jruby · Jan 22, 2016 · Jan 22, 2016 · Jan 22, 2016 · Jan 22, 2016 · Jan 22, 2016
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
@@ -0,0 +1,291 @@
+/*
+ * Copyright (c) 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:
+ *
+ * Eclipse Public License version 1.0
+ * GNU General Public License version 2
+ * GNU Lesser General Public License version 2.1
+ */
+
+package org.jruby.truffle.nodes.core;
+
+
+import com.oracle.truffle.api.CompilerDirectives;
+import com.oracle.truffle.api.dsl.Cached;
+import com.oracle.truffle.api.dsl.ImportStatic;
+import com.oracle.truffle.api.dsl.NodeChild;
+import com.oracle.truffle.api.dsl.NodeChildren;
+import com.oracle.truffle.api.dsl.Specialization;
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.source.SourceSection;
+import com.oracle.truffle.api.utilities.ConditionProfile;
+import org.jcodings.Encoding;
+import org.jruby.truffle.nodes.RubyNode;
+import org.jruby.truffle.runtime.RubyContext;
+import org.jruby.truffle.runtime.rope.AsciiOnlyLeafRope;
+import org.jruby.truffle.runtime.rope.ConcatRope;
+import org.jruby.truffle.runtime.rope.InvalidLeafRope;
+import org.jruby.truffle.runtime.rope.LeafRope;
+import org.jruby.truffle.runtime.rope.Rope;
+import org.jruby.truffle.runtime.rope.RopeOperations;
+import org.jruby.truffle.runtime.rope.SubstringRope;
+import org.jruby.truffle.runtime.rope.ValidLeafRope;
+import org.jruby.util.StringSupport;
+
+public abstract class RopeNodes {
+
+    @NodeChildren({
+            @NodeChild(type = RubyNode.class, value = "base"),
+            @NodeChild(type = RubyNode.class, value = "offset"),
+            @NodeChild(type = RubyNode.class, value = "byteLength")
+    })
+    public abstract static class MakeSubstringNode extends RubyNode {
+
+        public MakeSubstringNode(RubyContext context, SourceSection sourceSection) {
+            super(context, sourceSection);
+        }
+
+        public abstract Rope executeMake(Rope base, int offset, int byteLength);
+
+        @Specialization(guards = "byteLength == 0")
+        public Rope substringZeroLength(Rope base, int offset, int byteLength) {
+            return RopeOperations.withEncoding(RopeOperations.EMPTY_UTF8_ROPE, base.getEncoding());
+        }
+
+        @Specialization(guards = { "byteLength > 0", "sameAsBase(base, offset, byteLength)" })
+        public Rope substringSameAsBase(Rope base, int offset, int byteLength) {
+            return base;
+        }
+
+        @Specialization(guards = { "byteLength > 0", "!sameAsBase(base, offset, byteLength)", "isLeafRope(base)" })
+        public Rope substringLeafRope(LeafRope base, int offset, int byteLength,
+                                  @Cached("createBinaryProfile()") ConditionProfile is7BitProfile) {
+            return makeSubstring(base, offset, byteLength, is7BitProfile);
+        }
+
+        @Specialization(guards = { "byteLength > 0", "!sameAsBase(base, offset, byteLength)", "isSubstringRope(base)" })
+        public Rope substringSubstringRope(SubstringRope base, int offset, int byteLength,
+                                      @Cached("createBinaryProfile()") ConditionProfile is7BitProfile) {
+            return makeSubstring(base.getChild(), offset + base.getOffset(), byteLength, is7BitProfile);
+        }
+
+        @Specialization(guards = { "byteLength > 0", "!sameAsBase(base, offset, byteLength)", "isConcatRope(base)" })
+        public Rope substringConcatRope(ConcatRope base, int offset, int byteLength,
+                                      @Cached("createBinaryProfile()") ConditionProfile is7BitProfile) {
+            Rope root = base;
+
+            while (root instanceof ConcatRope) {
+                ConcatRope concatRoot = (ConcatRope) root;
+                Rope left = concatRoot.getLeft();
+                Rope right = concatRoot.getRight();
+
+                // CASE 1: Fits in left.
+                if (offset + byteLength <= left.byteLength()) {
+                    root = left;
+                    continue;
+                }
+
+                // CASE 2: Fits in right.
+                if (offset >= left.byteLength()) {
+                    offset -= left.byteLength();
+                    root = right;
+                    continue;
+                }
+
+                // CASE 3: Spans left and right.
+                if (byteLength == root.byteLength()) {
+                    return root;
+                } else {
+                    return makeSubstring(root, offset, byteLength, is7BitProfile);
+                }
+            }
+
+            return executeMake(root, offset, byteLength);
+        }
+
