[Bitcode] Use std::nullopt instead of None (NFC)

This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated.  The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

4 files changed, 37 insertions, 34 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp b/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp
index 97bc8280..bd80ee4 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp
@@ -28,7 +28,7 @@ static Optional<const char *> GetBlockName(unsigned BlockID,
   if (BlockID < bitc::FIRST_APPLICATION_BLOCKID) {
     if (BlockID == bitc::BLOCKINFO_BLOCK_ID)
       return "BLOCKINFO_BLOCK";
-    return None;
+    return std::nullopt;
   }
 
   // Check to see if we have a blockinfo record for this block, with a name.
@@ -39,11 +39,11 @@ static Optional<const char *> GetBlockName(unsigned BlockID,
   }
 
   if (CurStreamType != LLVMIRBitstream)
-    return None;
+    return std::nullopt;
 
   switch (BlockID) {
   default:
-    return None;
+    return std::nullopt;
   case bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID:
     return "OPERAND_BUNDLE_TAGS_BLOCK";
   case bitc::MODULE_BLOCK_ID:
@@ -92,7 +92,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
     if (BlockID == bitc::BLOCKINFO_BLOCK_ID) {
       switch (CodeID) {
       default:
-        return None;
+        return std::nullopt;
       case bitc::BLOCKINFO_CODE_SETBID:
         return "SETBID";
       case bitc::BLOCKINFO_CODE_BLOCKNAME:
@@ -101,7 +101,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
         return "SETRECORDNAME";
       }
     }
-    return None;
+    return std::nullopt;
   }
 
   // Check to see if we have a blockinfo record for this record, with a name.
@@ -113,18 +113,18 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   }
 
   if (CurStreamType != LLVMIRBitstream)
-    return None;
+    return std::nullopt;
 
 #define STRINGIFY_CODE(PREFIX, CODE)                                           \
   case bitc::PREFIX##_##CODE:                                                  \
     return #CODE;
   switch (BlockID) {
   default:
-    return None;
+    return std::nullopt;
   case bitc::MODULE_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(MODULE_CODE, VERSION)
       STRINGIFY_CODE(MODULE_CODE, TRIPLE)
       STRINGIFY_CODE(MODULE_CODE, DATALAYOUT)
@@ -144,14 +144,14 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::IDENTIFICATION_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(IDENTIFICATION_CODE, STRING)
       STRINGIFY_CODE(IDENTIFICATION_CODE, EPOCH)
     }
   case bitc::PARAMATTR_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
     // FIXME: Should these be different?
     case bitc::PARAMATTR_CODE_ENTRY_OLD:
       return "ENTRY";
@@ -161,14 +161,14 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::PARAMATTR_GROUP_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
     case bitc::PARAMATTR_GRP_CODE_ENTRY:
       return "ENTRY";
     }
   case bitc::TYPE_BLOCK_ID_NEW:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(TYPE_CODE, NUMENTRY)
       STRINGIFY_CODE(TYPE_CODE, VOID)
       STRINGIFY_CODE(TYPE_CODE, FLOAT)
@@ -196,7 +196,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::CONSTANTS_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(CST_CODE, SETTYPE)
       STRINGIFY_CODE(CST_CODE, NULL)
       STRINGIFY_CODE(CST_CODE, UNDEF)
@@ -227,7 +227,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::FUNCTION_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(FUNC_CODE, DECLAREBLOCKS)
       STRINGIFY_CODE(FUNC_CODE, INST_BINOP)
       STRINGIFY_CODE(FUNC_CODE, INST_CAST)
@@ -272,7 +272,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::VALUE_SYMTAB_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(VST_CODE, ENTRY)
       STRINGIFY_CODE(VST_CODE, BBENTRY)
       STRINGIFY_CODE(VST_CODE, FNENTRY)
@@ -281,7 +281,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::MODULE_STRTAB_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(MST_CODE, ENTRY)
       STRINGIFY_CODE(MST_CODE, HASH)
     }
@@ -289,7 +289,7 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(FS, PERMODULE)
       STRINGIFY_CODE(FS, PERMODULE_PROFILE)
       STRINGIFY_CODE(FS, PERMODULE_RELBF)
@@ -324,13 +324,13 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::METADATA_ATTACHMENT_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(METADATA, ATTACHMENT)
     }
   case bitc::METADATA_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(METADATA, STRING_OLD)
       STRINGIFY_CODE(METADATA, VALUE)
       STRINGIFY_CODE(METADATA, NODE)
@@ -374,13 +374,13 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::METADATA_KIND_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
       STRINGIFY_CODE(METADATA, KIND)
     }
   case bitc::USELIST_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
     case bitc::USELIST_CODE_DEFAULT:
       return "USELIST_CODE_DEFAULT";
     case bitc::USELIST_CODE_BB:
@@ -390,21 +390,21 @@ static Optional<const char *> GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
     case bitc::OPERAND_BUNDLE_TAG:
       return "OPERAND_BUNDLE_TAG";
     }
   case bitc::STRTAB_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
     case bitc::STRTAB_BLOB:
       return "BLOB";
     }
   case bitc::SYMTAB_BLOCK_ID:
     switch (CodeID) {
     default:
-      return None;
+      return std::nullopt;
     case bitc::SYMTAB_BLOB:
       return "BLOB";
     }
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 0b6c509..1d5d10a 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -554,7 +554,7 @@ public:
   Optional<unsigned> getInRangeIndex() const {
     assert(Opcode == Instruction::GetElementPtr);
     if (Extra == (unsigned)-1)
-      return None;
+      return std::nullopt;
     return Extra;
   }
 
