Merge branch 'master' into truffle-head

jruby · May 29, 2015 · 2cb91dc · 2cb91dc
2 parents 3afa8a5 + 13d3bfb
commit 2cb91dc
Showing 36 changed files with 369 additions and 435 deletions.
diff --git a/core/src/main/java/org/jruby/ir/IRBuilder.java b/core/src/main/java/org/jruby/ir/IRBuilder.java
@@ -975,7 +975,7 @@ private Operand receiveBreakException(Operand block, CodeBlock codeBlock) {
         addInstr(new LabelInstr(rBeginLabel));
         addInstr(new ExceptionRegionStartMarkerInstr(rescueLabel));
         Variable callResult = (Variable)codeBlock.run();
-        addInstr(new JumpInstr(rEndLabel));
+        addInstr(new JumpInstr(rEndLabel, true));
         addInstr(new ExceptionRegionEndMarkerInstr());
 
         // Receive exceptions (could be anything, but the handler only processes IRBreakJumps)
@@ -1331,8 +1331,8 @@ private Operand protectCodeWithRescue(CodeBlock protectedCode, CodeBlock rescueB
         addInstr(new ExceptionRegionStartMarkerInstr(rescueLabel));
         Object v1 = protectedCode.run(); // YIELD: Run the protected code block
         addInstr(new CopyInstr(rv, (Operand)v1));
+        addInstr(new JumpInstr(rEndLabel, true));
         addInstr(new ExceptionRegionEndMarkerInstr());
-        addInstr(new JumpInstr(rEndLabel));
 
         // SSS FIXME: Create an 'Exception' operand type to eliminate the constant lookup below
         // We could preload a set of constant objects that are preloaded at boot time and use them
@@ -3040,7 +3040,7 @@ public Operand buildRescue(RescueNode node) {
 
     private Operand buildRescueInternal(RescueNode rescueNode, EnsureBlockInfo ensure) {
         // Labels marking start, else, end of the begin-rescue(-ensure)-end block
-        Label rBeginLabel = ensure.regionStart;
+        Label rBeginLabel = getNewLabel();
         Label rEndLabel   = ensure.end;
         Label rescueLabel = getNewLabel(); // Label marking start of the first rescue code.
 
@@ -3092,7 +3092,7 @@ private Operand buildRescueInternal(RescueNode rescueNode, EnsureBlockInfo ensur
             // - If we dont have any ensure blocks, simply jump to the end of the rescue block
             // - If we do, execute the ensure code.
             ensure.cloneIntoHostScope(this);
-            addInstr(new JumpInstr(rEndLabel));
+            addInstr(new JumpInstr(rEndLabel, true));
         }   //else {
             // If the body had an explicit return, the return instruction IR build takes care of setting
             // up execution of all necessary ensure blocks.  So, nothing to do here!
@@ -3176,7 +3176,7 @@ private void buildRescueBodyInternal(RescueBodyNode rescueBodyNode, Variable rv,
             // around the current rescue block)
             activeEnsureBlockStack.peek().cloneIntoHostScope(this);
 
-            addInstr(new JumpInstr(endLabel));
+            addInstr(new JumpInstr(endLabel, true));
         }
     }
 

diff --git a/core/src/main/java/org/jruby/ir/instructions/JumpInstr.java b/core/src/main/java/org/jruby/ir/instructions/JumpInstr.java
@@ -9,8 +9,19 @@
 import org.jruby.ir.transformations.inlining.CloneInfo;
 
 public class JumpInstr extends Instr implements FixedArityInstr {
+    final boolean exitsExcRegion;
+
     public JumpInstr(Label target) {
+        this(target, false);
+    }
+
+    public JumpInstr(Label target, boolean exitsExcRegion) {
         super(Operation.JUMP, new Operand[] { target });
+        this.exitsExcRegion = exitsExcRegion;
+    }
+
+    public boolean exitsExcRegion() {
+        return this.exitsExcRegion;
     }
 
     public Label getJumpTarget() {
@@ -19,17 +30,18 @@ public Label getJumpTarget() {
 
