diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
index ca87da3a2df..7b61474a78a 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
@@ -37,6 +37,7 @@ import org.jetbrains.jet.codegen.inline.NameGenerator;
 import org.jetbrains.jet.codegen.intrinsics.IntrinsicMethod;
 import org.jetbrains.jet.codegen.state.GenerationState;
 import org.jetbrains.jet.codegen.state.JetTypeMapper;
+import org.jetbrains.jet.codegen.when.SwitchCodegen;
 import org.jetbrains.jet.codegen.when.SwitchCodegenUtil;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.diagnostics.DiagnosticUtils;
@@ -112,7 +113,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
      * When we create a temporary variable to hold some value not to compute it many times
      * we put it into this map to emit access to that variable instead of evaluating the whole expression
      */
-    final Map<JetElement, StackValue> tempVariables = Maps.newHashMap();
+    public final Map<JetElement, StackValue> tempVariables = Maps.newHashMap();
 
     private int myLastLineNumber = -1;
 
@@ -3725,8 +3726,10 @@ The "returned" value of try expression with no finally is either the last expres
 
         Type resultType = isStatement ? Type.VOID_TYPE : expressionType(expression);
 
-        if (SwitchCodegenUtil.canSwitchBeUsedIn(expression, subjectType, bindingContext)) {
-            return generateSwitch(expression, resultType, isStatement);
+        SwitchCodegen switchCodegen = SwitchCodegenUtil.buildAppropriateSwitchCodegenIfPossible(expression, isStatement, this);
+        if (switchCodegen != null) {
+            switchCodegen.generate();
+            return StackValue.onStack(resultType);
         }
 
         int subjectLocal = expr != null ? myFrameMap.enterTemp(subjectType) : -1;
@@ -3816,19 +3819,6 @@ The "returned" value of try expression with no finally is either the last expres
         }
     }
 
