diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
index 9f3c15f19c9..d0e031ca5da 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
@@ -1797,7 +1797,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
     }
 
     @Override
-    public StackValue visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression, StackValue receiver) {
+    public StackValue visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression, @NotNull StackValue receiver) {
         ResolvedCall<?> resolvedCall = getResolvedCall(expression, bindingContext);
 
         DeclarationDescriptor descriptor;
@@ -2810,7 +2810,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
     }
 
     @Override
-    public StackValue visitBinaryExpression(@NotNull JetBinaryExpression expression, StackValue receiver) {
+    public StackValue visitBinaryExpression(@NotNull JetBinaryExpression expression, @NotNull StackValue receiver) {
         JetSimpleNameExpression reference = expression.getOperationReference();
         IElementType opToken = reference.getReferencedNameElementType();
         if (opToken == JetTokens.EQ) {
@@ -3194,7 +3194,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
     }
 
     @Override
-    public StackValue visitPrefixExpression(@NotNull JetPrefixExpression expression, StackValue receiver) {
+    public StackValue visitPrefixExpression(@NotNull JetPrefixExpression expression, @NotNull StackValue receiver) {
         DeclarationDescriptor originalOperation = bindingContext.get(REFERENCE_TARGET, expression.getOperationReference());
         ResolvedCall<?> resolvedCall = getResolvedCallWithAssert(expression, bindingContext);
         CallableDescriptor op = resolvedCall.getResultingDescriptor();
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java b/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java
index a79f8f4b42f..4e7ca3420f9 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java
@@ -1005,7 +1005,7 @@ public abstract class StackValue {
                 ((CallableMethod) getter).invokeWithNotNullAssertion(v, state, resolvedGetCall);
             }
             else {
-                StackValue result = ((IntrinsicMethod) getter).generate(codegen, this.type, null, Collections.<JetExpression>emptyList(), null);
+                StackValue result = ((IntrinsicMethod) getter).generate(codegen, this.type, null, Collections.<JetExpression>emptyList(), StackValue.none());
                 result.put(result.type, v);
             }
             coerceTo(type, v);
@@ -1070,7 +1070,7 @@ public abstract class StackValue {
             }
             else {
                 //noinspection ConstantConditions
-                StackValue result = ((IntrinsicMethod) setter).generate(codegen, null, null, Collections.<JetExpression>emptyList(), null);
+                StackValue result = ((IntrinsicMethod) setter).generate(codegen, null, null, Collections.<JetExpression>emptyList(), StackValue.none());
                 result.put(result.type, v);
             }
         }
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayGet.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayGet.java
index c71453089d4..c87850e12d6 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayGet.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayGet.java
@@ -36,11 +36,11 @@ public class ArrayGet extends IntrinsicMethod {
             @NotNull InstructionAdapter v,
             @NotNull Type returnType,
             PsiElement element,
-            List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull List<JetExpression> arguments,
+            @NotNull StackValue receiver
     ) {
         int argumentIndex;
-        if (receiver == null || receiver == StackValue.none()) {
+        if (receiver == StackValue.none()) {
             receiver = codegen.gen(arguments.get(0));
             argumentIndex = 1;
         } else {
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayIterator.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayIterator.java
index 49348b66591..79f1cf6c378 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayIterator.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArrayIterator.java
@@ -50,7 +50,7 @@ public class ArrayIterator extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         receiver.put(receiver.type, v);
         JetCallExpression call = (JetCallExpression) element;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySet.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySet.java
index e050cb3c990..98264f6627b 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySet.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySet.java
@@ -37,7 +37,7 @@ public class ArraySet extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         receiver.put(receiver.type, v);
         Type type = correctElementType(receiver.type);
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySize.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySize.java
index 689cd5910fb..12df917ec35 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySize.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ArraySize.java
@@ -35,7 +35,7 @@ public class ArraySize extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         receiver.put(receiver.type, v);
         v.arraylength();
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/BinaryOp.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/BinaryOp.java
index 5d34352e9fa..f9a794fa57c 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/BinaryOp.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/BinaryOp.java
@@ -45,7 +45,7 @@ public class BinaryOp extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         assert isPrimitive(returnType) : "Return type of BinaryOp intrinsic should be of primitive type : " + returnType;
 
