Unroll short Stream.of(...) sequences (up to three elements)

Fixes IDEA-189143 Support unrolling of Stream.of(a, b, c)

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java

@@ -25,6 +25,7 @@ import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.ObjectUtils;
+import one.util.streamex.IntStreamEx;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -41,13 +42,18 @@ import java.util.function.Consumer;
 @SuppressWarnings("UnusedReturnValue")
 public class CFGBuilder {
   private final ControlFlowAnalyzer myAnalyzer;
-  private final Deque<JumpInstruction> myBranches = new ArrayDeque<>();
+  private final Deque<Runnable> myBranches = new ArrayDeque<>();
   private final Map<PsiExpression, DfaVariableValue> myMethodRefQualifiers = new HashMap<>();
 
   CFGBuilder(ControlFlowAnalyzer analyzer) {
     myAnalyzer = analyzer;
   }
 
+  private CFGBuilder add(Instruction instruction) {
+    myAnalyzer.addInstruction(instruction);
+    return this;
+  }
+
   /**
    * Generate instructions to push unknown DfaValue on stack.
    * <p>
@@ -72,8 +78,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder pushNull() {
-    myAnalyzer.addInstruction(new PushInstruction(getFactory().getConstFactory().getNull(), null));
-    return this;
+    return add(new PushInstruction(getFactory().getConstFactory().getNull(), null));
   }
 
   /**
@@ -102,8 +107,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder pushForWrite(DfaVariableValue variable) {
-    myAnalyzer.addInstruction(new PushInstruction(variable, null, true));
-    return this;
+    return add(new PushInstruction(variable, null, true));
   }
 
   /**
@@ -117,8 +121,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder push(DfaValue value) {
-    myAnalyzer.addInstruction(new PushInstruction(value, null));
-    return this;
+    return add(new PushInstruction(value, null));
   }
 
   /**
@@ -131,8 +134,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder pop() {
-    myAnalyzer.addInstruction(new PopInstruction());
-    return this;
+    return add(new PopInstruction());
   }
 
   /**
@@ -145,8 +147,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder dup() {
-    myAnalyzer.addInstruction(new DupInstruction());
-    return this;
+    return add(new DupInstruction());
   }
 
   /**
@@ -161,8 +162,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder splice(int count, int... replacement) {
-    myAnalyzer.addInstruction(new SpliceInstruction(count, replacement));
-    return this;
+    return add(new SpliceInstruction(count, replacement));
   }
 
   /**
@@ -175,8 +175,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder swap() {
-    myAnalyzer.addInstruction(new SwapInstruction());
-    return this;
+    return add(new SwapInstruction());
   }
 
   /**
@@ -189,8 +188,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder objectOf() {
-    myAnalyzer.addInstruction(new ObjectOfInstruction());
-    return this;
+    return add(new ObjectOfInstruction());
   }
 
   /**
@@ -204,8 +202,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder isInstance(PsiMethodCallExpression anchor) {
-    myAnalyzer.addInstruction(new InstanceofInstruction(anchor));
-    return this;
+    return add(new InstanceofInstruction(anchor));
   }
 
   /**
@@ -239,8 +236,7 @@ public class CFGBuilder {
    * @return this builder
    */
   private CFGBuilder compare(IElementType relation) {
-    myAnalyzer.addInstruction(new BinopInstruction(relation, null, PsiType.BOOLEAN));
-    return this;
+    return add(new BinopInstruction(relation, null, PsiType.BOOLEAN));
   }
 
   /**
@@ -250,7 +246,7 @@ public class CFGBuilder {
    * <p>
    * Stack after: ...
    * <p>
-   * The conditional block must end with {@link #endIf()} and may contain one {@link #elseBranch()} inside.
+   * The conditional block must end with {@link #end()} and may contain one {@link #elseBranch()} inside.
    * Nested conditional blocks are acceptable.
    *
    * @param value a value condition must have to visit conditional block
@@ -258,9 +254,8 @@ public class CFGBuilder {
    */
   public CFGBuilder ifConditionIs(boolean value) {
     ConditionalGotoInstruction gotoInstruction = new ConditionalGotoInstruction(null, value, null);
-    myBranches.add(gotoInstruction);
-    myAnalyzer.addInstruction(gotoInstruction);
-    return this;
+    myBranches.add(() -> gotoInstruction.setOffset(myAnalyzer.getInstructionCount()));
+    return add(gotoInstruction);
   }
 