     @Override
     public Instr clone(CloneInfo ii) {
-        return new JumpInstr(ii.getRenamedLabel(getJumpTarget()));
+        return new JumpInstr(ii.getRenamedLabel(getJumpTarget()), exitsExcRegion);
     }
 
     @Override
     public void encode(IRWriterEncoder e) {
         super.encode(e);
         e.encode(getJumpTarget());
+        e.encode(exitsExcRegion);
     }
 
     public static JumpInstr decode(IRReaderDecoder d) {
-        return new JumpInstr(d.decodeLabel());
+        return new JumpInstr(d.decodeLabel(), d.decodeBoolean());
     }
 
     @Override

diff --git a/core/src/main/java/org/jruby/ir/interpreter/StartupInterpreterEngine.java b/core/src/main/java/org/jruby/ir/interpreter/StartupInterpreterEngine.java
@@ -59,7 +59,7 @@ public IRubyObject interpret(ThreadContext context, IRubyObject self,
 
             Operation operation = instr.getOperation();
             if (debug) {
-                Interpreter.LOG.info("I: {" + ipc + "} ", instr);
+                Interpreter.LOG.info("I: {" + ipc + "} ", instr + "; <#RPCs=" + rescuePCs.size() + ">");
                 Interpreter.interpInstrsCount++;
             } else if (profile) {
                 Profiler.instrTick(operation);
@@ -81,8 +81,16 @@ public IRubyObject interpret(ThreadContext context, IRubyObject self,
                         return processReturnOp(context, instr, operation, currDynScope, temp, self, blockType, currScope);
                     case BRANCH_OP:
                         switch (operation) {
-                            case JUMP: ipc = ((JumpInstr)instr).getJumpTarget().getTargetPC(); break;
-                            default: ipc = instr.interpretAndGetNewIPC(context, currDynScope, currScope, self, temp, ipc); break;
+                            case JUMP:
+                                JumpInstr jump = ((JumpInstr)instr);
+                                if (jump.exitsExcRegion()) {
+                                    rescuePCs.pop();
+                                }
+                                ipc = jump.getJumpTarget().getTargetPC();
+                                break;
+                            default:
+                                ipc = instr.interpretAndGetNewIPC(context, currDynScope, currScope, self, temp, ipc);
+                                break;
                         }
                         break;
                     case BOOK_KEEPING_OP:

diff --git a/lib/ruby/truffle/truffle/zlib.rb b/lib/ruby/truffle/truffle/zlib.rb
@@ -8,11 +8,47 @@
 
 module Zlib
 
+  BINARY = 0
+  ASCII = 1
+  UNKNOWN = 2
+
+  DEF_MEM_LEVEL = 8
+  MAX_MEM_LEVEL = 9
+
+  OS_MSDOS = 0
+  OS_AMIGA = 1
+  OS_VMS = 2
+  OS_CODE = 3
+  OS_UNIX = 3
+  OS_VMCMS = 4
+  OS_ATARI = 5
+  OS_OS2 = 6
+  OS_MACOS = 7
+  OS_ZSYSTEM = 8
+  OS_CPM = 9
+  OS_TOPS20 = 10
+  OS_WIN32 = 11
+  OS_QDOS = 12
+  OS_RISCOS = 13
+  OS_UNKNOWN = 255
+
+  DEFAULT_STRATEGY = 0
+  FILTERED = 1
+  HUFFMAN_ONLY = 2
+
+  NO_FLUSH = 0
+  SYNC_FUSH = 2
+  FULL_FLUSH = 3
+  FINISH = 4
+
   NO_COMPRESSION      =  0
   BEST_SPEED          =  1
   BEST_COMPRESSION    =  9
   DEFAULT_COMPRESSION = -1
 
+  MAX_WBITS = 15
+
+
   def self.crc32(*args)
     Truffle::Zlib.crc32(*args)
   end