-    private StackValue generateSwitch(
-            @NotNull JetWhenExpression expression,
-            @NotNull Type resultType,
-            boolean isStatement
-    ) {
-        SwitchCodegenUtil.buildAppropriateSwitchCodegen(
-                expression, isStatement, this
-
-        ).generate();
-
-        return StackValue.onStack(resultType);
-    }
-
     private boolean isIntRangeExpr(JetExpression rangeExpression) {
         if (rangeExpression instanceof JetBinaryExpression) {
             JetBinaryExpression binaryExpression = (JetBinaryExpression) rangeExpression;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/when/StringSwitchCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/when/StringSwitchCodegen.java
new file mode 100644
index 00000000000..db5b334c104
--- /dev/null
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/when/StringSwitchCodegen.java
@@ -0,0 +1,122 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.codegen.when;
+
+import com.google.common.collect.Maps;
+import com.intellij.openapi.util.Pair;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.codegen.ExpressionCodegen;
+import org.jetbrains.jet.lang.psi.JetWhenExpression;
+import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
+import org.jetbrains.jet.lang.resolve.constants.StringValue;
+import org.jetbrains.org.objectweb.asm.Label;
+import org.jetbrains.org.objectweb.asm.Type;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class StringSwitchCodegen extends SwitchCodegen {
+    private static final String HASH_CODE_METHOD_DESC = Type.getMethodDescriptor(Type.INT_TYPE);
+    private static final String EQUALS_METHOD_DESC = Type.getMethodDescriptor(Type.BOOLEAN_TYPE, Type.getType(Object.class));
+
+    private final Map<Integer, List<Pair<String, Label>>> hashCodesToStringAndEntryLabel = Maps.newHashMap();
+    private int tempVarIndex;
+
+    public StringSwitchCodegen(
+            @NotNull JetWhenExpression expression,
+            boolean isStatement,
+            @NotNull ExpressionCodegen codegen
+    ) {
+        super(expression, isStatement, codegen);
+    }
+
+    @Override
+    protected void processConstant(
+            @NotNull CompileTimeConstant constant, @NotNull Label entryLabel
+    ) {
+        assert constant instanceof StringValue : "guaranteed by usage contract";
+        int hashCode = constant.hashCode();
+
+        if (!transitionsTable.containsKey(hashCode)) {
+            transitionsTable.put(hashCode, new Label());
+            hashCodesToStringAndEntryLabel.put(hashCode, new ArrayList<Pair<String, Label>>());
+        }
+
+        hashCodesToStringAndEntryLabel.get(hashCode).add(
+                new Pair<String, Label>(((StringValue) constant).getValue(), entryLabel)
+        );
+    }
+
+    @Override
+    public void generate() {
+        super.generate();
+        codegen.myFrameMap.leaveTemp(subjectType);
+    }
+
+    @Override
+    protected void generateSubject() {
+        tempVarIndex = codegen.myFrameMap.enterTemp(subjectType);
+        super.generateSubject();
+        v.store(tempVarIndex, subjectType);
+
+        v.load(tempVarIndex, subjectType);
+        v.invokevirtual(
+                subjectType.getInternalName(),
+                "hashCode", HASH_CODE_METHOD_DESC, false
+        );
+    }
+
+    @Override
+    protected void generateEntries() {
+        for (int hashCode : hashCodesToStringAndEntryLabel.keySet()) {
+            v.visitLabel(transitionsTable.get(hashCode));
+
+            List<Pair<String, Label>> items = hashCodesToStringAndEntryLabel.get(hashCode);
+            Label nextLabel = null;
+
+            for (int i = 0; i < items.size(); i++) {
+                if (nextLabel != null) {
+                    v.visitLabel(nextLabel);
+                }
+
+                Pair<String, Label> stringAndEntryLabel = items.get(i);
+
+                v.load(tempVarIndex, subjectType);
+                v.aconst(stringAndEntryLabel.first);
+                v.invokevirtual(
+                        subjectType.getInternalName(),
+                        "equals",
+                        EQUALS_METHOD_DESC,
+                        false
+                );
+
+                if (i + 1 < items.size()) {
+                    nextLabel = new Label();
+                }
+                else {
+                    nextLabel = defaultLabel;
+                }
+
+                v.ifeq(nextLabel);
+                v.goTo(stringAndEntryLabel.getSecond());
+            }
+        }
+
+        super.generateEntries();
+    }
+}
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegen.java
index 7f46cafca8e..d4ffa1158b9 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegen.java
@@ -19,7 +19,8 @@ package org.jetbrains.jet.codegen.when;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.codegen.ExpressionCodegen;
 import org.jetbrains.jet.codegen.FrameMap;
-import org.jetbrains.jet.lang.psi.*;
+import org.jetbrains.jet.lang.psi.JetWhenEntry;
+import org.jetbrains.jet.lang.psi.JetWhenExpression;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
 import org.jetbrains.org.objectweb.asm.Label;
@@ -41,6 +42,7 @@ abstract public class SwitchCodegen {
     protected final Collection<Label> entryLabels = new ArrayList<Label>();
     protected Label elseLabel = new Label();
     protected Label endLabel = new Label();
+    protected Label defaultLabel;
 
     public SwitchCodegen(
             @NotNull JetWhenExpression expression, boolean isStatement,
@@ -52,7 +54,7 @@ abstract public class SwitchCodegen {
         this.bindingContext = codegen.getBindingContext();
 
         subjectType = codegen.expressionType(expression.getSubjectExpression());
-        resultType = codegen.expressionType(expression);
+        resultType = isStatement ? Type.VOID_TYPE : codegen.expressionType(expression);
         v = codegen.v;
     }
 
@@ -66,25 +68,11 @@ abstract public class SwitchCodegen {
 
         generateSubject();
 
-        generateSwitchInstructionByTransitionsTable(
-                transitionsTable,
-                // if there is no else-entry and it's statement then default --- endLabel
-                (hasElse || !isStatement) ? elseLabel : endLabel
-        );
+        // if there is no else-entry and it's statement then default --- endLabel
+        defaultLabel = (hasElse || !isStatement) ? elseLabel : endLabel;
+        generateSwitchInstructionByTransitionsTable();
 
