGenTypes::computeRecordLayout(const RecordDecl *rd, cir::RecordType *ty) {
       ty ? *ty : cir::RecordType{}, baseTy ? baseTy : cir::RecordType{},
       (bool)lowering.zeroInitializable, (bool)lowering.zeroInitializableAsBase);
 
-  assert(!cir::MissingFeatures::recordZeroInit());
-
   rl->nonVirtualBases.swap(lowering.nonVirtualBases);
   rl->completeObjectVirtualBases.swap(lowering.virtualBases);
 
-  assert(!cir::MissingFeatures::bitfields());
-
   // Add all the field numbers.
   rl->fieldIdxMap.swap(lowering.fieldIdxMap);