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/RubyGuards.java b/truffle/src/main/java/org/jruby/truffle/nodes/RubyGuards.java
@@ -14,13 +14,13 @@
 import org.jruby.truffle.nodes.core.MethodNodes;
 import org.jruby.truffle.nodes.core.UnboundMethodNodes;
 import org.jruby.truffle.runtime.ThreadLocalObject;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.core.*;
 
 public abstract class RubyGuards {
 
-    public static boolean isUndefinedPlaceholder(Object value) {
-        return value instanceof UndefinedPlaceholder;
+    public static boolean isNotProvided(Object value) {
+        return value instanceof NotProvided;
     }
 
     public static boolean isBoolean(Object value) {

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/RubyNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/RubyNode.java
@@ -27,7 +27,7 @@
 import org.jruby.truffle.nodes.instrument.RubyWrapperNode;
 import org.jruby.truffle.runtime.RubyArguments;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.sockets.NativeSockets;
 
@@ -66,11 +66,11 @@ public void executeVoid(VirtualFrame frame) {
 
     // Utility methods to execute and expect a particular type
 
-    public UndefinedPlaceholder executeUndefinedPlaceholder(VirtualFrame frame) throws UnexpectedResultException {
+    public NotProvided executeNotProvided(VirtualFrame frame) throws UnexpectedResultException {
         final Object value = execute(frame);
 
-        if (value instanceof UndefinedPlaceholder) {
-            return (UndefinedPlaceholder) value;
+        if (value instanceof NotProvided) {
+            return (NotProvided) value;
         } else {
             throw new UnexpectedResultException(value);
         }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/arguments/ReadPreArgumentNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/arguments/ReadPreArgumentNode.java
@@ -16,7 +16,7 @@
 import org.jruby.truffle.nodes.RubyNode;
 import org.jruby.truffle.runtime.RubyArguments;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 
 /**
  * Read pre-optional argument.
@@ -46,7 +46,7 @@ public Object execute(VirtualFrame frame) {
                     break;
 
                 case UNDEFINED:
-                    return UndefinedPlaceholder.INSTANCE;
+                    return NotProvided.INSTANCE;
 
                 case NIL:
                     return nil();

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/cast/TaintResultNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/cast/TaintResultNode.java
@@ -81,7 +81,7 @@ public Object execute(VirtualFrame frame) {
             }
 
             // It's possible the taintFromParameter value was misconfigured by the user, but the far more likely
-            // scenario is that the argument at that position is an UndefinedPlaceholder, which doesn't take up
+            // scenario is that the argument at that position is a NotProvided argument, which doesn't take up
             // a space in the frame.
             if (taintFromParameter < RubyArguments.getUserArgumentsCount(frame.getArguments())) {
                 final Object argument = RubyArguments.getUserArgument(frame.getArguments(), taintFromParameter);

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
@@ -24,7 +24,7 @@
 import org.jruby.truffle.nodes.methods.UnsupportedOperationBehavior;
 import org.jruby.truffle.nodes.yield.YieldDispatchHeadNode;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.array.ArrayUtils;
@@ -177,14 +177,14 @@ public InstanceEvalNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object instanceEval(VirtualFrame frame, Object receiver, RubyString string, UndefinedPlaceholder block) {
+        public Object instanceEval(VirtualFrame frame, Object receiver, RubyString string, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
 
             return getContext().instanceEval(string.getByteList(), receiver, this);
         }
 
         @Specialization
-        public Object instanceEval(VirtualFrame frame, Object receiver, UndefinedPlaceholder string, RubyProc block) {
+        public Object instanceEval(VirtualFrame frame, Object receiver, NotProvided string, RubyProc block) {
             return yield.dispatchWithModifiedSelf(frame, block, receiver, receiver);
         }
 
@@ -205,7 +205,7 @@ public Object instanceExec(VirtualFrame frame, Object receiver, Object[] argumen
         }
 