   /**
@@ -271,7 +266,7 @@ public class CFGBuilder {
    * <p>
    * Stack after: ...
    * <p>
-   * The conditional block must end with {@link #endIf()} and may contain one {@link #elseBranch()} inside.
+   * The conditional block must end with {@link #end()} and may contain one {@link #elseBranch()} inside.
    * Nested conditional blocks are acceptable.
    *
    * @param relation a relation to use to compare two stack values. Conditional block will be executed if "val1 relation val2" is true.
@@ -288,7 +283,7 @@ public class CFGBuilder {
    * <p>
    * Stack after: ...
    * <p>
-   * The conditional block must end with {@link #endIf()} and may contain one {@link #elseBranch()} inside.
+   * The conditional block must end with {@link #end()} and may contain one {@link #elseBranch()} inside.
    * Nested conditional blocks are acceptable.
    *
    * @return this builder
@@ -304,7 +299,7 @@ public class CFGBuilder {
    * <p>
    * Stack after: ...
    * <p>
-   * The conditional block must end with {@link #endIf()} and may contain one {@link #elseBranch()} inside.
+   * The conditional block must end with {@link #end()} and may contain one {@link #elseBranch()} inside.
    * Nested conditional blocks are acceptable.
    *
    * @return this builder
@@ -314,13 +309,12 @@ public class CFGBuilder {
   }
 
   /**
-   * Generate instructions to finish a conditional block started with {@link #ifCondition(IElementType)}, {@link #ifConditionIs(boolean)},
-   * {@link #ifNull()} or {@link #ifNotNull()}. Stack is unchanged.
+   * Generate instructions to finish a conditional block or a loop. Stack is unchanged.
    *
    * @return this builder
    */
-  public CFGBuilder endIf() {
-    myBranches.removeLast().setOffset(myAnalyzer.getInstructionCount());
+  public CFGBuilder end() {
+    myBranches.removeLast().run();
     return this;
   }
 
@@ -333,33 +327,21 @@ public class CFGBuilder {
    */
   public CFGBuilder elseBranch() {
     GotoInstruction gotoInstruction = new GotoInstruction(null);
-    myAnalyzer.addInstruction(gotoInstruction);
-    endIf();
-    myBranches.add(gotoInstruction);
+    add(gotoInstruction).end();
+    myBranches.add(() -> gotoInstruction.setOffset(myAnalyzer.getInstructionCount()));
     return this;
   }
 
   /**
-   * Generate instructions to start a loop. Stack is unchanged. Loop must be terminated via {@link #endWhileUnknown()}.
+   * Generate instructions to start a loop. Stack is unchanged. Loop must be terminated via {@link #end()}.
    * Nested loops are acceptable.
    *
    * @return this builder
    */
-  public CFGBuilder doWhile() {
+  public CFGBuilder doWhileUnknown() {
     ConditionalGotoInstruction jump = new ConditionalGotoInstruction(null, false, null);
     jump.setOffset(myAnalyzer.getInstructionCount());
-    myBranches.add(jump);
-    return this;
-  }
-
-  /**
-   * Generate instructions to end a loop started via {@link #doWhile()} by unknown condition. Stack is unchanged.
-   *
-   * @return this builder
-   */
-  public CFGBuilder endWhileUnknown() {
-    pushUnknown();
-    myAnalyzer.addInstruction((ConditionalGotoInstruction)myBranches.removeLast());
+    myBranches.add(() -> pushUnknown().add(jump));
     return this;
   }
 
@@ -404,8 +386,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder flushFields() {
-    myAnalyzer.addInstruction(new FlushFieldsInstruction());
-    return this;
+    return add(new FlushFieldsInstruction());
   }
 
   /**
@@ -417,8 +398,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public <T extends PsiElement> CFGBuilder checkNotNull(T expression, NullabilityProblemKind<T> kind) {
-    myAnalyzer.addInstruction(new CheckNotNullInstruction(kind.problem(expression)));
-    return this;
+    return add(new CheckNotNullInstruction(kind.problem(expression)));
   }
 