-        // resolving entries' entryLabels and generating entries' code
-        Iterator<Label> entryLabelsIterator = entryLabels.iterator();
-        for (JetWhenEntry entry : expression.getEntries()) {
-            v.visitLabel(entryLabelsIterator.next());
-
-            FrameMap.Mark mark = codegen.myFrameMap.mark();
-            codegen.gen(entry.getExpression(), resultType);
-            mark.dropTo();
-
-            if (!entry.isElse()) {
-                v.goTo(endLabel);
-            }
-        }
+        generateEntries();
 
         // there is no else-entry but this is not statement, so we should return Unit
         if (!hasElse && !isStatement) {
@@ -120,7 +108,7 @@ abstract public class SwitchCodegen {
             @NotNull CompileTimeConstant constant,
             @NotNull Label entryLabel
     );
-    
+
     protected void putTransitionOnce(int value, @NotNull Label entryLabel) {
         if (!transitionsTable.containsKey(value)) {
             transitionsTable.put(value, entryLabel);
@@ -136,14 +124,12 @@ abstract public class SwitchCodegen {
         codegen.gen(expression.getSubjectExpression(), subjectType);
     }
 
-    private void generateSwitchInstructionByTransitionsTable(
-            @NotNull Map<Integer, Label> transitions, @NotNull Label defaultLabel
-    ) {
-        int[] keys = new int[transitions.size()];
-        Label[] labels = new Label[transitions.size()];
+    private void generateSwitchInstructionByTransitionsTable() {
+        int[] keys = new int[transitionsTable.size()];
+        Label[] labels = new Label[transitionsTable.size()];
         int i = 0;
 
-        for (Map.Entry<Integer, Label> transition : transitions.entrySet()) {
+        for (Map.Entry<Integer, Label> transition : transitionsTable.entrySet()) {
             keys[i] = transition.getKey();
             labels[i] = transition.getValue();
 
@@ -181,4 +167,20 @@ abstract public class SwitchCodegen {
 
         v.tableswitch(lo, hi, defaultLabel, sparseLabels);
     }
+
+    protected void generateEntries() {
+        // resolving entries' entryLabels and generating entries' code
+        Iterator<Label> entryLabelsIterator = entryLabels.iterator();
+        for (JetWhenEntry entry : expression.getEntries()) {
+            v.visitLabel(entryLabelsIterator.next());
+
+            FrameMap.Mark mark = codegen.myFrameMap.mark();
+            codegen.gen(entry.getExpression(), resultType);
+            mark.dropTo();
+
+            if (!entry.isElse()) {
+                v.goTo(endLabel);
+            }
+        }
+    }
 }
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegenUtil.java b/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegenUtil.java
index c8ed6a94cec..a45f446542c 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegenUtil.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/when/SwitchCodegenUtil.java
@@ -25,39 +25,13 @@ import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
 import org.jetbrains.jet.lang.resolve.constants.IntegerValueConstant;
+import org.jetbrains.jet.lang.resolve.constants.StringValue;
 import org.jetbrains.org.objectweb.asm.Type;
 
 import java.util.ArrayList;
 import java.util.List;
 
 public class SwitchCodegenUtil {
-    public static boolean canSwitchBeUsedIn(
-            @NotNull JetWhenExpression expression,
-            @NotNull Type subjectType,
-            @NotNull BindingContext bindingContext
-    ) {
-        // *switch opcode can be used if each item is enum entry or integral constant
-        // in case of enum CodegenAnnotationVisitor should put mappings into bindingContext
-        if (bindingContext.get(CodegenBinding.MAPPING_FOR_WHEN_BY_ENUM, expression) != null) {
-            return true;
-        }
-
-        int typeSort = subjectType.getSort();
-
-        if (typeSort != Type.INT && typeSort != Type.CHAR && typeSort != Type.SHORT && typeSort != Type.BYTE) {
-            return false;
-        }
-
-        return checkAllItemsAreConstantsSatisfying(expression, bindingContext, new Function1<CompileTimeConstant, Boolean>() {
-            @Override
-            public Boolean invoke(
-                    @NotNull CompileTimeConstant constant
-            ) {
-                return constant instanceof IntegerValueConstant;
-            }
-        });
-    }
-
     public static boolean checkAllItemsAreConstantsSatisfying(
             @NotNull JetWhenExpression expression,
             @NotNull BindingContext bindingContext,
@@ -121,18 +95,70 @@ public class SwitchCodegenUtil {
         return result;
     }
 
