Introduce the notion of function addresses in Subzero.

src/IceGlobalInits.h

Index: src/IceGlobalInits.h
diff --git a/src/IceGlobalInits.h b/src/IceGlobalInits.h
index 09e5574a0b01139f94f2f4cda63aadda10612c86..939b4b60eaaf572b9b115ce0c5833e7d8977d437 100644
--- a/src/IceGlobalInits.h
+++ b/src/IceGlobalInits.h
@@ -17,6 +17,10 @@
 #define SUBZERO_SRC_ICEGLOBALINITS_H
 
 #include "IceDefs.h"
+#include "IceTypes.h"
+
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/GlobalValue.h" // for GlobalValue::LinkageTypes
 
 namespace llvm {
 // TODO(kschimpf): Remove this dependency on LLVM IR.
@@ -25,12 +29,90 @@ class Value;
 
 namespace Ice {
 
-/// Models a global address, and its initializers.
+/// Base class for global and function addresses.
 class GlobalAddress {
   GlobalAddress(const GlobalAddress &) = delete;
   GlobalAddress &operator=(const GlobalAddress &) = delete;
 
 public:
+  /// Discriminator for LLVM-style RTTI.
+  enum GlobalAddressKind { FunctionKind, GlobalVariableKind };
+  GlobalAddressKind getKind() const { return Kind; }
+  const IceString &getName() const { return Name; }
+  void setName(const IceString &NewName) { Name = NewName; }
+  bool hasName() const { return !Name.empty(); }
+  IceString mangleName(GlobalContext *Ctx) const;
+
+  virtual ~GlobalAddress() {}
+
+  /// Returns true if address is external.
+  virtual bool getIsExternal() const = 0;
+
+  /// Returns true if initialized (or defined if function).
+  virtual bool hasInitializer() const = 0;
+
+  /// Prints out type of the global address.
+  virtual void dumpType(Ostream &Stream) const = 0;
+
+  /// Prints out the declaration of the global address.
+  virtual void dump(Ostream &Stream) const = 0;
+
+protected:
+  GlobalAddress(GlobalAddressKind Kind) : Kind(Kind) {}
+
+  const GlobalAddressKind Kind;
+  // The name for the global address.
+  IceString Name;
+};
+
+// Models a function address. Also defines the type signature of the function,
+// it's calling conventions, and its linkage.

[Jim Stichnoth, 2014/10/10 13:15:00]

its

[Karl, 2014/10/10 20:17:30]

Done.

+class Function : public GlobalAddress {

[Jim Stichnoth, 2014/10/10 13:15:00]

Could we use a different name than "Function" for this?  When I read it, it
makes me think of a fully defined function, like what Cfg captures.

[Karl, 2014/10/10 20:17:30]

Changing as follows:

GlobalAddress -> GlobalDeclaration
Function -> FunctionDeclaration
GlobalVariable -> VariableDeclaration

Chose these names to clarify usage as declarations, make names easy to
differentiate, and to not conflict between namespaces.

+  Function(const Function &) = delete;
+  Function &operator=(const Function &) = delete;
+  friend class GlobalContext;
+
+public:
+  static Function *create(GlobalContext *Ctx, const FuncSigType &Signature,
+                          llvm::CallingConv::ID CallingConv,
+                          llvm::GlobalValue::LinkageTypes Linkage,
+                          bool IsProto);
+  ~Function() final {}
+  const FuncSigType &getSignature() const { return Signature; }
+  llvm::CallingConv::ID getCallingConv() const { return CallingConv; }
+  llvm::GlobalValue::LinkageTypes getLinkage() const { return Linkage; }
+  // isProto implies that there isn't a (local) definition for the function.
+  bool isProto() const { return IsProto; }
+  static bool classof(const GlobalAddress *Addr) {
+    return Addr->getKind() == FunctionKind;
+  }
+  void dumpType(Ostream &Stream) const final;
+  void dump(Ostream &Stream) const final;
+  bool getIsExternal() const final {
+    return Linkage == llvm::GlobalValue::ExternalLinkage;
+  }
+  bool hasInitializer() const final { return !IsProto; }
+
+private:
+  const Ice::FuncSigType Signature;
+  llvm::CallingConv::ID CallingConv;
+  llvm::GlobalValue::LinkageTypes Linkage;
+  bool IsProto;
+
+  Function(const FuncSigType &Signature, llvm::CallingConv::ID CallingConv,
+           llvm::GlobalValue::LinkageTypes Linkage, bool IsProto)
+      : GlobalAddress(FunctionKind), Signature(Signature),
+        CallingConv(CallingConv), Linkage(Linkage), IsProto(IsProto) {}
+};
+
+/// Models a global address, and its initializers.

