IDEA-240402 Dataflow to here: narrow filters during the dataflow

GitOrigin-RevId: 3fb73062b31ec664aebe8bfe167726d421752cb2

java/java-impl/src/com/intellij/slicer/JavaDfaSliceValueFilter.java

@@ -42,18 +42,32 @@ public class JavaDfaSliceValueFilter implements SliceValueFilter {
         return Objects.equals(value, constValue);
       }
     }
-    if (!(element instanceof PsiExpression)) return true;
+    DfType dfType = getElementDfType(element);
+    return dfType.meet(myDfType) != DfTypes.BOTTOM;
+  }
+
+  @Nullable JavaDfaSliceValueFilter mergeFilter(@NotNull PsiElement element) {
+    DfType type = getElementDfType(element);
+    if (type instanceof DfReferenceType) {
+      type = ((DfReferenceType)type).dropLocality().dropMutability();
+    }
+    DfType meet = type.meet(myDfType);
+    if (meet == DfTypes.TOP && myNextFilter == null) return null;
+    if (meet == DfTypes.BOTTOM || meet.equals(myDfType)) return this;
+    return new JavaDfaSliceValueFilter(myNextFilter, meet);
+  }
+
+  private @NotNull DfType getElementDfType(@NotNull PsiElement element) {
+    if (!(element instanceof PsiExpression)) return DfTypes.TOP;
     PsiExpression expression = (PsiExpression)element;
-    DfType dfType;
     PsiType expressionType = expression.getType();
     if (TypeConversionUtil.isPrimitiveAndNotNull(expressionType) && myDfType instanceof DfReferenceType) {
-      dfType = DfTypes.typedObject(((PsiPrimitiveType)expressionType).getBoxedType(expression), Nullability.NOT_NULL);
-    } else if (!(expressionType instanceof PsiPrimitiveType) && myDfType instanceof DfPrimitiveType) {
-      dfType = DfTypes.typedObject(PsiPrimitiveType.getUnboxedType(expressionType), Nullability.NOT_NULL); 
-    } else {
-      dfType = CommonDataflow.getDfType(expression);
+      return DfTypes.typedObject(((PsiPrimitiveType)expressionType).getBoxedType(expression), Nullability.NOT_NULL);
     }
-    return dfType.meet(myDfType) != DfTypes.BOTTOM;
+    if (!(expressionType instanceof PsiPrimitiveType) && myDfType instanceof DfPrimitiveType) {
+      return DfTypes.typedObject(PsiPrimitiveType.getUnboxedType(expressionType), Nullability.NOT_NULL);
+    }
+    return CommonDataflow.getDfType(expression);
   }
 
   @Override

java/java-impl/src/com/intellij/slicer/JavaSliceBuilder.java

@@ -1,6 +1,7 @@
 // Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.slicer;
 
+import com.intellij.codeInspection.dataFlow.types.DfTypes;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Comparing;
 import com.intellij.psi.*;
@@ -74,8 +75,16 @@ final class JavaSliceBuilder {
     final PsiElement realExpression = element.getParent() instanceof DummyHolder ? element.getParent().getContext() : element;
     assert realExpression != null;
     if (!(realExpression instanceof PsiCompiledElement)) {
-      return processor
-        .process(new JavaSliceUsage(realExpression, myParent, myAnalysisParams, mySubstitutor, myIndexNesting, mySyntheticField));
+      JavaDfaSliceValueFilter curFilter = myAnalysisParams.valueFilter instanceof JavaDfaSliceValueFilter
+                                          ? (JavaDfaSliceValueFilter)myAnalysisParams.valueFilter
+                                          : new JavaDfaSliceValueFilter(DfTypes.TOP);
+      JavaDfaSliceValueFilter filter = curFilter.mergeFilter(realExpression);
+      SliceAnalysisParams params = myAnalysisParams;
+      if (filter != curFilter) {
+        params = new SliceAnalysisParams(params);
+        params.valueFilter = filter;
+      }
+      return processor.process(new JavaSliceUsage(realExpression, myParent, params, mySubstitutor, myIndexNesting, mySyntheticField));
     }
     return true;
   }
@@ -87,14 +96,14 @@ final class JavaSliceBuilder {
    */
   @Contract(pure = true)
   @NotNull JavaSliceBuilder updateNesting(@NotNull Flow anno) {
-    int nestingDelta = (anno.sourceIsContainer() ? 1 : 0) - (anno.targetIsContainer() ? 1 : 0);
-    if (nestingDelta > 0) {
-      return incrementNesting();
+    JavaSliceBuilder result = this;
+    if (anno.targetIsContainer()) {
+      result = result.decrementNesting();
     }
-    if (nestingDelta < 0) {
-      return decrementNesting();
+    if (anno.sourceIsContainer()) {
+      result = result.incrementNesting();
     }
-    return this;
+    return result;
   }
 
   @Contract(pure = true)

java/java-tests/testData/codeInsight/slice/backward/NarrowFilter.java

@@ -0,0 +1,17 @@
+public class NarrowFilter {
+  void test(int <flown11>x) {
+    if (x > 0) {
+      foo(<flown1>x);
+    } else {
+      bar(x);
+    }
+  }
+
+  void foo(int <caret>x) { }
+  void bar(int x) { }
+
+  void call() {
+    test(<flown111>1);
+    test(-1);
+  }
+}

java/java-tests/testSrc/com/intellij/java/slicer/SliceBackwardTest.java

@@ -95,4 +95,5 @@ public class SliceBackwardTest extends SliceTestCase {
   public void testFilterIntRange() throws Exception { doTest(">=0");}
   public void testFilterIntRangeArray() throws Exception { doTest(">=0");}
   public void testFilterNull() throws Exception { doTest("null");}
+  public void testNarrowFilter() throws Exception { doTest();}
 }