MC: Add dyn_cast support to MCSection.

- Of questionable utility, since in general anything which wants to do this should probably be within a target specific hook, which can rely on the sections being of the appropriate type. However, it can be useful for short term hacks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103980 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCSection.h

@@ -17,6 +17,7 @@
 #include <string>
 #include "llvm/ADT/StringRef.h"
 #include "llvm/MC/SectionKind.h"
+#include "llvm/Support/Casting.h"
 
 namespace llvm {
   class MCContext;
@@ -27,15 +28,27 @@ namespace llvm {
   /// section in the current translation unit.  The MCContext class uniques and
   /// creates these.
   class MCSection {
+  public:
+    enum SectionVariant {
+      SV_COFF = 0,
+      SV_ELF,
+      SV_MachO,
+      SV_PIC16
+    };
+
+  private:
     MCSection(const MCSection&);      // DO NOT IMPLEMENT
     void operator=(const MCSection&); // DO NOT IMPLEMENT
   protected:
-    MCSection(SectionKind K) : Kind(K) {}
+    MCSection(SectionVariant V, SectionKind K) : Variant(V), Kind(K) {}
+    SectionVariant Variant;
     SectionKind Kind;
   public:
     virtual ~MCSection();
 
     SectionKind getKind() const { return Kind; }
+
+    SectionVariant getVariant() const { return Variant; }
     
     virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                       raw_ostream &OS) const = 0;
@@ -47,6 +60,8 @@ namespace llvm {
     virtual bool isBaseAddressKnownZero() const {
       return false;
     }
+
+    static bool classof(const MCSection *) { return true; }
   };
   
 } // end namespace llvm

include/llvm/MC/MCSectionCOFF.h

@@ -35,8 +35,8 @@ namespace llvm {
     friend class MCContext;
     MCSectionCOFF(StringRef Section, unsigned Characteristics,
                   int Selection, SectionKind K)
-      : MCSection(K), SectionName(Section), Characteristics(Characteristics),
-        Selection (Selection) {
+      : MCSection(SV_COFF, K), SectionName(Section),
+        Characteristics(Characteristics), Selection (Selection) {
       assert ((Characteristics & 0x00F00000) == 0 &&
         "alignment must not be set upon section creation");
     }
@@ -103,6 +103,11 @@ namespace llvm {
     
     virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                       raw_ostream &OS) const;
+
+    static bool classof(const MCSection *S) {
+      return S->getVariant() == SV_COFF;
+    }
+    static bool classof(const MCSectionCOFF *) { return true; }
   };
 
 } // end namespace llvm

include/llvm/MC/MCSectionELF.h

@@ -40,7 +40,7 @@ private:
   friend class MCContext;
   MCSectionELF(StringRef Section, unsigned type, unsigned flags,
                SectionKind K, bool isExplicit)
-    : MCSection(K), SectionName(Section), Type(type), Flags(flags), 
+    : MCSection(SV_ELF, K), SectionName(Section), Type(type), Flags(flags),
       IsExplicit(isExplicit) {}
   ~MCSectionELF();
 public:
@@ -178,6 +178,11 @@ public:
   virtual bool isBaseAddressKnownZero() const {
     return (getFlags() & SHF_ALLOC) == 0;
   }
+
+  static bool classof(const MCSection *S) {
+    return S->getVariant() == SV_ELF;
+  }
+  static bool classof(const MCSectionELF *) { return true; }
 };
 
 } // end namespace llvm

include/llvm/MC/MCSectionMachO.h

@@ -165,6 +165,11 @@ public:
 
   virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                     raw_ostream &OS) const;
+
+  static bool classof(const MCSection *S) {
+    return S->getVariant() == SV_MachO;
+  }
+  static bool classof(const MCSectionMachO *) { return true; }
 };
 
 } // end namespace llvm

lib/MC/MCSectionMachO.cpp

@@ -73,7 +73,7 @@ ENTRY(0 /*FIXME*/,           S_ATTR_LOC_RELOC)
 
 MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section,
                                unsigned TAA, unsigned reserved2, SectionKind K)
-  : MCSection(K), TypeAndAttributes(TAA), Reserved2(reserved2) {
+  : MCSection(SV_MachO, K), TypeAndAttributes(TAA), Reserved2(reserved2) {
   assert(Segment.size() <= 16 && Section.size() <= 16 &&
          "Segment or section string too long");
   for (unsigned i = 0; i != 16; ++i) {

lib/Target/PIC16/PIC16Section.h

@@ -44,7 +44,8 @@ namespace llvm {
     unsigned Size;
     
     PIC16Section(StringRef name, SectionKind K, StringRef addr, int color)
-      : MCSection(K), Name(name), Address(addr), Color(color), Size(0) {
+      : MCSection(SV_PIC16, K), Name(name), Address(addr),
+        Color(color), Size(0) {
     }
     
   public:
@@ -86,6 +87,11 @@ namespace llvm {
     /// to a section.
     virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                       raw_ostream &OS) const;
+
+    static bool classof(const MCSection *S) {
+      return S->getVariant() == SV_PIC16;
+    }
+    static bool classof(const PIC16Section *) { return true; }
   };
 
 } // end namespace llvm