diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CommonDataflow.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CommonDataflow.java
index 2db6fe5abd30..3dc630827bc4 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CommonDataflow.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CommonDataflow.java
@@ -15,13 +15,16 @@
  */
 package com.intellij.codeInspection.dataFlow;
 
+import com.intellij.codeInspection.dataFlow.instructions.MethodCallInstruction;
 import com.intellij.codeInspection.dataFlow.instructions.PushInstruction;
+import com.intellij.codeInspection.dataFlow.value.DfaConstValue;
 import com.intellij.codeInspection.dataFlow.value.DfaValue;
 import com.intellij.psi.*;
 import com.intellij.psi.util.CachedValueProvider;
 import com.intellij.psi.util.CachedValuesManager;
 import com.intellij.psi.util.PsiModificationTracker;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.util.ObjectUtils;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.Nullable;
 
@@ -46,6 +49,7 @@ public class CommonDataflow {
   private static DataflowResult runDFA(@Nullable PsiElement block) {
     if (block == null) return null;
     DataFlowRunner runner = new DataFlowRunner(false, true);
+    DfaConstValue fail = runner.getFactory().getConstFactory().getContractFail();
     DataflowResult dfr = new DataflowResult();
     StandardInstructionVisitor visitor = new StandardInstructionVisitor() {
       @Override
@@ -59,6 +63,23 @@ public class CommonDataflow {
         }
         return states;
       }
+
+      @Override
+      public DfaInstructionState[] visitMethodCall(MethodCallInstruction instruction,
+                                                   DataFlowRunner runner,
+                                                   DfaMemoryState memState) {
+        DfaInstructionState[] states = super.visitMethodCall(instruction, runner, memState);
+        PsiExpression context = ObjectUtils.tryCast(instruction.getContext(), PsiExpression.class);
+        if (context != null) {
+          for (DfaInstructionState state : states) {
+            DfaValue value = state.getMemoryState().peek();
+            if(value != fail) {
+              dfr.add(context, (DfaMemoryStateImpl)state.getMemoryState());
+            }
+          }
+        }
+        return states;
+      }
     };
     RunnerResult result = runner.analyzeMethod(block, visitor);
     return result == RunnerResult.OK ? dfr : null;
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties
index 09f77533730d..316f4bc5e186 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties
@@ -1908,6 +1908,7 @@ empty.directory.display.name=Empty directory
 empty.directories.problem.descriptor=Empty directory <code>{0}</code>
 empty.directories.only.under.source.roots.option=Only report empty directories located under a source folder
 empty.directories.delete.quickfix=Delete empty directory ''{0}''
+simplifiable.equals.expression.option.non.constant=Report equals with non-constant not-null argument
 simplifiable.equals.expression.display.name=Unnecessary 'null' check before 'equals()' call
 simplifiable.equals.expression.problem.descriptor=Unnecessary ''null'' check before ''{0}()'' call #loc
 simplifiable.equals.expression.quickfix=Flip ''.{0}()'' and remove unnecessary ''null'' check
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspection.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspection.java
index 45bddf71a939..12fd9f86eccb 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspection.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspection.java
@@ -17,6 +17,9 @@ package com.siyeh.ig.controlflow;
 
 import com.intellij.codeInspection.CleanupLocalInspectionTool;
 import com.intellij.codeInspection.ProblemDescriptor;
+import com.intellij.codeInspection.dataFlow.CommonDataflow;
+import com.intellij.codeInspection.dataFlow.DfaFactType;
+import com.intellij.codeInspection.ui.SingleCheckboxOptionsPanel;
 import com.intellij.openapi.project.Project;
 import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
@@ -29,11 +32,25 @@ import com.siyeh.ig.InspectionGadgetsFix;
 import com.siyeh.ig.PsiReplacementUtil;
 import com.siyeh.ig.psiutils.ExpressionUtils;
 import com.siyeh.ig.psiutils.ParenthesesUtils;
+import com.siyeh.ig.psiutils.SideEffectChecker;
+import com.siyeh.ig.psiutils.VariableAccessUtils;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import javax.swing.*;
 
 public class SimplifiableEqualsExpressionInspection extends BaseInspection implements CleanupLocalInspectionTool {
+  public boolean REPORT_NON_CONSTANT = true;
+
+  @Nullable
+  @Override
+  public JComponent createOptionsPanel() {
+    return new SingleCheckboxOptionsPanel(InspectionGadgetsBundle.message("simplifiable.equals.expression.option.non.constant"), this,
+                                          "REPORT_NON_CONSTANT");
+  }
+
   @Nls
   @NotNull
   @Override
@@ -154,7 +171,7 @@ public class SimplifiableEqualsExpressionInspection extends BaseInspection imple
     return new SimplifiableEqualsExpressionVisitor();
   }
 
-  private static class SimplifiableEqualsExpressionVisitor extends BaseInspectionVisitor {
+  private class SimplifiableEqualsExpressionVisitor extends BaseInspectionVisitor {
 
     @Override
     public void visitPolyadicExpression(PsiPolyadicExpression expression) {
@@ -202,12 +219,12 @@ public class SimplifiableEqualsExpressionInspection extends BaseInspection imple
       }
     }
 
-    private static String getMethodName(PsiMethodCallExpression methodCallExpression) {
+    private String getMethodName(PsiMethodCallExpression methodCallExpression) {
       final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
       return methodExpression.getReferenceName();
     }
 