-    @NotNull
-    public static SwitchCodegen buildAppropriateSwitchCodegen(
+    @Nullable
+    public static SwitchCodegen buildAppropriateSwitchCodegenIfPossible(
             @NotNull JetWhenExpression expression,
             boolean isStatement,
             @NotNull ExpressionCodegen codegen
     ) {
+        Type subjectType = codegen.expressionType(expression.getSubjectExpression());
+        BindingContext bindingContext = codegen.getBindingContext();
+
         WhenByEnumsMapping mapping = codegen.getBindingContext().get(CodegenBinding.MAPPING_FOR_WHEN_BY_ENUM, expression);
 
         if (mapping != null) {
             return new EnumSwitchCodegen(expression, isStatement, codegen, mapping);
         }
 
-        return new IntegralConstantsSwitchCodegen(expression, isStatement, codegen);
+        if (isIntegralConstantsSwitch(expression, subjectType, bindingContext)) {
+            return new IntegralConstantsSwitchCodegen(expression, isStatement, codegen);
+        }
+
+        if (isStringConstantsSwitch(expression, subjectType, bindingContext)) {
+            return new StringSwitchCodegen(expression, isStatement, codegen);
+        }
+
+        return null;
+    }
+
+    private static boolean isIntegralConstantsSwitch(
+            @NotNull JetWhenExpression expression,
+            @NotNull Type subjectType,
+            @NotNull BindingContext bindingContext
+    ) {
+        int typeSort = subjectType.getSort();
+
+        if (typeSort != Type.INT && typeSort != Type.CHAR && typeSort != Type.SHORT && typeSort != Type.BYTE) {
+            return false;
+        }
+
+        return checkAllItemsAreConstantsSatisfying(expression, bindingContext, new Function1<CompileTimeConstant, Boolean>() {
+            @Override
+            public Boolean invoke(
+                    @NotNull CompileTimeConstant constant
+            ) {
+                return constant instanceof IntegerValueConstant;
+            }
+        });
+    }
+
+    private static boolean isStringConstantsSwitch(
+            @NotNull JetWhenExpression expression,
+            @NotNull Type subjectType,
+            @NotNull BindingContext bindingContext
+    ) {
+
+        if (!subjectType.getClassName().equals(String.class.getName())) {
+            return false;
+        }
+
+        return checkAllItemsAreConstantsSatisfying(expression, bindingContext, new Function1<CompileTimeConstant, Boolean>() {
+            @Override
+            public Boolean invoke(
+                    @NotNull CompileTimeConstant constant
+            ) {
+                return constant instanceof StringValue;
+            }
+        });
     }
 }
diff --git a/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItems.kt b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItems.kt
new file mode 100644
index 00000000000..3f63575a06d
--- /dev/null
+++ b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItems.kt
@@ -0,0 +1,20 @@
+import kotlin.test.assertEquals
+
+fun foo(x : String) : String {
+    when (x) {
+        "abc" -> return "abc"
+        "efg", "ghi", "abc" -> return "efg_ghi"
+        else -> return "other"
+    }
+}
+
+fun box() : String {
+    assertEquals("abc", foo("abc"))
+    assertEquals("efg_ghi", foo("efg"))
+    assertEquals("efg_ghi", foo("ghi"))
+
+    assertEquals("other", foo("xyz"))
+
+    return "OK"
+}
+
diff --git a/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItemsSameHashCode.kt b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItemsSameHashCode.kt
new file mode 100644
index 00000000000..ec44ca0f332
--- /dev/null
+++ b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItemsSameHashCode.kt
@@ -0,0 +1,24 @@
+import kotlin.test.assertEquals
+
+fun foo(x : String) : String {
+    assert("abz]".hashCode() == "aby|".hashCode())
+
+    when (x) {
+        "abz]" -> return "abz"
+        "ghi"  -> return "ghi"
+        "aby|" -> return "aby"
+        "abz]" -> return "fail"
+    }
+
+    return "other"
+}
+
+fun box() : String {
+    assertEquals("abz", foo("abz]"))
