IDEA-205011 DFA: limited support for shift-left

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/instructions/BinopInstruction.java

@@ -32,7 +32,7 @@ import static com.intellij.psi.JavaTokenType.*;
 
 public class BinopInstruction extends BranchingInstruction implements ExpressionPushingInstruction {
   private static final TokenSet ourSignificantOperations =
-    TokenSet.create(EQEQ, NE, LT, GT, LE, GE, INSTANCEOF_KEYWORD, PLUS, MINUS, AND, PERC, DIV, ASTERISK, GTGT, GTGTGT);
+    TokenSet.create(EQEQ, NE, LT, GT, LE, GE, INSTANCEOF_KEYWORD, PLUS, MINUS, AND, PERC, DIV, ASTERISK, GTGT, GTGTGT, LTLT);
   private final IElementType myOperationSign;
   private final @Nullable PsiType myResultType;
   private final int myLastOperand;

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/rangeSet/LongRangeSet.java

@@ -184,6 +184,9 @@ public abstract class LongRangeSet {
     if (token.equals(JavaTokenType.DIV)) {
       return div(right, isLong);
     }
+    if (token.equals(JavaTokenType.LTLT)) {
+      return shiftLeft(right, isLong);
+    }
     if (token.equals(JavaTokenType.GTGT)) {
       return shiftRight(right, isLong);
     }
@@ -371,6 +374,25 @@ public abstract class LongRangeSet {
                    .unite(point(-1).minus(point(-1).minus(negative, isLong).shrPositive(min, max, isLong), isLong));
   }
 
+  /**
+   * Returns a range which represents all the possible values after applying {@code x << y} operation for
+   * all {@code x} from this set and for all {@code y} from the shiftSize set. The resulting set may contain
+   * some more values.
+   *
+   * @param shiftSize set of possible shift sizes (number of bits to shift to the left)
+   * @param isLong whether the operation is performed on long type (if false, the int type is assumed).
+   * @return a new range
+   */
+  @NotNull
+  public LongRangeSet shiftLeft(LongRangeSet shiftSize, boolean isLong) {
+    if (isEmpty() || shiftSize.isEmpty()) return empty();
+    if (shiftSize instanceof Point) {
+      long shift = ((Point)shiftSize).myValue & ((isLong ? Long.SIZE : Integer.SIZE)-1);
+      return point(1 << shift).mul(this, isLong);
+    }
+    return isLong ? Range.LONG_RANGE : Range.INT_RANGE;
+  }
+
   /**
    * Returns a range which represents all the possible values after applying {@code x >>> y} operation for
    * all {@code x} from this set and for all {@code y} from the shiftSize set. The resulting set may contain

java/java-tests/testSrc/com/intellij/java/codeInspection/dataFlow/rangeSet/LongRangeSetTest.java

@@ -432,6 +432,17 @@ public class LongRangeSetTest {
     checkShr(range(1000000, 1000020), range(3, 5), true, "{31250..125002}");
   }
 
+  @Test
+  public void testShl() {
+    assertEquals(empty(), empty().shiftLeft(all(), true));
+    assertEquals(empty(), all().shiftLeft(empty(), true));
+    assertEquals(all(), all().shiftLeft(all(), true));
+    checkShl(point(1), point(3), false, "{8}");
+    checkShl(range(0, 10), point(3), false, "{0..80}");
+    checkShl(range(0, 15), point(28), false, "{Integer.MIN_VALUE..Integer.MAX_VALUE}");
+    checkShl(range(0, 15), point(28), true, "{0..4026531840}");
+  }
+
   @Test
   public void testUShr() {
     assertEquals(empty(), empty().unsignedShiftRight(all(), true));
@@ -549,6 +560,11 @@ public class LongRangeSetTest {
     checkBinOp(arg, shiftSize, result, x -> true, (a, b) -> isLong ? a >> b : ((int)a >> (int)b), expected, ">>");
   }
 
+  void checkShl(LongRangeSet arg, LongRangeSet shiftSize, boolean isLong, String expected) {
+    LongRangeSet result = arg.shiftLeft(shiftSize, isLong);
+    checkBinOp(arg, shiftSize, result, x -> true, (a, b) -> isLong ? a << b : ((int)a << (int)b), expected, "<<");
+  }
+
   void checkUShr(LongRangeSet arg, LongRangeSet shiftSize, boolean isLong, String expected) {
     LongRangeSet result = arg.unsignedShiftRight(shiftSize, isLong);
     checkBinOp(arg, shiftSize, result, x -> true, (a, b) -> isLong ? a >>> b : ((int)a >>> (int)b), expected, ">>>");