[jvoung (off chromium), 2014/10/10 01:47:28]

nit: How about "global variable address" otherwise, it looks like the
"GlobalAddress" class?

[Karl, 2014/10/10 20:17:30]

See renaming above. 

+class GlobalVariable : public GlobalAddress {
+  GlobalVariable(const GlobalVariable &) = delete;
+  GlobalVariable &operator=(const GlobalVariable &) = delete;
+  friend class GlobalContext;
+  // TODO(kschimpf) Factor out allocation of initializers into global context,
+  // so that memory allocation/collection can be optimized.
+public:
   /// Base class for a global variable initializer.
   class Initializer {
     Initializer(const Initializer &) = delete;
@@ -81,8 +163,8 @@ public:
     }
     ~DataInitializer() override {}
     const DataVecType &getContents() const { return Contents; }
-    SizeT getNumBytes() const override { return Contents.size(); }
-    void dump(Ostream &Stream) const override;
+    SizeT getNumBytes() const final { return Contents.size(); }
+    void dump(Ostream &Stream) const final;
     static bool classof(const Initializer *D) {
       return D->getKind() == DataInitializerKind;
     }
@@ -101,8 +183,8 @@ public:
     explicit ZeroInitializer(SizeT Size)
         : Initializer(ZeroInitializerKind), Size(Size) {}
     ~ZeroInitializer() override {}
-    SizeT getNumBytes() const override { return Size; }
-    void dump(Ostream &Stream) const override;
+    SizeT getNumBytes() const final { return Size; }
+    void dump(Ostream &Stream) const final;
     static bool classof(const Initializer *Z) {
       return Z->getKind() == ZeroInitializerKind;
     }
@@ -112,51 +194,6 @@ public:
     SizeT Size;
   };
 
-  /// Defines the kind of relocation addresses allowed.
-  enum RelocationKind { FunctionRelocation, GlobalAddressRelocation };
-
-  /// Defines a relocation address (i.e. reference to a function
-  /// or global variable address).
-  class RelocationAddress {
-    RelocationAddress &operator=(const RelocationAddress &) = delete;
-
-  public:
-    explicit RelocationAddress(const RelocationAddress &Addr)
-        : Kind(Addr.Kind) {
-      switch (Kind) {
-      case FunctionRelocation:
-        Address.Function = Addr.Address.Function;
-        break;
-      case GlobalAddressRelocation:
-        Address.GlobalAddr = Addr.Address.GlobalAddr;
-      }
-    }
-    explicit RelocationAddress(llvm::Value *Function)
-        : Kind(FunctionRelocation) {
-      Address.Function = Function;
-    }
-    explicit RelocationAddress(GlobalAddress *GlobalAddr)
-        : Kind(GlobalAddressRelocation) {
-      Address.GlobalAddr = GlobalAddr;
-    }
-    RelocationKind getKind() const { return Kind; }
-    llvm::Value *getFunction() const {
-      assert(Kind == FunctionRelocation);
-      return Address.Function;
-    }
-    GlobalAddress *getGlobalAddr() const {
-      assert(Kind == GlobalAddressRelocation);
-      return Address.GlobalAddr;
-    }
-  private:
-    const RelocationKind Kind;
-    union {
-      // TODO(kschimpf) Integrate Functions into ICE model.
-      llvm::Value *Function;
-      GlobalAddress *GlobalAddr;
-    } Address;
-  };
-
   // Relocation address offsets must be 32 bit values.
   typedef int32_t RelocOffsetType;
   static const SizeT RelocAddrSize = 4;
@@ -167,21 +204,21 @@ public:
     RelocInitializer &operator=(const RelocInitializer &) = delete;
 