+    assertEquals("aby", foo("aby|"))
+    assertEquals("ghi", foo("ghi"))
+
+    assertEquals("other", foo("xyz"))
+
+    return "OK"
+}
diff --git a/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/expression.kt b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/expression.kt
new file mode 100644
index 00000000000..50cf056d00e
--- /dev/null
+++ b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/expression.kt
@@ -0,0 +1,20 @@
+import kotlin.test.assertEquals
+
+fun foo(x : String) : String {
+    return when (x) {
+        "abc", "cde" -> "abc_cde"
+        "efg", "ghi" -> "efg_ghi"
+        else -> "other"
+    }
+}
+
+fun box() : String {
+    assertEquals("abc_cde", foo("abc"))
+    assertEquals("abc_cde", foo("cde"))
+    assertEquals("efg_ghi", foo("efg"))
+    assertEquals("efg_ghi", foo("ghi"))
+
+    assertEquals("other", foo("xyz"))
+
+    return "OK"
+}
diff --git a/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/sameHashCode.kt b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/sameHashCode.kt
new file mode 100644
index 00000000000..80bd3d166b6
--- /dev/null
+++ b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/sameHashCode.kt
@@ -0,0 +1,23 @@
+import kotlin.test.assertEquals
+
+fun foo(x : String) : String {
+    assert("abz]".hashCode() == "aby|".hashCode())
+
+    when (x) {
+        "abz]", "cde" -> return "abz_cde"
+        "aby|", "ghi", "abz]" -> return "aby_ghi"
+    }
+
+    return "other"
+}
+
+fun box() : String {
+    assertEquals("abz_cde", foo("abz]"))
+    assertEquals("abz_cde", foo("cde"))
+    assertEquals("aby_ghi", foo("aby|"))
+    assertEquals("aby_ghi", foo("ghi"))
+
+    assertEquals("other", foo("xyz"))
+
+    return "OK"
+}
diff --git a/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/statement.kt b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/statement.kt
new file mode 100644
index 00000000000..bf3e24c4a21
--- /dev/null
+++ b/compiler/testData/codegen/boxWithStdlib/whenStringOptimization/statement.kt
@@ -0,0 +1,38 @@
+import kotlin.test.assertEquals
+
+fun foo1(x : String) : String {
+    when (x) {
+        "abc", "cde" -> return "abc_cde"
+        "efg", "ghi" -> return "efg_ghi"
+    }
+
+    return "other"
+}
+
+fun foo2(x : String) : String {
+    when (x) {
+        "abc", "cde" -> return "abc_cde"
+        "efg", "ghi" -> return "efg_ghi"
+        else -> return "other"
+    }
+}
+
+fun box() : String {
+    //foo1
+    assertEquals("abc_cde", foo1("abc"))
+    assertEquals("abc_cde", foo1("cde"))
+    assertEquals("efg_ghi", foo1("efg"))
+    assertEquals("efg_ghi", foo1("ghi"))
+
+    assertEquals("other", foo1("xyz"))
+
+    //foo2
+    assertEquals("abc_cde", foo2("abc"))
+    assertEquals("abc_cde", foo2("cde"))
+    assertEquals("efg_ghi", foo2("efg"))
+    assertEquals("efg_ghi", foo2("ghi"))
+
+    assertEquals("other", foo2("xyz"))
+
+    return "OK"
+}
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/denseHashCode.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/denseHashCode.kt
new file mode 100644
index 00000000000..6323c19699b
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/denseHashCode.kt
@@ -0,0 +1,15 @@
+
+fun foo() : Int {
+    val x : String = "dsa"
+    when (x) {
+        "a" -> return 1
+        "b" -> return 1
+        "c" -> return 1
+        "d" -> return 1
+        "e" -> return 1
+        "f" -> return 1
+        else -> return -1
+    }
+}
+
+// 1 TABLESWITCH
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItems.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItems.kt
new file mode 100644
index 00000000000..15a2ebde392
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItems.kt
@@ -0,0 +1,11 @@
+import kotlin.test.assertEquals
+
+fun foo(x : String) : String {
+    when (x) {
+        "abc" -> return "abc"
+        "efg", "ghi", "abc" -> return "efg_ghi"
+        else -> return "other"
+    }
+}
+
+// 1 LOOKUPSWITCH
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItemsSameHashCode.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItemsSameHashCode.kt
