From f2f23f3610e71ad45a00b91226c4c69dc61adfa2 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Mon, 18 Jun 2018 17:15:21 +0700
Subject: [PATCH] LongRangeSet.RangeSet#plus: convert to simple range if number
 of sets exceeds 3

Fixes IDEA-193987 IDE freeze when turn on code inspection data flow for Java
---
 .../dataFlow/rangeSet/LongRangeSet.java       |  3 +++
 ...yAdditionsDoNotCauseExponentialBlowUp.java | 26 +++++++++++++++++++
 .../DataFlowRangeAnalysisTest.java            |  2 ++
 3 files changed, 31 insertions(+)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/ManyAdditionsDoNotCauseExponentialBlowUp.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/rangeSet/LongRangeSet.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/rangeSet/LongRangeSet.java
index 0ccf501b8465..d48a12c466cc 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/rangeSet/LongRangeSet.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/rangeSet/LongRangeSet.java
@@ -1256,6 +1256,9 @@ public abstract class LongRangeSet {
     @NotNull
     @Override
     public LongRangeSet plus(LongRangeSet other, boolean isLong) {
+      if (myRanges.length > 6) {
+        return range(min(), max()).plus(other, isLong);
+      }
       LongRangeSet result = empty();
       for (int i = 0; i < myRanges.length; i += 2) {
         result = result.union(range(myRanges[i], myRanges[i + 1]).plus(other, isLong));
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/ManyAdditionsDoNotCauseExponentialBlowUp.java b/java/java-tests/testData/inspection/dataFlow/fixture/ManyAdditionsDoNotCauseExponentialBlowUp.java
new file mode 100644
index 000000000000..0a1c8286007b
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/ManyAdditionsDoNotCauseExponentialBlowUp.java
@@ -0,0 +1,26 @@
+import java.util.*;
+
+class Test {
+  native boolean get();
+
+  void test() {
+    int x = get() ? 0 : 1<<30;
+    x = x + (get() ? 0 : 1<<29);
+    x = x + (get() ? 0 : 1<<28);
+    x = x + (get() ? 0 : 1<<27);
+    x = x + (get() ? 0 : 1<<26);
+    x = x + (get() ? 0 : 1<<25);
+    x = x + (get() ? 0 : 1<<24);
+    x = x + (get() ? 0 : 1<<23);
+    x = x + (get() ? 0 : 1<<22);
+    x = x + (get() ? 0 : 1<<21);
+    x = x + (get() ? 0 : 1<<20);
+    x = x + (get() ? 0 : 1<<19);
+    x = x + (get() ? 0 : 1<<18);
+    x = x + (get() ? 0 : 1<<17);
+
+    if (<warning descr="Condition 'x < 0' is always 'false'">x < 0</warning>) {
+      System.out.println("Impossible");
+    }
+  }
+}
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowRangeAnalysisTest.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowRangeAnalysisTest.java
index 269aea633089..d0f8c1f88b04 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowRangeAnalysisTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowRangeAnalysisTest.java
@@ -62,4 +62,6 @@ public class DataFlowRangeAnalysisTest extends DataFlowInspectionTestCase {
 
   public void testLongRangePlusMinus() { doTest(); }
   public void testFebruary31() { doTest(); }
+
+  public void testManyAdditionsDoNotCauseExponentialBlowUp() { doTest(); }
 }