diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java
index 986792786fbc..9706e45196b6 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java
@@ -235,7 +235,7 @@ public class CFGBuilder {
    * @param relation relation to use for comparison
    * @return this builder
    */
-  private CFGBuilder compare(IElementType relation) {
+  CFGBuilder compare(IElementType relation) {
     return add(new BinopInstruction(relation, null, PsiType.BOOLEAN));
   }
 
@@ -415,6 +415,49 @@ public class CFGBuilder {
     return add(new AssignInstruction(null, null));
   }
 
+  /**
+   * Generate instructions to assign given source value to the given target value. Stack remains unchanged.
+   * May skip generating instructions if target is not writable (e.g. not a variable)
+   *
+   * @param target target to write
+   * @param source source value
+   * @return this builder
+   */
+  public CFGBuilder assignAndPop(DfaValue target, DfaValue source) {
+    if (target instanceof DfaVariableValue) {
+      if (source == DfaUnknownValue.getInstance()) {
+        add(new FlushVariableInstruction((DfaVariableValue)target));
+      } else {
+        pushForWrite((DfaVariableValue)target).push(source).assign().pop();
+      }
+    }
+    return this;
+  }
+
+  /**
+   * Generate instructions to assign given source value to the given target value and leave the result on stack.
+   * <p>
+   * Stack before: ...
+   * <p>
+   * Stack after: ... target
+   *
+   * @param target target to write
+   * @param source source value
+   * @return this builder
+   */
+  public CFGBuilder assign(DfaValue target, DfaValue source) {
+    if (target instanceof DfaVariableValue) {
+      if (source == DfaUnknownValue.getInstance()) {
+        add(new FlushVariableInstruction((DfaVariableValue)target)).push(target);
+      } else {
+        pushForWrite((DfaVariableValue)target).push(source).assign();
+      }
+    } else {
+      push(source);
+    }
+    return this;
+  }
+
   /**
    * Generate instructions to assign top stack value to the specified variable
    * <p>
@@ -638,8 +681,7 @@ public class CFGBuilder {
       ConditionalGotoInstruction condGoto = new ConditionalGotoInstruction(null, false, null);
       condGoto.setOffset(myAnalyzer.getInstructionCount());
       myBranches.add(() -> pushUnknown().add(condGoto));
-      DfaValue loopElement = factory.createCommonValue(expressions);
-      pushForWrite(targetVariable).push(loopElement).assign();
+      assign(targetVariable, factory.createCommonValue(expressions));
     } else {
       push(factory.getConstFactory().getSentinel());
       for (PsiExpression expression : expressions) {
diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/CollectionFactoryInliner.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/CollectionFactoryInliner.java
index a7bcc2aca5d5..e66bdff26b01 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/CollectionFactoryInliner.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/CollectionFactoryInliner.java
@@ -104,13 +104,10 @@ public class CollectionFactoryInliner implements CallInliner {
       builder.push(result);
     } else {
       DfaVariableValue variableValue = builder.createTempVariable(call.getType());
-      builder.pushForWrite(variableValue) // tmpVar = <Value of collection type>
-        .push(result)
-        .assign() // leave tmpVar on stack: it's result of method call
-        .push(factoryInfo.mySizeField.createValue(factory, variableValue)) // tmpVar.size = <size>
-        .push(factory.getInt(factoryInfo.mySize))
-        .assign()
-        .pop();
+      // tmpVar = <Value of collection type>; leave tmpVar on stack: it's result of method call
+      builder.assign(variableValue, result);
+      // tmpVar.size = <size>
+      builder.assignAndPop(factoryInfo.mySizeField.createValue(factory, variableValue), factory.getInt(factoryInfo.mySize));
     }
     return true;
   }
diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/StreamChainInliner.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/StreamChainInliner.java
index a967ceedc650..86a13bdbea61 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/StreamChainInliner.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/StreamChainInliner.java
@@ -16,6 +16,8 @@
 package com.intellij.codeInspection.dataFlow.inliner;
 
 import com.intellij.codeInspection.dataFlow.*;
+import com.intellij.codeInspection.dataFlow.value.DfaConstValue;
+import com.intellij.codeInspection.dataFlow.value.DfaUnknownValue;
 import com.intellij.codeInspection.dataFlow.value.DfaValue;
 import com.intellij.codeInspection.dataFlow.value.DfaVariableValue;
 import com.intellij.psi.*;
@@ -243,7 +245,7 @@ public class StreamChainInliner implements CallInliner {
 
     @Override
     void iteration(CFGBuilder builder) {
-      builder.pushForWrite(myResult).pushUnknown().assign().splice(2);
+      builder.pop().assignAndPop(myResult, DfaUnknownValue.getInstance());
     }
   }
 
@@ -262,7 +264,7 @@ public class StreamChainInliner implements CallInliner {
       if (myFunction != null) {
         builder.pushUnknown().invokeFunction(2, myFunction);
       }
-      builder.pushForWrite(myResult).push(builder.getFactory().getFactValue(DfaFactType.OPTIONAL_PRESENCE, true)).assign().splice(2);
+      builder.assign(myResult, builder.getFactory().getFactValue(DfaFactType.OPTIONAL_PRESENCE, true)).splice(2);
     }
   }
 
@@ -288,7 +290,7 @@ public class StreamChainInliner implements CallInliner {
     @Override
     void iteration(CFGBuilder builder) {
       myComparatorModel.invoke(builder);
-      builder.pushForWrite(myResult).push(builder.getFactory().getFactValue(DfaFactType.OPTIONAL_PRESENCE, true)).assign().pop();
+      builder.assignAndPop(myResult, builder.getFactory().getFactValue(DfaFactType.OPTIONAL_PRESENCE, true));
     }
 
     @Override
@@ -309,12 +311,10 @@ public class StreamChainInliner implements CallInliner {
 
     @Override
     void iteration(CFGBuilder builder) {
+      DfaConstValue result = builder.getFactory().getBoolean("anyMatch".equals(myCall.getMethodExpression().getReferenceName()));
       builder.invokeFunction(1, myFunction)
              .ifConditionIs(!"allMatch".equals(myCall.getMethodExpression().getReferenceName()))
-             .pushForWrite(myResult)
-             .push(builder.getFactory().getBoolean("anyMatch".equals(myCall.getMethodExpression().getReferenceName())))
-             .assign()
-             .pop()
+             .assignAndPop(myResult, result)
              .end();
     }
   }
@@ -731,9 +731,7 @@ public class StreamChainInliner implements CallInliner {
 
   private static void makeMainLoop(CFGBuilder builder, Step firstStep, PsiType inType) {
     builder.doWhileUnknown()
-           .pushForWrite(builder.createTempVariable(inType))
-           .push(builder.getFactory().createTypeValue(inType, DfaPsiUtil.getTypeNullability(inType)))
-           .assign()
+           .assign(builder.createTempVariable(inType), builder.getFactory().createTypeValue(inType, DfaPsiUtil.getTypeNullability(inType)))
            .chain(firstStep::iteration).end();
   }