   /**
@@ -432,8 +412,7 @@ public class CFGBuilder {
    * @return this builder
    */
   public CFGBuilder assign() {
-    myAnalyzer.addInstruction(new AssignInstruction(null, null));
-    return this;
+    return add(new AssignInstruction(null, null));
   }
 
   /**
@@ -596,7 +575,7 @@ public class CFGBuilder {
     if (qualifier == null) return false;
     PsiType type = qualifier.getOperand().getType();
     push(getFactory().createTypeValue(type, Nullness.NOT_NULL));
-    myAnalyzer.addInstruction(new InstanceofInstruction(methodRef, null, type));
+    add(new InstanceofInstruction(methodRef, null, type));
     return true;
   }
 
@@ -649,6 +628,45 @@ public class CFGBuilder {
     return this;
   }
 
+  public CFGBuilder loopOver(PsiExpression[] expressions, DfaVariableValue targetVariable) {
+    DfaValueFactory factory = getFactory();
+    if (expressions.length > ControlFlowAnalyzer.MAX_UNROLL_SIZE) {
+      DfaValue loopElement = null;
+      for (PsiExpression expression : expressions) {
+        pushExpression(expression);
+        DfaValue expressionValue = factory.createValue(expression);
+        if (expressionValue == null) {
+          expressionValue = factory.createTypeValue(expression.getType(), NullnessUtil.getExpressionNullness(expression));
+        }
+        loopElement = loopElement == null ? expressionValue : loopElement.union(expressionValue);
+        pop();
+      }
+      ConditionalGotoInstruction condGoto = new ConditionalGotoInstruction(null, false, null);
+      condGoto.setOffset(myAnalyzer.getInstructionCount());
+      myBranches.add(() -> pushUnknown().add(condGoto));
+      pushForWrite(targetVariable).push(loopElement).assign();
+    } else {
+      push(factory.getConstFactory().getSentinel());
+      for (PsiExpression expression : expressions) {
+        pushExpression(expression);
+      }
+      // Revert order
+      add(new SpliceInstruction(expressions.length, IntStreamEx.ofIndices(expressions).toArray()));
+      GotoInstruction gotoInstruction = new GotoInstruction(null);
+      gotoInstruction.setOffset(myAnalyzer.getInstructionCount());
+      dup().push(factory.getConstFactory().getSentinel()).compare(JavaTokenType.EQEQ);
+      ConditionalGotoInstruction condGoto = new ConditionalGotoInstruction(null, false, null);
+      add(condGoto);
+      assignTo(targetVariable);
+      myBranches.add(() -> {
+        add(gotoInstruction);
+        condGoto.setOffset(myAnalyzer.getInstructionCount());
+        pop();
+      });
+    }
+    return this;
+  }
+
   /**
    * Create a synthetic variable (not declared in the original code) to be used within this control flow.
    *

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/ControlFlowAnalyzer.java

@@ -51,7 +51,7 @@ import static com.intellij.psi.CommonClassNames.*;
 public class ControlFlowAnalyzer extends JavaElementVisitor {
   private static final Logger LOG = Logger.getInstance("#com.intellij.codeInspection.dataFlow.ControlFlowAnalyzer");
   public static final String ORG_JETBRAINS_ANNOTATIONS_CONTRACT = Contract.class.getName();
-  private static final int MAX_UNROLL_SIZE = 3;
+  static final int MAX_UNROLL_SIZE = 3;
   private final PsiElement myCodeFragment;
   private final boolean myIgnoreAssertions;
   private final boolean myInlining;

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java

@@ -892,10 +892,13 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
       return true;
     }
 
-    final boolean containsCalls = dfaLeft instanceof DfaVariableValue && ((DfaVariableValue)dfaLeft).containsCalls();
-
     if (dfaLeft == dfaRight) {
-      return containsCalls || !isNegated;
+      return !isNegated || (dfaLeft instanceof DfaVariableValue && ((DfaVariableValue)dfaLeft).containsCalls());
+    }
+
+    DfaConstValue sentinel = getFactory().getConstFactory().getSentinel();
+    if (dfaLeft == sentinel || dfaRight == sentinel) {
+      return isNegated;
     }
 
     if (isNull(dfaLeft) && isNotNull(dfaRight) || isNull(dfaRight) && isNotNull(dfaLeft)) {