         @Specialization
-        public Object instanceExec(Object receiver, Object[] arguments, UndefinedPlaceholder block) {
+        public Object instanceExec(Object receiver, Object[] arguments, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
 
             throw new RaiseException(getContext().getCoreLibrary().localJumpError("no block given", this));
@@ -221,7 +221,7 @@ public MethodMissingNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object methodMissing(Object self, Object[] args, UndefinedPlaceholder block) {
+        public Object methodMissing(Object self, Object[] args, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
 
             return methodMissing(self, args, (RubyProc) null);
@@ -281,7 +281,7 @@ public SendNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object send(VirtualFrame frame, Object self, Object[] args, UndefinedPlaceholder block) {
+        public Object send(VirtualFrame frame, Object self, Object[] args, NotProvided block) {
             return send(frame, self, args, (RubyProc) null);
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/BignumNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/BignumNodes.java
@@ -23,7 +23,7 @@
 import org.jruby.truffle.nodes.dispatch.CallDispatchHeadNode;
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 
@@ -661,7 +661,7 @@ public ToSNode(RubyContext context, SourceSection sourceSection) {
 
         @TruffleBoundary
         @Specialization
-        public RubyString toS(RubyBasicObject value, UndefinedPlaceholder undefined) {
+        public RubyString toS(RubyBasicObject value, NotProvided base) {
             return getContext().makeString(getBigIntegerValue(value).toString());
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ClassNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ClassNodes.java
@@ -18,7 +18,7 @@
 import org.jruby.truffle.nodes.dispatch.CallDispatchHeadNode;
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.RubyBasicObject;
 import org.jruby.truffle.runtime.core.RubyClass;
@@ -60,7 +60,7 @@ public NewNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object newInstance(VirtualFrame frame, RubyClass rubyClass, Object[] args, UndefinedPlaceholder block) {
+        public Object newInstance(VirtualFrame frame, RubyClass rubyClass, Object[] args, NotProvided block) {
             return doNewInstance(frame, rubyClass, args, null);
         }
 
@@ -94,18 +94,18 @@ void moduleInitialize(VirtualFrame frame, RubyClass rubyClass, RubyProc block) {
         }
 
         @Specialization
-        public RubyClass initialize(RubyClass rubyClass, UndefinedPlaceholder superclass, UndefinedPlaceholder block) {
+        public RubyClass initialize(RubyClass rubyClass, NotProvided superclass, NotProvided block) {
             return initialize(rubyClass, getContext().getCoreLibrary().getObjectClass(), block);
         }
 
         @Specialization
-        public RubyClass initialize(RubyClass rubyClass, RubyClass superclass, UndefinedPlaceholder block) {
+        public RubyClass initialize(RubyClass rubyClass, RubyClass superclass, NotProvided block) {
             rubyClass.initialize(superclass);
             return rubyClass;
         }
 
         @Specialization
-        public RubyClass initialize(VirtualFrame frame, RubyClass rubyClass, UndefinedPlaceholder superclass, RubyProc block) {
+        public RubyClass initialize(VirtualFrame frame, RubyClass rubyClass, NotProvided superclass, RubyProc block) {
             return initialize(frame, rubyClass, getContext().getCoreLibrary().getObjectClass(), block);
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/CoreMethodNodeManager.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/CoreMethodNodeManager.java
@@ -198,7 +198,7 @@ private static RubyRootNode makeGenericMethod(RubyContext context, MethodDetails
         }
 
         if (method.needsBlock()) {
-            argumentsNodes.add(new ReadBlockNode(context, sourceSection, UndefinedPlaceholder.INSTANCE));
+            argumentsNodes.add(new ReadBlockNode(context, sourceSection, NotProvided.INSTANCE));
         }
 
         final RubyNode methodNode;