new file mode 100644
index 00000000000..7f4f18fdf1d
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItemsSameHashCode.kt
@@ -0,0 +1,16 @@
+import kotlin.test.assertEquals
+
+fun foo(x : String) : String {
+    assert("abz]".hashCode() == "aby|".hashCode())
+
+    when (x) {
+        "abz]" -> return "abz"
+        "ghi"  -> return "ghi"
+        "aby|" -> return "aby"
+        "abz]" -> return "fail"
+    }
+
+    return "other"
+}
+
+// 1 LOOKUPSWITCH
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/expression.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/expression.kt
new file mode 100644
index 00000000000..4831cfb6df9
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/expression.kt
@@ -0,0 +1,9 @@
+fun foo(x : String) : String {
+    return when (x) {
+        "abc", "cde" -> "abc_cde"
+        "efg", "ghi" -> "efg_ghi"
+        else -> "other"
+    }
+}
+
+// 1 LOOKUPSWITCH
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/nonInlinedConst.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/nonInlinedConst.kt
new file mode 100644
index 00000000000..f5b8d524824
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/nonInlinedConst.kt
@@ -0,0 +1,11 @@
+fun foo(x : String) : String {
+    val y = "cde"
+    when (x) {
+        "abc", "${y}" -> return "abc_cde"
+        "e" + "fg", "ghi" -> return "efg_ghi"
+    }
+
+    return "other"
+}
+
+// 1 LOOKUPSWITCH
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/sameHashCode.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/sameHashCode.kt
new file mode 100644
index 00000000000..f5f0d55b265
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/sameHashCode.kt
@@ -0,0 +1,12 @@
+fun foo(x : String) : String {
+    assert("abz]".hashCode() == "aby|".hashCode())
+
+    when (x) {
+        "abz]", "cde" -> return "abz_cde"
+        "aby|", "ghi" -> return "aby_ghi"
+    }
+
+    return "other"
+}
+
+// 1 LOOKUPSWITCH
diff --git a/compiler/testData/codegen/bytecodeText/whenStringOptimization/statement.kt b/compiler/testData/codegen/bytecodeText/whenStringOptimization/statement.kt
new file mode 100644
index 00000000000..7e07e9961d7
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/whenStringOptimization/statement.kt
@@ -0,0 +1,19 @@
+fun foo1(x : String) : String {
+    when (x) {
+        "abc", "cde" -> return "abc_cde"
+        "efg", "ghi" -> return "efg_ghi"
+    }
+
+    return "other"
+}
+
+fun foo2(x : String) : String {
+    when (x) {
+        "abc", "cde" -> return "abc_cde"
+        "efg", "ghi" -> return "efg_ghi"
+        else -> return "other"
+    }
+}
+
+// 2 LOOKUPSWITCH
+
diff --git a/compiler/tests/org/jetbrains/jet/codegen/BytecodeTextTestGenerated.java b/compiler/tests/org/jetbrains/jet/codegen/BytecodeTextTestGenerated.java
index 8dde716183d..52541da43b4 100644
--- a/compiler/tests/org/jetbrains/jet/codegen/BytecodeTextTestGenerated.java
+++ b/compiler/tests/org/jetbrains/jet/codegen/BytecodeTextTestGenerated.java
@@ -31,7 +31,7 @@ import org.jetbrains.jet.codegen.AbstractBytecodeTextTest;
 /** This class is generated by {@link org.jetbrains.jet.generators.tests.TestsPackage}. DO NOT MODIFY MANUALLY */
 @SuppressWarnings("all")
 @TestMetadata("compiler/testData/codegen/bytecodeText")
-@InnerTestClasses({BytecodeTextTestGenerated.BoxingOptimization.class, BytecodeTextTestGenerated.Constants.class, BytecodeTextTestGenerated.DirectInvoke.class, BytecodeTextTestGenerated.Statements.class, BytecodeTextTestGenerated.WhenEnumOptimization.class})
+@InnerTestClasses({BytecodeTextTestGenerated.BoxingOptimization.class, BytecodeTextTestGenerated.Constants.class, BytecodeTextTestGenerated.DirectInvoke.class, BytecodeTextTestGenerated.Statements.class, BytecodeTextTestGenerated.WhenEnumOptimization.class, BytecodeTextTestGenerated.WhenStringOptimization.class})
 public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
     @TestMetadata("accessorForProtected.kt")
     public void testAccessorForProtected() throws Exception {
@@ -352,6 +352,49 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
         