+        private Rope makeSubstring(Rope base, int offset, int byteLength, ConditionProfile is7BitProfile) {
+            if (is7BitProfile.profile(base.getCodeRange() == StringSupport.CR_7BIT)) {
+                return new SubstringRope(base, offset, byteLength, byteLength, StringSupport.CR_7BIT);
+            }
+
+            return makeSubstringNon7Bit(base, offset, byteLength);
+        }
+
+        @CompilerDirectives.TruffleBoundary
+        private Rope makeSubstringNon7Bit(Rope base, int offset, int byteLength) {
+            final long packedLengthAndCodeRange = RopeOperations.calculateCodeRangeAndLength(base.getEncoding(), base.getBytes(), offset, offset + byteLength);
+            final int codeRange = StringSupport.unpackArg(packedLengthAndCodeRange);
+            final int characterLength = StringSupport.unpackResult(packedLengthAndCodeRange);
+
+            return new SubstringRope(base, offset, byteLength, characterLength, codeRange);
+        }
+
+        protected static boolean sameAsBase(Rope base, int offset, int byteLength) {
+            return (byteLength - offset) == base.byteLength();
+        }
+
+        protected static boolean is7Bit(Rope base) {
+            return base.getCodeRange() == StringSupport.CR_7BIT;
+        }
+
+        protected static boolean isLeafRope(Rope rope) {
+            return (rope instanceof LeafRope);
+        }
+
+        protected static boolean isSubstringRope(Rope rope) {
+            return (rope instanceof SubstringRope);
+        }
+
+        protected static boolean isConcatRope(Rope rope) {
+            return (rope instanceof ConcatRope);
+        }
+
+    }
+
+    @NodeChildren({
+            @NodeChild(type = RubyNode.class, value = "left"),
+            @NodeChild(type = RubyNode.class, value = "right"),
+            @NodeChild(type = RubyNode.class, value = "encoding")
+    })
+    public abstract static class MakeConcatNode extends RubyNode {
+
+        public MakeConcatNode(RubyContext context, SourceSection sourceSection) {
+            super(context, sourceSection);
+        }
+
+        public abstract Rope executeMake(Rope left, Rope right, Encoding encoding);
+
+        @Specialization(guards = { "left.isEmpty()", "right.getEncoding() == encoding" })
+        public Rope concatEmptyLeftSameEncoding(Rope left, Rope right, Encoding encoding) {
+            return right;
+        }
+
+        @Specialization(guards = { "left.isEmpty()", "right.getEncoding() != encoding" })
+        public Rope concatEmptyLeftDifferentEncoding(Rope left, Rope right, Encoding encoding) {
+            return RopeOperations.withEncoding(right, encoding);
+        }
+
+        @Specialization(guards = { "right.isEmpty()", "left.getEncoding() == encoding" })
+        public Rope concatEmptyRightSameEncoding(Rope left, Rope right, Encoding encoding) {
+            return left;
+        }
+
+        @Specialization(guards = { "right.isEmpty()", "left.getEncoding() != encoding" })
+        public Rope concatEmptyRightDifferentEncoding(Rope left, Rope right, Encoding encoding) {
+            return RopeOperations.withEncoding(left, encoding);
+        }
+
+        @Specialization(guards = { "!left.isEmpty()", "!right.isEmpty()" })
+        public Rope concat(Rope left, Rope right, Encoding encoding,
+                           @Cached("createBinaryProfile()") ConditionProfile sameCodeRangeProfile,
+                           @Cached("createBinaryProfile()") ConditionProfile brokenCodeRangeProfile,
+                           @Cached("createBinaryProfile()") ConditionProfile isLeftSingleByteOptimizableProfile,
+                           @Cached("createBinaryProfile()") ConditionProfile leftDepthGreaterThanRightProfile) {
+            return new ConcatRope(left, right, encoding,
+                    commonCodeRange(left.getCodeRange(), right.getCodeRange(), sameCodeRangeProfile, brokenCodeRangeProfile),
+                    isSingleByteOptimizable(left, right, isLeftSingleByteOptimizableProfile),
+                    depth(left, right, leftDepthGreaterThanRightProfile));
+        }
+
+        private int commonCodeRange(int first, int second,
+                                    ConditionProfile sameCodeRangeProfile,
+                                    ConditionProfile brokenCodeRangeProfile) {
+            if (sameCodeRangeProfile.profile(first == second)) {
+                return first;
+            }
+
+            if (brokenCodeRangeProfile.profile((first == StringSupport.CR_BROKEN) || (second == StringSupport.CR_BROKEN))) {
+                return StringSupport.CR_BROKEN;
+            }
+