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ExceptionNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ExceptionNodes.java
@@ -16,7 +16,7 @@
 import org.jruby.truffle.nodes.objectstorage.ReadHeadObjectFieldNode;
 import org.jruby.truffle.runtime.RubyCallStack;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.backtrace.Backtrace;
 import org.jruby.truffle.runtime.core.RubyBasicObject;
 import org.jruby.truffle.runtime.core.RubyException;
@@ -33,12 +33,12 @@ public InitializeNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyBasicObject initialize(RubyException exception, UndefinedPlaceholder message) {
+        public RubyBasicObject initialize(RubyException exception, NotProvided message) {
             exception.initialize(nil());
             return exception;
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(message)")
+        @Specialization(guards = "!isNotProvided(message)")
         public RubyBasicObject initialize(RubyException exception, Object message) {
             exception.initialize(message);
             return exception;
@@ -78,7 +78,7 @@ public CaptureBacktraceNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyBasicObject captureBacktrace(RubyException exception, UndefinedPlaceholder offset) {
+        public RubyBasicObject captureBacktrace(RubyException exception, NotProvided offset) {
             return captureBacktrace(exception, 1);
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/FloatNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/FloatNodes.java
@@ -20,7 +20,7 @@
 import org.jruby.truffle.nodes.dispatch.CallDispatchHeadNode;
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 
@@ -48,11 +48,6 @@ public AddNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public double add(double a, int b) {
-            return a + b;
-        }
-
         @Specialization
         public double add(double a, long b) {
             return a + b;
@@ -77,11 +72,6 @@ public SubNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public double sub(double a, int b) {
-            return a - b;
-        }
-
         @Specialization
         public double sub(double a, long b) {
             return a - b;
@@ -111,11 +101,6 @@ public MulNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public double mul(double a, int b) {
-            return a * b;
-        }
-
         @Specialization
         public double mul(double a, long b) {
             return a * b;
@@ -150,11 +135,6 @@ public PowNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public double pow(double a, int b) {
-            return Math.pow(a, b);
-        }
-
         @Specialization
         public double pow(double a, long b) {
             return Math.pow(a, b);
@@ -198,11 +178,6 @@ public DivNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public double div(double a, int b) {
-            return a / b;
-        }
-
         @Specialization
         public double div(double a, long b) {
             return a / b;
@@ -243,11 +218,6 @@ public ModNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public double mod(double a, int b) {
-            return mod(a, (double) b);
-        }
-
         @Specialization
         public double mod(double a, long b) {
             return mod(a, (double) b);
@@ -286,11 +256,6 @@ public DivModNode(RubyContext context, SourceSection sourceSection) {
             divModNode = new GeneralDivModNode(context, sourceSection);
         }
 
-        @Specialization
-        public RubyArray divMod(double a, int b) {
-            return divModNode.execute(a, b);
-        }
-
         @Specialization
         public RubyArray divMod(double a, long b) {
             return divModNode.execute(a, b);
@@ -315,11 +280,6 @@ public LessNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public boolean less(double a, int b) {
-            return a < b;
-        }
-
         @Specialization
         public boolean less(double a, long b) {
             return a < b;
@@ -349,11 +309,6 @@ public LessEqualNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public boolean lessEqual(double a, int b) {
-            return a <= b;
-        }
-
         @Specialization
         public boolean lessEqual(double a, long b) {
             return a <= b;
@@ -385,11 +340,6 @@ public EqualNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public boolean equal(double a, int b) {
-            return a == b;
-        }
-
         @Specialization
         public boolean equal(double a, long b) {
             return a == b;
@@ -433,11 +383,6 @@ public RubyBasicObject compareSecondNaN(Object a, double b) {
             return nil();
         }
 
-        @Specialization(guards = {"!isNaN(a)"})
-        public int compare(double a, int b) {
-            return Double.compare(a, b);
-        }
-
         @Specialization(guards = {"!isNaN(a)"})
         public int compare(double a, long b) {
             return Double.compare(a, b);
@@ -476,11 +421,6 @@ public GreaterEqualNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public boolean greaterEqual(double a, int b) {
-            return a >= b;
-        }
-
         @Specialization
         public boolean greaterEqual(double a, long b) {
             return a >= b;
@@ -510,11 +450,6 @@ public GreaterNode(RubyContext context, SourceSection sourceSection) {
             super(context, sourceSection);
         }
 