     }
     
+    @TestMetadata("compiler/testData/codegen/bytecodeText/whenStringOptimization")
+    public static class WhenStringOptimization extends AbstractBytecodeTextTest {
+        public void testAllFilesPresentInWhenStringOptimization() throws Exception {
+            JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.TestsPackage", new File("compiler/testData/codegen/bytecodeText/whenStringOptimization"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+        
+        @TestMetadata("denseHashCode.kt")
+        public void testDenseHashCode() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/denseHashCode.kt");
+        }
+        
+        @TestMetadata("duplicatingItems.kt")
+        public void testDuplicatingItems() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItems.kt");
+        }
+        
+        @TestMetadata("duplicatingItemsSameHashCode.kt")
+        public void testDuplicatingItemsSameHashCode() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/duplicatingItemsSameHashCode.kt");
+        }
+        
+        @TestMetadata("expression.kt")
+        public void testExpression() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/expression.kt");
+        }
+        
+        @TestMetadata("nonInlinedConst.kt")
+        public void testNonInlinedConst() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/nonInlinedConst.kt");
+        }
+        
+        @TestMetadata("sameHashCode.kt")
+        public void testSameHashCode() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/sameHashCode.kt");
+        }
+        
+        @TestMetadata("statement.kt")
+        public void testStatement() throws Exception {
+            doTest("compiler/testData/codegen/bytecodeText/whenStringOptimization/statement.kt");
+        }
+        
+    }
+    
     public static Test suite() {
         TestSuite suite = new TestSuite("BytecodeTextTestGenerated");
         suite.addTestSuite(BytecodeTextTestGenerated.class);
@@ -360,6 +403,7 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
         suite.addTestSuite(DirectInvoke.class);
         suite.addTestSuite(Statements.class);
         suite.addTestSuite(WhenEnumOptimization.class);
+        suite.addTestSuite(WhenStringOptimization.class);
         return suite;
     }
 }
diff --git a/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java b/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java
index 6183101a18e..5d97188a6f0 100644
--- a/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java
+++ b/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java
@@ -31,7 +31,7 @@ import org.jetbrains.jet.codegen.generated.AbstractBlackBoxCodegenTest;
 /** This class is generated by {@link org.jetbrains.jet.generators.tests.TestsPackage}. DO NOT MODIFY MANUALLY */
 @SuppressWarnings("all")
 @TestMetadata("compiler/testData/codegen/boxWithStdlib")
-@InnerTestClasses({BlackBoxWithStdlibCodegenTestGenerated.Annotations.class, BlackBoxWithStdlibCodegenTestGenerated.Arrays.class, BlackBoxWithStdlibCodegenTestGenerated.BoxingOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.CallableReference.class, BlackBoxWithStdlibCodegenTestGenerated.Casts.class, BlackBoxWithStdlibCodegenTestGenerated.DataClasses.class, BlackBoxWithStdlibCodegenTestGenerated.Evaluate.class, BlackBoxWithStdlibCodegenTestGenerated.FullJdk.class, BlackBoxWithStdlibCodegenTestGenerated.HashPMap.class, BlackBoxWithStdlibCodegenTestGenerated.JdkAnnotations.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformNames.class, BlackBoxWithStdlibCodegenTestGenerated.Ranges.class, BlackBoxWithStdlibCodegenTestGenerated.Reflection.class, BlackBoxWithStdlibCodegenTestGenerated.Regressions.class, BlackBoxWithStdlibCodegenTestGenerated.Strings.class, BlackBoxWithStdlibCodegenTestGenerated.ToArray.class, BlackBoxWithStdlibCodegenTestGenerated.Vararg.class, BlackBoxWithStdlibCodegenTestGenerated.When.class, BlackBoxWithStdlibCodegenTestGenerated.WhenEnumOptimization.class})
+@InnerTestClasses({BlackBoxWithStdlibCodegenTestGenerated.Annotations.class, BlackBoxWithStdlibCodegenTestGenerated.Arrays.class, BlackBoxWithStdlibCodegenTestGenerated.BoxingOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.CallableReference.class, BlackBoxWithStdlibCodegenTestGenerated.Casts.class, BlackBoxWithStdlibCodegenTestGenerated.DataClasses.class, BlackBoxWithStdlibCodegenTestGenerated.Evaluate.class, BlackBoxWithStdlibCodegenTestGenerated.FullJdk.class, BlackBoxWithStdlibCodegenTestGenerated.HashPMap.class, BlackBoxWithStdlibCodegenTestGenerated.JdkAnnotations.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformNames.class, BlackBoxWithStdlibCodegenTestGenerated.Ranges.class, BlackBoxWithStdlibCodegenTestGenerated.Reflection.class, BlackBoxWithStdlibCodegenTestGenerated.Regressions.class, BlackBoxWithStdlibCodegenTestGenerated.Strings.class, BlackBoxWithStdlibCodegenTestGenerated.ToArray.class, BlackBoxWithStdlibCodegenTestGenerated.Vararg.class, BlackBoxWithStdlibCodegenTestGenerated.When.class, BlackBoxWithStdlibCodegenTestGenerated.WhenEnumOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.WhenStringOptimization.class})
 public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
     public void testAllFilesPresentInBoxWithStdlib() throws Exception {
         JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.TestsPackage", new File("compiler/testData/codegen/boxWithStdlib"), Pattern.compile("^(.+)\\.kt$"), true);
@@ -2005,6 +2005,39 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
         
