Merge branch 'master' into truffle-head

jruby · Jan 27, 2016 · e4d7808 · e4d7808
2 parents 1e4cfde + 983325b
commit e4d7808
Showing 81 changed files with 3,063 additions and 1,212 deletions.
diff --git a/VERSION b/VERSION
@@ -1 +1 @@
-9.0.5.0
+9.1.0.0-SNAPSHOT
diff --git a/bin/jruby.bash b/bin/jruby.bash
@@ -383,7 +383,7 @@ if [ "$VERIFY_JRUBY" != "" ]; then
     "-Djruby.home=$JRUBY_HOME" \
     "-Djruby.lib=$JRUBY_HOME/lib" -Djruby.script=jruby \
     "-Djruby.shell=$JRUBY_SHELL" \
-    $java_class $JRUBY_OPTS "$@"
+    $java_class $mode "$@"
 
   # Record the exit status immediately, or it will be overridden.
   JRUBY_STATUS=$?

diff --git a/core/pom.xml b/core/pom.xml
@@ -12,7 +12,7 @@ DO NOT MODIFIY - GENERATED CODE
   <parent>
     <groupId>org.jruby</groupId>
     <artifactId>jruby-parent</artifactId>
-    <version>9.0.5.0</version>
+    <version>9.1.0.0-SNAPSHOT</version>
   </parent>
   <artifactId>jruby-core</artifactId>
   <name>JRuby Core</name>

diff --git a/core/src/main/java/org/jruby/util/StringSupport.java b/core/src/main/java/org/jruby/util/StringSupport.java
@@ -319,7 +319,7 @@ public static long strLengthWithCodeRange(Encoding enc, byte[]bytes, int p, int
         }
     }
 
-    private static long strLengthWithCodeRangeAsciiCompatible(Encoding enc, byte[]bytes, int p, int end) {
+    public static long strLengthWithCodeRangeAsciiCompatible(Encoding enc, byte[]bytes, int p, int end) {
         int cr = 0, c = 0;
         while (p < end) {
             if (Encoding.isAscii(bytes[p])) {
@@ -341,7 +341,7 @@ private static long strLengthWithCodeRangeAsciiCompatible(Encoding enc, byte[]by
         return pack(c, cr == 0 ? CR_7BIT : cr);
     }
 
-    private static long strLengthWithCodeRangeNonAsciiCompatible(Encoding enc, byte[]bytes, int p, int end) {
+    public static long strLengthWithCodeRangeNonAsciiCompatible(Encoding enc, byte[]bytes, int p, int end) {
         int cr = 0, c = 0;
         for (c = 0; p < end; c++) {
             int cl = preciseLength(enc, bytes, p, end);
@@ -365,7 +365,7 @@ public static long strLengthWithCodeRange(ByteList bytes, Encoding enc) {
     }
 
     // arg cannot be negative
-    static long pack(int result, int arg) {
+    public static long pack(int result, int arg) {
         return ((long)arg << 31) | result;
     }
 

diff --git a/core/src/main/java/org/jruby/util/io/EncodingUtils.java b/core/src/main/java/org/jruby/util/io/EncodingUtils.java
@@ -1842,12 +1842,12 @@ public static Encoding getEncoding(ByteList str) {
 
     // MRI: get_actual_encoding
     public static Encoding getActualEncoding(Encoding enc, ByteList byteList) {
+        return getActualEncoding(enc, byteList.getUnsafeBytes(), byteList.begin(), byteList.begin() + byteList.realSize());
+    }
+
+    public static Encoding getActualEncoding(Encoding enc, byte[] bytes, int p, int end) {
         if (enc.isDummy() && enc instanceof UnicodeEncoding) {
             // handle dummy UTF-16 and UTF-32 by scanning for BOM, as in MRI
-            byte[] bytes = byteList.unsafeBytes();
-            int p = byteList.begin();
-            int end = p + byteList.getRealSize();
-
             if (enc == UTF16Dummy && end - p >= 2) {
                 int c0 = bytes[p] & 0xff;
                 int c1 = bytes[p + 1] & 0xff;

diff --git a/lib/pom.xml b/lib/pom.xml
@@ -12,7 +12,7 @@ DO NOT MODIFIY - GENERATED CODE
   <parent>
     <groupId>org.jruby</groupId>
     <artifactId>jruby-parent</artifactId>
-    <version>9.0.5.0</version>
+    <version>9.1.0.0-SNAPSHOT</version>
   </parent>
   <artifactId>jruby-stdlib</artifactId>
   <name>JRuby Lib Setup</name>
@@ -28,7 +28,7 @@ DO NOT MODIFIY - GENERATED CODE
     <dependency>
       <groupId>org.jruby</groupId>
       <artifactId>jruby-core</artifactId>
-      <version>9.0.5.0</version>
+      <version>9.1.0.0-SNAPSHOT</version>
       <scope>test</scope>
     </dependency>
     <dependency>

diff --git a/maven/jruby/src/it/extended/src/test/java/org/example/BaseTest.java b/maven/jruby/src/it/extended/src/test/java/org/example/BaseTest.java
@@ -1,19 +1,13 @@
 package org.example;
 
-import static org.junit.Assert.assertEquals;
-
 import java.util.Arrays;
 import java.io.File;
-import java.io.StringWriter;
 import java.net.URL;
 import java.net.URLClassLoader;
 
 import org.jruby.embed.LocalContextScope;
 import org.jruby.embed.ScriptingContainer;
 
-import org.junit.Before;
-import org.junit.Test;
-
 public class BaseTest {
 
     private final String basedir = new File( System.getProperty("basedir"), "../../../../../" ).getAbsolutePath();
@@ -31,38 +25,39 @@ private void runTests(ScriptingContainer container) throws Exception {
         container.terminate();
     }
 
-    private void collectTests(ScriptingContainer container, String index) throws Exception {
-        container.runScriptlet("File.open(File.join('test', '" + index + ".index')) do |f|\n" +
-                               "      f.each_line.each do |line|\n" +
-                               "        next if line =~ /^#/ or line.strip.empty?\n" +
-                               "        filename = \"test/mri/#{line.chomp}\"\n" +
-                               "        filename = \"test/jruby/#{line.chomp}.rb\" unless File.exist? filename\n" +
-                               "        filename = \"test/#{line.chomp}.rb\" unless File.exist? filename\n" +
-                               "        next unless File.file? filename\n" +
-                               "        next if filename =~ /mri\\/net\\/http\\//\n" +
-                               "        next if filename =~ /mri\\/ruby\\/test_class/\n" +
-                               "        next if filename =~ /mri\\/ruby\\/test_io/\n" +
-                               "        next if filename =~ /mri\\/ruby\\/test_econv/\n" +
-                               // TODO find a way to obey the minitest/excludes and get those back
-                               "        next if filename =~ /psych\\/test_encoding.rb/\n" +
-                               "        next if filename =~ /psych\\/test_parser.rb/\n" +
-                               "        next if filename =~ /psych\\/test_psych.rb/\n" +
-                               "        next if filename =~ /psych\\/visitors\\/test_yaml_tree.rb/\n" +
-                               "        next if filename =~ /psych\\/test_document.rb/\n" +
-                               "        next if filename =~ /psych\\/test_tree_builder.rb/\n" +
-                               "        next if filename =~ /psych\\/test_date_time.rb/\n" +
-                               "        next if filename =~ /psych\\/test_nil.rb/\n" +
-                               // TODO file an issue or so
-                               "        next if filename =~ /test_load_compiled_ruby.rb/\n" +
-                               "        next if filename =~ /compiler\\/test_jrubyc.rb/\n" +
-                               // TODO remove the following after fix of #2215
-                               "        next if filename =~ /test_jar_on_load_path.rb/\n" +
-                               "        next if filename =~ /test_file.rb/\n" +
-                               "        filename.sub!( /.*\\/test\\//, 'test/' )\n" +
-                               "        puts filename\n" +
-                               "        require filename\n" +
-                               "      end\n" +
-                               "    end");
+    protected void collectTests(ScriptingContainer container, String index) throws Exception {
+        container.runScriptlet(
+            "File.open(File.join('test', '" + index + ".index')) do |f|\n" +
+            "      f.each_line do |line|\n" +
+            "        next if line =~ /^#/ or line.strip.empty?\n" +
+            "        filename = \"test/mri/#{line.chomp}\"\n" +
+            "        filename = \"test/jruby/#{line.chomp}.rb\" unless File.exist? filename\n" +
+            "        filename = \"test/#{line.chomp}.rb\" unless File.exist? filename\n" +
+            "        next unless File.file? filename\n" +
+            "        next if filename =~ /mri\\/net\\/http\\//\n" +
+            "        next if filename =~ /mri\\/ruby\\/test_class/\n" +
+            "        next if filename =~ /mri\\/ruby\\/test_io/\n" +
+            "        next if filename =~ /mri\\/ruby\\/test_econv/\n" +
+            // TODO find a way to obey the minitest/excludes and get those back
+            "        next if filename =~ /psych\\/test_encoding.rb/\n" +
+            "        next if filename =~ /psych\\/test_parser.rb/\n" +
+            "        next if filename =~ /psych\\/test_psych.rb/\n" +
+            "        next if filename =~ /psych\\/visitors\\/test_yaml_tree.rb/\n" +
+            "        next if filename =~ /psych\\/test_document.rb/\n" +
+            "        next if filename =~ /psych\\/test_tree_builder.rb/\n" +
+            "        next if filename =~ /psych\\/test_date_time.rb/\n" +
+            "        next if filename =~ /psych\\/test_nil.rb/\n" +
+            // TODO file an issue or so
+            "        next if filename =~ /test_load_compiled_ruby.rb/\n" +
+            "        next if filename =~ /compiler\\/test_jrubyc.rb/\n" +
+            // TODO remove the following after fix of #2215
+            "        next if filename =~ /test_jar_on_load_path.rb/\n" +
+            "        next if filename =~ /test_file.rb/\n" +
+            "        filename.sub!( /.*\\/test\\//, 'test/' )\n" +
+            "        puts filename\n" +
+            "        require filename\n" +
+            "      end\n" +
+            "    end" );
     }
 
     void runIt(String index) throws Exception {

diff --git a/maven/jruby/src/it/extended/src/test/java/org/example/JRubyTest.java b/maven/jruby/src/it/extended/src/test/java/org/example/JRubyTest.java
@@ -1,23 +1,37 @@
 package org.example;
 
-import static org.junit.Assert.assertEquals;
-
-import java.util.Arrays;
-import java.io.File;
-import java.io.StringWriter;
-import java.net.URL;
-import java.net.URLClassLoader;
+import org.junit.Test;
 
-import org.jruby.embed.LocalContextScope;
 import org.jruby.embed.ScriptingContainer;
 
-import org.junit.Before;
-import org.junit.Test;
-
 public class JRubyTest extends BaseTest {
 
     @Test
     public void testJRuby() throws Exception {
         runIt("jruby");
     }
+
+    protected void collectTests(ScriptingContainer container, String index) {
+        container.runScriptlet(
+            "File.open(File.join('test', '" + index + ".index')) do |f|\n" +
+            "      f.each_line do |line|\n" +
+            "        next if line =~ /^#/ or line.strip.empty?\n" +
+            "        filename = \"test/jruby/#{line.chomp}.rb\"\n" +
+            "        filename = \"test/#{line.chomp}.rb\" unless File.exist? filename\n" +
+            "        next unless File.file? filename\n" +
+
+            // TODO file an issue or so
+            "        next if filename =~ /test_load_compiled_ruby.rb/\n" +
+            "        next if filename =~ /compiler\\/test_jrubyc.rb/\n" +
+            // TODO remove the following after fix of #2215
+            "        next if filename =~ /test_jar_on_load_path.rb/\n" +
+            "        next if filename =~ /test_file.rb/\n" +
+
+            "        filename.sub!( /.*\\/test\\//, 'test/' )\n" +
+            "        puts filename\n" +
+            "        require filename\n" +
+            "      end\n" +
+            "    end" );
+    }
+
 }
diff --git a/maven/jruby/src/it/extended/src/test/java/org/example/MRITest.java b/maven/jruby/src/it/extended/src/test/java/org/example/MRITest.java
@@ -1,23 +1,44 @@
 package org.example;
 
-import static org.junit.Assert.assertEquals;
-
-import java.util.Arrays;
-import java.io.File;
-import java.io.StringWriter;
-import java.net.URL;
-import java.net.URLClassLoader;
+import org.junit.Test;
 
-import org.jruby.embed.LocalContextScope;
 import org.jruby.embed.ScriptingContainer;
 
-import org.junit.Before;
-import org.junit.Test;
-
 public class MRITest extends BaseTest {
 
     @Test
     public void testMRI() throws Exception {
         runIt("mri", "ENV['EXCLUDE_DIR']='test/mri/excludes';");
     }
+
+    protected void collectTests(ScriptingContainer container, String index) {
+        container.runScriptlet(
+            "File.open(File.join('test', '" + index + ".index')) do |f|\n" +
+            "      f.each_line do |line|\n" +
+            "        next if line =~ /^#/ or line.strip.empty?\n" +
+            "        filename = \"test/mri/#{line.chomp}\"\n" +
+            "        filename = \"test/#{line.chomp}.rb\" unless File.exist? filename\n" +
+            "        next unless File.file? filename\n" +
+
+            "        next if filename =~ /mri\\/net\\/http\\//\n" +
+            "        next if filename =~ /mri\\/ruby\\/test_class/\n" +
+            "        next if filename =~ /mri\\/ruby\\/test_io/\n" +
+            "        next if filename =~ /mri\\/ruby\\/test_econv/\n" +
+            // TODO find a way to obey the minitest/excludes and get those back
+            "        next if filename =~ /psych\\/test_encoding.rb/\n" +
+            "        next if filename =~ /psych\\/test_parser.rb/\n" +
+            "        next if filename =~ /psych\\/test_psych.rb/\n" +
+            "        next if filename =~ /psych\\/visitors\\/test_yaml_tree.rb/\n" +
+            "        next if filename =~ /psych\\/test_document.rb/\n" +
+            "        next if filename =~ /psych\\/test_tree_builder.rb/\n" +
+            "        next if filename =~ /psych\\/test_date_time.rb/\n" +
+            "        next if filename =~ /psych\\/test_nil.rb/\n" +
+
+            "        filename.sub!( /.*\\/test\\//, 'test/' )\n" +
+            "        puts filename\n" +
+            "        require filename\n" +
+            "      end\n" +
+            "    end" );
+    }
+
 }
diff --git a/maven/jruby/src/it/extended/src/test/java/org/example/ObjectspaceTest.java b/maven/jruby/src/it/extended/src/test/java/org/example/ObjectspaceTest.java
@@ -1,17 +1,5 @@
 package org.example;
 