   public:
-    RelocInitializer(const RelocationAddress &Address, RelocOffsetType Offset)
+    RelocInitializer(const GlobalAddress *Address, RelocOffsetType Offset)
         : Initializer(RelocInitializerKind), Address(Address), Offset(Offset) {}
     ~RelocInitializer() override {}
     RelocOffsetType getOffset() const { return Offset; }
-    IceString getName() const;
-    SizeT getNumBytes() const override { return RelocAddrSize; }
-    void dump(Ostream &Stream) const override;
-    virtual void dumpType(Ostream &Stream) const;
+    const GlobalAddress *getAddress() const { return Address; }
+    SizeT getNumBytes() const final { return RelocAddrSize; }
+    void dump(Ostream &Stream) const final;
+    void dumpType(Ostream &Stream) const final;
     static bool classof(const Initializer *R) {
       return R->getKind() == RelocInitializerKind;
     }
 
   private:
     // The global address used in the relocation.
-    const RelocationAddress Address;
+    const GlobalAddress *Address;
     // The offset to add to the relocation.
     const RelocOffsetType Offset;
   };
@@ -189,19 +226,21 @@ public:
   /// Models the list of initializers.
   typedef std::vector<Initializer *> InitializerListType;
 
-  GlobalAddress() : Alignment(0), IsConstant(false), IsInternal(true) {}
-  ~GlobalAddress();
+  static GlobalVariable *create(GlobalContext *Ctx);
+  ~GlobalVariable() final;
 
   const InitializerListType &getInitializers() const { return Initializers; }
-  bool hasName() const { return !Name.empty(); }
-  const IceString &getName() const { return Name; }
-  void setName(const IceString &NewName) { Name = NewName; }
   bool getIsConstant() const { return IsConstant; }
   void setIsConstant(bool NewValue) { IsConstant = NewValue; }
   uint32_t getAlignment() const { return Alignment; }
   void setAlignment(uint32_t NewAlignment) { Alignment = NewAlignment; }
   bool getIsInternal() const { return IsInternal; }
   void setIsInternal(bool NewValue) { IsInternal = NewValue; }
+  bool getIsExternal() const final { return !getIsInternal(); }
+  bool hasInitializer() const final {
+    return !(Initializers.size() == 1 &&
+             llvm::isa<ZeroInitializer>(Initializers[0]));
+  }
 
   /// Returns the number of bytes for the initializer of the global
   /// address.
@@ -221,34 +260,40 @@ public:
 
   /// Prints out type for initializer associated with the global address
   /// to Stream.
-  void dumpType(Ostream &Stream) const;
+  void dumpType(Ostream &Stream) const final;
 
   /// Prints out the definition of the global address (including
   /// initialization).
-  void dump(Ostream &Stream) const;
+  void dump(Ostream &Stream) const final;
+
+  static bool classof(const GlobalAddress *Addr) {
+    return Addr->getKind() == GlobalVariableKind;
+  }
 
 private:
   // list of initializers associated with the global address.
   InitializerListType Initializers;
-  // The name for the global.
-  IceString Name;
   // The alignment of the initializer.
   uint32_t Alignment;
   // True if a constant initializer.
   bool IsConstant;
   // True if the address is internal.
   bool IsInternal;
+
+  GlobalVariable()
+      : GlobalAddress(GlobalVariableKind), Alignment(0), IsConstant(false),
+        IsInternal(true) {}
 };
 
 template <class StreamType>
 inline StreamType &operator<<(StreamType &Stream,
-                              const GlobalAddress::Initializer &Init) {
+                              const GlobalVariable::Initializer &Init) {
   Init.dump(Stream);
   return Stream;
 }
 
 template <class StreamType>
-inline StreamType &operator<<(StreamType &Stream, const GlobalAddress &Addr) {
+inline StreamType &operator<<(StreamType &Stream, const GlobalVariable &Addr) {
   Addr.dump(Stream);
   return Stream;
 }