+            // If we get this far, one must be CR_7BIT and the other must be CR_VALID, so promote to the more general code range.
+            return StringSupport.CR_VALID;
+        }
+
+        private boolean isSingleByteOptimizable(Rope left, Rope right, ConditionProfile isLeftSingleByteOptimizableProfile) {
+            if (isLeftSingleByteOptimizableProfile.profile(left.isSingleByteOptimizable())) {
+                return right.isSingleByteOptimizable();
+            }
+
+            return false;
+        }
+
+        private int depth(Rope left, Rope right, ConditionProfile leftDepthGreaterThanRightProfile) {
+            if (leftDepthGreaterThanRightProfile.profile(left.depth() >= right.depth())) {
+                return left.depth() + 1;
+            }
+
+            return right.depth() + 1;
+        }
+
+    }
+
+
+    @NodeChildren({
+            @NodeChild(type = RubyNode.class, value = "bytes"),
+            @NodeChild(type = RubyNode.class, value = "encoding"),
+            @NodeChild(type = RubyNode.class, value = "codeRange")
+    })
+    public abstract static class MakeLeafRopeNode extends RubyNode {
+
+        public MakeLeafRopeNode(RubyContext context, SourceSection sourceSection) {
+            super(context, sourceSection);
+        }
+
+        public abstract LeafRope executeMake(byte[] bytes, Encoding encoding, int codeRange);
+
+        @Specialization(guards = "is7Bit(codeRange)")
+        public LeafRope makeAsciiOnlyLeafRope(byte[] bytes, Encoding encoding, int codeRange) {
+            return new AsciiOnlyLeafRope(bytes, encoding);
+        }
+
+        @Specialization(guards = "isValid(codeRange)")
+        public LeafRope makeValidLeafRope(byte[] bytes, Encoding encoding, int codeRange) {
+            final int characterLength = RopeOperations.strLength(encoding, bytes, 0, bytes.length);
+
+            return new ValidLeafRope(bytes, encoding, characterLength);
+        }
+
+        @Specialization(guards = "isBroken(codeRange)")
+        public LeafRope makeInvalidLeafRope(byte[] bytes, Encoding encoding, int codeRange) {
+            return new InvalidLeafRope(bytes, encoding);
+        }
+
+        @Specialization(guards = "isUnknown(codeRange)")
+        public LeafRope makeUnknownLeafRope(byte[] bytes, Encoding encoding, int codeRange,
+                                            @Cached("createBinaryProfile()") ConditionProfile discovered7BitProfile,
+                                            @Cached("createBinaryProfile()") ConditionProfile discoveredValidProfile) {
+            final long packedLengthAndCodeRange = RopeOperations.calculateCodeRangeAndLength(encoding, bytes, 0, bytes.length);
+            final int newCodeRange = StringSupport.unpackArg(packedLengthAndCodeRange);
+            final int characterLength = StringSupport.unpackResult(packedLengthAndCodeRange);
+
+            if (discovered7BitProfile.profile(newCodeRange == StringSupport.CR_7BIT)) {
+                return new AsciiOnlyLeafRope(bytes, encoding);
+            }
+
+            if (discoveredValidProfile.profile(newCodeRange == StringSupport.CR_VALID)) {
+                return new ValidLeafRope(bytes, encoding, characterLength);
+            }
+
+            return new InvalidLeafRope(bytes, encoding);
+        }
+
+
+        protected static boolean is7Bit(int codeRange) {
+            return codeRange == StringSupport.CR_7BIT;
+        }
+
+        protected static boolean isValid(int codeRange) {
+            return codeRange == StringSupport.CR_VALID;
+        }
+
+        protected static boolean isBroken(int codeRange) {
+            return codeRange == StringSupport.CR_BROKEN;
+        }
+
+        protected static boolean isUnknown(int codeRange) {
+            return codeRange == StringSupport.CR_UNKNOWN;
+        }
+    }
+}
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/dispatch/CachedDispatchNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/dispatch/CachedDispatchNode.java
@@ -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.getByteListReadOnly((DynamicObject) cachedName).equal(StringOperations.getByteListReadOnly((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/rubinius/EncodingConverterPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/EncodingConverterPrimitiveNodes.java
@@ -23,6 +23,8 @@
 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;
@@ -57,8 +59,11 @@ public Object encodingConverterAllocate(DynamicObject encodingConverterClass, No
     @RubiniusPrimitive(name = "encoding_converter_primitive_convert")
     public static abstract class PrimitiveConvertNode extends RubiniusPrimitiveNode {
 