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/ComparatorModel.java

@@ -103,7 +103,7 @@ abstract class ComparatorModel {
 
     @Override
     void invoke(CFGBuilder builder) {
-      builder.dup().ifNotNull().chain(myDownstream::invoke).elseBranch().pop().endIf();
+      builder.dup().ifNotNull().chain(myDownstream::invoke).elseBranch().pop().end();
     }
   }
 

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/MapUpdateInliner.java

@@ -74,7 +74,7 @@ public class MapUpdateInliner implements CallInliner {
         .push(builder.getFactory().createTypeValue(type, Nullness.NOT_NULL))
         .swap()
         .invokeFunction(2, function)
-        .endIf()
+        .end()
         .flushFields();
       return true;
     }
@@ -92,7 +92,7 @@ public class MapUpdateInliner implements CallInliner {
       .elseBranch()
       .pop()
       .push(builder.getFactory().createTypeValue(type, Nullness.NOT_NULL))
-      .endIf();
+      .end();
   }
 
   private static void inlineComputeIfPresent(@NotNull CFGBuilder builder,
@@ -110,7 +110,7 @@ public class MapUpdateInliner implements CallInliner {
       .elseBranch()
       .pop()
       .pushNull()
-      .endIf();
+      .end();
   }
 
   private static void inlineCompute(@NotNull CFGBuilder builder,

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/OptionalChainInliner.java

@@ -80,7 +80,7 @@ public class OptionalChainInliner implements CallInliner {
           .splice(2, 0, 1, 1) // stack: .. elseValue, optValue, optValue
           .ifNotNull()
           .swap() // stack: .. optValue, elseValue
-          .endIf()
+          .end()
           .pop();
       })
       .register(OPTIONAL_OR_NULL, (builder, call) -> {
@@ -94,7 +94,7 @@ public class OptionalChainInliner implements CallInliner {
           .ifNull()
           .pop()
           .invokeFunction(0, fn)
-          .endIf();
+          .end();
       })
       .register(OPTIONAL_IF_PRESENT, (builder, call) -> {
         PsiExpression fn = call.getArgumentList().getExpressions()[0];
@@ -106,7 +106,7 @@ public class OptionalChainInliner implements CallInliner {
           .elseBranch()
           .pop()
           .pushUnknown()
-          .endIf();
+          .end();
       });
 
   private static final CallMapper<BiConsumer<CFGBuilder, PsiExpression>> INTERMEDIATE_MAPPER =
@@ -122,19 +122,19 @@ public class OptionalChainInliner implements CallInliner {
         .ifConditionIs(false)
         .pop()
         .pushNull()
-        .endIf()
-        .endIf())
+        .end()
+        .end())
       .register(OPTIONAL_FLAT_MAP, (builder, function) -> builder
         .dup()
         .ifNotNull()
         .chain(b -> invokeAndUnwrapOptional(b, 1, function))
-        .endIf())
+        .end())
       .register(OPTIONAL_OR, (builder, function) -> builder
         .dup()
         .ifNull()
         .pop()
         .chain(b -> invokeAndUnwrapOptional(b, 0, function))
-        .endIf())
+        .end())
       .register(GUAVA_TO_JAVA, (builder, stub) -> {/* no op */});
 
   @Override
@@ -154,7 +154,7 @@ public class OptionalChainInliner implements CallInliner {
         .push(factFactory.getFactValue(DfaFactType.OPTIONAL_PRESENCE, true))
         .elseBranch()
         .push(factFactory.getFactValue(DfaFactType.OPTIONAL_PRESENCE, false))
-        .endIf();
+        .end();
       return true;
     }
     if (OPTIONAL_EMPTY.test(call)) {
@@ -200,7 +200,7 @@ public class OptionalChainInliner implements CallInliner {
       .push(builder.getFactory().createTypeValue(optionalElementType, Nullness.NOT_NULL))
       .elseBranch()
       .pushNull()
-      .endIf()
+      .end()
       .assignTo(builder.createTempVariable(optionalElementType));
     return true;
   }
@@ -251,7 +251,7 @@ public class OptionalChainInliner implements CallInliner {
       .dup()
       .ifNotNull()
       .invokeFunction(1, function, resultNullness)
-      .endIf();
+      .end();
   }
 
   private static void inlineOf(CFGBuilder builder, PsiType optionalElementType, PsiMethodCallExpression qualifierCall) {