-        @Specialization
-        public boolean equal(double a, int b) {
-            return a > b;
-        }
-
         @Specialization
         public boolean equal(double a, long b) {
             return a > b;
@@ -635,7 +570,7 @@ public RoundNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object round(double n, UndefinedPlaceholder undefinedPlaceholder) {
+        public Object round(double n, NotProvided ndigits) {
             // Algorithm copied from JRuby - not shared as we want to branch profile it
 
             if (Double.isInfinite(n)) {
@@ -671,7 +606,7 @@ public Object round(double n, UndefinedPlaceholder undefinedPlaceholder) {
             return fixnumOrBignum.fixnumOrBignum(f);
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(ndigits)")
+        @Specialization(guards = "!isNotProvided(ndigits)")
         public Object round(VirtualFrame frame, double n, Object ndigits) {
             return ruby(frame, "round_internal(ndigits)", "ndigits", ndigits);
         }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/GeneralDivModNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/GeneralDivModNode.java
@@ -40,10 +40,6 @@ public GeneralDivModNode(RubyContext context, SourceSection sourceSection) {
         fixnumOrBignumRemainder = new FixnumOrBignumNode(context, sourceSection);
     }
 
-    public RubyArray execute(int a, double b) {
-        return divMod(a, b);
-    }
-
     public RubyArray execute(long a, long b) {
         return divMod(a, b);
     }
@@ -64,10 +60,6 @@ public RubyArray execute(BigInteger a, BigInteger b) {
         return divMod(a, b);
     }
 
-    public RubyArray execute(double a, int b) {
-        return divMod(a, b);
-    }
-
     public RubyArray execute(double a, long b) {
         return divMod(a, b);
     }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/IntegerNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/IntegerNodes.java
@@ -16,7 +16,7 @@
 import com.oracle.truffle.api.utilities.BranchProfile;
 import org.jruby.truffle.nodes.methods.UnsupportedOperationBehavior;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.NextException;
 import org.jruby.truffle.runtime.control.RedoException;
 import org.jruby.truffle.runtime.core.RubyArray;
@@ -136,7 +136,7 @@ public TimesNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray times(VirtualFrame frame, int n, UndefinedPlaceholder block) {
+        public RubyArray times(VirtualFrame frame, int n, NotProvided block) {
             final int[] array = new int[n];
 
             for (int i = 0; i < n; i++) {

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
@@ -301,12 +301,12 @@ public CallerLocationsNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray callerLocations(UndefinedPlaceholder undefined1, UndefinedPlaceholder undefined2) {
+        public RubyArray callerLocations(NotProvided omit, NotProvided length) {
             return callerLocations(1, -1);
         }
 
         @Specialization
-        public RubyArray callerLocations(int omit, UndefinedPlaceholder undefined) {
+        public RubyArray callerLocations(int omit, NotProvided length) {
             return callerLocations(omit, -1);
         }
 
@@ -468,7 +468,7 @@ protected RubyBinding getCallerBinding(VirtualFrame frame) {
         }
 
         @Specialization
-        public Object eval(VirtualFrame frame, RubyString source, UndefinedPlaceholder binding, UndefinedPlaceholder filename, UndefinedPlaceholder lineNumber) {
+        public Object eval(VirtualFrame frame, RubyString source, NotProvided binding, NotProvided filename, NotProvided lineNumber) {
             CompilerDirectives.transferToInterpreter();
 
             return getContext().eval(source.getByteList(), getCallerBinding(frame), true, this);
@@ -479,18 +479,18 @@ public Object eval(VirtualFrame frame, RubyString source, Object noBinding, Ruby
             CompilerDirectives.transferToInterpreter();
 
             // TODO (nirvdrum Dec. 29, 2014) Do something with the supplied filename.
-            return eval(frame, source, UndefinedPlaceholder.INSTANCE, UndefinedPlaceholder.INSTANCE, UndefinedPlaceholder.INSTANCE);
+            return eval(frame, source, NotProvided.INSTANCE, NotProvided.INSTANCE, NotProvided.INSTANCE);
         }
 
