dfa: take into account known variable values when handling number comparisons (IDEA-126446)

java/java-tests/testData/inspection/dataFlow/caseAndNpe/expected.xml

@@ -20,6 +20,11 @@
     <line>49</line>
     <description>Switch label 'case 2:' is unreachable</description>
   </problem>
+  <problem>
+    <file>CaseAndNpe.java</file>
+    <line>56</line>
+    <description>Condition &lt;code&gt;i &lt; 5&lt;/code&gt; is always &lt;code&gt;false&lt;/code&gt;</description>
+  </problem>
   <problem>
     <file>CaseAndNpe.java</file>
     <line>80</line>

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

@@ -0,0 +1,16 @@
+import java.util.Arrays;
+
+class Test {
+  int[] mIndex = null;
+  int mSize = 0;
+
+  void indexValues() {
+    float loadFactor = mIndex == null ? 1.f : ((float) mSize) / ((float) mIndex.length);
+
+    if (loadFactor < 0.25f || 0.75f <= loadFactor) {
+      mIndex = new int[mSize * 2];
+    }
+
+    mIndex[0] = -1;
+  }
+}

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java

@@ -251,6 +251,8 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
 
   public void testUseInferredContracts() { doTest(); }
 
+  public void testNumberComparisonsWhenValueIsKnown() { doTest(); }
+
   public void testParametersAreNonnullByDefault() {
     myFixture.addClass("package javax.annotation; public @interface ParametersAreNonnullByDefault {}");
     myFixture.addClass("package javax.annotation; public @interface ParametersAreNullableByDefault {}");