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/StreamChainInliner.java

@@ -310,12 +310,12 @@ public class StreamChainInliner implements CallInliner {
     @Override
     void iteration(CFGBuilder builder) {
       builder.invokeFunction(1, myFunction)
-        .ifConditionIs(!"allMatch".equals(myCall.getMethodExpression().getReferenceName()))
-        .pushForWrite(myResult)
-        .push(builder.getFactory().getBoolean("anyMatch".equals(myCall.getMethodExpression().getReferenceName())))
-        .assign()
-        .pop()
-        .endIf();
+             .ifConditionIs(!"allMatch".equals(myCall.getMethodExpression().getReferenceName()))
+             .pushForWrite(myResult)
+             .push(builder.getFactory().getBoolean("anyMatch".equals(myCall.getMethodExpression().getReferenceName())))
+             .assign()
+             .pop()
+             .end();
     }
   }
 
@@ -333,7 +333,7 @@ public class StreamChainInliner implements CallInliner {
         .chain(myNext::iteration)
         .elseBranch()
         .pop()
-        .endIf();
+        .end();
     }
   }
 
@@ -415,13 +415,13 @@ public class StreamChainInliner implements CallInliner {
       } else {
         PsiType outType = StreamApiUtil.getStreamElementType(myCall.getType());
         builder.pop()
-          .pushUnknown()
-          .ifConditionIs(true)
-          .doWhile()
-          .push(builder.getFactory().createTypeValue(outType, Nullness.UNKNOWN))
-          .chain(myNext::iteration)
-          .endWhileUnknown()
-          .endIf();
+               .pushUnknown()
+               .ifConditionIs(true)
+                 .doWhileUnknown()
+                   .push(builder.getFactory().createTypeValue(outType, Nullness.UNKNOWN))
+                   .chain(myNext::iteration)
+                 .end()
+               .end();
       }
     }
   }
@@ -467,7 +467,7 @@ public class StreamChainInliner implements CallInliner {
         .chain(myNext::iteration)
         .elseBranch()
         .pop()
-        .endIf();
+        .end();
     }
   }
 
@@ -595,7 +595,7 @@ public class StreamChainInliner implements CallInliner {
                .ifConditionIs(true)
                .push(builder.getFactory().getFactValue(DfaFactType.CAN_BE_NULL, false))
                .invokeFunction(2, myMerger)
-               .endIf();
+               .end();
       }
       // Actual addition of Map element is unnecessary for current analysis
       builder.pop();
@@ -620,10 +620,10 @@ public class StreamChainInliner implements CallInliner {
     PsiExpression originalQualifier = firstStep.myCall.getMethodExpression().getQualifierExpression();
     if (originalQualifier == null) return false;
     builder.pushUnknown()
-      .ifConditionIs(true)
-      .chain(b -> buildStreamCFG(b, firstStep, originalQualifier))
-      .endIf()
-      .push(builder.getFactory().createTypeValue(call.getType(), Nullness.NOT_NULL));
+           .ifConditionIs(true)
+           .chain(b -> buildStreamCFG(b, firstStep, originalQualifier))
+           .end()
+           .push(builder.getFactory().createTypeValue(call.getType(), Nullness.NOT_NULL));
     return true;
   }
 