+        @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)"})
@@ -141,7 +146,7 @@ private Object primitiveConvertHelper(DynamicObject encodingConverter, DynamicOb
                 outBytes.setRealSize(outPtr.p - outBytes.begin());
 
                 if (nonNullSource) {
-                    sourceRope = RopeOperations.substring(sourceRope, inPtr.p, sourceRope.byteLength() - inPtr.p);
+                    sourceRope = makeSubstringNode.executeMake(sourceRope, inPtr.p, sourceRope.byteLength() - inPtr.p);
                     Layouts.STRING.setRope(source, sourceRope);
                 }
 

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
@@ -21,6 +21,8 @@
 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;
@@ -698,8 +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
@@ -708,7 +713,7 @@ public DynamicObject getcwd(DynamicObject resultPath, int maxSize) {
             // We just ignore maxSize - I think this is ok
 
             final String path = getContext().getRuntime().getCurrentDirectory();
-            Layouts.STRING.setRope(resultPath, RopeOperations.create(path.getBytes(StandardCharsets.UTF_8), Layouts.STRING.getRope(resultPath).getEncoding(), StringSupport.CR_UNKNOWN));
+            Layouts.STRING.setRope(resultPath, makeLeafRopeNode.executeMake(path.getBytes(StandardCharsets.UTF_8), Layouts.STRING.getRope(resultPath).getEncoding(), StringSupport.CR_UNKNOWN));
             return resultPath;
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/StringPrimitiveNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/rubinius/StringPrimitiveNodes.java
diff --git a/truffle/src/main/java/org/jruby/truffle/runtime/core/StringOperations.java b/truffle/src/main/java/org/jruby/truffle/runtime/core/StringOperations.java
@@ -199,14 +199,13 @@ public static int clampExclusiveIndex(DynamicObject string, int index) {
         return ArrayOperations.clampExclusiveIndex(StringOperations.rope(string).byteLength(), index);
     }
 
-    @CompilerDirectives.TruffleBoundary
-    public static Encoding checkEncoding(RubyContext context, DynamicObject string, CodeRangeable other, Node node) {
-        final Encoding encoding = StringSupport.areCompatible(getCodeRangeableReadOnly(string), other);
+    public static Encoding checkEncoding(RubyContext context, DynamicObject string, DynamicObject other, Node node) {
+        final Encoding encoding = EncodingNodes.CompatibleQueryNode.compatibleEncodingForStrings(string, other);
 
         if (encoding == null) {
             throw new RaiseException(context.getCoreLibrary().encodingCompatibilityErrorIncompatible(
-                    Layouts.STRING.getRope(string).getEncoding().toString(),
-                    other.getByteList().getEncoding().toString(),
+                    rope(string).getEncoding().toString(),
+                    rope(other).getEncoding().toString(),
                     node));
         }
 
@@ -231,23 +230,6 @@ public static int byteLength(DynamicObject object) {
         return Layouts.STRING.getRope(object).byteLength();
     }
 
-    public static int commonCodeRange(int first, int second) {
-        if (first == second) {
-            return first;
-        }
-
-        if ((first == StringSupport.CR_UNKNOWN) || (second == StringSupport.CR_UNKNOWN)) {
-            return StringSupport.CR_UNKNOWN;
-        }
-
-        if ((first == StringSupport.CR_BROKEN) || (second == StringSupport.CR_BROKEN)) {
-            return StringSupport.CR_BROKEN;
-        }
-
-        // If we get this far, one must be CR_7BIT and the other must be CR_VALID, so promote to the more general code range.
-        return StringSupport.CR_VALID;
-    }
-
     public static Rope ropeFromByteList(ByteList byteList) {
         return RopeOperations.create(byteList.bytes(), byteList.getEncoding(), StringSupport.CR_UNKNOWN);
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/runtime/rope/ConcatRope.java b/truffle/src/main/java/org/jruby/truffle/runtime/rope/ConcatRope.java
@@ -11,7 +11,6 @@
 
