From 0f1494e02a86734644e62377809d28af37be2301 Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Sun, 15 Sep 2013 15:33:00 +0400
Subject: [PATCH] dfa: don't multiply eq classes until really needed

---
 .../dataFlow/DfaMemoryStateImpl.java          | 21 +++++++++----------
 .../dataFlow/unboxingNPE/expected.xml         |  6 ++++++
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
index 89e813a9d617..374415aae0b1 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
@@ -511,13 +511,12 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
   @Override
   public boolean isNull(DfaValue dfaValue) {
     if (dfaValue instanceof DfaTypeValue && ((DfaTypeValue)dfaValue).isNotNull()) return false;
+    
+    if (dfaValue instanceof DfaConstValue) return ((DfaConstValue)dfaValue).getConstant() == null;
 
-    if (dfaValue instanceof DfaVariableValue || dfaValue instanceof DfaConstValue) {
-      DfaConstValue dfaNull = myFactory.getConstFactory().getNull();
-      Integer c1Index = getOrCreateEqClassIndex(dfaValue);
-      Integer c2Index = getOrCreateEqClassIndex(dfaNull);
-
-      return c1Index != null && c1Index.equals(c2Index);
+    if (dfaValue instanceof DfaVariableValue) {
+      int c1Index = getEqClassIndex(dfaValue);
+      return c1Index >= 0 && c1Index == getEqClassIndex(myFactory.getConstFactory().getNull());
     }
 
     return false;
@@ -530,16 +529,16 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
     }
 
     DfaConstValue dfaNull = myFactory.getConstFactory().getNull();
-    Integer c1Index = getOrCreateEqClassIndex(dfaVar);
-    Integer c2Index = getOrCreateEqClassIndex(dfaNull);
-    if (c1Index == null || c2Index == null) {
+    int c1Index = getEqClassIndex(dfaVar);
+    int c2Index = getEqClassIndex(dfaNull);
+    if (c1Index < 0 || c2Index < 0) {
       return false;
     }
 
     long[] pairs = myDistinctClasses.toArray();
     for (long pair : pairs) {
-      if (c1Index.equals(low(pair)) && c2Index.equals(high(pair)) ||
-          c1Index.equals(high(pair)) && c2Index.equals(low(pair))) {
+      if (c1Index == low(pair) && c2Index == high(pair) ||
+          c1Index == high(pair) && c2Index == low(pair)) {
         return true;
       }
     }
diff --git a/java/java-tests/testData/inspection/dataFlow/unboxingNPE/expected.xml b/java/java-tests/testData/inspection/dataFlow/unboxingNPE/expected.xml
index 000168e3d991..caab45d3b56a 100644
--- a/java/java-tests/testData/inspection/dataFlow/unboxingNPE/expected.xml
+++ b/java/java-tests/testData/inspection/dataFlow/unboxingNPE/expected.xml
@@ -384,4 +384,10 @@
     <description>Condition &lt;code&gt;i&lt;/code&gt; is always &lt;code&gt;true&lt;/code&gt; when reached</description>
   </problem>
 
+  <problem>
+    <file>Test.java</file>
+    <line>62</line>
+    <module>testUnboxingNPE_7454908424878253728</module>
+    <description>Switch label&lt;code&gt;case 0:&lt;/code&gt; is unreachable</description>
+  </problem>
 </problems>