-    private static boolean isEqualsConstant(PsiExpression expression, PsiVariable variable) {
+    private boolean isEqualsConstant(PsiExpression expression, PsiVariable variable) {
       if (!(expression instanceof PsiMethodCallExpression)) {
         return false;
       }
@@ -217,13 +234,7 @@ public class SimplifiableEqualsExpressionInspection extends BaseInspection imple
       if (!HardcodedMethodConstants.EQUALS.equals(methodName) && !HardcodedMethodConstants.EQUALS_IGNORE_CASE.equals(methodName)) {
         return false;
       }
-      final PsiExpression qualifier = methodExpression.getQualifierExpression();
-      if (!(qualifier instanceof PsiReferenceExpression)) {
-        return false;
-      }
-      final PsiReferenceExpression referenceExpression = (PsiReferenceExpression)qualifier;
-      final PsiElement target = referenceExpression.resolve();
-      if (!variable.equals(target)) {
+      if (!ExpressionUtils.isReferenceTo(methodExpression.getQualifierExpression(), variable)) {
         return false;
       }
       final PsiExpressionList argumentList = methodCallExpression.getArgumentList();
@@ -232,7 +243,11 @@ public class SimplifiableEqualsExpressionInspection extends BaseInspection imple
         return false;
       }
       final PsiExpression argument = arguments[0];
-      return PsiUtil.isConstantExpression(argument);
+      if (PsiUtil.isConstantExpression(argument)) return true;
+      return REPORT_NON_CONSTANT &&
+             !VariableAccessUtils.variableIsUsed(variable, argument) &&
+             !SideEffectChecker.mayHaveSideEffects(argument) &&
+             Boolean.FALSE.equals(CommonDataflow.getExpressionFact(argument, DfaFactType.CAN_BE_NULL));
     }
   }
 }
diff --git a/plugins/InspectionGadgets/src/inspectionDescriptions/SimplifiableEqualsExpression.html b/plugins/InspectionGadgets/src/inspectionDescriptions/SimplifiableEqualsExpression.html
index 271ab045724d..fb6ed6e9d857 100644
--- a/plugins/InspectionGadgets/src/inspectionDescriptions/SimplifiableEqualsExpression.html
+++ b/plugins/InspectionGadgets/src/inspectionDescriptions/SimplifiableEqualsExpression.html
@@ -11,7 +11,11 @@ And the quickfix will replace that with:
 <code><pre>
     <b>if</b> ("literal".equals(s)) {}
 </pre></code>
-  <!-- tooltip end -->
+</p>
 <p>
+    When checkbox is checked, 'equals()' with non-constant argument may also be reported if 'equals()' argument
+    is proven to be not-null.
+</p>
+  <!-- tooltip end -->
 </body>
 </html>
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/controlflow/simplifiable_equals_expression/SimplifiableEqualsExpression.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/controlflow/simplifiable_equals_expression/SimplifiableEqualsExpression.java
index 0a99fcfe7e25..d66fa185b565 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/controlflow/simplifiable_equals_expression/SimplifiableEqualsExpression.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/controlflow/simplifiable_equals_expression/SimplifiableEqualsExpression.java
@@ -1,5 +1,7 @@
 package com.siyeh.igtest.controlflow.simplifiable_equals_expression;
 
+import java.util.*;
+
 public class SimplifiableEqualsExpression {
 
   void foo(String namespace) {
@@ -31,4 +33,28 @@ public class SimplifiableEqualsExpression {
       return;
     }
   }
+
+  private Optional<Long> getOptional() {
+    return Optional.of(1L);
+  }
+
+  // IDEA-177798 Simplifiable equals expression: support non-constant argument
+  public boolean foo(Long previousGroupHead) {
+    Long aLong = getOptional().get();
+
+    return <warning descr="Unnecessary 'null' check before 'equals()' call">previousGroupHead != null</warning> && previousGroupHead.equals(aLong);
+  }
+
+  void trimTest(String s1, String s2) {
+    if(<warning descr="Unnecessary 'null' check before 'equals()' call">s1 == null</warning> || !s1.equals(s2.trim())) {
+      System.out.println("...");
+    }
+  }
+
+  void test(List<String> list) {
+    String s = list.get(0);
+    if(s != null && s.equals(list.get(1))) {
+      System.out.println("???");
+    }
+  }
 }
diff --git a/plugins/InspectionGadgets/testsrc/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspectionTest.java b/plugins/InspectionGadgets/testsrc/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspectionTest.java
index 4442a53d70e3..42daf165846b 100644
--- a/plugins/InspectionGadgets/testsrc/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspectionTest.java
+++ b/plugins/InspectionGadgets/testsrc/com/siyeh/ig/controlflow/SimplifiableEqualsExpressionInspectionTest.java
@@ -1,7 +1,9 @@
 package com.siyeh.ig.controlflow;
 
 import com.intellij.codeInspection.InspectionProfileEntry;
+import com.intellij.testFramework.LightProjectDescriptor;
 import com.siyeh.ig.LightInspectionTestCase;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 public class SimplifiableEqualsExpressionInspectionTest extends LightInspectionTestCase {
@@ -10,6 +12,12 @@ public class SimplifiableEqualsExpressionInspectionTest extends LightInspectionT
     doTest();
   }
 
+  @NotNull
+  @Override
+  protected LightProjectDescriptor getProjectDescriptor() {
+    return JAVA_8;
+  }
+
   @Nullable
   @Override
   protected InspectionProfileEntry getInspection() {