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import org.jcodings.Encoding;
-import org.jruby.truffle.runtime.core.StringOperations;
 
 public class ConcatRope extends Rope {
 
@@ -20,13 +19,13 @@ public class ConcatRope extends Rope {
 
     private byte[] bytes;
 
-    public ConcatRope(Rope left, Rope right, Encoding encoding) {
+    public ConcatRope(Rope left, Rope right, Encoding encoding, int codeRange, boolean singleByteOptimizable, int depth) {
         super(encoding,
-                StringOperations.commonCodeRange(left.getCodeRange(), right.getCodeRange()),
-                left.isSingleByteOptimizable() && right.isSingleByteOptimizable(),
+                codeRange,
+                singleByteOptimizable,
                 left.byteLength() + right.byteLength(),
                 left.characterLength() + right.characterLength(),
-                Math.max(left.depth(), right.depth()) + 1);
+                depth);
 
         this.left = left;
         this.right = right;

diff --git a/truffle/src/main/java/org/jruby/truffle/runtime/rope/Rope.java b/truffle/src/main/java/org/jruby/truffle/runtime/rope/Rope.java
@@ -23,7 +23,7 @@ public abstract class Rope {
     private final int byteLength;
     private final int characterLength;
     private final int ropeDepth;
-    @CompilationFinal private int hashCode = -1;
+    private int hashCode = 0;
 
     protected Rope(Encoding encoding, int codeRange, boolean singleByteOptimizable, int byteLength, int characterLength, int ropeDepth) {
         this.encoding = encoding;
@@ -96,7 +96,7 @@ public int getRealSize() {
 
     @Override
     public int hashCode() {
-        if (hashCode == -1) {
+        if (hashCode == 0) {
             hashCode = RopeOperations.hashForRange(this, 1, 0, byteLength);
         }
 
@@ -112,6 +112,10 @@ public boolean equals(Object o) {
         if (o instanceof Rope) {
             final Rope other = (Rope) o;
 
+            if ((hashCode != 0) && (other.hashCode != 0) && (hashCode != other.hashCode)) {
+                return false;
+            }
+
             // TODO (nirvdrum 21-Jan-16): We really should be taking the encoding into account here. We're currenly not because it breaks the symbol table.
             return byteLength() == other.byteLength() && Arrays.equals(getBytes(), other.getBytes());
         }

diff --git a/truffle/src/main/java/org/jruby/truffle/runtime/rope/RopeOperations.java b/truffle/src/main/java/org/jruby/truffle/runtime/rope/RopeOperations.java
@@ -54,69 +54,6 @@ public static LeafRope create(byte[] bytes, Encoding encoding, int codeRange) {
         }
     }
 
-    @TruffleBoundary
-    public static Rope concat(Rope left, Rope right, Encoding encoding) {
-        if (right.isEmpty()) {
-            return withEncoding(left, encoding);
-        }
-
-        if (left.isEmpty()) {
-            return withEncoding(right, encoding);
-        }
-
-        return new ConcatRope(left, right, encoding);
-    }
-
-    public static Rope substring(Rope base, int offset, int byteLength) {
-        if (byteLength == 0) {
-            return withEncoding(EMPTY_UTF8_ROPE, base.getEncoding());
-        }
-
-        if (byteLength - offset == base.byteLength()) {
-            return base;
-        }
-
-        if (base instanceof SubstringRope) {
-            return substringSubstringRope((SubstringRope) base, offset, byteLength);
-        } else if (base instanceof ConcatRope) {
-            return substringConcatRope((ConcatRope) base, offset, byteLength);
-        }
-
-        return makeSubstring(base, offset, byteLength);
-    }
-
-    private static Rope substringSubstringRope(SubstringRope base, int offset, int byteLength) {
-        return makeSubstring(base.getChild(), offset + base.getOffset(), byteLength);
-    }
-
-    @TruffleBoundary
-    private static Rope substringConcatRope(ConcatRope base, int offset, int byteLength) {
-        if (offset + byteLength <= base.getLeft().byteLength()) {
-            return substring(base.getLeft(), offset, byteLength);
-        } else if (offset >= base.getLeft().byteLength()) {
-            return substring(base.getRight(), offset - base.getLeft().byteLength(), byteLength);
-        }
-
-        return makeSubstring(base, offset, byteLength);
-    }
-
-    private static Rope makeSubstring(Rope base, int offset, int byteLength) {
-        if (base.getCodeRange() == StringSupport.CR_7BIT) {
-            return new SubstringRope(base, offset, byteLength, byteLength, StringSupport.CR_7BIT);
-        }
-
-        return makeSubstringNon7Bit(base, offset, byteLength);
-    }
-
-    @TruffleBoundary
-    private static Rope makeSubstringNon7Bit(Rope base, int offset, int byteLength) {
-        final long packedLengthAndCodeRange = calculateCodeRangeAndLength(base.getEncoding(), base.getBytes(), offset, offset + byteLength);
-        final int codeRange = StringSupport.unpackArg(packedLengthAndCodeRange);
-        final int characterLength = StringSupport.unpackResult(packedLengthAndCodeRange);
-
-        return new SubstringRope(base, offset, byteLength, characterLength, codeRange);
-    }
-
     public static Rope withEncoding(Rope originalRope, Encoding newEncoding, int newCodeRange) {
         if ((originalRope.getEncoding() == newEncoding) && (originalRope.getCodeRange() == newCodeRange)) {
             return originalRope;
@@ -125,7 +62,6 @@ public static Rope withEncoding(Rope originalRope, Encoding newEncoding, int new
         return create(originalRope.getBytes(), newEncoding, newCodeRange);
     }
 