     }
     
+    @TestMetadata("compiler/testData/codegen/boxWithStdlib/whenStringOptimization")
+    public static class WhenStringOptimization extends AbstractBlackBoxCodegenTest {
+        public void testAllFilesPresentInWhenStringOptimization() throws Exception {
+            JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.TestsPackage", new File("compiler/testData/codegen/boxWithStdlib/whenStringOptimization"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+        
+        @TestMetadata("duplicatingItems.kt")
+        public void testDuplicatingItems() throws Exception {
+            doTestWithStdlib("compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItems.kt");
+        }
+        
+        @TestMetadata("duplicatingItemsSameHashCode.kt")
+        public void testDuplicatingItemsSameHashCode() throws Exception {
+            doTestWithStdlib("compiler/testData/codegen/boxWithStdlib/whenStringOptimization/duplicatingItemsSameHashCode.kt");
+        }
+        
+        @TestMetadata("expression.kt")
+        public void testExpression() throws Exception {
+            doTestWithStdlib("compiler/testData/codegen/boxWithStdlib/whenStringOptimization/expression.kt");
+        }
+        
+        @TestMetadata("sameHashCode.kt")
+        public void testSameHashCode() throws Exception {
+            doTestWithStdlib("compiler/testData/codegen/boxWithStdlib/whenStringOptimization/sameHashCode.kt");
+        }
+        
+        @TestMetadata("statement.kt")
+        public void testStatement() throws Exception {
+            doTestWithStdlib("compiler/testData/codegen/boxWithStdlib/whenStringOptimization/statement.kt");
+        }
+        
+    }
+    
     public static Test suite() {
         TestSuite suite = new TestSuite("BlackBoxWithStdlibCodegenTestGenerated");
         suite.addTestSuite(BlackBoxWithStdlibCodegenTestGenerated.class);
@@ -2027,6 +2060,7 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
         suite.addTestSuite(Vararg.class);
         suite.addTestSuite(When.class);
         suite.addTestSuite(WhenEnumOptimization.class);
+        suite.addTestSuite(WhenStringOptimization.class);
         return suite;
     }
 }