Move MCSection::printSwitchToSection to MCAsmInfo

This removes the only virtual function of MCSection.

NVPTXTargetStreamer::changeSection uses the MCSectionELF print method.
Change it to just print the section name.

Author: MaskRay

llvm/include/llvm/MC/MCAsmInfo.h

@@ -35,6 +35,7 @@ class MCStreamer;
 class MCSubtargetInfo;
 class MCSymbol;
 class MCValue;
+class Triple;
 class raw_ostream;
 
 namespace WinEH {
@@ -485,6 +486,9 @@ class LLVM_ABI MCAsmInfo {
   /// syntactically correct.
   virtual bool isValidUnquotedName(StringRef Name) const;
 
+  virtual void printSwitchToSection(const MCSection &, uint32_t Subsection,
+                                    const Triple &, raw_ostream &) const {}
+
   /// Return true if the .section directive should be omitted when
   /// emitting \p SectionName.  For example:
   ///

llvm/include/llvm/MC/MCAsmInfoCOFF.h

@@ -15,6 +15,8 @@ namespace llvm {
 
 class MCAsmInfoCOFF : public MCAsmInfo {
   virtual void anchor();
+  void printSwitchToSection(const MCSection &, uint32_t, const Triple &,
+                            raw_ostream &) const final;
   bool useCodeAlign(const MCSection &Sec) const final;
 
 protected:

llvm/include/llvm/MC/MCAsmInfoDarwin.h

@@ -21,6 +21,8 @@ namespace llvm {
 class MCAsmInfoDarwin : public MCAsmInfo {
 public:
   explicit MCAsmInfoDarwin();
+  void printSwitchToSection(const MCSection &, uint32_t, const Triple &,
+                            raw_ostream &) const final;
   bool useCodeAlign(const MCSection &Sec) const final;
 
   /// True if the section is atomized using the symbols in it.

llvm/include/llvm/MC/MCAsmInfoELF.h

@@ -16,6 +16,8 @@ namespace llvm {
 class MCAsmInfoELF : public MCAsmInfo {
   virtual void anchor();
   MCSection *getNonexecutableStackSection(MCContext &Ctx) const final;
+  void printSwitchToSection(const MCSection &, uint32_t, const Triple &,
+                            raw_ostream &) const final;
   bool useCodeAlign(const MCSection &Sec) const final;
 
 protected:

llvm/include/llvm/MC/MCAsmInfoGOFF.h

@@ -19,7 +19,8 @@
 
 namespace llvm {
 class MCAsmInfoGOFF : public MCAsmInfo {
-  virtual void anchor();
+  void printSwitchToSection(const MCSection &, uint32_t, const Triple &,
+                            raw_ostream &) const final;
 
 protected:
   MCAsmInfoGOFF();

llvm/include/llvm/MC/MCAsmInfoWasm.h

@@ -13,7 +13,8 @@
 
 namespace llvm {
 class MCAsmInfoWasm : public MCAsmInfo {
-  virtual void anchor();
+  void printSwitchToSection(const MCSection &, uint32_t, const Triple &,
+                            raw_ostream &) const final;
 
 protected:
   MCAsmInfoWasm();

llvm/include/llvm/MC/MCAsmInfoXCOFF.h

@@ -16,6 +16,8 @@ namespace llvm {
 class MCAsmInfoXCOFF : public MCAsmInfo {
 protected:
   MCAsmInfoXCOFF();
+  void printSwitchToSection(const MCSection &, uint32_t, const Triple &,
+                            raw_ostream &) const final;
   bool useCodeAlign(const MCSection &Sec) const final;
 
 public:

llvm/include/llvm/MC/MCSection.h

@@ -597,8 +597,6 @@ class LLVM_ABI MCSection {
   StringRef Name;
 
   MCSection(StringRef Name, bool IsText, bool IsBss, MCSymbol *Begin);
-  // Protected non-virtual dtor prevents destroy through a base class pointer.
-  ~MCSection() {}
 
 public:
   MCSection(const MCSection &) = delete;
@@ -648,10 +646,6 @@ class LLVM_ABI MCSection {
   void dump(DenseMap<const MCFragment *, SmallVector<const MCSymbol *, 0>>
                 *FragToSyms = nullptr) const;
 
-  virtual void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
-                                    raw_ostream &OS,
-                                    uint32_t Subsection) const {}
-
   /// Check whether this section is "virtual", that is has no actual object
   /// file contents.
   bool isBssSection() const { return IsBss; }

llvm/include/llvm/MC/MCSectionCOFF.h

@@ -51,6 +51,7 @@ class MCSectionCOFF final : public MCSection {
 
 private:
   friend class MCContext;
+  friend class MCAsmInfoCOFF;
   // The storage of Name is owned by MCContext's COFFUniquingMap.
   MCSectionCOFF(StringRef Name, unsigned Characteristics,
                 MCSymbol *COMDATSymbol, int Selection, unsigned UniqueID,
@@ -67,7 +68,7 @@ class MCSectionCOFF final : public MCSection {
 public:
   /// Decides whether a '.section' directive should be printed before the
   /// section name
-  bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
+  bool shouldOmitSectionDirective(StringRef Name) const;
 
   unsigned getCharacteristics() const { return Characteristics; }
   MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
@@ -78,10 +79,6 @@ class MCSectionCOFF final : public MCSection {
   bool isUnique() const { return UniqueID != NonUniqueID; }
   unsigned getUniqueID() const { return UniqueID; }
 
-  void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
-                            raw_ostream &OS,
-                            uint32_t Subsection) const override;
-
   unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
     if (WinCFISectionID == ~0U)
       WinCFISectionID = (*NextID)++;

llvm/include/llvm/MC/MCSectionELF.h

@@ -52,6 +52,7 @@ class MCSectionELF final : public MCSection {
 
 private:
   friend class MCContext;
+  friend class MCAsmInfoELF;
 
   // The storage of Name is owned by MCContext's ELFUniquingMap.
   MCSectionELF(StringRef Name, unsigned type, unsigned flags,
@@ -69,21 +70,13 @@ class MCSectionELF final : public MCSection {
   }
 
 public:
-  /// Decides whether a '.section' directive should be printed before the
-  /// section name
-  bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
-
   unsigned getType() const { return Type; }
   unsigned getFlags() const { return Flags; }
   unsigned getEntrySize() const { return EntrySize; }
   void setFlags(unsigned F) { Flags = F; }
   const MCSymbolELF *getGroup() const { return Group.getPointer(); }
   bool isComdat() const { return Group.getInt(); }
 
-  void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
-                            raw_ostream &OS,
-                            uint32_t Subsection) const override;
-
   bool isUnique() const { return UniqueID != NonUniqueID; }
   unsigned getUniqueID() const { return UniqueID; }