[MC] Replace MCContext::GenericSectionID with MCSection::NonUniqueID (#126202)

They have same semantics. NonUniqueID is more friendly for isUnique
implementation in MCSectionELF.

History: 97837b7 added support for unique IDs in sections and added
GenericSectionID. Later, 1dc16c7 added NonUniqueID.

Author: HaohaiWen

llvm/include/llvm/MC/MCContext.h

@@ -527,13 +527,6 @@ class MCContext {
   /// \name Section Management
   /// @{
 
-  enum : unsigned {
-    /// Pass this value as the UniqueID during section creation to get the
-    /// generic section with the given name and characteristics. The usual
-    /// sections such as .text use this ID.
-    GenericSectionID = ~0U
-  };
-
   /// Return the MCSection for the specified mach-o section.  This requires
   /// the operands to be valid.
   MCSectionMachO *getMachOSection(StringRef Segment, StringRef Section,
@@ -611,7 +604,7 @@ class MCContext {
 
   MCSectionCOFF *getCOFFSection(StringRef Section, unsigned Characteristics,
                                 StringRef COMDATSymName, int Selection,
-                                unsigned UniqueID = GenericSectionID);
+                                unsigned UniqueID = MCSection::NonUniqueID);
 
   MCSectionCOFF *getCOFFSection(StringRef Section, unsigned Characteristics);
 
@@ -621,7 +614,7 @@ class MCContext {
   /// as Sec and the function symbol as KeySym.
   MCSectionCOFF *
   getAssociativeCOFFSection(MCSectionCOFF *Sec, const MCSymbol *KeySym,
-                            unsigned UniqueID = GenericSectionID);
+                            unsigned UniqueID = MCSection::NonUniqueID);
 
   MCSectionSPIRV *getSPIRVSection();
 

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -758,7 +758,7 @@ calcUniqueIDUpdateFlagsAndSize(const GlobalObject *GO, StringRef SectionName,
   if (!SupportsUnique) {
     Flags &= ~ELF::SHF_MERGE;
     EntrySize = 0;
-    return MCContext::GenericSectionID;
+    return MCSection::NonUniqueID;
   }
 
   const bool SymbolMergeable = Flags & ELF::SHF_MERGE;
@@ -770,16 +770,16 @@ calcUniqueIDUpdateFlagsAndSize(const GlobalObject *GO, StringRef SectionName,
     if (TM.getSeparateNamedSections())
       return NextUniqueID++;
     else
-      return MCContext::GenericSectionID;
+      return MCSection::NonUniqueID;
   }
 
   // Symbols must be placed into sections with compatible entry sizes. Generate
   // unique sections for symbols that have not been assigned to compatible
   // sections.
   const auto PreviousID =
       Ctx.getELFUniqueIDForEntsize(SectionName, Flags, EntrySize);
-  if (PreviousID && (!TM.getSeparateNamedSections() ||
-                     *PreviousID == MCContext::GenericSectionID))
+  if (PreviousID &&
+      (!TM.getSeparateNamedSections() || *PreviousID == MCSection::NonUniqueID))
     return *PreviousID;
 
   // If the user has specified the same section name as would be created
@@ -791,7 +791,7 @@ calcUniqueIDUpdateFlagsAndSize(const GlobalObject *GO, StringRef SectionName,
   if (SymbolMergeable &&
       Ctx.isELFImplicitMergeableSectionNamePrefix(SectionName) &&
       SectionName.starts_with(ImplicitSectionNameStem))
-    return MCContext::GenericSectionID;
+    return MCSection::NonUniqueID;
 
   // We have seen this section name before, but with different flags or entity
   // size. Create a new unique ID.
@@ -903,7 +903,7 @@ static MCSectionELF *selectELFSectionForGlobal(
   unsigned EntrySize = getEntrySizeForKind(Kind);
 
   bool UniqueSectionName = false;
-  unsigned UniqueID = MCContext::GenericSectionID;
+  unsigned UniqueID = MCSection::NonUniqueID;
   if (EmitUniqueSection) {
     if (TM.getUniqueSectionNames()) {
       UniqueSectionName = true;
@@ -1073,7 +1073,7 @@ MCSection *TargetLoweringObjectFileELF::getSectionForMachineBasicBlock(
     const Function &F, const MachineBasicBlock &MBB,
     const TargetMachine &TM) const {
   assert(MBB.isBeginSection() && "Basic block does not start a section!");
-  unsigned UniqueID = MCContext::GenericSectionID;
+  unsigned UniqueID = MCSection::NonUniqueID;
 
