DMD Issue 5416 - null should have a type of its own

dmd/mtype.h

@@ -106,6 +106,7 @@ enum TY
     Ttuple,
     Tslice,
     Treturn,
+    Tnull,
     TMAX
 };
 

gen/statements.cpp

@@ -96,6 +96,8 @@ void ReturnStatement::toIR(IRState* p)
             if (!exp && (p->topfunc() == p->mainFunc)) {
                 v = LLConstant::getNullValue(p->mainFunc->getReturnType());
             } else {
+                if (exp->op == TOKnull)
+                    exp->type = p->func()->type->next;
 #if DMDV2
                 DValue* dval = 0;
                 // call postblit if necessary

gen/toir.cpp

@@ -1551,7 +1551,7 @@ DValue* CmpExp::toElem(IRState* p)
 
     LLValue* eval = 0;
 
-    if (t->isintegral() || t->ty == Tpointer)
+    if (t->isintegral() || t->ty == Tpointer || t->ty == Tnull)
     {
         llvm::ICmpInst::Predicate cmpop;
         bool skip = false;
@@ -1677,7 +1677,7 @@ DValue* EqualExp::toElem(IRState* p)
 
     // the Tclass catches interface comparisons, regular
     // class equality should be rewritten as a.opEquals(b) by this time
-    if (t->isintegral() || t->ty == Tpointer || t->ty == Tclass)
+    if (t->isintegral() || t->ty == Tpointer || t->ty == Tclass || t->ty == Tnull)
     {
         Logger::println("integral or pointer or interface");
         llvm::ICmpInst::Predicate cmpop;

gen/tollvm.cpp

@@ -95,6 +95,7 @@ LLType* DtoType(Type* t)
     }
 
     // pointers
+    case Tnull:
     case Tpointer:
     {
         t->irtype = new IrTypePointer(t);

gen/typinf.cpp

@@ -380,7 +380,11 @@ void DtoDeclareTypeInfo(TypeInfoDeclaration* tid)
 
 void TypeInfoDeclaration::llvmDefine()
 {
-    assert(0 && "cannot generate generic typeinfo");
+    Logger::println("TypeInfoDeclaration::llvmDefine() %s", toChars());
+    LOG_SCOPE;
+
+    RTTIBuilder b(Type::typeinfo);
+    b.finalize(ir.irGlobal);
 }
 
 /* ========================================================================= */

ir/irtype.cpp

@@ -137,7 +137,7 @@ llvm::Type * IrTypeBasic::basic2llvm(Type* t)
 //////////////////////////////////////////////////////////////////////////////
 
 IrTypePointer::IrTypePointer(Type * dt)
-: IrType(dt, pointer2llvm(dt))
+: IrType(dt, dt->ty == Tnull ? null2llvm(dt) : pointer2llvm(dt))
 {
 }
 
@@ -160,6 +160,13 @@ llvm::Type * IrTypePointer::pointer2llvm(Type * dt)
     return llvm::PointerType::get(elemType, 0);
 }
 
+llvm::Type* IrTypePointer::null2llvm(Type* dt)
+{
+    assert(dt->ty == Tnull && "not null type");
+    LLType* elemType = llvm::Type::getInt8Ty(llvm::getGlobalContext());
+    return llvm::PointerType::get(elemType, 0);
+}
+
 //////////////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////////

ir/irtype.h

@@ -105,6 +105,8 @@ public:
 protected:
     ///
     llvm::Type* pointer2llvm(Type* t);
+    ///
+    llvm::Type* null2llvm(Type* t);
 };
 
 //////////////////////////////////////////////////////////////////////////////