@@ -53,7 +53,7 @@ public class BinaryOp extends IntrinsicMethod {
 
         if (arguments.size() == 1) {
             // Intrinsic is called as an ordinary function
-            if (receiver != null) {
+            if (receiver != StackValue.none()) {
                 receiver.put(operandType, v);
             }
             codegen.gen(arguments.get(0), shift() ? Type.INT_TYPE : operandType);
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Clone.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Clone.java
index 380342d9ee9..18e52fb0728 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Clone.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Clone.java
@@ -44,7 +44,7 @@ public class Clone extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            @Nullable StackValue receiver
+            @NotNull StackValue receiver
     ) {
         ResolvedCall<?> resolvedCall = getResolvedCallWithAssert(((JetElement) element), codegen.getBindingContext());
         StackValue.receiver(resolvedCall, receiver, codegen, null).put(OBJECT_TYPE, v);
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CompareTo.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CompareTo.java
index 9a77078d71a..d3f291162d7 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CompareTo.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CompareTo.java
@@ -38,10 +38,9 @@ public class CompareTo extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         JetExpression argument;
-        assert arguments != null;
         if (arguments.size() == 1) {
             argument = arguments.get(0);
         }
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Concat.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Concat.java
index c82076b4675..a9c151aaa5e 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Concat.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Concat.java
@@ -40,9 +40,9 @@ public class Concat extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
-        if (receiver == null || receiver == StackValue.none()) {
+        if (receiver == StackValue.none()) {
             // LHS + RHS
             genStringBuilderConstructor(v);
             codegen.invokeAppend(arguments.get(0));
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CopyToArray.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CopyToArray.java
index a93ec1f6058..b7c880e89b7 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CopyToArray.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/CopyToArray.java
@@ -39,9 +39,8 @@ public class CopyToArray extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            @Nullable StackValue receiver
+            @NotNull StackValue receiver
     ) {
-        assert receiver != null;
         receiver.put(receiver.type, v);
         v.dup();
         v.invokeinterface("java/util/Collection", "size", "()I");
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Equals.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Equals.java
index 6090b2aca82..a7dcaddecf9 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Equals.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Equals.java
@@ -40,7 +40,7 @@ public class Equals extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         StackValue leftExpr;
         JetExpression rightExpr;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/HashCode.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/HashCode.java
index 1f78fd6b7ee..5762faedae5 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/HashCode.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/HashCode.java
@@ -38,7 +38,7 @@ public class HashCode extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         receiver.put(AsmTypeConstants.OBJECT_TYPE, v);
         v.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Object", "hashCode", "()I", false);
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IdentityEquals.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IdentityEquals.java
index 5e973860274..4a80f29ae89 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IdentityEquals.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IdentityEquals.java
@@ -40,7 +40,7 @@ public class IdentityEquals extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         StackValue left;
         StackValue right;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Increment.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Increment.java
index f57423fbde7..0ce4dd90be2 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Increment.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Increment.java
@@ -44,7 +44,7 @@ public class Increment extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         assert isPrimitive(returnType) : "Return type of Increment intrinsic should be of primitive type : " + returnType;
 
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethod.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethod.java
index a390002fffa..a8746647975 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethod.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethod.java
@@ -36,7 +36,7 @@ public abstract class IntrinsicMethod implements Callable {
             @NotNull final Type returnType,
             @Nullable final PsiElement element,
             @NotNull final List<JetExpression> arguments,
-            @Nullable final StackValue receiver
+            @NotNull final StackValue receiver
     ) {
         return StackValue.operation(returnType, new Function1<InstructionAdapter, Unit>() {
 
@@ -56,6 +56,6 @@ public abstract class IntrinsicMethod implements Callable {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            @Nullable StackValue receiver
+            @NotNull StackValue receiver
     );
 }
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Inv.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Inv.java
index b199d4686f9..5a338e23289 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Inv.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Inv.java
@@ -38,7 +38,7 @@ public class Inv extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         assert isPrimitive(returnType) : "Return type of Inv intrinsic should be of primitive type : " + returnType;
 