-    @TruffleBoundary
     public static Rope withEncoding(Rope originalRope, Encoding newEncoding) {
         return withEncoding(originalRope, newEncoding, originalRope.getCodeRange());
     }
@@ -137,26 +73,38 @@ public static String decodeUTF8(Rope rope) {
 
     @TruffleBoundary
     public static String decodeRope(Ruby runtime, Rope value) {
-        int begin = value.getBegin();
-        int length = value.byteLength();
+        if (value instanceof LeafRope) {
+            int begin = value.getBegin();
+            int length = value.byteLength();
 
-        Encoding encoding = value.getEncoding();
+            Encoding encoding = value.getEncoding();
 
-        if (encoding == UTF8Encoding.INSTANCE) {
-            return RubyEncoding.decodeUTF8(value.getBytes(), begin, length);
-        }
+            if (encoding == UTF8Encoding.INSTANCE) {
+                return RubyEncoding.decodeUTF8(value.getBytes(), begin, length);
+            }
 
-        Charset charset = runtime.getEncodingService().charsetForEncoding(encoding);
+            Charset charset = runtime.getEncodingService().charsetForEncoding(encoding);
 
-        if (charset == null) {
-            try {
-                return new String(value.getBytes(), begin, length, encoding.toString());
-            } catch (UnsupportedEncodingException uee) {
-                return value.toString();
+            if (charset == null) {
+                try {
+                    return new String(value.getBytes(), begin, length, encoding.toString());
+                } catch (UnsupportedEncodingException uee) {
+                    return value.toString();
+                }
             }
-        }
 
-        return RubyEncoding.decode(value.getBytes(), begin, length, charset);
+            return RubyEncoding.decode(value.getBytes(), begin, length, charset);
+        } else if (value instanceof SubstringRope) {
+            final SubstringRope substringRope = (SubstringRope) value;
+
+            return decodeRope(runtime, substringRope.getChild()).substring(substringRope.getOffset(), substringRope.getOffset() + substringRope.characterLength());
+        } else if (value instanceof ConcatRope) {
+            final ConcatRope concatRope = (ConcatRope) value;
+
+            return decodeRope(runtime, concatRope.getLeft()) + decodeRope(runtime, concatRope.getRight());
+        } else {
+            throw new RuntimeException("Decoding to String is not supported for rope of type: " + value.getClass().getName());
+        }
     }
 
     // MRI: get_actual_encoding
@@ -166,7 +114,7 @@ public static Encoding STR_ENC_GET(Rope rope) {
     }
 
     @TruffleBoundary
-    private static long calculateCodeRangeAndLength(Encoding encoding, byte[] bytes, int start, int end) {
+    public static long calculateCodeRangeAndLength(Encoding encoding, byte[] bytes, int start, int end) {
         if (bytes.length == 0) {
             return StringSupport.pack(0, encoding.isAsciiCompatible() ? StringSupport.CR_7BIT : StringSupport.CR_VALID);
         } else if (encoding.isAsciiCompatible()) {