-import static org.junit.Assert.assertEquals;
-
-import java.util.Arrays;
-import java.io.File;
-import java.io.StringWriter;
-import java.net.URL;
-import java.net.URLClassLoader;
-
-import org.jruby.embed.LocalContextScope;
-import org.jruby.embed.ScriptingContainer;
-
-import org.junit.Before;
 import org.junit.Test;
 
 public class ObjectspaceTest extends BaseTest {

diff --git a/maven/jruby/src/it/extended/src/test/java/org/example/SlowTest.java b/maven/jruby/src/it/extended/src/test/java/org/example/SlowTest.java
@@ -1,17 +1,5 @@
 package org.example;
 
-import static org.junit.Assert.assertEquals;
-
-import java.util.Arrays;
-import java.io.File;
-import java.io.StringWriter;
-import java.net.URL;
-import java.net.URLClassLoader;
-
-import org.jruby.embed.LocalContextScope;
-import org.jruby.embed.ScriptingContainer;
-
-import org.junit.Before;
 import org.junit.Test;
 
 public class SlowTest extends BaseTest {

diff --git a/pom.xml b/pom.xml
@@ -16,7 +16,7 @@ DO NOT MODIFIY - GENERATED CODE
   </parent>
   <groupId>org.jruby</groupId>
   <artifactId>jruby-parent</artifactId>
-  <version>9.0.5.0</version>
+  <version>9.1.0.0-SNAPSHOT</version>
   <packaging>pom</packaging>
   <name>JRuby</name>
   <description>JRuby is the effort to recreate the Ruby (http://www.ruby-lang.org) interpreter in Java.</description>

diff --git a/test/truffle/compiler/pe/core/string_pe.rb b/test/truffle/compiler/pe/core/string_pe.rb
@@ -12,4 +12,25 @@
 example "Truffle::Primitive.create_simple_string.getbyte(0)", simple_string.getbyte(0)
 
 example "'abc'.length", 3
-tagged_example "'abc' == 'abc'", true # seems to fail sometimes
+example "'こにちわ'.length", 4
+
+example "'abc'.bytesize", 3
+example "'こにちわ'.bytesize", 12
+
+example "'abc' == 'abc'", true
+example "x = 'abc'; x == x", true
+example "x = 'abc'; x == x.dup", true
+example "x = 'abc'; 'abc' == x.dup", true
+
+example "'abc'.ascii_only?", true
+example "'こにちわ'.ascii_only?", false
+
+example "''.ascii?", false
+example "'abc'.ascii?", true
+
+example "'abc'.valid_encoding?", true
+example "'こにちわ'.valid_encoding?", true
+
+example "''.empty?", true
+example "'abc'.empty?", false
+example "'こにちわ'.empty?", false
diff --git a/truffle/pom.xml b/truffle/pom.xml
@@ -12,7 +12,7 @@ DO NOT MODIFIY - GENERATED CODE
   <parent>
     <groupId>org.jruby</groupId>
     <artifactId>jruby-parent</artifactId>
-    <version>9.0.5.0</version>
+    <version>9.1.0.0-SNAPSHOT</version>
   </parent>
   <artifactId>jruby-truffle</artifactId>
   <name>JRuby Truffle</name>

diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadBase64StringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadBase64StringNode.java
@@ -20,6 +20,7 @@
 import org.jruby.truffle.format.nodes.SourceNode;
 import org.jruby.truffle.format.runtime.exceptions.FormatException;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.util.ByteList;
 import org.jruby.util.Pack;
@@ -168,7 +169,7 @@ public Object read(VirtualFrame frame, byte[] source) {
         final ByteList result = new ByteList(lElem, 0, index, encoding, false);
         setSourcePosition(frame, encode.position());
 
-        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), result, StringSupport.CR_UNKNOWN, null);
+        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(result, StringSupport.CR_UNKNOWN), null);
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadBinaryStringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadBinaryStringNode.java
@@ -18,6 +18,7 @@
 import org.jruby.truffle.format.nodes.SourceNode;
 import org.jruby.truffle.format.runtime.MissingValue;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.util.ByteList;
 import org.jruby.util.StringSupport;
@@ -109,7 +110,7 @@ public Object read(VirtualFrame frame, byte[] source) {
 
         setSourcePosition(frame, start + length);
 
-        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), result, StringSupport.CR_UNKNOWN, null);
+        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(result, StringSupport.CR_UNKNOWN), null);
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadBitStringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadBitStringNode.java
@@ -17,6 +17,7 @@
 import org.jruby.truffle.format.nodes.PackNode;
 import org.jruby.truffle.format.nodes.SourceNode;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.util.ByteList;
 import org.jruby.util.StringSupport;
@@ -83,7 +84,7 @@ public Object read(VirtualFrame frame, byte[] source) {
         final ByteList result = new ByteList(lElem, encoding, false);
         setSourcePosition(frame, encode.position());
 
-        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), result, StringSupport.CR_UNKNOWN, null);
+        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(result, StringSupport.CR_UNKNOWN), null);
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadHexStringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadHexStringNode.java
@@ -17,6 +17,7 @@
 import org.jruby.truffle.format.nodes.PackNode;
 import org.jruby.truffle.format.nodes.SourceNode;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.util.ByteList;
 import org.jruby.util.Pack;
@@ -84,7 +85,7 @@ public Object read(VirtualFrame frame, byte[] source) {
         final ByteList result = new ByteList(lElem, encoding, false);
         setSourcePosition(frame, encode.position());
 
-        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), result, StringSupport.CR_UNKNOWN, null);
+        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(result, StringSupport.CR_UNKNOWN), null);
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadMIMEStringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadMIMEStringNode.java
@@ -18,6 +18,7 @@
 import org.jruby.truffle.format.nodes.PackNode;
 import org.jruby.truffle.format.nodes.SourceNode;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.util.ByteList;
 import org.jruby.util.Pack;
@@ -75,7 +76,7 @@ public Object read(VirtualFrame frame, byte[] source) {
         final ByteList result = new ByteList(lElem, 0, index, encoding, false);
         setSourcePosition(frame, encode.position());
 
-        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), result, StringSupport.CR_UNKNOWN, null);
+        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(result, StringSupport.CR_UNKNOWN), null);
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadUUStringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/read/ReadUUStringNode.java
@@ -21,6 +21,7 @@
 import org.jruby.truffle.format.nodes.SourceNode;
 import org.jruby.truffle.format.runtime.exceptions.NoImplicitConversionException;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.util.ByteList;
 import org.jruby.util.Pack;
@@ -156,7 +157,7 @@ else if (encode.hasRemaining()) {
 
         setSourcePosition(frame, encode.position());
 
-        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), result, StringSupport.CR_UNKNOWN, null);
+        return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(result, StringSupport.CR_UNKNOWN), null);
     }
 
     private static int safeGet(ByteBuffer encode) {

diff --git a/truffle/src/main/java/org/jruby/truffle/format/nodes/type/ToStringNode.java b/truffle/src/main/java/org/jruby/truffle/format/nodes/type/ToStringNode.java
@@ -99,7 +99,7 @@ public ByteList toStringString(VirtualFrame frame, DynamicObject string) {
             setTainted(frame);
         }
 
-        return StringOperations.getByteList(string);
+        return StringOperations.getByteListReadOnly(string);
     }
 
     @Specialization(guards = "isRubyArray(array)")
@@ -116,7 +116,7 @@ public ByteList toString(VirtualFrame frame, DynamicObject array) {
                 setTainted(frame);
             }
 
-            return StringOperations.getByteList((DynamicObject) value);
+            return StringOperations.getByteListReadOnly((DynamicObject) value);
         }
 
         CompilerDirectives.transferToInterpreter();
@@ -142,7 +142,7 @@ public ByteList toString(VirtualFrame frame, Object object) {
                 setTainted(frame);
             }
 
-            return StringOperations.getByteList((DynamicObject) value);
+            return StringOperations.getByteListReadOnly((DynamicObject) value);
         }
 
         if (inspectOnConversionFailure) {
@@ -152,7 +152,7 @@ public ByteList toString(VirtualFrame frame, Object object) {
                         getEncapsulatingSourceSection(), new RubyNode[]{null}));
             }
 
-            return StringOperations.getByteList(inspectNode.toS(frame, object));
+            return StringOperations.getByteListReadOnly(inspectNode.toS(frame, object));
         }
 
         CompilerDirectives.transferToInterpreter();

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/RubyNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/RubyNode.java
@@ -24,6 +24,7 @@
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.truffle.runtime.sockets.NativeSockets;
 import org.jruby.util.ByteList;
 
@@ -156,6 +157,10 @@ public DynamicObject getSymbol(ByteList name) {
         return getContext().getSymbol(name);
     }
 
+    public DynamicObject getSymbol(Rope name) {
+        return getContext().getSymbol(name);
+    }
+
     /** Creates a String from the ByteList, with unknown CR */
     protected DynamicObject createString(ByteList bytes) {
         return StringOperations.createString(getContext(), bytes);
@@ -166,6 +171,10 @@ protected DynamicObject create7BitString(ByteList bytes) {
         return StringOperations.create7BitString(getContext(), bytes);
     }
 
+    protected DynamicObject createString(Rope rope) {
+        return StringOperations.createString(getContext(), rope);
+    }
+
     protected POSIX posix() {
         return getContext().getPosix();
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/StringCachingGuards.java b/truffle/src/main/java/org/jruby/truffle/nodes/StringCachingGuards.java
@@ -12,33 +12,38 @@
 
 import com.oracle.truffle.api.object.DynamicObject;
 import org.jruby.truffle.runtime.core.StringOperations;
+import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 
 public abstract class StringCachingGuards {
 
-    public static ByteList privatizeByteList(DynamicObject string) {
+    public static Rope privatizeRope(DynamicObject string) {
         if (RubyGuards.isRubyString(string)) {
-            return StringOperations.getByteList(string).dup();
+            // TODO (nirvdrum 25-Jan-16) Should we flatten the rope to avoid caching a potentially deep rope tree?
+            return StringOperations.rope(string);
         } else {
             return null;
         }
     }
 
-    public static boolean byteListsEqual(DynamicObject string, ByteList byteList) {
+    public static boolean ropesEqual(DynamicObject string, Rope rope) {
         if (RubyGuards.isRubyString(string)) {
+            final Rope stringRope = StringOperations.rope(string);
+
             // equal below does not check encoding
-            if (StringOperations.getByteList(string).getEncoding() != byteList.getEncoding()) {
+            if (stringRope.getEncoding() != rope.getEncoding()) {
                 return false;
             }
-            // TODO CS 8-Nov-15 this code goes off into the woods - need to break it apart and branch profile it
-            return StringOperations.getByteList(string).equal(byteList);
+
+            return stringRope.equals(rope);
         } else {
             return false;
         }
     }
 
-    public static int byteListLength(ByteList byteList) {
-        return byteList.length();
+    public static int ropeLength(Rope rope) {
+        return rope.byteLength();
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/conversion/ToSymbolNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/conversion/ToSymbolNode.java
@@ -36,7 +36,7 @@ protected DynamicObject toSymbolSymbol(DynamicObject symbol) {
 
     @Specialization(guards = "isRubyString(string)")
     protected DynamicObject toSymbolString(DynamicObject string) {
-        return getSymbol(StringOperations.getByteList(string));
+        return getSymbol(StringOperations.rope(string));
     }
 
     @Specialization

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/BasicObjectNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/BasicObjectNodes.java
@@ -152,7 +152,7 @@ public InstanceEvalNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(string)")
         public Object instanceEval(Object receiver, DynamicObject string, NotProvided block) {
-            return getContext().instanceEval(StringOperations.getByteList(string), receiver, "(eval)", this);
+            return getContext().instanceEval(StringOperations.getByteListReadOnly(string), receiver, "(eval)", this);
         }
 