         @Specialization
-        public Object eval(RubyString source, RubyBinding binding, UndefinedPlaceholder filename, UndefinedPlaceholder lineNumber) {
+        public Object eval(RubyString source, RubyBinding binding, NotProvided filename, NotProvided lineNumber) {
             CompilerDirectives.transferToInterpreter();
 
             return getContext().eval(source.getByteList(), binding, false, this);
         }
 
         @Specialization
-        public Object eval(RubyString source, RubyBinding binding, RubyString filename, UndefinedPlaceholder lineNumber) {
+        public Object eval(RubyString source, RubyBinding binding, RubyString filename, NotProvided lineNumber) {
             CompilerDirectives.transferToInterpreter();
 
             return getContext().eval(source.getByteList(), binding, false, filename.toString(), this);
@@ -504,7 +504,7 @@ public Object eval(RubyString source, RubyBinding binding, RubyString filename,
         }
 
         @Specialization(guards = "!isRubyBinding(badBinding)")
-        public Object eval(RubyString source, RubyBasicObject badBinding, UndefinedPlaceholder filename, UndefinedPlaceholder lineNumber) {
+        public Object eval(RubyString source, RubyBasicObject badBinding, NotProvided filename, NotProvided lineNumber) {
             throw new RaiseException(getContext().getCoreLibrary().typeErrorWrongArgumentType(badBinding, "binding", this));
         }
     }
@@ -571,7 +571,7 @@ public ExitNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object exit(UndefinedPlaceholder exitCode) {
+        public Object exit(NotProvided exitCode) {
             return exit(0);
         }
 
@@ -603,7 +603,7 @@ public ExitBangNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyBasicObject exit(UndefinedPlaceholder exitCode) {
+        public RubyBasicObject exit(NotProvided exitCode) {
             return exit(1);
         }
 
@@ -991,7 +991,7 @@ public boolean load(RubyString file, boolean wrap) {
         }
 
         @Specialization
-        public boolean load(RubyString file, UndefinedPlaceholder wrap) {
+        public boolean load(RubyString file, NotProvided wrap) {
             return load(file, false);
         }
     }
@@ -1084,7 +1084,7 @@ public MethodsNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray methods(VirtualFrame frame, Object self, UndefinedPlaceholder regular) {
+        public RubyArray methods(VirtualFrame frame, Object self, NotProvided regular) {
             return methods(frame, self, true);
         }
 
@@ -1141,7 +1141,7 @@ public PrivateMethodsNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray privateMethods(VirtualFrame frame, Object self, UndefinedPlaceholder includeAncestors) {
+        public RubyArray privateMethods(VirtualFrame frame, Object self, NotProvided includeAncestors) {
             return privateMethods(frame, self, true);
         }
 
@@ -1195,7 +1195,7 @@ public ProtectedMethodsNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray protectedMethods(VirtualFrame frame, Object self, UndefinedPlaceholder includeAncestors) {
+        public RubyArray protectedMethods(VirtualFrame frame, Object self, NotProvided includeAncestors) {
             return protectedMethods(frame, self, true);
         }
 
@@ -1231,7 +1231,7 @@ public PublicMethodsNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray publicMethods(VirtualFrame frame, Object self, UndefinedPlaceholder includeAncestors) {
+        public RubyArray publicMethods(VirtualFrame frame, Object self, NotProvided includeAncestors) {
             return publicMethods(frame, self, true);
         }
 
@@ -1263,7 +1263,7 @@ public RandNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public double rand(UndefinedPlaceholder undefined) {
+        public double rand(NotProvided max) {
             return getContext().getRandom().nextDouble();
         }
 
@@ -1408,7 +1408,7 @@ public RespondToNode(RubyContext context, SourceSection sourceSection) {
         public abstract boolean executeDoesRespondTo(VirtualFrame frame, Object object, Object name, boolean includePrivate);
 
         @Specialization
-        public boolean doesRespondTo(VirtualFrame frame, Object object, RubyString name, UndefinedPlaceholder checkVisibility) {
+        public boolean doesRespondTo(VirtualFrame frame, Object object, RubyString name, NotProvided checkVisibility) {
             return doesRespondTo(frame, object, name, false);
         }
 