@@ -822,7 +822,9 @@ private:
   Error parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);
   Error parseModule(
       uint64_t ResumeBit, bool ShouldLazyLoadMetadata = false,
-      DataLayoutCallbackTy DataLayoutCallback = [](StringRef) { return None; });
+      DataLayoutCallbackTy DataLayoutCallback = [](StringRef) {
+        return std::nullopt;
+      });
 
   Error parseComdatRecord(ArrayRef<uint64_t> Record);
   Error parseGlobalVarRecord(ArrayRef<uint64_t> Record);
@@ -7915,7 +7917,7 @@ Expected<std::unique_ptr<Module>>
 BitcodeModule::getLazyModule(LLVMContext &Context, bool ShouldLazyLoadMetadata,
                              bool IsImporting) {
   return getModuleImpl(Context, false, ShouldLazyLoadMetadata, IsImporting,
-                       [](StringRef) { return None; });
+                       [](StringRef) { return std::nullopt; });
 }
 
 // Parse the specified bitcode buffer and merge the index into CombinedIndex.
diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
index 1ac1502..fd493a5 100644
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
@@ -222,7 +222,7 @@ Metadata *BitcodeReaderMetadataList::getMetadataFwdRef(unsigned Idx) {
 
   // Create and return a placeholder, which will later be RAUW'd.
   ++NumMDNodeTemporary;
-  Metadata *MD = MDNode::getTemporary(Context, None).release();
+  Metadata *MD = MDNode::getTemporary(Context, std::nullopt).release();
   MetadataPtrs[Idx].reset(MD);
   return MD;
 }
@@ -304,7 +304,7 @@ Metadata *BitcodeReaderMetadataList::upgradeTypeRef(Metadata *MaybeUUID) {
 
   auto &Ref = OldTypeRefs.Unknown[UUID];
   if (!Ref)
-    Ref = MDNode::getTemporary(Context, None);
+    Ref = MDNode::getTemporary(Context, std::nullopt);
   return Ref.get();
 }
 
@@ -321,7 +321,7 @@ Metadata *BitcodeReaderMetadataList::upgradeTypeRefArray(Metadata *MaybeTuple) {
   // resolveTypeRefArrays() will be resolve this forward reference.
   OldTypeRefs.Arrays.emplace_back(
       std::piecewise_construct, std::forward_as_tuple(Tuple),
-      std::forward_as_tuple(MDTuple::getTemporary(Context, None)));
+      std::forward_as_tuple(MDTuple::getTemporary(Context, std::nullopt)));
   return OldTypeRefs.Arrays.back().second.get();
 }
 
@@ -1212,7 +1212,8 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     // If this isn't a LocalAsMetadata record, we're dropping it.  This used
     // to be legal, but there's no upgrade path.
     auto dropRecord = [&] {
-      MetadataList.assignValue(MDNode::get(Context, None), NextMetadataNo);
+      MetadataList.assignValue(MDNode::get(Context, std::nullopt),
+                               NextMetadataNo);
       NextMetadataNo++;
     };
     if (Record.size() != 2) {
@@ -1624,7 +1625,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
             DIFile,
             (Context, getMDString(Record[1]), getMDString(Record[2]), Checksum,
              Record.size() > 5 ? Optional<MDString *>(getMDString(Record[5]))
-                               : None)),
+                               : std::nullopt)),
         NextMetadataNo);
     NextMetadataNo++;
     break;
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index bed9d6d..ff64435 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -528,7 +528,7 @@ private:
   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
     auto VMI = GUIDToValueIdMap.find(ValGUID);
     if (VMI == GUIDToValueIdMap.end())
-      return None;
+      return std::nullopt;
     return VMI->second;
   }
 
@@ -4431,7 +4431,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
 
     auto GetValueId = [&](const ValueInfo &VI) -> Optional<unsigned> {
       if (!VI)
-        return None;
+        return std::nullopt;
       return getValueId(VI.getGUID());
     };