@@ -646,12 +646,11 @@ public class StreamChainInliner implements CallInliner {
       builder
         .evaluateFunction(fn)
         .chain(firstStep::before)
-        .doWhile()
+        .doWhileUnknown()
         .pushForWrite(builder.createTempVariable(inType))
         .invokeFunction(0, fn)
         .assign()
-        .chain(firstStep::iteration)
-        .endWhileUnknown();
+        .chain(firstStep::iteration).end();
       return;
     }
     boolean empty = STREAM_EMPTY.test(sourceCall);
@@ -669,10 +668,9 @@ public class StreamChainInliner implements CallInliner {
         }
       } else {
         builder
-          .pushExpression(originalQualifier)
-          .pop()
           .chain(firstStep::before)
-          .chain(b -> makeMainLoop(b, firstStep, inType));
+          .loopOver(args, builder.createTempVariable(inType))
+          .chain(firstStep::iteration).end();
         return;
       }
     }
@@ -693,14 +691,14 @@ public class StreamChainInliner implements CallInliner {
       DfaValue qualifierValue = builder.getFactory().createValue(qualifierExpression);
       if (qualifierValue != null) {
         builder.pushExpression(qualifierExpression)
-          .chain(firstStep::before)
-          .checkNotNull(qualifierExpression, NullabilityProblemKind.passingNullableToNotNullParameter)
-          .pop()
-          .push(SpecialField.ARRAY_LENGTH.createValue(builder.getFactory(), qualifierValue))
-          .push(builder.getFactory().getInt(0))
-          .ifCondition(JavaTokenType.GT)
-          .chain(b -> makeMainLoop(b, firstStep, inType))
-          .endIf();
+               .chain(firstStep::before)
+               .checkNotNull(qualifierExpression, NullabilityProblemKind.passingNullableToNotNullParameter)
+               .pop()
+               .push(SpecialField.ARRAY_LENGTH.createValue(builder.getFactory(), qualifierValue))
+               .push(builder.getFactory().getInt(0))
+               .ifCondition(JavaTokenType.GT)
+               .chain(b -> makeMainLoop(b, firstStep, inType))
+               .end();
         return;
       }
     }
@@ -709,14 +707,14 @@ public class StreamChainInliner implements CallInliner {
       DfaValue qualifierValue = builder.getFactory().createValue(qualifierExpression);
       if (qualifierValue != null) {
         builder.pushExpression(qualifierExpression)
-          .chain(firstStep::before)
-          .checkNotNull(sourceCall, NullabilityProblemKind.callNPE)
-          .pop()
-          .push(SpecialField.COLLECTION_SIZE.createValue(builder.getFactory(), qualifierValue))
-          .push(builder.getFactory().getInt(0))
-          .ifCondition(JavaTokenType.GT)
-          .chain(b -> makeMainLoop(b, firstStep, inType))
-          .endIf();
+               .chain(firstStep::before)
+               .checkNotNull(sourceCall, NullabilityProblemKind.callNPE)
+               .pop()
+               .push(SpecialField.COLLECTION_SIZE.createValue(builder.getFactory(), qualifierValue))
+               .push(builder.getFactory().getInt(0))
+               .ifCondition(JavaTokenType.GT)
+               .chain(b -> makeMainLoop(b, firstStep, inType))
+               .end();
         return;
       }
     }
@@ -728,16 +726,15 @@ public class StreamChainInliner implements CallInliner {
       .pushUnknown()
       .ifConditionIs(true)
       .chain(b -> makeMainLoop(b, firstStep, inType))
-      .endIf();
+      .end();
   }
 
   private static void makeMainLoop(CFGBuilder builder, Step firstStep, PsiType inType) {
-    builder.doWhile()
-      .pushForWrite(builder.createTempVariable(inType))
-      .push(builder.getFactory().createTypeValue(inType, DfaPsiUtil.getTypeNullability(inType)))
-      .assign()
-      .chain(firstStep::iteration)
-      .endWhileUnknown();
+    builder.doWhileUnknown()
+           .pushForWrite(builder.createTempVariable(inType))
+           .push(builder.getFactory().createTypeValue(inType, DfaPsiUtil.getTypeNullability(inType)))
+           .assign()
+           .chain(firstStep::iteration).end();
   }
 
   static Step buildChain(PsiMethodCallExpression qualifierCall, Step terminalStep) {