         @Specialization

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/EncodingNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/EncodingNodes.java
@@ -32,7 +32,9 @@
 import org.jruby.truffle.runtime.core.EncodingOperations;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
+import org.jruby.util.StringSupport;
 
 import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
@@ -128,7 +130,7 @@ public DynamicObject isCompatibleStringStringCached(DynamicObject first, Dynamic
                 "isRubyString(first)", "isRubyString(second)"
         }, contains =  "isCompatibleStringStringCached")
         public DynamicObject isCompatibleStringStringUncached(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = areCompatible(first, second);
+            final Encoding compatibleEncoding = compatibleEncodingForStrings(first, second);
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -154,7 +156,7 @@ public Object isCompatibleEncodingEncoding(DynamicObject first, DynamicObject se
         @TruffleBoundary
         @Specialization(guards = {"isRubyString(first)", "isRubyRegexp(second)"})
         public Object isCompatibleStringRegexp(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(StringOperations.getByteList(first).getEncoding(), Layouts.REGEXP.getRegex(second).getEncoding());
+            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.STRING.getRope(first).getEncoding(), Layouts.REGEXP.getRegex(second).getEncoding());
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -166,7 +168,7 @@ public Object isCompatibleStringRegexp(DynamicObject first, DynamicObject second
         @TruffleBoundary
         @Specialization(guards = {"isRubyRegexp(first)", "isRubyString(second)"})
         public Object isCompatibleRegexpString(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.REGEXP.getRegex(first).getEncoding(), StringOperations.getByteList(second).getEncoding());
+            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.REGEXP.getRegex(first).getEncoding(), Layouts.STRING.getRope(second).getEncoding());
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -190,7 +192,7 @@ public Object isCompatibleRegexpRegexp(DynamicObject first, DynamicObject second
         @TruffleBoundary
         @Specialization(guards = {"isRubyRegexp(first)", "isRubySymbol(second)"})
         public Object isCompatibleRegexpSymbol(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.REGEXP.getRegex(first).getEncoding(), Layouts.SYMBOL.getByteList(second).getEncoding());
+            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.REGEXP.getRegex(first).getEncoding(), Layouts.SYMBOL.getRope(second).getEncoding());
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -202,7 +204,7 @@ public Object isCompatibleRegexpSymbol(DynamicObject first, DynamicObject second
         @TruffleBoundary
         @Specialization(guards = {"isRubySymbol(first)", "isRubyRegexp(second)"})
         public Object isCompatibleSymbolRegexp(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.SYMBOL.getByteList(first).getEncoding(), Layouts.REGEXP.getRegex(second).getEncoding());
+            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.SYMBOL.getRope(first).getEncoding(), Layouts.REGEXP.getRegex(second).getEncoding());
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -214,7 +216,7 @@ public Object isCompatibleSymbolRegexp(DynamicObject first, DynamicObject second
         @TruffleBoundary
         @Specialization(guards = {"isRubyString(first)", "isRubySymbol(second)"})
         public Object isCompatibleStringSymbol(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(StringOperations.getCodeRangeable(first), SymbolNodes.getCodeRangeable(second));
+            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(StringOperations.getCodeRangeableReadOnly(first), SymbolNodes.getCodeRangeable(second));
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -238,7 +240,7 @@ public Object isCompatibleSymbolSymbol(DynamicObject first, DynamicObject second
         @TruffleBoundary
         @Specialization(guards = {"isRubyString(first)", "isRubyEncoding(second)"})
         public Object isCompatibleStringEncoding(DynamicObject first, DynamicObject second) {
-            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(StringOperations.getByteList(first).getEncoding(), EncodingOperations.getEncoding(second));
+            final Encoding compatibleEncoding = org.jruby.RubyEncoding.areCompatible(Layouts.STRING.getRope(first).getEncoding(), EncodingOperations.getEncoding(second));
 
             if (compatibleEncoding != null) {
                 return getEncoding(compatibleEncoding);
@@ -247,26 +249,47 @@ public Object isCompatibleStringEncoding(DynamicObject first, DynamicObject seco
             }
         }
 
-        private Encoding areCompatible(DynamicObject first, DynamicObject second) {
+        @TruffleBoundary
+        public static Encoding compatibleEncodingForStrings(DynamicObject first, DynamicObject second) {
+            // Taken from org.jruby.RubyEncoding#areCompatible.
+
             assert RubyGuards.isRubyString(first);
             assert RubyGuards.isRubyString(second);
 
-            final ByteList firstByteList = StringOperations.getByteList(first);
-            final ByteList secondByteList = StringOperations.getByteList(second);
+            final Rope firstRope = StringOperations.rope(first);
+            final Rope secondRope = StringOperations.rope(second);
+
+            final Encoding firstEncoding = firstRope.getEncoding();
+            final Encoding secondEncoding = secondRope.getEncoding();
+
+            if (firstEncoding == null || secondEncoding == null) return null;
+            if (firstEncoding == secondEncoding) return firstEncoding;
+
+            if (secondRope.isEmpty()) return firstEncoding;
+            if (firstRope.isEmpty()) {
+                return firstEncoding.isAsciiCompatible() && isAsciiOnly(secondRope) ? firstEncoding : secondEncoding;
+            }
 
-            final Encoding firstEncoding = firstByteList.getEncoding();
-            final Encoding secondEncoding = secondByteList.getEncoding();
+            if (!firstEncoding.isAsciiCompatible() || !secondEncoding.isAsciiCompatible()) return null;
 
-            if (firstEncoding == secondEncoding) {
-                return firstEncoding;
+            if (firstRope.getCodeRange() != secondRope.getCodeRange()) {
+                if (firstRope.getCodeRange() == StringSupport.CR_7BIT) return secondEncoding;
+                if (secondRope.getCodeRange() == StringSupport.CR_7BIT) return firstEncoding;
             }
+            if (secondRope.getCodeRange() == StringSupport.CR_7BIT) return firstEncoding;
+            if (firstRope.getCodeRange() == StringSupport.CR_7BIT) return secondEncoding;
 
-            return org.jruby.RubyEncoding.areCompatible(StringOperations.getCodeRangeable(first), StringOperations.getCodeRangeable(second));
+            return null;
+        }
+
+        @TruffleBoundary
+        private static boolean isAsciiOnly(Rope rope) {
+            return rope.getEncoding().isAsciiCompatible() && rope.getCodeRange() == StringSupport.CR_7BIT;
         }
 
         protected Encoding extractEncoding(DynamicObject string) {
             if (RubyGuards.isRubyString(string)) {
-                return StringOperations.getByteList(string).getEncoding();
+                return Layouts.STRING.getRope(string).getEncoding();
             }
 
             return null;

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/InterpolatedRegexpNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/InterpolatedRegexpNode.java
@@ -19,6 +19,8 @@
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
+import org.jruby.truffle.runtime.rope.RopeOperations;
 import org.jruby.truffle.translator.BodyTranslator;
 import org.jruby.util.RegexpOptions;
 
@@ -43,18 +45,20 @@ public Object execute(VirtualFrame frame) {
 
         for (int n = 0; n < children.length; n++) {
             final Object child = children[n].execute(frame);
-            strings[n] = org.jruby.RubyString.newString(getContext().getRuntime(), StringOperations.getByteList((DynamicObject) toS.call(frame, child, "to_s", null)));
+            strings[n] = org.jruby.RubyString.newString(getContext().getRuntime(), StringOperations.getByteListReadOnly((DynamicObject) toS.call(frame, child, "to_s", null)));
         }
 
         final org.jruby.RubyString preprocessed = org.jruby.RubyRegexp.preprocessDRegexp(getContext().getRuntime(), strings, options);
 
-        final DynamicObject regexp = RegexpNodes.createRubyRegexp(getContext(), this, getContext().getCoreLibrary().getRegexpClass(), preprocessed.getByteList(), options);
+        final DynamicObject regexp = RegexpNodes.createRubyRegexp(getContext(), this, getContext().getCoreLibrary().getRegexpClass(), StringOperations.ropeFromByteList(preprocessed.getByteList()), options);
 
         if (options.isEncodingNone()) {
+            final Rope source = Layouts.REGEXP.getSource(regexp);
+
             if (!BodyTranslator.all7Bit(preprocessed.getByteList().bytes())) {
-                Layouts.REGEXP.getSource(regexp).setEncoding(getContext().getRuntime().getEncodingService().getAscii8bitEncoding());
+                Layouts.REGEXP.setSource(regexp, RopeOperations.withEncoding(source, getContext().getRuntime().getEncodingService().getAscii8bitEncoding()));
             } else {
-                Layouts.REGEXP.getSource(regexp).setEncoding(getContext().getRuntime().getEncodingService().getUSAsciiEncoding());
+                Layouts.REGEXP.setSource(regexp, RopeOperations.withEncoding(source, getContext().getRuntime().getEncodingService().getUSAsciiEncoding()));
             }
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/InterpolatedStringNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/InterpolatedStringNode.java
@@ -31,7 +31,7 @@ public final class InterpolatedStringNode extends RubyNode {
 
     @Children private final ToSNode[] children;
 
-    @Child private CallDispatchHeadNode concatNode;
+    @Child private CallDispatchHeadNode appendNode;
     @Child private CallDispatchHeadNode dupNode;
     @Child private IsTaintedNode isTaintedNode;
     @Child private TaintNode taintNode;
@@ -41,7 +41,7 @@ public final class InterpolatedStringNode extends RubyNode {
     public InterpolatedStringNode(RubyContext context, SourceSection sourceSection, ToSNode[] children) {
         super(context, sourceSection);
         this.children = children;
-        concatNode = DispatchHeadNodeFactory.createMethodCall(context);
+        appendNode = DispatchHeadNodeFactory.createMethodCall(context);
         dupNode = DispatchHeadNodeFactory.createMethodCall(context);
         isTaintedNode = IsTaintedNodeGen.create(context, sourceSection, null);
         taintNode = TaintNodeGen.create(context, sourceSection, null);
@@ -74,13 +74,14 @@ private Object concat(VirtualFrame frame, Object[] strings) {
 
         Object builder = null;
 
+        // TODO (nirvdrum 11-Jan-16) Rewrite to avoid massively unbalanced trees.
         for (Object string : strings) {
             assert RubyGuards.isRubyString(string);
 
             if (builder == null) {
                 builder = dupNode.call(frame, string, "dup", null);
             } else {
-                builder = concatNode.call(frame, builder, "concat", null, string);
+                builder = appendNode.call(frame, builder, "append", null, string);
             }
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/KernelNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/KernelNodes.java
@@ -72,6 +72,7 @@
 import org.jruby.truffle.runtime.loader.FeatureLoader;
 import org.jruby.truffle.runtime.methods.InternalMethod;
 import org.jruby.truffle.runtime.methods.SharedMethodInfo;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.truffle.runtime.subsystems.ThreadManager.BlockingAction;
 import org.jruby.truffle.translator.TranslatorDriver;
 import org.jruby.truffle.translator.TranslatorDriver.ParserContext;
@@ -511,7 +512,7 @@ public RubyRootNode getRootNode() {
 
         @Specialization(guards = {
                 "isRubyString(source)",
-                "byteListsEqual(source, cachedSource)",
+                "ropesEqual(source, cachedSource)",
                 "!parseDependsOnDeclarationFrame(cachedRootNode)"
         }, limit = "getCacheLimit()")
         public Object evalNoBindingCached(
@@ -520,7 +521,7 @@ public Object evalNoBindingCached(
                 NotProvided binding,
                 NotProvided filename,
                 NotProvided lineNumber,
-                @Cached("privatizeByteList(source)") ByteList cachedSource,
+                @Cached("privatizeRope(source)") Rope cachedSource,
                 @Cached("compileSource(frame, source)") RootNodeWrapper cachedRootNode,
                 @Cached("createCallTarget(cachedRootNode)") CallTarget cachedCallTarget,
                 @Cached("create(cachedCallTarget)") DirectCallNode callNode
@@ -621,7 +622,7 @@ public Object evalBadBinding(DynamicObject source, DynamicObject badBinding, Not
 
         @TruffleBoundary
         private Object doEval(DynamicObject source, DynamicObject binding, String filename, boolean ownScopeForAssignments) {
-            final Object result = getContext().eval(ParserContext.EVAL, StringOperations.getByteList(source), binding, ownScopeForAssignments, filename, this);
+            final Object result = getContext().eval(ParserContext.EVAL, StringOperations.getByteListReadOnly(source), binding, ownScopeForAssignments, filename, this);
             assert result != null;
             return result;
         }
@@ -632,7 +633,7 @@ protected RootNodeWrapper compileSource(VirtualFrame frame, DynamicObject source
             final DynamicObject callerBinding = getCallerBinding(frame);
             final MaterializedFrame parentFrame = Layouts.BINDING.getFrame(callerBinding);
 
-            final Encoding encoding = StringOperations.getByteList(sourceText).getEncoding();
+            final Encoding encoding = Layouts.STRING.getRope(sourceText).getEncoding();
             final Source source = Source.fromText(sourceText.toString(), "(eval)");
 
             final TranslatorDriver translator = new TranslatorDriver(getContext());
@@ -1870,13 +1871,13 @@ public SprintfNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization(guards = { "isRubyString(format)", "byteListsEqual(format, cachedFormat)" })
+        @Specialization(guards = { "isRubyString(format)", "ropesEqual(format, cachedFormat)" })
         public DynamicObject formatCached(
                 VirtualFrame frame,
                 DynamicObject format,
                 Object[] arguments,
-                @Cached("privatizeByteList(format)") ByteList cachedFormat,
-                @Cached("byteListLength(cachedFormat)") int cachedFormatLength,
+                @Cached("privatizeRope(format)") Rope cachedFormat,
+                @Cached("ropeLength(cachedFormat)") int cachedFormatLength,
                 @Cached("create(compileFormat(format))") DirectCallNode callPackNode) {
             final PackResult result;
 
@@ -1905,7 +1906,7 @@ public DynamicObject formatUncached(
                 throw handleException(e);
             }
 
-            return finishFormat(StringOperations.getByteList(format).length(), result);
+            return finishFormat(Layouts.STRING.getRope(format).byteLength(), result);
         }
 
         private RuntimeException handleException(PackException exception) {
@@ -1964,7 +1965,7 @@ protected CallTarget compileFormat(DynamicObject format) {
             assert RubyGuards.isRubyString(format);
 
             try {
-                return new PrintfCompiler(getContext(), this).compile(StringOperations.getByteList(format));
+                return new PrintfCompiler(getContext(), this).compile(StringOperations.getByteListReadOnly(format));
             } catch (FormatException e) {
                 CompilerDirectives.transferToInterpreter();
                 throw new RaiseException(getContext().getCoreLibrary().argumentError(e.getMessage(), this));

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/MatchDataNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/MatchDataNodes.java
@@ -33,6 +33,7 @@
 import org.jruby.truffle.runtime.core.ArrayOperations;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 import org.jruby.util.StringSupport;
 
@@ -154,7 +155,7 @@ public static Region getCharOffsets(DynamicObject matchData) {
 
