Introduce model of global initializers in Subzero.

src/IceGlobalInits.h

Index: src/IceGlobalInits.h
diff --git a/src/IceGlobalInits.h b/src/IceGlobalInits.h
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+//===- subzero/src/IceGlobalInits.h - Global initializers -------*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the representation of global addresses

[Jim Stichnoth, 2014/10/03 01:28:08]

Reformat?  e.g. "and" ought to fit on this line.

[Karl, 2014/10/04 16:28:34]

Done.

+// and initializers in Subzero. Global initializers are represented as
+// a sequence of simple initializers.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICEGLOBALINITS_H
+#define SUBZERO_SRC_ICEGLOBALINITS_H
+
+#include "IceDefs.h"
+
+namespace llvm {
+// TODO(kschimpf): Remove this dependency on LLVM IR.
+class Value;
+}
+
+namespace Ice {
+
+/// Models a global address, and its initializers.
+class GlobalAddress {
+public:
+  /// Base class for a global variable initializer.
+  class Initializer {
+  public:
+    /// Discriminator for LLVM-style RTTI.
+    enum InitializerKind {
+      DataInitializerKind,
+      ZeroInitializerKind,
+      RelocInitializerKind
+    };
+    InitializerKind getKind() const { return Kind; }
+    virtual ~Initializer() {}
+    virtual SizeT getNumBytes() const = 0;
+    virtual void dump(Ostream &Stream) const = 0;
+    virtual void dumpType(Ostream &Stream) const;
+
+  protected:
+    Initializer(InitializerKind Kind) : Kind(Kind) {}
+
+  private:
+    const InitializerKind Kind;
+  };
+
+  // Models the data in a data initializer.
+  typedef std::vector<uint8_t> DataVecType;
+
+  /// Defines a sequence of byte values as a data initializer.
+  class DataInitializer : public Initializer {
+  public:
+    template <class Data>
+    DataInitializer(const Data &Values)
+        : Initializer(DataInitializerKind), Contents(Values.size()) {
+      size_t i = 0;
+      for (auto &V : Values) {
+        Contents[i] = static_cast<uint8_t>(V);

[jvoung (off chromium), 2014/10/03 16:15:29]

Would it be cleaner to just:
Contents.push_back(...);

[Karl, 2014/10/04 16:28:34]

The reason I factored it this way was to optimize allocation. By specifying the
size up front, memory is allocated only once.

+        ++i;
+      }
+    }
+    DataInitializer(const char *Str, size_t StrLen)
+        : Initializer(DataInitializerKind), Contents(StrLen) {
+      for (size_t i = 0; i < StrLen; ++i)
+        Contents[i] = static_cast<uint8_t>(Str[i]);
+    }
+    ~DataInitializer() override {}
+    const DataVecType &getContents() const { return Contents; }
+    SizeT getNumBytes() const override { return Contents.size(); }
+    void dump(Ostream &Stream) const override;
+    static bool classof(const Initializer *D) {
+      return D->getKind() == DataInitializerKind;
+    }
+
+  private:
+    // The byte contents of the data initializer.
+    DataVecType Contents;

[jvoung (off chromium), 2014/10/03 16:15:30]

Disallow copy/assign for these initializer types?

[Karl, 2014/10/04 16:28:34]

Done.

+  };
+
+  /// Defines a sequence of bytes initialized to zero.
+  class ZeroInitializer : public Initializer {
+  public:
+    ZeroInitializer(SizeT Size)

[jvoung (off chromium), 2014/10/03 16:15:29]

explicit

[Karl, 2014/10/04 16:28:34]

Done.

+        : Initializer(ZeroInitializerKind), Size(Size) {}
+    ~ZeroInitializer() override {}
+    SizeT getNumBytes() const override { return Size; }
+    void dump(Ostream &Stream) const override;
+    static bool classof(const Initializer *Z) {
+      return Z->getKind() == ZeroInitializerKind;
+    }
+
+  private:
+    // The number of bytes to be zero initialized.
+    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).
+  struct RelocationAddress {
+    RelocationAddress(llvm::Value *Function) : Kind(FunctionRelocation) {
+      Address.Function = Function;
+    }
+    RelocationAddress(GlobalAddress *GlobalAddr)
+        : Kind(GlobalAddressRelocation) {
+      Address.GlobalAddr = GlobalAddr;
+    }
+    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;
+
+  /// Defines the relocation value of another address.
+  class RelocInitializer : public Initializer {
+  public:
+    RelocInitializer(const RelocationAddress &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;
+    static bool classof(const Initializer *R) {
+      return R->getKind() == RelocInitializerKind;
+    }
+
+  private:
+    // The global address used in the relocation.
+    RelocationAddress Address;
+    // The offset to add to the relocation.
+    RelocOffsetType Offset;
+  };
+
+  /// Models the list of initializers.
+  typedef std::vector<Initializer *> InitializerListType;
+
+  GlobalAddress() : Alignment(0), IsConstant(false), IsInternal(true) {}
+  ~GlobalAddress();
+
+  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; }
+
+  /// Returns the number of bytes for the initializer of the global
+  /// address.
+  SizeT getNumBytes() const {
+    SizeT Count = 0;
+    for (Initializer *Init : Initializers) {
+      Count += Init->getNumBytes();
+    }
+    return Count;
+  }
+
+  /// Addes Initializer to the list of initializers. Takes ownership of

[jvoung (off chromium), 2014/10/03 16:15:30]

Adds

[Karl, 2014/10/04 16:28:34]

Done.

+  /// the initializer.
+  void AddInitializer(Initializer *Initializer) {

[jvoung (off chromium), 2014/10/03 16:15:30]

naming style: addInitializer(...) ?

[Karl, 2014/10/04 16:28:34]

Done.

+    Initializers.push_back(Initializer);
+  }
+
+  /// Prints out type for initializer associated with the global address
+  /// to Stream.
+  void dumpType(Ostream &Stream) const;
+
+  /// Prints out the definition of the global address (including
+  /// initialization).
+  void dump(Ostream &Stream) const;
+
+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;
+};
+
+template <class StreamType>
+inline StreamType &operator<<(StreamType &Stream,
+                              const GlobalAddress::Initializer &Init) {
+  Init.dump(Stream);
+  return Stream;
+}
+
+template <class StreamType>
+inline StreamType &operator<<(StreamType &Stream, const GlobalAddress &Addr) {
+  Addr.dump(Stream);
+  return Stream;
+}
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICEGLOBALINITS_H