Add support for undef values in ICE IR.

src/IceGlobalContext.cpp

 //===- subzero/src/IceGlobalContext.cpp - Global context defs ---*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines aspects of the compilation that persist across
@@ skipping 56 matching lines @@
       if (KeyTypeHasFP)
         return memcmp(&A.second, &B.second, sizeof(KeyType)) < 0;
       return A.second < B.second;
     }
   };
   typedef std::map<const TupleType, ValueType *, TupleCompare> ContainerType;
   ContainerType Pool;
   uint32_t NextPoolID;
 };
 
+// UndefPool maps ICE types to the corresponding ConstantUndef values.
+class UndefPool {
+  UndefPool(const UndefPool &) LLVM_DELETED_FUNCTION;
+  UndefPool &operator=(const UndefPool &) LLVM_DELETED_FUNCTION;
+
+public:
+  UndefPool() : NextPoolID(0) {}
+
+  ConstantUndef *getOrAdd(GlobalContext *Ctx, Type Ty) {
+    ContainerType::iterator I = Pool.find(Ty);
+    if (I != Pool.end())
+      return I->second;
+    ConstantUndef *Undef = ConstantUndef::create(Ctx, Ty, NextPoolID++);
+    Pool[Ty] = Undef;
+    return Undef;
+  }
+
+private:
+  uint32_t NextPoolID;
+  typedef std::map<Type, ConstantUndef *> ContainerType;
+  ContainerType Pool;
+};
+
 // The global constant pool bundles individual pools of each type of
 // interest.
 class ConstantPool {
   ConstantPool(const ConstantPool &) LLVM_DELETED_FUNCTION;
   ConstantPool &operator=(const ConstantPool &) LLVM_DELETED_FUNCTION;
 
 public:
   ConstantPool() {}
   TypePool<float, ConstantFloat, true> Floats;
   TypePool<double, ConstantDouble, true> Doubles;
   TypePool<uint64_t, ConstantInteger> Integers;
   TypePool<RelocatableTuple, ConstantRelocatable> Relocatables;
+  UndefPool Undefs;
 };
 
 GlobalContext::GlobalContext(llvm::raw_ostream *OsDump,
                              llvm::raw_ostream *OsEmit, VerboseMask Mask,
                              TargetArch Arch, OptLevel Opt,
                              IceString TestPrefix)
     : StrDump(OsDump), StrEmit(OsEmit), VMask(Mask),
       ConstPool(new ConstantPool()), Arch(Arch), Opt(Opt),
       TestPrefix(TestPrefix), HasEmittedFirstMethod(false) {}
 
@@ skipping 86 matching lines @@
   return ConstPool->Doubles.getOrAdd(this, IceType_f64, ConstantDouble);
 }
 
 Constant *GlobalContext::getConstantSym(Type Ty, int64_t Offset,
                                         const IceString &Name,
                                         bool SuppressMangling) {
   return ConstPool->Relocatables.getOrAdd(
       this, Ty, RelocatableTuple(Offset, Name, SuppressMangling));
 }
 
+Constant *GlobalContext::getConstantUndef(Type Ty) {
+  return ConstPool->Undefs.getOrAdd(this, Ty);
+}
+
+Constant *GlobalContext::getConstantZero(Type Ty) {
+  switch (Ty) {
+  case IceType_i1:
+  case IceType_i8:
+  case IceType_i16:
+  case IceType_i32:
+  case IceType_i64:
+    return getConstantInt(Ty, 0);
+  case IceType_f32:
+    return getConstantFloat(0);
+  case IceType_f64:
+    return getConstantDouble(0);
+  case IceType_void:
+  case IceType_NUM:
+    break;
+  }
+  llvm_unreachable("Unknown type");
+}
+
 ConstantList GlobalContext::getConstantPool(Type Ty) const {
   switch (Ty) {
   case IceType_i1:
   case IceType_i8:
   case IceType_i16:
   case IceType_i32:
   case IceType_i64:
     return ConstPool->Integers.getConstantPool();
   case IceType_f32:
     return ConstPool->Floats.getConstantPool();
   case IceType_f64:
     return ConstPool->Doubles.getConstantPool();
   case IceType_void:
   case IceType_NUM:
     break;
   }
   llvm_unreachable("Unknown type");
 }
 
 void Timer::printElapsedUs(GlobalContext *Ctx, const IceString &Tag) const {
   if (Ctx->isVerbose(IceV_Timing)) {
     // Prefixing with '#' allows timing strings to be included
     // without error in textual assembly output.
     Ctx->getStrDump() << "# " << getElapsedUs() << " usec " << Tag << "\n";
   }
 }
 
 } // end of namespace Ice