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaConstValue.java

@@ -21,6 +21,7 @@ import com.intellij.psi.*;
 import com.intellij.psi.util.PsiTypesUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.psi.util.TypeConversionUtil;
+import com.intellij.util.ObjectUtils;
 import com.intellij.util.containers.ContainerUtil;
 import com.siyeh.ig.psiutils.ExpressionUtils;
 import org.jetbrains.annotations.NonNls;
@@ -31,11 +32,13 @@ import java.util.Map;
 
 public class DfaConstValue extends DfaValue {
   private static final Throwable ourThrowable = new Throwable();
+  private static final Object SENTINEL = ObjectUtils.sentinel("SENTINEL");
   public static class Factory {
     private final DfaConstValue dfaNull;
     private final DfaConstValue dfaFalse;
     private final DfaConstValue dfaTrue;
     private final DfaConstValue dfaFail;
+    private final DfaConstValue dfaSentinel;
     private final DfaValueFactory myFactory;
     private final Map<Object, DfaConstValue> myValues = ContainerUtil.newHashMap();
 
@@ -45,6 +48,7 @@ public class DfaConstValue extends DfaValue {
       dfaFalse = new DfaConstValue(Boolean.FALSE, PsiType.BOOLEAN, factory, null);
       dfaTrue = new DfaConstValue(Boolean.TRUE, PsiType.BOOLEAN, factory, null);
       dfaFail = new DfaConstValue(ourThrowable, PsiType.VOID, factory, null);
+      dfaSentinel = new DfaConstValue(SENTINEL, PsiType.VOID, factory, null);
     }
 
     @Nullable
@@ -139,6 +143,14 @@ public class DfaConstValue extends DfaValue {
     public DfaConstValue getNull() {
       return dfaNull;
     }
+
+    /**
+     * Sentinel value is special value used internally by dataflow. It cannot be stored to any variable, and equals to itself only
+     * @return sentinel value
+     */
+    public DfaConstValue getSentinel() {
+      return dfaSentinel;
+    }
   }
 
   private final Object myValue;

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaValue.java

@@ -42,6 +42,7 @@ public abstract class DfaValue {
    */
   public DfaValue union(DfaValue other) {
     if(this == other) return this;
+    if(this == DfaUnknownValue.getInstance() || other == DfaUnknownValue.getInstance()) return DfaUnknownValue.getInstance();
     return myFactory.getFactFactory().createValue(DfaFactMap.fromDfaValue(this).union(DfaFactMap.fromDfaValue(other)));
   }
 

java/java-tests/testData/inspection/dataFlow/fixture/StreamKnownSource.java

@@ -125,4 +125,22 @@ public class StreamKnownSource {
       System.out.println("Always");
     }
   }
+
+  void testLongVararg() {
+    IntStream.of(1, 2, 3, 4, 5).anyMatch(x -> <warning descr="Condition 'x > 6' is always 'false'">x > 6</warning>);
+    Stream.of("foo", "bar", "baz", "qux").filter(<warning descr="Method reference result is always 'true'">Objects::nonNull</warning>).forEach(System.out::println);
+  }
+
+  void testShortVararg(String a, String b) {
+    if(Stream.of(a, b).allMatch(Objects::isNull)) {
+      if(<warning descr="Condition 'a != null' is always 'false'">a != null</warning>) {
+        System.out.println("Impossible");
+      }
+      if(<warning descr="Condition 'b != null' is always 'false'">b != null</warning>) {
+        System.out.println("Impossible");
+      }
+    }
+    IntStream.of(1, 2).anyMatch(x -> <warning descr="Condition 'x > 6' is always 'false'">x > 6</warning>);
+    Stream.of("foo", "bar").filter(<warning descr="Method reference result is always 'true'">Objects::nonNull</warning>).forEach(System.out::println);
+  }
 }

java/java-tests/testData/inspection/optionalGet/OptionalGet.java

@@ -350,6 +350,14 @@ class OptionalGet {
     // Non-empty stream: get() is fine
     return Stream.of("foo", "bar", "baz").map(String::toUpperCase).max(Comparator.naturalOrder()).get();
   }
+
+  void testStreamOfUnrolling(Optional<String> optionalOne, Optional<String> optionalTwo, Optional<String> optionalThree) {
+    if (Stream.of(optionalOne, optionalTwo).allMatch(Optional::isPresent)) {
+      System.out.println(optionalOne.get());
+      System.out.println(optionalTwo.get());
+      System.out.println(optionalThree.<warning descr="'Optional.get()' without 'isPresent()' check">get</warning>());
+    }
+  }
 }
 
 class CtorTest {