     @TruffleBoundary
     private static Region createCharOffsets(DynamicObject matchData) {
-        final ByteList source = StringOperations.getByteList(Layouts.MATCH_DATA.getSource(matchData));
+        final ByteList source = StringOperations.getByteListReadOnly(Layouts.MATCH_DATA.getSource(matchData));
         final Encoding enc = source.getEncoding();
         final Region charOffsets = getCharOffsetsManyRegs(matchData, source, enc);
         Layouts.MATCH_DATA.setCharOffsets(matchData, charOffsets);
@@ -197,8 +198,8 @@ public Object getIndex(DynamicObject matchData, int index, int length) {
         @Specialization(guards = "isRubySymbol(index)")
         public Object getIndexSymbol(DynamicObject matchData, DynamicObject index, NotProvided length) {
             try {
-                ByteList value = Layouts.SYMBOL.getByteList(index);
-                final int i = Layouts.REGEXP.getRegex(Layouts.MATCH_DATA.getRegexp(matchData)).nameToBackrefNumber(value.getUnsafeBytes(), value.getBegin(), value.getBegin() + value.getRealSize(), Layouts.MATCH_DATA.getRegion(matchData));
+                final Rope value = Layouts.SYMBOL.getRope(index);
+                final int i = Layouts.REGEXP.getRegex(Layouts.MATCH_DATA.getRegexp(matchData)).nameToBackrefNumber(value.getBytes(), value.getBegin(), value.getBegin() + value.getRealSize(), Layouts.MATCH_DATA.getRegion(matchData));
 
                 return getIndex(matchData, i, NotProvided.INSTANCE);
             } catch (final ValueException e) {
@@ -213,7 +214,7 @@ public Object getIndexSymbol(DynamicObject matchData, DynamicObject index, NotPr
         @Specialization(guards = "isRubyString(index)")
         public Object getIndexString(DynamicObject matchData, DynamicObject index, NotProvided length) {
             try {
-                ByteList value = StringOperations.getByteList(index);
+                ByteList value = StringOperations.getByteListReadOnly(index);
                 final int i = Layouts.REGEXP.getRegex(Layouts.MATCH_DATA.getRegexp(matchData)).nameToBackrefNumber(value.getUnsafeBytes(), value.getBegin(), value.getBegin() + value.getRealSize(), Layouts.MATCH_DATA.getRegion(matchData));
 
                 return getIndex(matchData, i, NotProvided.INSTANCE);
@@ -421,7 +422,7 @@ public ToSNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization
         public DynamicObject toS(DynamicObject matchData) {
-            final ByteList bytes = StringOperations.getByteList(Layouts.MATCH_DATA.getGlobal(matchData)).dup();
+            final ByteList bytes = StringOperations.getByteListReadOnly(Layouts.MATCH_DATA.getGlobal(matchData)).dup();
             return createString(bytes);
         }
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ModuleNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ModuleNodes.java
@@ -641,7 +641,7 @@ private Object classEvalSource(DynamicObject module, DynamicObject code, String
 
             final MaterializedFrame callerFrame = RubyCallStack.getCallerFrame(getContext())
                     .getFrame(FrameInstance.FrameAccess.MATERIALIZE, true).materialize();
-            Encoding encoding = StringOperations.getByteList(code).getEncoding();
+            Encoding encoding = Layouts.STRING.getRope(code).getEncoding();
 
             CompilerDirectives.transferToInterpreter();
             // TODO (pitr 15-Oct-2015): fix this ugly hack, required for AS

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/RegexpGuards.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/RegexpGuards.java
@@ -26,7 +26,7 @@ public static boolean isRegexpLiteral(DynamicObject regexp) {
     }
 
     public static boolean isValidEncoding(DynamicObject string) {
-        return StringOperations.scanForCodeRange(string) != StringSupport.CR_BROKEN;
+        return StringOperations.codeRange(string) != StringSupport.CR_BROKEN;
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/RegexpNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/RegexpNodes.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2016 Oracle and/or its affiliates. All rights reserved. This
+ * Copyright (c) 2013, 2015, 2016 Oracle and/or its affiliates. All rights reserved. This
  * code is released under a tri EPL/GPL/LGPL license. You can use it,
  * redistribute it and/or modify it under the terms of the:
  *
@@ -39,6 +39,8 @@
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
+import org.jruby.truffle.runtime.rope.RopeOperations;
 import org.jruby.util.*;
 
 import java.nio.charset.StandardCharsets;
@@ -54,25 +56,25 @@ public static Object matchCommon(RubyContext context, DynamicObject regexp, Dyna
         assert RubyGuards.isRubyRegexp(regexp);
         assert RubyGuards.isRubyString(source);
 
-        final ByteList sourceByteList = StringOperations.getByteList(source);
+        final Rope sourceRope = StringOperations.rope(source);
 
-        final ByteList bl = Layouts.REGEXP.getSource(regexp);
-        final Encoding enc = checkEncoding(regexp, StringOperations.getCodeRangeable(source), true);
-        final ByteList preprocessed = RegexpSupport.preprocess(context.getRuntime(), bl, enc, new Encoding[] { null }, RegexpSupport.ErrorMode.RAISE);
+        final Rope regexpSourceRope = Layouts.REGEXP.getSource(regexp);
+        final Encoding enc = checkEncoding(regexp, sourceRope, true);
+        final ByteList preprocessed = RegexpSupport.preprocess(context.getRuntime(), regexpSourceRope.getUnsafeByteList(), enc, new Encoding[] { null }, RegexpSupport.ErrorMode.RAISE);
 
-        final Regex r = new Regex(preprocessed.getUnsafeBytes(), preprocessed.getBegin(), preprocessed.getBegin() + preprocessed.getRealSize(), Layouts.REGEXP.getOptions(regexp).toJoniOptions(), checkEncoding(regexp, StringOperations.getCodeRangeable(source), true));
-        final Matcher matcher = r.matcher(sourceByteList.unsafeBytes(), sourceByteList.begin(), sourceByteList.begin() + sourceByteList.realSize());
-        int range = sourceByteList.begin() + sourceByteList.realSize();
+        final Regex r = new Regex(preprocessed.getUnsafeBytes(), preprocessed.getBegin(), preprocessed.getBegin() + preprocessed.getRealSize(), Layouts.REGEXP.getOptions(regexp).toJoniOptions(), checkEncoding(regexp, sourceRope, true));
+        final Matcher matcher = r.matcher(sourceRope.getBytes(), sourceRope.begin(), sourceRope.begin() + sourceRope.realSize());
+        int range = sourceRope.begin() + sourceRope.realSize();
 
-        return matchCommon(context, regexp, source, operator, setNamedCaptures, matcher, sourceByteList.begin() + startPos, range);
+        return matchCommon(context, regexp, source, operator, setNamedCaptures, matcher, sourceRope.begin() + startPos, range);
     }
 
     @TruffleBoundary
     public static Object matchCommon(RubyContext context, DynamicObject regexp, DynamicObject source, boolean operator, boolean setNamedCaptures, Matcher matcher, int startPos, int range) {
         assert RubyGuards.isRubyRegexp(regexp);
         assert RubyGuards.isRubyString(source);
 
-        final ByteList bytes = StringOperations.getByteList(source);
+        final ByteList bytes = StringOperations.getByteListReadOnly(source);
 
         final int match = matcher.search(startPos, range, Option.DEFAULT);
 
@@ -176,10 +178,8 @@ public static Object matchCommon(RubyContext context, DynamicObject regexp, Dyna
     private static DynamicObject createSubstring(DynamicObject source, int start, int length) {
         assert RubyGuards.isRubyString(source);
 
-        final ByteList bytes = new ByteList(StringOperations.getByteList(source), start, length);
-        final DynamicObject ret = Layouts.STRING.createString(Layouts.CLASS.getInstanceFactory(Layouts.BASIC_OBJECT.getLogicalClass(source)), bytes, StringSupport.CR_UNKNOWN, null);
-
-        Layouts.STRING.setCodeRange(ret, Layouts.STRING.getCodeRange(source));
+        final ByteList bytes = new ByteList(StringOperations.getByteListReadOnly(source), start, length);
+        final DynamicObject ret = Layouts.STRING.createString(Layouts.CLASS.getInstanceFactory(Layouts.BASIC_OBJECT.getLogicalClass(source)), StringOperations.ropeFromByteList(bytes, StringOperations.getCodeRange(source)), null);
 
         return ret;
     }
@@ -198,7 +198,7 @@ private static void setLocalVariable(Frame frame, String name, Object value) {
         }
     }
 
-    public static ByteList shimModifiers(ByteList bytes) {
+    public static Rope shimModifiers(Rope bytes) {
         // Joni doesn't support (?u) etc but we can shim some common cases
 
         String bytesString = bytes.toString();
@@ -224,14 +224,15 @@ public static ByteList shimModifiers(ByteList bytes) {
                     throw new UnsupportedOperationException();
             }
 
-            bytes = ByteList.create(bytesString);
+            // TODO (nirvdrum 25-Jan-16): We probably just want a way to create a Rope from a java.lang.String.
+            bytes = StringOperations.ropeFromByteList(ByteList.create(bytesString));
         }
 
         return bytes;
     }
 
     @TruffleBoundary
-    public static Regex compile(Node currentNode, RubyContext context, ByteList bytes, RegexpOptions options) {
+    public static Regex compile(Node currentNode, RubyContext context, Rope bytes, RegexpOptions options) {
         bytes = shimModifiers(bytes);
 
         try {
@@ -250,13 +251,14 @@ public static Regex compile(Node currentNode, RubyContext context, ByteList byte
         }
              */
 
+            final ByteList byteList = bytes.getUnsafeByteList();
             Encoding enc = bytes.getEncoding();
             Encoding[] fixedEnc = new Encoding[]{null};
-            ByteList unescaped = RegexpSupport.preprocess(context.getRuntime(), bytes, enc, fixedEnc, RegexpSupport.ErrorMode.RAISE);
+            ByteList unescaped = RegexpSupport.preprocess(context.getRuntime(), byteList, enc, fixedEnc, RegexpSupport.ErrorMode.RAISE);
             if (fixedEnc[0] != null) {
                 if ((fixedEnc[0] != enc && options.isFixed()) ||
                         (fixedEnc[0] != ASCIIEncoding.INSTANCE && options.isEncodingNone())) {
-                    RegexpSupport.raiseRegexpError19(context.getRuntime(), bytes, enc, options, "incompatible character encoding");
+                    RegexpSupport.raiseRegexpError19(context.getRuntime(), byteList, enc, options, "incompatible character encoding");
                 }
                 if (fixedEnc[0] != ASCIIEncoding.INSTANCE) {
                     options.setFixed(true);
@@ -269,10 +271,8 @@ public static Regex compile(Node currentNode, RubyContext context, ByteList byte
             if (fixedEnc[0] != null) options.setFixed(true);
             //if (regexpOptions.isEncodingNone()) setEncodingNone();
 
-            bytes.setEncoding(enc);
-
             Regex ret = new Regex(unescaped.getUnsafeBytes(), unescaped.getBegin(), unescaped.getBegin() + unescaped.getRealSize(), options.toJoniOptions(), enc, Syntax.RUBY);
-            ret.setUserObject(bytes);
+            ret.setUserObject(RopeOperations.withEncoding(bytes, enc));
 
             return ret;
         } catch (ValueException e) {
@@ -294,7 +294,7 @@ public static void setRegex(DynamicObject regexp, Regex regex) {
         Layouts.REGEXP.setRegex(regexp, regex);
     }
 
-    public static void setSource(DynamicObject regexp, ByteList source) {
+    public static void setSource(DynamicObject regexp, Rope source) {
         Layouts.REGEXP.setSource(regexp, source);
     }
 
@@ -303,7 +303,7 @@ public static void setOptions(DynamicObject regexp, RegexpOptions options) {
     }
 
     // TODO (nirvdrum 03-June-15) Unify with JRuby in RegexpSupport.
-    public static Encoding checkEncoding(DynamicObject regexp, CodeRangeable str, boolean warn) {
+    public static Encoding checkEncoding(DynamicObject regexp, Rope str, boolean warn) {
         assert RubyGuards.isRubyRegexp(regexp);
 
         final Regex pattern = Layouts.REGEXP.getRegex(regexp);
@@ -314,7 +314,7 @@ public static Encoding checkEncoding(DynamicObject regexp, CodeRangeable str, bo
         }
         */
         //check();
-        Encoding enc = str.getByteList().getEncoding();
+        Encoding enc = str.getEncoding();
         if (!enc.isAsciiCompatible()) {
             if (enc != pattern.getEncoding()) {
                 //encodingMatchError(getRuntime(), pattern, enc);
@@ -337,31 +337,42 @@ public static Encoding checkEncoding(DynamicObject regexp, CodeRangeable str, bo
         return enc;
     }
 
-    public static void initialize(RubyContext context, DynamicObject regexp, Node currentNode, ByteList setSource, int options) {
+    public static void initialize(RubyContext context, DynamicObject regexp, Node currentNode, Rope setSource, int options) {
         assert RubyGuards.isRubyRegexp(regexp);
-        setSource(regexp, setSource);
-        setOptions(regexp, RegexpOptions.fromEmbeddedOptions(options));
-        setRegex(regexp, compile(currentNode, context, setSource, Layouts.REGEXP.getOptions(regexp)));
+        final RegexpOptions regexpOptions = RegexpOptions.fromEmbeddedOptions(options);
+        final Regex regex = compile(currentNode, context, setSource, regexpOptions);
+
+        // The RegexpNodes.compile operation may modify the encoding of the source rope. This modified copy is stored
+        // in the Regex object as the "user object". Since ropes are immutable, we need to take this updated copy when
+        // constructing the final regexp.
+        setSource(regexp, (Rope) regex.getUserObject());
+        setOptions(regexp, regexpOptions);
+        setRegex(regexp, regex);
     }
 
-    public static void initialize(DynamicObject regexp, Regex setRegex, ByteList setSource) {
+    public static void initialize(DynamicObject regexp, Regex setRegex, Rope setSource) {
         assert RubyGuards.isRubyRegexp(regexp);
         setRegex(regexp, setRegex);
         setSource(regexp, setSource);
     }
 
-    public static DynamicObject createRubyRegexp(RubyContext context, Node currentNode, DynamicObject regexpClass, ByteList regex, RegexpOptions options) {
-        return Layouts.REGEXP.createRegexp(Layouts.CLASS.getInstanceFactory(regexpClass), RegexpNodes.compile(currentNode, context, regex, options), regex, options, null);
+    public static DynamicObject createRubyRegexp(RubyContext context, Node currentNode, DynamicObject regexpClass, Rope source, RegexpOptions options) {
+        final Regex regexp = RegexpNodes.compile(currentNode, context, source, options);
+
+        // The RegexpNodes.compile operation may modify the encoding of the source rope. This modified copy is stored
+        // in the Regex object as the "user object". Since ropes are immutable, we need to take this updated copy when
+        // constructing the final regexp.
+        return Layouts.REGEXP.createRegexp(Layouts.CLASS.getInstanceFactory(regexpClass), regexp, (Rope) regexp.getUserObject(), options, null);
     }
 
