Add Om1 lowering with no optimizations

src/IceTypes.cpp

 //===- subzero/src/IceTypes.cpp - Primitive type properties ---------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines a few attributes of Subzero primitive types.
@@ skipping 23 matching lines @@
     sizeof(TypeAttributes) / sizeof(*TypeAttributes);
 
 } // end anonymous namespace
 
 size_t typeWidthInBytes(Type Ty) {
   size_t Width = 0;
   size_t Index = static_cast<size_t>(Ty);
   if (Index < TypeAttributesSize) {
     Width = TypeAttributes[Index].TypeWidthInBytes;
   } else {
-    assert(0 && "Invalid type for typeWidthInBytes()");
+    llvm_unreachable("Invalid type for typeWidthInBytes()");
   }
   return Width;
 }
 
 size_t typeAlignInBytes(Type Ty) {
   size_t Align = 0;
   size_t Index = static_cast<size_t>(Ty);
   if (Index < TypeAttributesSize) {
     Align = TypeAttributes[Index].TypeAlignInBytes;
   } else {
-    assert(0 && "Invalid type for typeAlignInBytes()");
+    llvm_unreachable("Invalid type for typeAlignInBytes()");
   }
   return Align;
 }
 
 // ======================== Dump routines ======================== //
 
 template <> Ostream &operator<<(Ostream &Str, const Type &Ty) {
   size_t Index = static_cast<size_t>(Ty);
   if (Index < TypeAttributesSize) {
     Str << TypeAttributes[Index].DisplayString;
   } else {
     Str << "???";
-    assert(0 && "Invalid type for printing");
+    llvm_unreachable("Invalid type for printing");
   }
 
   return Str;
 }
 
 } // end of namespace Ice