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IteratorNext.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IteratorNext.java
index df7934918ac..b4b58a3eb70 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IteratorNext.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IteratorNext.java
@@ -38,7 +38,7 @@ public class IteratorNext extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         String name;
         if (returnType == Type.CHAR_TYPE) {
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassArray.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassArray.java
index 274d7406c0c..ad775e19d28 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassArray.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassArray.java
@@ -44,7 +44,7 @@ public class JavaClassArray extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         assert element != null : "Element should not be null";
         ResolvedCall<?> resolvedCall = getResolvedCallWithAssert((JetElement) element, codegen.getBindingContext());
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassFunction.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassFunction.java
index 5b3ec6e027e..ab7ddfb38b9 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassFunction.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassFunction.java
@@ -44,7 +44,7 @@ public class JavaClassFunction extends IntrinsicMethod {
             @NotNull Type expectedType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         ResolvedCall<?> resolvedCall = CallUtilPackage.getResolvedCallWithAssert(
                 (JetElement) element, codegen.getBindingContext());
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassProperty.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassProperty.java
index 77dcc5c572d..62b21106fbc 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassProperty.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassProperty.java
@@ -41,7 +41,7 @@ public class JavaClassProperty extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         Type type = receiver.type;
         if (isPrimitive(type)) {
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/MonitorInstruction.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/MonitorInstruction.java
index 501bac9e5c6..6f87aa958d0 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/MonitorInstruction.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/MonitorInstruction.java
@@ -55,7 +55,7 @@ public class MonitorInstruction extends IntrinsicMethod {
             @NotNull Type returnType,
             @Nullable PsiElement element,
             @NotNull List<JetExpression> arguments,
-            @Nullable StackValue receiver
+            @NotNull StackValue receiver
     ) {
         assert element != null : "Element should not be null";
 
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NewArray.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NewArray.java
index 6c799167a90..60f81656953 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NewArray.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NewArray.java
@@ -36,7 +36,7 @@ public class NewArray extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         codegen.generateNewArray((JetCallExpression) element).put(returnType, v);
         return returnType;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Not.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Not.java
index bce856446d6..344646f68b7 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Not.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Not.java
@@ -34,8 +34,8 @@ public class Not extends IntrinsicMethod {
             @NotNull InstructionAdapter v,
             @NotNull Type returnType,
             PsiElement element,
-            List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull List<JetExpression> arguments,
+            @NotNull StackValue receiver
     ) {
         StackValue stackValue;
         if (arguments.size() == 1) {
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NumberCast.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NumberCast.java
index a0fe1d53a57..e0b9855fa56 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NumberCast.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/NumberCast.java
@@ -35,7 +35,7 @@ public class NumberCast extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         receiver.put(returnType, v);
         return returnType;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/RangeTo.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/RangeTo.java
index 197de40e09c..2671998a4c3 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/RangeTo.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/RangeTo.java
@@ -38,7 +38,7 @@ public class RangeTo extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         v.anew(returnType);
         v.dup();
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringGetChar.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringGetChar.java
index 385e9fb40de..dd2682f6acf 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringGetChar.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringGetChar.java
@@ -35,9 +35,9 @@ public class StringGetChar extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
-        if (receiver != null) {
+        if (receiver != StackValue.none()) {
             receiver.put(receiver.type, v);
         }
         if (!arguments.isEmpty()) {
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringPlus.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringPlus.java
index 5c67d63b979..e09cefc2330 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringPlus.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringPlus.java
@@ -38,9 +38,9 @@ public class StringPlus extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
-        if (receiver == null || receiver == StackValue.none()) {
+        if (receiver == StackValue.none()) {
             codegen.gen(arguments.get(0)).put(JAVA_STRING_TYPE, v);
             codegen.gen(arguments.get(1)).put(OBJECT_TYPE, v);
         }
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ToString.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ToString.java
index 85e1fe7b937..adbecc5aff2 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ToString.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/ToString.java
@@ -37,7 +37,7 @@ public class ToString extends IntrinsicMethod {
             @NotNull Type returnType,
             PsiElement element,
             @NotNull List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull StackValue receiver
     ) {
         genToString(v, receiver, receiver.type).put(returnType, v);
         return returnType;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/UnaryPlus.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/UnaryPlus.java
index 60f80d5bd21..0bd6fa8ed7b 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/UnaryPlus.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/UnaryPlus.java
@@ -37,16 +37,16 @@ public class UnaryPlus extends IntrinsicMethod {
             @NotNull InstructionAdapter v,
             @NotNull Type returnType,
             @Nullable PsiElement element,
-            @Nullable List<JetExpression> arguments,
-            StackValue receiver
+            @NotNull List<JetExpression> arguments,
+            @NotNull StackValue receiver
     ) {
         assert isPrimitive(returnType) : "Return type of UnaryPlus intrinsic should be of primitive type : " + returnType;
 
-        if (receiver != null && receiver != StackValue.none()) {
+        if (receiver != StackValue.none()) {
             receiver.put(returnType, v);
         }
         else {
-            assert arguments != null;
+            assert !arguments.isEmpty();
             codegen.gen(arguments.get(0), returnType);
         }
         return returnType;