-    public static DynamicObject createRubyRegexp(DynamicObject regexpClass, Regex regex, ByteList source, RegexpOptions options) {
+    public static DynamicObject createRubyRegexp(DynamicObject regexpClass, Regex regex, Rope source, RegexpOptions options) {
         final DynamicObject regexp = Layouts.REGEXP.createRegexp(Layouts.CLASS.getInstanceFactory(regexpClass), null, null, RegexpOptions.NULL_OPTIONS, null);
         RegexpNodes.setOptions(regexp, options);
         RegexpNodes.initialize(regexp, regex, source);
         return regexp;
     }
 
-    public static DynamicObject createRubyRegexp(DynamicObject regexpClass, Regex regex, ByteList source) {
+    public static DynamicObject createRubyRegexp(DynamicObject regexpClass, Regex regex, Rope source) {
         final DynamicObject regexp = Layouts.REGEXP.createRegexp(Layouts.CLASS.getInstanceFactory(regexpClass), null, null, RegexpOptions.NULL_OPTIONS, null);
         RegexpNodes.initialize(regexp, regex, source);
         return regexp;
@@ -419,7 +430,7 @@ public EscapeNode(RubyContext context, SourceSection sourceSection) {
         @TruffleBoundary
         @Specialization(guards = "isRubyString(pattern)")
         public DynamicObject escape(DynamicObject pattern) {
-            return createString(StringOperations.encodeByteList(org.jruby.RubyRegexp.quote19(new ByteList(StringOperations.getByteList(pattern)), true).toString(), UTF8Encoding.INSTANCE));
+            return createString(StringOperations.encodeByteList(org.jruby.RubyRegexp.quote19(new ByteList(StringOperations.getByteListReadOnly(pattern)), true).toString(), UTF8Encoding.INSTANCE));
         }
 
     }
@@ -468,8 +479,9 @@ public QuoteNode(RubyContext context, SourceSection sourceSection) {
         @TruffleBoundary
         @Specialization(guards = "isRubyString(raw)")
         public DynamicObject quoteString(DynamicObject raw) {
-            boolean isAsciiOnly = StringOperations.getByteList(raw).getEncoding().isAsciiCompatible() && StringOperations.scanForCodeRange(raw) == CR_7BIT;
-            return createString(org.jruby.RubyRegexp.quote19(StringOperations.getByteList(raw), isAsciiOnly));
+            final Rope rope = StringOperations.rope(raw);
+            boolean isAsciiOnly = rope.getEncoding().isAsciiCompatible() && rope.getCodeRange() == CR_7BIT;
+            return createString(org.jruby.RubyRegexp.quote19(StringOperations.getByteListReadOnly(raw), isAsciiOnly));
         }
 
         @Specialization(guards = "isRubySymbol(raw)")
@@ -502,7 +514,7 @@ public SourceNode(RubyContext context, SourceSection sourceSection) {
 
         @Specialization
         public DynamicObject source(DynamicObject regexp) {
-            return createString(Layouts.REGEXP.getSource(regexp).dup());
+            return createString(Layouts.REGEXP.getSource(regexp));
         }
 
     }
@@ -517,7 +529,7 @@ public ToSNode(RubyContext context, SourceSection sourceSection) {
         @TruffleBoundary
         @Specialization
         public DynamicObject toS(DynamicObject regexp) {
-            return createString(((org.jruby.RubyString) org.jruby.RubyRegexp.newRegexp(getContext().getRuntime(), Layouts.REGEXP.getSource(regexp), Layouts.REGEXP.getRegex(regexp).getOptions()).to_s()).getByteList());
+            return createString(((org.jruby.RubyString) org.jruby.RubyRegexp.newRegexp(getContext().getRuntime(), Layouts.REGEXP.getSource(regexp).getUnsafeByteList(), Layouts.REGEXP.getRegex(regexp).getOptions()).to_s()).getByteList());
         }
 
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/RopeNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/RopeNodes.java
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/StringGuards.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/StringGuards.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Oracle and/or its affiliates. All rights reserved. This
+ * Copyright (c) 2015, 2016 Oracle and/or its affiliates. All rights reserved. This
  * code is released under a tri EPL/GPL/LGPL license. You can use it,
  * redistribute it and/or modify it under the terms of the:
  *
@@ -15,49 +15,62 @@
 import org.jruby.truffle.nodes.RubyGuards;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.CodeRangeSupport;
 import org.jruby.util.StringSupport;
 
 public class StringGuards {
 
     public static boolean isSingleByteOptimizable(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return Layouts.STRING.getCodeRange(string) == StringSupport.CR_7BIT || StringOperations.getByteList(string).getEncoding().maxLength() == 1;
+        return Layouts.STRING.getRope(string).isSingleByteOptimizable();
     }
 
     public static boolean is7Bit(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return Layouts.STRING.getCodeRange(string) == StringSupport.CR_7BIT;
+        return StringOperations.getCodeRange(string) == StringSupport.CR_7BIT;
     }
 
     public static boolean isAsciiCompatible(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return StringOperations.getByteList(string).getEncoding().isAsciiCompatible();
+        return Layouts.STRING.getRope(string).getEncoding().isAsciiCompatible();
     }
 
     public static boolean isSingleByteOptimizableOrAsciiOnly(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        // TODO (nirvdrnum 08-Jun-15) Rubinius tracks whether a String is ASCII-only via a field in the String.
+        // TODO (nirvdrum 08-Jun-15) Rubinius tracks whether a String is ASCII-only via a field in the String.
         return isSingleByteOptimizable(string);
     }
 
     public static boolean isSingleByte(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return StringOperations.getByteList(string).getEncoding().isSingleByte();
+        return Layouts.STRING.getRope(string).getEncoding().isSingleByte();
     }
 
     public static boolean isValidOr7BitEncoding(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return StringOperations.isCodeRangeValid(string) || CodeRangeSupport.isCodeRangeAsciiOnly(StringOperations.getCodeRangeable(string));
+        final Rope rope = StringOperations.rope(string);
+
+        return (rope.getCodeRange() == StringSupport.CR_VALID) || (rope.getCodeRange() == StringSupport.CR_7BIT);
     }
 
     public static boolean isFixedWidthEncoding(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return StringOperations.getByteList(string).getEncoding().isFixedWidth();
+        return Layouts.STRING.getRope(string).getEncoding().isFixedWidth();
     }
 
     public static boolean isValidUtf8(DynamicObject string) {
         assert RubyGuards.isRubyString(string);
-        return StringOperations.isCodeRangeValid(string) && StringOperations.getByteList(string).getEncoding() instanceof UTF8Encoding;
+        return StringOperations.isCodeRangeValid(string) && Layouts.STRING.getRope(string).getEncoding() instanceof UTF8Encoding;
+    }
+
+    public static boolean isEmpty(DynamicObject string) {
+        assert RubyGuards.isRubyString(string);
+        return Layouts.STRING.getRope(string).isEmpty();
+    }
+
+    public static boolean isBrokenCodeRange(DynamicObject string) {
+        assert RubyGuards.isRubyString(string);
+        return StringOperations.codeRange(string) == StringSupport.CR_BROKEN;
     }
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/StringNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/StringNodes.java
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/SymbolNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/SymbolNodes.java
@@ -94,7 +94,7 @@ public EncodingNode(RubyContext context, SourceSection sourceSection) {
 
         @Specialization
         public DynamicObject encoding(DynamicObject symbol) {
-            return EncodingNodes.getEncoding(Layouts.SYMBOL.getByteList(symbol).getEncoding());
+            return EncodingNodes.getEncoding(Layouts.SYMBOL.getRope(symbol).getEncoding());
         }
 
     }
@@ -176,7 +176,7 @@ public ToSNode(RubyContext context, SourceSection sourceSection) {
 
         @Specialization
         public DynamicObject toS(DynamicObject symbol) {
-            return createString(Layouts.SYMBOL.getByteList(symbol).dup());
+            return createString(Layouts.SYMBOL.getRope(symbol));
         }
 
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/TruffleInteropNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/TruffleInteropNodes.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015 Oracle and/or its affiliates. All rights reserved. This
+ * Copyright (c) 2014, 2015, 2016 Oracle and/or its affiliates. All rights reserved. This
  * code is released under a tri EPL/GPL/LGPL license. You can use it,
  * redistribute it and/or modify it under the terms of the:
  *
@@ -26,7 +26,10 @@
 import com.oracle.truffle.api.source.SourceSection;
 import org.jruby.truffle.nodes.StringCachingGuards;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
+import org.jruby.truffle.runtime.rope.RopeOperations;
 import org.jruby.util.ByteList;
 import org.jruby.util.StringSupport;
 
@@ -232,11 +235,11 @@ public Object readProperty(VirtualFrame frame,
             return ForeignAccess.execute(readNode, frame, receiver, identifierString);
         }
 
-        @Specialization(guards = {"isRubyString(identifier)", "byteListsEqual(identifier, cachedIdentifier)"})
+        @Specialization(guards = {"isRubyString(identifier)", "ropesEqual(identifier, cachedIdentifier)"})
         public Object readProperty(VirtualFrame frame,
                                    TruffleObject receiver,
                                    DynamicObject identifier,
-                                   @Cached("privatizeByteList(identifier)") ByteList cachedIdentifier,
+                                   @Cached("privatizeRope(identifier)") Rope cachedIdentifier,
                                    @Cached("identifier.toString()") String identifierString,
                                    @Cached("createReadNode()") Node readNode) {
             return ForeignAccess.execute(readNode, frame, receiver, identifierString);
@@ -280,12 +283,12 @@ public Object writeProperty(VirtualFrame frame,
             return ForeignAccess.execute(writeNode, frame, receiver, identifierString, value);
         }
 
-        @Specialization(guards = {"isRubyString(identifier)", "byteListsEqual(identifier, cachedIdentifier)"})
+        @Specialization(guards = {"isRubyString(identifier)", "ropesEqual(identifier, cachedIdentifier)"})
         public Object writeProperty(VirtualFrame frame,
                                     TruffleObject receiver,
                                     DynamicObject identifier,
                                     Object value,
-                                    @Cached("privatizeByteList(identifier)") ByteList cachedIdentifier,
+                                    @Cached("privatizeRope(identifier)") Rope cachedIdentifier,
                                     @Cached("identifier.toString()") String identifierString,
                                     @Cached("createWriteNode()") Node writeNode) {
             return ForeignAccess.execute(writeNode, frame, receiver, identifierString, value);
@@ -341,7 +344,7 @@ public double unbox(VirtualFrame frame, double receiver) {
         public DynamicObject executeForeign(VirtualFrame frame, CharSequence receiver) {
             // TODO CS-21-Dec-15 this shouldn't be needed - we need to convert j.l.String to Ruby's String automatically
 
-            return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), ByteList.create(receiver), StringSupport.CR_UNKNOWN, null);
+            return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(ByteList.create(receiver)), null);
         }
 
         @Specialization
@@ -437,15 +440,15 @@ public EvalNode(RubyContext context, SourceSection sourceSection) {
         @Specialization(guards = {
                 "isRubyString(mimeType)",
                 "isRubyString(source)",
-                "byteListsEqual(mimeType, cachedMimeType)",
-                "byteListsEqual(source, cachedSource)"
+                "ropesEqual(mimeType, cachedMimeType)",
+                "ropesEqual(source, cachedSource)"
         }, limit = "getCacheLimit()")
         public Object evalCached(
                 VirtualFrame frame,
                 DynamicObject mimeType,
                 DynamicObject source,
-                @Cached("privatizeByteList(mimeType)") ByteList cachedMimeType,
-                @Cached("privatizeByteList(source)") ByteList cachedSource,
+                @Cached("privatizeRope(mimeType)") Rope cachedMimeType,
+                @Cached("privatizeRope(source)") Rope cachedSource,
                 @Cached("create(parse(mimeType, source))") DirectCallNode callNode
         ) {
             return callNode.call(frame, new Object[]{});
@@ -486,7 +489,7 @@ public JavaStringToRubyNode(RubyContext context, SourceSection sourceSection) {
         @Specialization
         @TruffleBoundary
         public DynamicObject javaStringToRuby(String string) {
-            return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), ByteList.create(string), StringSupport.CR_UNKNOWN, null);
+            return Layouts.STRING.createString(getContext().getCoreLibrary().getStringFactory(), StringOperations.ropeFromByteList(ByteList.create(string), StringSupport.CR_UNKNOWN), null);
         }
 
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/TrufflePrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/TrufflePrimitiveNodes.java
@@ -43,9 +43,12 @@
 import org.jruby.truffle.runtime.hash.BucketsStrategy;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.truffle.runtime.methods.InternalMethod;
+import org.jruby.truffle.runtime.rope.Rope;
+import org.jruby.truffle.runtime.rope.RopeOperations;
 import org.jruby.truffle.runtime.subsystems.SimpleShell;
 import org.jruby.util.ByteList;
 import org.jruby.util.Memo;
+import org.jruby.util.StringSupport;
 import org.jruby.util.unsafe.UnsafeHolder;
 
 import java.io.IOException;
@@ -214,7 +217,7 @@ public DumpStringNode(RubyContext context, SourceSection sourceSection) {
         public DynamicObject dumpString(DynamicObject string) {
             final StringBuilder builder = new StringBuilder();
 
-            final ByteList byteList = StringOperations.getByteList(string);
+            final ByteList byteList = StringOperations.getByteListReadOnly(string);
 
             for (int i = 0; i < byteList.length(); i++) {
                 builder.append(String.format("\\x%02x", byteList.get(i)));
@@ -454,6 +457,57 @@ public DynamicObject debugPrint(DynamicObject string) {
 