   // For cold sections use the .text.split. prefix along with the parent
   // function name. All cold blocks for the same function go to the same
@@ -1774,7 +1774,7 @@ MCSection *TargetLoweringObjectFileCOFF::SelectSectionForGlobal(
     else
       ComdatGV = GO;
 
-    unsigned UniqueID = MCContext::GenericSectionID;
+    unsigned UniqueID = MCSection::NonUniqueID;
     if (EmitUniquedSection)
       UniqueID = NextUniqueID++;
 
@@ -2220,8 +2220,8 @@ MCSection *TargetLoweringObjectFileWasm::getExplicitSectionGlobal(
   }
 
   unsigned Flags = getWasmSectionFlags(Kind, Used.count(GO));
-  MCSectionWasm *Section = getContext().getWasmSection(
-      Name, Kind, Flags, Group, MCContext::GenericSectionID);
+  MCSectionWasm *Section = getContext().getWasmSection(Name, Kind, Flags, Group,
+                                                       MCSection::NonUniqueID);
 
   return Section;
 }
@@ -2249,7 +2249,7 @@ selectWasmSectionForGlobal(MCContext &Ctx, const GlobalObject *GO,
     Name.push_back('.');
     TM.getNameWithPrefix(Name, GO, Mang, true);
   }
-  unsigned UniqueID = MCContext::GenericSectionID;
+  unsigned UniqueID = MCSection::NonUniqueID;
   if (EmitUniqueSection && !UniqueSectionNames) {
     UniqueID = *NextUniqueID;
     (*NextUniqueID)++;

llvm/lib/MC/MCContext.cpp

@@ -636,7 +636,7 @@ void MCContext::recordELFMergeableSectionInfo(StringRef SectionName,
                                               unsigned Flags, unsigned UniqueID,
                                               unsigned EntrySize) {
   bool IsMergeable = Flags & ELF::SHF_MERGE;
-  if (UniqueID == GenericSectionID) {
+  if (UniqueID == MCSection::NonUniqueID) {
     ELFSeenGenericMergeableSections.insert(SectionName);
     // Minor performance optimization: avoid hash map lookup in
     // isELFGenericMergeableSection, which will return true for SectionName.
@@ -727,14 +727,15 @@ MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
 
 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
                                          unsigned Characteristics) {
-  return getCOFFSection(Section, Characteristics, "", 0, GenericSectionID);
+  return getCOFFSection(Section, Characteristics, "", 0,
+                        MCSection::NonUniqueID);
 }
 
 MCSectionCOFF *MCContext::getAssociativeCOFFSection(MCSectionCOFF *Sec,
                                                     const MCSymbol *KeySym,
                                                     unsigned UniqueID) {
   // Return the normal section if we don't have to be associative or unique.
-  if (!KeySym && UniqueID == GenericSectionID)
+  if (!KeySym && UniqueID == MCSection::NonUniqueID)
     return Sec;
 
   // If we have a key symbol, make an associative section with the same name and

llvm/lib/MC/MCObjectFileInfo.cpp

@@ -1066,7 +1066,7 @@ MCSection *MCObjectFileInfo::getDwarfComdatSection(const char *Name,
                               utostr(Hash), /*IsComdat=*/true);
   case Triple::Wasm:
     return Ctx->getWasmSection(Name, SectionKind::getMetadata(), 0,
-                               utostr(Hash), MCContext::GenericSectionID);
+                               utostr(Hash), MCSection::NonUniqueID);
   case Triple::MachO:
   case Triple::COFF:
   case Triple::GOFF:

llvm/lib/MC/MCParser/WasmAsmParser.cpp

@@ -193,7 +193,7 @@ class WasmAsmParser : public MCAsmParserExtension {
 
     // TODO: Parse UniqueID
     MCSectionWasm *WS = getContext().getWasmSection(
-        Name, *Kind, Flags, GroupName, MCContext::GenericSectionID);
+        Name, *Kind, Flags, GroupName, MCSection::NonUniqueID);
 
     if (WS->getSegmentFlags() != Flags)
       Parser->Error(loc, "changed section flags for " + Name +

llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp

@@ -1246,7 +1246,7 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
     if (Group)
       WasmSym->setComdat(true);
     auto *WS = getContext().getWasmSection(SecName, SectionKind::getText(), 0,
-                                           Group, MCContext::GenericSectionID);
+                                           Group, MCSection::NonUniqueID);
     getStreamer().switchSection(WS);
     // Also generate DWARF for this section if requested.
     if (getContext().getGenDwarfForAssembly())