     }
 
+    @CoreMethod(names = "debug_print_rope", onSingleton = true, required = 1, optional = 1)
+    public abstract static class DebugPrintRopeNode extends CoreMethodArrayArgumentsNode {
+
+        @Child private RopeNodes.DebugPrintRopeNode debugPrintRopeNode;
+
+        public DebugPrintRopeNode(RubyContext context, SourceSection sourceSection) {
+            super(context, sourceSection);
+            debugPrintRopeNode = RopeNodesFactory.DebugPrintRopeNodeGen.create(context, sourceSection, null, null, null);
+        }
+
+        @TruffleBoundary
+        @Specialization(guards = "isRubyString(string)")
+        public DynamicObject debugPrintDefault(DynamicObject string, NotProvided printString) {
+            return debugPrint(string, true);
+        }
+
+        @TruffleBoundary
+        @Specialization(guards = "isRubyString(string)")
+        public DynamicObject debugPrint(DynamicObject string, boolean printString) {
+            System.err.println("Legend: ");
+            System.err.println("BN = Bytes Null? (byte[] not yet populated)");
+            System.err.println("BL = Byte Length");
+            System.err.println("CL = Character Length");
+            System.err.println("CR = Code Range");
+            System.err.println("O = Offset (SubstringRope only)");
+            System.err.println("D = Depth");
+            System.err.println("LD = Left Depth (ConcatRope only)");
+            System.err.println("RD = Right Depth (ConcatRope only)");
+
+            return debugPrintRopeNode.executeDebugPrint(StringOperations.rope(string), 0, printString);
+        }
+
+    }
+
+    @CoreMethod(names = "flatten_rope", onSingleton = true, required = 1)
+    public abstract static class FlattenRopeNode extends CoreMethodArrayArgumentsNode {
+
+        public FlattenRopeNode(RubyContext context, SourceSection sourceSection) {
+            super(context, sourceSection);
+        }
+
+        @TruffleBoundary
+        @Specialization(guards = "isRubyString(string)")
+        public DynamicObject debugPrint(DynamicObject string) {
+            final Rope flattened = RopeOperations.flatten(StringOperations.rope(string));
+
+            return createString(flattened);
+        }
+
+    }
+
     @CoreMethod(names = "jruby_home_directory", onSingleton = true)
     public abstract static class JRubyHomeDirectoryNode extends CoreMethodNode {
 
@@ -809,7 +863,7 @@ public CreateSimpleStringNode(RubyContext context, SourceSection sourceSection)
 
         @Specialization
         public DynamicObject createSimpleString() {
-            return createString(new ByteList(new byte[]{'t', 'e', 's', 't'}, false));
+            return createString(RopeOperations.create(new byte[]{'t', 'e', 's', 't'}, UTF8Encoding.INSTANCE, StringSupport.CR_7BIT));
         }
     }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/array/ArrayNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/array/ArrayNodes.java
@@ -62,6 +62,7 @@
 import org.jruby.truffle.runtime.methods.Arity;
 import org.jruby.truffle.runtime.methods.InternalMethod;
 import org.jruby.truffle.runtime.methods.SharedMethodInfo;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 import org.jruby.util.Memo;
 
@@ -2403,13 +2404,13 @@ public PackNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization(guards = {"isRubyString(format)", "byteListsEqual(format, cachedFormat)"}, limit = "getCacheLimit()")
+        @Specialization(guards = {"isRubyString(format)", "ropesEqual(format, cachedFormat)"}, limit = "getCacheLimit()")
         public DynamicObject packCached(
                 VirtualFrame frame,
                 DynamicObject array,
                 DynamicObject format,
-                @Cached("privatizeByteList(format)") ByteList cachedFormat,
-                @Cached("byteListLength(cachedFormat)") int cachedFormatLength,
+                @Cached("privatizeRope(format)") Rope cachedFormat,
+                @Cached("ropeLength(cachedFormat)") int cachedFormatLength,
                 @Cached("create(compileFormat(format))") DirectCallNode callPackNode) {
             final PackResult result;
 
@@ -2438,7 +2439,7 @@ public DynamicObject packUncached(
                 throw handleException(e);
             }
 
-            return finishPack(StringOperations.getByteList(format).length(), result);
+            return finishPack(Layouts.STRING.getRope(format).byteLength(), result);
         }
 
         private RuntimeException handleException(PackException exception) {

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/dispatch/CachedDispatchNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/dispatch/CachedDispatchNode.java
@@ -44,7 +44,7 @@ public CachedDispatchNode(
         if (RubyGuards.isRubySymbol(cachedName)) {
             cachedNameAsSymbol = (DynamicObject) cachedName;
         } else if (RubyGuards.isRubyString(cachedName)) {
-            cachedNameAsSymbol = context.getSymbol(StringOperations.getByteList((DynamicObject) cachedName));
+            cachedNameAsSymbol = context.getSymbol(StringOperations.rope((DynamicObject) cachedName));
         } else if (cachedName instanceof String) {
             cachedNameAsSymbol = context.getSymbol((String) cachedName);
         } else {
@@ -72,7 +72,7 @@ protected final boolean guardName(Object methodName) {
             // TODO(CS, 11-Jan-15) this just repeats the above guard...
             return cachedName == methodName;
         } else if (RubyGuards.isRubyString(cachedName)) {
-            return (RubyGuards.isRubyString(methodName)) && StringOperations.getByteList((DynamicObject) cachedName).equal(StringOperations.getByteList((DynamicObject) methodName));
+            return (RubyGuards.isRubyString(methodName)) && StringOperations.rope((DynamicObject) cachedName).equals(StringOperations.rope((DynamicObject) methodName));
         } else {
             throw new UnsupportedOperationException();
         }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/ext/DigestNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/ext/DigestNodes.java
@@ -21,6 +21,7 @@
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
 import org.jruby.truffle.runtime.layouts.ext.DigestLayoutImpl;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 
 import java.security.MessageDigest;
@@ -146,8 +147,9 @@ public UpdateNode(RubyContext context, SourceSection sourceSection) {
         @TruffleBoundary
         @Specialization(guards = "isRubyString(message)")
         public DynamicObject update(DynamicObject digestObject, DynamicObject message) {
-            final ByteList bytes = StringOperations.getByteList(message);
-            DigestLayoutImpl.INSTANCE.getDigest(digestObject).update(bytes.getUnsafeBytes(), bytes.begin(), bytes.length());
+            final Rope rope = StringOperations.rope(message);
+
+            DigestLayoutImpl.INSTANCE.getDigest(digestObject).update(rope.getBytes(), rope.begin(), rope.byteLength());
             return digestObject;
         }
 
@@ -221,8 +223,9 @@ public BubbleBabbleNode(RubyContext context, SourceSection sourceSection) {
         @TruffleBoundary
         @Specialization(guards = "isRubyString(message)")
         public DynamicObject bubblebabble(DynamicObject message) {
-            final ByteList byteList = StringOperations.getByteList(message);
-            return createString(BubbleBabble.bubblebabble(byteList.unsafeBytes(), byteList.begin(), byteList.length()));
+            final Rope rope = StringOperations.rope(message);
+
+            return createString(BubbleBabble.bubblebabble(rope.getBytes(), rope.begin(), rope.byteLength()));
         }
 
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/ext/ObjSpaceNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/ext/ObjSpaceNodes.java
@@ -70,7 +70,7 @@ public int memsizeOfHash(DynamicObject object) {
 
         @Specialization(guards = "isRubyString(object)")
         public int memsizeOfString(DynamicObject object) {
-            return 1 + object.getShape().getPropertyListInternal(false).size() + StringOperations.getByteList(object).getRealSize();
+            return 1 + object.getShape().getPropertyListInternal(false).size() + StringOperations.rope(object).byteLength();
         }
 
         @Specialization(guards = "isRubyMatchData(object)")

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/ext/psych/PsychParserNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/ext/psych/PsychParserNodes.java
@@ -215,7 +215,7 @@ private StreamReader readerFor(VirtualFrame frame, DynamicObject yaml) {
                 return new StreamReader(new InputStreamReader(new InputStreamAdapter(getContext(), yaml), charset));
             }
 
-            ByteList byteList = StringOperations.getByteList(toStrNode.coerceObject(frame, yaml));
+            ByteList byteList = StringOperations.getByteListReadOnly(toStrNode.coerceObject(frame, yaml));
             Encoding enc = byteList.getEncoding();
 
             // if not unicode, transcode to UTF8

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/interop/InteropNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/interop/InteropNode.java
@@ -261,7 +261,7 @@ public InteropStringIsBoxed(RubyContext context, SourceSection sourceSection) {
         @Override
         public Object execute(VirtualFrame frame) {
             Object o = ForeignAccess.getReceiver(frame);
-            return RubyGuards.isRubyString(o) && StringOperations.getByteList(((DynamicObject) o)).length() == 1;
+            return RubyGuards.isRubyString(o) && StringOperations.rope((DynamicObject) o).byteLength() == 1;
         }
     }
 
@@ -273,7 +273,7 @@ public InteropStringUnboxNode(RubyContext context, SourceSection sourceSection)
 
         @Override
         public Object execute(VirtualFrame frame) {
-            return StringOperations.getByteList(((DynamicObject) ForeignAccess.getReceiver(frame))).get(0);
+            return StringOperations.getByteListReadOnly(((DynamicObject) ForeignAccess.getReceiver(frame))).get(0);
         }
     }
 
@@ -367,10 +367,10 @@ public Object execute(VirtualFrame frame) {
             if (RubyGuards.isRubyString(ForeignAccess.getReceiver(frame))) {
                 final DynamicObject string = (DynamicObject) ForeignAccess.getReceiver(frame);
                 final int index = (int) ForeignAccess.getArguments(frame).get(labelIndex);
-                if (index >= StringOperations.getByteList(string).length()) {
+                if (index >= Layouts.STRING.getRope(string).byteLength()) {
                     return 0;
                 } else {
-                    return (byte) StringOperations.getByteList(string).get(index);
+                    return (byte) StringOperations.getByteListReadOnly(string).get(index);
                 }
             } else {
                 CompilerDirectives.transferToInterpreter();

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/literal/StringLiteralNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/literal/StringLiteralNode.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2015 Oracle and/or its affiliates. All rights reserved. This
+ * Copyright (c) 2013, 2015, 2016 Oracle and/or its affiliates. All rights reserved. This
  * code is released under a tri EPL/GPL/LGPL license. You can use it,
  * redistribute it and/or modify it under the terms of the:
  *
@@ -9,41 +9,32 @@
  */
 package org.jruby.truffle.nodes.literal;
 
-import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.object.DynamicObject;
 import com.oracle.truffle.api.source.SourceSection;
-import org.jcodings.Encoding;
 import org.jruby.truffle.nodes.RubyNode;
 import org.jruby.truffle.nodes.objects.AllocateObjectNode;
 import org.jruby.truffle.nodes.objects.AllocateObjectNodeGen;
 import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 
-import java.util.Arrays;
-
 public class StringLiteralNode extends RubyNode {
 
-    private @CompilationFinal byte[] bytes; // deeply immutable
-    private final Encoding encoding;
-    private final int codeRange;
+    private final Rope rope;
 
     @Child private AllocateObjectNode allocateObjectNode;
 
     public StringLiteralNode(RubyContext context, SourceSection sourceSection, ByteList byteList, int codeRange) {
         super(context, sourceSection);
         assert byteList != null;
-        this.bytes = byteList.bytes();
-        this.encoding = byteList.getEncoding();
-        this.codeRange = codeRange;
+        this.rope = context.getRopeTable().getRope(byteList.bytes(), byteList.getEncoding(), codeRange);
         allocateObjectNode = AllocateObjectNodeGen.create(context, sourceSection, false, null, null);
     }
 
     @Override
     public DynamicObject execute(VirtualFrame frame) {
-        final byte[] copy = Arrays.copyOf(bytes, bytes.length);
-        final ByteList byteList = new ByteList(copy, encoding, false);
-        return allocateObjectNode.allocate(getContext().getCoreLibrary().getStringClass(), byteList, codeRange, null);
+        return allocateObjectNode.allocate(getContext().getCoreLibrary().getStringClass(), rope, null);
     }
 
 }
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/ByteArrayNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/ByteArrayNodes.java
@@ -11,17 +11,20 @@
 
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
+import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.object.DynamicObject;
 import com.oracle.truffle.api.object.DynamicObjectFactory;
 import com.oracle.truffle.api.source.SourceSection;
+import com.oracle.truffle.api.utilities.ConditionProfile;
 import org.jruby.truffle.nodes.RubyNode;
 import org.jruby.truffle.nodes.core.*;
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 
 @CoreClass(name = "Rubinius::ByteArray")
@@ -39,8 +42,21 @@ public GetByteNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public int getByte(DynamicObject bytes, int index) {
-            return Layouts.BYTE_ARRAY.getBytes(bytes).get(index) & 0xff;
+        public int getByte(DynamicObject bytes, int index,
+                              @Cached("createBinaryProfile()") ConditionProfile nullByteIndexProfile) {
+            final ByteList byteList = Layouts.BYTE_ARRAY.getBytes(bytes);
+
+            // Handling out-of-bounds issues like this is non-standard. In Rubinius, it would raise an exception instead.
+            // We're modifying the semantics to address a primary use case for this class: Rubinius's @data array
+            // in the String class. Rubinius Strings are NULL-terminated and their code working with Strings takes
+            // advantage of that fact. So, where they expect to receive a NULL byte, we'd be out-of-bounds and raise
+            // an exception. Simply appending a NULL byte may trigger a full copy of the original byte[], which we
+            // want to avoid. The compromise is bending on the semantics here.
+            if (nullByteIndexProfile.profile(index == byteList.realSize())) {
+                return 0;
+            }
+
+            return byteList.get(index) & 0xff;
         }
 
     }
@@ -54,11 +70,12 @@ public PrependNode(RubyContext context, SourceSection sourceSection) {
 
         @Specialization(guards = "isRubyString(string)")
         public DynamicObject prepend(DynamicObject bytes, DynamicObject string) {
-            final int prependLength = StringOperations.getByteList(string).getUnsafeBytes().length;
+            final Rope rope = StringOperations.rope(string);
+            final int prependLength = rope.byteLength();
             final int originalLength = Layouts.BYTE_ARRAY.getBytes(bytes).getUnsafeBytes().length;
             final int newLength = prependLength + originalLength;
             final byte[] prependedBytes = new byte[newLength];
-            System.arraycopy(StringOperations.getByteList(string).getUnsafeBytes(), 0, prependedBytes, 0, prependLength);
+            System.arraycopy(rope.getBytes(), 0, prependedBytes, 0, prependLength);
             System.arraycopy(Layouts.BYTE_ARRAY.getBytes(bytes).getUnsafeBytes(), 0, prependedBytes, prependLength, originalLength);
             return ByteArrayNodes.createByteArray(getContext().getCoreLibrary().getByteArrayFactory(), new ByteList(prependedBytes));
         }
@@ -102,21 +119,18 @@ public int size(DynamicObject bytes) {
     @CoreMethod(names = "locate", required = 3, lowerFixnumParameters = {1, 2})
     public abstract static class LocateNode extends CoreMethodArrayArgumentsNode {
 
-        @Child private StringNodes.SizeNode sizeNode;
-
         public LocateNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
-            sizeNode = StringNodesFactory.SizeNodeFactory.create(context, sourceSection, new RubyNode[] {});
         }
 
         @Specialization(guards = "isRubyString(pattern)")
-        public Object getByte(VirtualFrame frame, DynamicObject bytes, DynamicObject pattern, int start, int length) {
-            final int index = new ByteList(Layouts.BYTE_ARRAY.getBytes(bytes), start, length).indexOf(StringOperations.getByteList(pattern));
+        public Object getByte(DynamicObject bytes, DynamicObject pattern, int start, int length) {
+            final int index = new ByteList(Layouts.BYTE_ARRAY.getBytes(bytes), start, length).indexOf(StringOperations.getByteListReadOnly(pattern));
 
             if (index == -1) {
                 return nil();
             } else {
-                return start + index + sizeNode.executeInteger(frame, pattern);
+                return start + index + StringOperations.rope(pattern).characterLength();
             }
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/EncodingConverterPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/EncodingConverterPrimitiveNodes.java
@@ -23,14 +23,19 @@
 import org.jcodings.transcode.EConvResult;
 import org.jruby.truffle.nodes.RubyGuards;
 import org.jruby.truffle.nodes.core.EncodingConverterNodes;
+import org.jruby.truffle.nodes.core.RopeNodes;
+import org.jruby.truffle.nodes.core.RopeNodesFactory;
 import org.jruby.truffle.nodes.dispatch.CallDispatchHeadNode;
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
+import org.jruby.truffle.runtime.rope.RopeOperations;
 import org.jruby.util.ByteList;
+import static org.jruby.truffle.runtime.core.StringOperations.rope;
 
 /**
  * Rubinius primitives associated with the Ruby {@code Encoding::Converter} class..
@@ -54,10 +59,11 @@ public Object encodingConverterAllocate(DynamicObject encodingConverterClass, No
     @RubiniusPrimitive(name = "encoding_converter_primitive_convert")
     public static abstract class PrimitiveConvertNode extends RubiniusPrimitiveNode {
 
-        private final ConditionProfile nonNullSourceProfile = ConditionProfile.createBinaryProfile();
+        @Child private RopeNodes.MakeSubstringNode makeSubstringNode;
 
         public PrimitiveConvertNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
+            makeSubstringNode = RopeNodesFactory.MakeSubstringNodeGen.create(context, sourceSection, null, null, null);
         }
 
         @Specialization(guards = {"isRubyString(source)", "isRubyString(target)", "isRubyHash(options)"})
@@ -69,7 +75,7 @@ public Object encodingConverterPrimitiveConvert(DynamicObject encodingConverter,
         @Specialization(guards = {"isNil(source)", "isRubyString(target)"})
         public Object primitiveConvertNilSource(DynamicObject encodingConverter, DynamicObject source,
                                                         DynamicObject target, int offset, int size, int options) {
-            return primitiveConvertHelper(encodingConverter, new ByteList(), source, target, offset, size, options);
+            return primitiveConvertHelper(encodingConverter, source, target, offset, size, options);
         }
 
         @Specialization(guards = {"isRubyString(source)", "isRubyString(target)"})
@@ -78,23 +84,18 @@ public Object encodingConverterPrimitiveConvert(DynamicObject encodingConverter,
 
             // Taken from org.jruby.RubyConverter#primitive_convert.
 
-            StringOperations.modify(source);
-            StringOperations.clearCodeRange(source);
-
-            return primitiveConvertHelper(encodingConverter, StringOperations.getByteList(source), source, target, offset, size, options);
+            return primitiveConvertHelper(encodingConverter, source, target, offset, size, options);
         }
 
         @TruffleBoundary
-        private Object primitiveConvertHelper(DynamicObject encodingConverter, ByteList inBytes, DynamicObject source,
+        private Object primitiveConvertHelper(DynamicObject encodingConverter, DynamicObject source,
                                               DynamicObject target, int offset, int size, int options) {
             // Taken from org.jruby.RubyConverter#primitive_convert.
 
             final boolean nonNullSource = source != nil();
-
-            StringOperations.modify(target);
-            StringOperations.clearCodeRange(target);
-
-            final ByteList outBytes = StringOperations.getByteList(target);
+            Rope sourceRope = nonNullSource ? rope(source) : RopeOperations.EMPTY_UTF8_ROPE;
+            final Rope targetRope = rope(target);
+            final ByteList outBytes = targetRope.toByteListCopy();
 
             final Ptr inPtr = new Ptr();
             final Ptr outPtr = new Ptr();
@@ -107,9 +108,9 @@ private Object primitiveConvertHelper(DynamicObject encodingConverter, ByteList
             if (size == -1) {
                 size = 16; // in MRI, this is RSTRING_EMBED_LEN_MAX
 
-                if (nonNullSourceProfile.profile(nonNullSource)) {
-                    if (size < StringOperations.getByteList(source).getRealSize()) {
-                        size = StringOperations.getByteList(source).getRealSize();
+                if (nonNullSource) {
+                    if (size < sourceRope.byteLength()) {
+                        size = sourceRope.byteLength();
                     }
                 }
             }
@@ -137,16 +138,16 @@ private Object primitiveConvertHelper(DynamicObject encodingConverter, ByteList
 
                 outBytes.ensure((int) outputByteEnd);
 
-                inPtr.p = inBytes.getBegin();
-                outPtr.p = outBytes.getBegin() + offset;
+                inPtr.p = 0;
+                outPtr.p = offset;
                 int os = outPtr.p + size;
-                EConvResult res = ec.convert(inBytes.getUnsafeBytes(), inPtr, inBytes.getRealSize() + inPtr.p, outBytes.getUnsafeBytes(), outPtr, os, options);
+                EConvResult res = ec.convert(sourceRope.getBytes(), inPtr, sourceRope.byteLength() + inPtr.p, outBytes.getUnsafeBytes(), outPtr, os, options);
 
                 outBytes.setRealSize(outPtr.p - outBytes.begin());
 
-                if (nonNullSourceProfile.profile(nonNullSource)) {
-                    StringOperations.getByteList(source).setRealSize(inBytes.getRealSize() - (inPtr.p - inBytes.getBegin()));
-                    StringOperations.getByteList(source).setBegin(inPtr.p);
+                if (nonNullSource) {
+                    sourceRope = makeSubstringNode.executeMake(sourceRope, inPtr.p, sourceRope.byteLength() - inPtr.p);
+                    StringOperations.setRope(source, sourceRope);
                 }
 
                 if (growOutputBuffer && res == EConvResult.DestinationBufferFull) {
@@ -163,6 +164,8 @@ private Object primitiveConvertHelper(DynamicObject encodingConverter, ByteList
                     outBytes.setEncoding(ec.destinationEncoding);
                 }
 
+                StringOperations.setRope(target, StringOperations.ropeFromByteList(outBytes));
+
                 return getSymbol(res.symbolicName());
             }
         }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/EncodingPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/EncodingPrimitiveNodes.java
@@ -31,12 +31,12 @@ public EncodingGetObjectEncodingNode(RubyContext context, SourceSection sourceSe
 
         @Specialization(guards = "isRubyString(string)")
         public DynamicObject encodingGetObjectEncodingString(DynamicObject string) {
-            return EncodingNodes.getEncoding(StringOperations.getByteList(string).getEncoding());
+            return EncodingNodes.getEncoding(Layouts.STRING.getRope(string).getEncoding());
         }
 
         @Specialization(guards = "isRubySymbol(symbol)")
         public DynamicObject encodingGetObjectEncodingSymbol(DynamicObject symbol) {
-            return EncodingNodes.getEncoding(Layouts.SYMBOL.getByteList(symbol).getEncoding());
+            return EncodingNodes.getEncoding(Layouts.SYMBOL.getRope(symbol).getEncoding());
         }
 
         @Specialization(guards = "isRubyEncoding(encoding)")

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/IOBufferPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/IOBufferPrimitiveNodes.java
@@ -51,6 +51,7 @@
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 
 public abstract class IOBufferPrimitiveNodes {
@@ -90,8 +91,8 @@ public IOBufferUnshiftPrimitiveNode(RubyContext context, SourceSection sourceSec
         public int unshift(VirtualFrame frame, DynamicObject ioBuffer, DynamicObject string, int startPosition) {
             Layouts.IO_BUFFER.setWriteSynced(ioBuffer, false);
 
-            final ByteList byteList = StringOperations.getByteList(string);
-            int stringSize = byteList.realSize() - startPosition;
+            final Rope rope = StringOperations.rope(string);
+            int stringSize = rope.byteLength() - startPosition;
             final int usedSpace = Layouts.IO_BUFFER.getUsed(ioBuffer);
             final int availableSpace = IOBUFFER_SIZE - usedSpace;
 
@@ -102,7 +103,7 @@ public int unshift(VirtualFrame frame, DynamicObject ioBuffer, DynamicObject str
             ByteList storage = Layouts.BYTE_ARRAY.getBytes(Layouts.IO_BUFFER.getStorage(ioBuffer));
 
             // Data is copied here - can we do something COW?
-            System.arraycopy(byteList.unsafeBytes(), byteList.begin() + startPosition, storage.getUnsafeBytes(), storage.begin() + usedSpace, stringSize);
+            System.arraycopy(rope.getBytes(), startPosition, storage.getUnsafeBytes(), storage.begin() + usedSpace, stringSize);
 
             Layouts.IO_BUFFER.setUsed(ioBuffer, usedSpace + stringSize);
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/IOPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/IOPrimitiveNodes.java
@@ -205,8 +205,8 @@ public IOFNMatchPrimitiveNode(RubyContext context, SourceSection sourceSection)
         @TruffleBoundary
         @Specialization(guards = {"isRubyString(pattern)", "isRubyString(path)"})
         public boolean fnmatch(DynamicObject pattern, DynamicObject path, int flags) {
-            final ByteList patternBytes = StringOperations.getByteList(pattern);
-            final ByteList pathBytes = StringOperations.getByteList(path);
+            final ByteList patternBytes = StringOperations.getByteListReadOnly(pattern);
+            final ByteList pathBytes = StringOperations.getByteListReadOnly(path);
             return Dir.fnmatch(patternBytes.getUnsafeBytes(),
                     patternBytes.getBegin(),
                     patternBytes.getBegin() + patternBytes.getRealSize(),
@@ -404,7 +404,7 @@ public IOWritePrimitiveNode(RubyContext context, SourceSection sourceSection) {
         public int write(DynamicObject file, DynamicObject string) {
             final int fd = Layouts.IO.getDescriptor(file);
 
-            final ByteList byteList = StringOperations.getByteList(string);
+            final ByteList byteList = StringOperations.getByteListReadOnly(string);
 
             if (getContext().getDebugStandardOut() != null && fd == STDOUT) {
                 getContext().getDebugStandardOut().write(byteList.unsafeBytes(), byteList.begin(), byteList.length());

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/PointerPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/PointerPrimitiveNodes.java
@@ -24,6 +24,7 @@
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.truffle.runtime.rubinius.RubiniusTypes;
 import org.jruby.util.ByteList;
 import org.jruby.util.unsafe.UnsafeHolder;
@@ -338,9 +339,9 @@ public PointerWriteStringPrimitiveNode(RubyContext context, SourceSection source
 
         @Specialization(guards = "isRubyString(string)")
         public DynamicObject address(DynamicObject pointer, DynamicObject string, int maxLength) {
-            final ByteList bytes = StringOperations.getByteList(string);
-            final int length = Math.min(bytes.length(), maxLength);
-            Layouts.POINTER.getPointer(pointer).put(0, bytes.unsafeBytes(), bytes.begin(), length);
+            final Rope rope = StringOperations.rope(string);
+            final int length = Math.min(rope.byteLength(), maxLength);
+            Layouts.POINTER.getPointer(pointer).put(0, rope.getBytes(), 0, length);
             return pointer;
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/PosixNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/PosixNodes.java
@@ -17,18 +17,21 @@
 import jnr.constants.platform.Fcntl;
 import jnr.ffi.Pointer;
 import org.jcodings.specific.UTF8Encoding;
-import org.jruby.RubyEncoding;
 import org.jruby.platform.Platform;
 import org.jruby.truffle.nodes.core.CoreClass;
 import org.jruby.truffle.nodes.core.CoreMethod;
 import org.jruby.truffle.nodes.core.CoreMethodArrayArgumentsNode;
+import org.jruby.truffle.nodes.core.RopeNodes;
+import org.jruby.truffle.nodes.core.RopeNodesFactory;
 import org.jruby.truffle.nodes.objects.AllocateObjectNode;
 import org.jruby.truffle.nodes.objects.AllocateObjectNodeGen;
 import org.jruby.truffle.runtime.RubyContext;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
-import org.jruby.util.ByteList;
+import org.jruby.truffle.runtime.rope.RopeOperations;
+import org.jruby.util.StringSupport;
+import static org.jruby.truffle.runtime.core.StringOperations.decodeUTF8;
 
 import java.nio.charset.StandardCharsets;
 
@@ -45,7 +48,7 @@ public AccessNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(path)")
         public int access(DynamicObject path, int mode) {
-            final String pathString = RubyEncoding.decodeUTF8(StringOperations.getByteList(path).getUnsafeBytes(), StringOperations.getByteList(path).getBegin(), StringOperations.getByteList(path).getRealSize());
+            final String pathString = decodeUTF8(path);
             return posix().access(pathString, mode);
         }
 
@@ -61,7 +64,7 @@ public ChmodNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(path)")
         public int chmod(DynamicObject path, int mode) {
-            return posix().chmod(path.toString(), mode);
+            return posix().chmod(decodeUTF8(path), mode);
         }
 
     }
@@ -76,7 +79,7 @@ public ChownNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(path)")
         public int chown(DynamicObject path, int owner, int group) {
-            return posix().chown(path.toString(), owner, group);
+            return posix().chown(decodeUTF8(path), owner, group);
         }
 
     }
@@ -179,9 +182,7 @@ public GetenvNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(name)")
         public DynamicObject getenv(DynamicObject name) {
-            final String nameString = RubyEncoding.decodeUTF8(StringOperations.getByteList(name).getUnsafeBytes(), StringOperations.getByteList(name).getBegin(), StringOperations.getByteList(name).getRealSize());
-
-            Object result = posix().getenv(nameString);
+            Object result = posix().getenv(decodeUTF8(name));
 
             if (result == null) {
                 return nil();
@@ -330,10 +331,7 @@ public ReadlinkNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = {"isRubyString(path)", "isRubyPointer(pointer)"})
         public int readlink(DynamicObject path, DynamicObject pointer, int bufsize) {
-            final ByteList byteList = StringOperations.getByteList(path);
-            final String pathString = RubyEncoding.decodeUTF8(byteList.unsafeBytes(), byteList.begin(), byteList.length());
-
-            final int result = posix().readlink(pathString, Layouts.POINTER.getPointer(pointer), bufsize);
+            final int result = posix().readlink(decodeUTF8(path), Layouts.POINTER.getPointer(pointer), bufsize);
             if (result == -1) {
                 CompilerDirectives.transferToInterpreter();
                 throw new RaiseException(getContext().getCoreLibrary().errnoError(posix().errno(), this));
@@ -354,10 +352,7 @@ public SetenvNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = { "isRubyString(name)", "isRubyString(value)" })
         public int setenv(DynamicObject name, DynamicObject value, int overwrite) {
-            final String nameString = RubyEncoding.decodeUTF8(StringOperations.getByteList(name).getUnsafeBytes(), StringOperations.getByteList(name).getBegin(), StringOperations.getByteList(name).getRealSize());
-            final String valueString = RubyEncoding.decodeUTF8(StringOperations.getByteList(value).getUnsafeBytes(), StringOperations.getByteList(value).getBegin(), StringOperations.getByteList(value).getRealSize());
-
-            return posix().setenv(nameString, valueString, overwrite);
+            return posix().setenv(decodeUTF8(name), decodeUTF8(value), overwrite);
         }
 
     }
@@ -372,9 +367,7 @@ public LinkNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = {"isRubyString(path)", "isRubyString(other)"})
         public int link(DynamicObject path, DynamicObject other) {
-            final String pathString = RubyEncoding.decodeUTF8(StringOperations.getByteList(path).getUnsafeBytes(), StringOperations.getByteList(path).getBegin(), StringOperations.getByteList(path).getRealSize());
-            final String otherString = RubyEncoding.decodeUTF8(StringOperations.getByteList(other).getUnsafeBytes(), StringOperations.getByteList(other).getBegin(), StringOperations.getByteList(other).getRealSize());
-            return posix().link(pathString, otherString);
+            return posix().link(decodeUTF8(path), decodeUTF8(other));
         }
 
     }
@@ -389,8 +382,7 @@ public UnlinkNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(path)")
         public int unlink(DynamicObject path) {
-            final ByteList byteList = StringOperations.getByteList(path);
-            return posix().unlink(RubyEncoding.decodeUTF8(byteList.getUnsafeBytes(), byteList.getBegin(), byteList.getRealSize()));
+            return posix().unlink(decodeUTF8(path));
         }
 
     }
@@ -419,10 +411,7 @@ public UnsetenvNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = "isRubyString(name)")
         public int unsetenv(DynamicObject name) {
-            final ByteList byteList = StringOperations.getByteList(name);
-            final String nameString = RubyEncoding.decodeUTF8(byteList.getUnsafeBytes(), byteList.getBegin(), byteList.getRealSize());
-
-            return posix().unsetenv(nameString);
+            return posix().unsetenv(decodeUTF8(name));
         }
 
     }
@@ -437,10 +426,7 @@ public UtimesNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = {"isRubyString(path)", "isRubyPointer(pointer)"})
         public int utimes(DynamicObject path, DynamicObject pointer) {
-            final ByteList byteList = StringOperations.getByteList(path);
-            final String pathString = RubyEncoding.decodeUTF8(byteList.getUnsafeBytes(), byteList.getBegin(), byteList.getRealSize());
-
-            final int result = posix().utimes(pathString, Layouts.POINTER.getPointer(pointer));
+            final int result = posix().utimes(decodeUTF8(path), Layouts.POINTER.getPointer(pointer));
             if (result == -1) {
                 CompilerDirectives.transferToInterpreter();
                 throw new RaiseException(getContext().getCoreLibrary().errnoError(posix().errno(), this));
@@ -691,9 +677,7 @@ public RenameNode(RubyContext context, SourceSection sourceSection) {
         @CompilerDirectives.TruffleBoundary
         @Specialization(guards = {"isRubyString(path)", "isRubyString(other)"})
         public int rename(DynamicObject path, DynamicObject other) {
-            final String pathString = RubyEncoding.decodeUTF8(StringOperations.getByteList(path).getUnsafeBytes(), StringOperations.getByteList(path).getBegin(), StringOperations.getByteList(path).getRealSize());
-            final String otherString = RubyEncoding.decodeUTF8(StringOperations.getByteList(other).getUnsafeBytes(), StringOperations.getByteList(other).getBegin(), StringOperations.getByteList(other).getRealSize());
-            return posix().rename(pathString, otherString);
+            return posix().rename(decodeUTF8(path), decodeUTF8(other));
         }
 
     }
@@ -716,8 +700,11 @@ public int rmdir(DynamicObject path) {
     @CoreMethod(names = "getcwd", isModuleFunction = true, required = 2)
     public abstract static class GetcwdNode extends CoreMethodArrayArgumentsNode {
 
+        @Child private RopeNodes.MakeLeafRopeNode makeLeafRopeNode;
+
         public GetcwdNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
+            makeLeafRopeNode = RopeNodesFactory.MakeLeafRopeNodeGen.create(context, sourceSection, null, null, null);
         }
 
         @CompilerDirectives.TruffleBoundary
@@ -726,7 +713,7 @@ public DynamicObject getcwd(DynamicObject resultPath, int maxSize) {
             // We just ignore maxSize - I think this is ok
 
             final String path = getContext().getRuntime().getCurrentDirectory();
-            StringOperations.getByteList(resultPath).replace(path.getBytes(StandardCharsets.UTF_8));
+            StringOperations.setRope(resultPath, makeLeafRopeNode.executeMake(path.getBytes(StandardCharsets.UTF_8), Layouts.STRING.getRope(resultPath).getEncoding(), StringSupport.CR_UNKNOWN));
             return resultPath;
         }
 
@@ -870,8 +857,8 @@ public int getaddrinfoNil(DynamicObject hostName, DynamicObject serviceName, Dyn
         @Specialization(guards = {"isRubyString(hostName)", "isRubyString(serviceName)", "isRubyPointer(hintsPointer)", "isRubyPointer(resultsPointer)"})
         public int getaddrinfoString(DynamicObject hostName, DynamicObject serviceName, DynamicObject hintsPointer, DynamicObject resultsPointer) {
             return nativeSockets().getaddrinfo(
-                    StringOperations.getByteList(hostName),
-                    StringOperations.getByteList(serviceName),
+                    StringOperations.getByteListReadOnly(hostName),
+                    StringOperations.getByteListReadOnly(serviceName),
                     Layouts.POINTER.getPointer(hintsPointer),
                     Layouts.POINTER.getPointer(resultsPointer));
         }
@@ -880,7 +867,7 @@ public int getaddrinfoString(DynamicObject hostName, DynamicObject serviceName,
         @Specialization(guards = {"isRubyString(hostName)", "isNil(serviceName)", "isRubyPointer(hintsPointer)", "isRubyPointer(resultsPointer)"})
         public int getaddrinfo(DynamicObject hostName, DynamicObject serviceName, DynamicObject hintsPointer, DynamicObject resultsPointer) {
             return nativeSockets().getaddrinfo(
-                    StringOperations.getByteList(hostName),
+                    StringOperations.getByteListReadOnly(hostName),
                     null,
                     Layouts.POINTER.getPointer(hintsPointer),
                     Layouts.POINTER.getPointer(resultsPointer));

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/RegexpPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/RegexpPrimitiveNodes.java
@@ -24,6 +24,7 @@
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.StringOperations;
 import org.jruby.truffle.runtime.layouts.Layouts;
+import org.jruby.truffle.runtime.rope.Rope;
 import org.jruby.util.ByteList;
 import org.jruby.util.RegexpSupport;
 
@@ -69,7 +70,7 @@ public DynamicObject initializeAlreadyInitialized(DynamicObject regexp, DynamicO
 
         @Specialization(guards = {"!isRegexpLiteral(regexp)", "!isInitialized(regexp)", "isRubyString(pattern)"})
         public DynamicObject initialize(DynamicObject regexp, DynamicObject pattern, int options) {
-            RegexpNodes.initialize(getContext(), regexp, this, StringOperations.getByteList(pattern), options);
+            RegexpNodes.initialize(getContext(), regexp, this, StringOperations.rope(pattern), options);
             return regexp;
         }
 
@@ -129,26 +130,26 @@ public Object searchRegionNotInitialized(DynamicObject regexp, DynamicObject str
         public Object searchRegionInvalidEncoding(DynamicObject regexp, DynamicObject string, int start, int end, boolean forward) {
             CompilerDirectives.transferToInterpreter();
             throw new RaiseException(getContext().getCoreLibrary().argumentError(
-                    String.format("invalid byte sequence in %s", StringOperations.getByteList(string).getEncoding()), this));
+                    String.format("invalid byte sequence in %s", Layouts.STRING.getRope(string).getEncoding()), this));
         }
 
         @TruffleBoundary
         @Specialization(guards = {"isInitialized(regexp)", "isRubyString(string)", "isValidEncoding(string)"})
         public Object searchRegion(DynamicObject regexp, DynamicObject string, int start, int end, boolean forward) {
-            final ByteList stringBl = StringOperations.getByteList(string);
-            final ByteList bl = Layouts.REGEXP.getSource(regexp);
-            final Encoding enc = RegexpNodes.checkEncoding(regexp, StringOperations.getCodeRangeable(string), true);
-            ByteList preprocessed = RegexpSupport.preprocess(getContext().getRuntime(), bl, enc, new Encoding[]{null}, RegexpSupport.ErrorMode.RAISE);
-            preprocessed = RegexpNodes.shimModifiers(preprocessed);
-            final Regex r = new Regex(preprocessed.getUnsafeBytes(), preprocessed.getBegin(), preprocessed.getBegin() + preprocessed.getRealSize(), Layouts.REGEXP.getRegex(regexp).getOptions(), RegexpNodes.checkEncoding(regexp, StringOperations.getCodeRangeable(string), true));
-            final Matcher matcher = r.matcher(stringBl.getUnsafeBytes(), stringBl.begin(), stringBl.begin() + stringBl.realSize());
+            final Rope stringRope = StringOperations.rope(string);
+            final Rope regexpSourceRope = Layouts.REGEXP.getSource(regexp);
+            final Encoding enc = RegexpNodes.checkEncoding(regexp, stringRope, true);
+            ByteList preprocessed = RegexpSupport.preprocess(getContext().getRuntime(), regexpSourceRope.getUnsafeByteList(), enc, new Encoding[]{null}, RegexpSupport.ErrorMode.RAISE);
+            Rope preprocessedRope = RegexpNodes.shimModifiers(StringOperations.ropeFromByteList(preprocessed));
+            final Regex r = new Regex(preprocessedRope.getBytes(), preprocessedRope.getBegin(), preprocessedRope.getBegin() + preprocessedRope.getRealSize(), Layouts.REGEXP.getRegex(regexp).getOptions(), RegexpNodes.checkEncoding(regexp, stringRope, true));
+            final Matcher matcher = r.matcher(stringRope.getBytes(), stringRope.begin(), stringRope.begin() + stringRope.realSize());
 
             if (forward) {
                 // Search forward through the string.
-                return RegexpNodes.matchCommon(getContext(), regexp, string, false, false, matcher, start + stringBl.begin(), end + stringBl.begin());
+                return RegexpNodes.matchCommon(getContext(), regexp, string, false, false, matcher, start + stringRope.begin(), end + stringRope.begin());
             } else {
                 // Search backward through the string.
-                return RegexpNodes.matchCommon(getContext(), regexp, string, false, false, matcher, end + stringBl.begin(), start + stringBl.begin());
+                return RegexpNodes.matchCommon(getContext(), regexp, string, false, false, matcher, end + stringRope.begin(), start + stringRope.begin());
             }
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/StatPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/StatPrimitiveNodes.java
@@ -172,9 +172,7 @@ public StatStatPrimitiveNode(RubyContext context, SourceSection sourceSection) {
         @Specialization(guards = "isRubyString(path)")
         public int stat(DynamicObject rubyStat, DynamicObject path) {
             final FileStat stat = posix().allocateStat();
-            final ByteList byteList = StringOperations.getByteList(path);
-            final String pathString = RubyEncoding.decodeUTF8(byteList.getUnsafeBytes(), byteList.getBegin(), byteList.getRealSize());
-            final int code = posix().stat(pathString, stat);
+            final int code = posix().stat(StringOperations.decodeUTF8(path), stat);
 
             if (code == 0) {
                 writeStatNode.execute(rubyStat, stat);