@@ -1427,7 +1427,7 @@ public boolean doesRespondTo(VirtualFrame frame, Object object, RubyString name,
         }
 
         @Specialization
-        public boolean doesRespondTo(VirtualFrame frame, Object object, RubySymbol name, UndefinedPlaceholder checkVisibility) {
+        public boolean doesRespondTo(VirtualFrame frame, Object object, RubySymbol name, NotProvided checkVisibility) {
             return doesRespondTo(frame, object, name, false);
         }
 
@@ -1455,12 +1455,12 @@ public RespondToMissingNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public boolean doesRespondToMissing(Object object, RubyString name, UndefinedPlaceholder includeAll) {
+        public boolean doesRespondToMissing(Object object, RubyString name, NotProvided includeAll) {
             return false;
         }
 
         @Specialization
-        public boolean doesRespondToMissing(Object object, RubySymbol name, UndefinedPlaceholder includeAll) {
+        public boolean doesRespondToMissing(Object object, RubySymbol name, NotProvided includeAll) {
             return false;
         }
 
@@ -1531,7 +1531,7 @@ public SingletonMethodsNode(RubyContext context, SourceSection sourceSection) {
         public abstract RubyArray executeSingletonMethods(VirtualFrame frame, Object self, boolean includeAncestors);
 
         @Specialization
-        public RubyArray singletonMethods(VirtualFrame frame, Object self, UndefinedPlaceholder includeAncestors) {
+        public RubyArray singletonMethods(VirtualFrame frame, Object self, NotProvided includeAncestors) {
             return singletonMethods(frame, self, true);
         }
 
@@ -1591,7 +1591,7 @@ public SleepNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public long sleep(UndefinedPlaceholder duration) {
+        public long sleep(NotProvided duration) {
             // TODO: this should actually be "forever".
             return doSleepMillis(Long.MAX_VALUE);
         }
@@ -1613,7 +1613,7 @@ public long sleep(double duration) {
 
         @Specialization(guards = "isRubiniusUndefined(duration)")
         public long sleep(RubyBasicObject duration) {
-            return sleep(UndefinedPlaceholder.INSTANCE);
+            return sleep(NotProvided.INSTANCE);
         }
 
         @Specialization(guards = "!isRubiniusUndefined(duration)")

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
@@ -21,7 +21,7 @@
 import org.jruby.truffle.nodes.coerce.ToIntNodeGen;
 import org.jruby.truffle.nodes.core.array.ArrayNodes;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.util.ByteList;
@@ -41,7 +41,7 @@ public GetIndexNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object getIndex(RubyMatchData matchData, int index, UndefinedPlaceholder undefinedPlaceholder) {
+        public Object getIndex(RubyMatchData matchData, int index, NotProvided length) {
             CompilerDirectives.transferToInterpreter();
 
             final Object[] values = matchData.getValues();
@@ -65,13 +65,13 @@ public Object getIndex(RubyMatchData matchData, int index, int length) {
         }
 
         @Specialization
-        public Object getIndex(RubyMatchData matchData, RubySymbol index, UndefinedPlaceholder undefinedPlaceholder) {
+        public Object getIndex(RubyMatchData matchData, RubySymbol index, NotProvided length) {
             CompilerDirectives.transferToInterpreter();
 
             try {
                 final int i = matchData.getBackrefNumber(index.getSymbolBytes());
 
-                return getIndex(matchData, i, UndefinedPlaceholder.INSTANCE);
+                return getIndex(matchData, i, NotProvided.INSTANCE);
             } catch (final ValueException e) {
                 CompilerDirectives.transferToInterpreter();
 
@@ -81,13 +81,13 @@ public Object getIndex(RubyMatchData matchData, RubySymbol index, UndefinedPlace
         }
 
         @Specialization
-        public Object getIndex(RubyMatchData matchData, RubyString index, UndefinedPlaceholder undefinedPlaceholder) {
+        public Object getIndex(RubyMatchData matchData, RubyString index, NotProvided length) {
             CompilerDirectives.transferToInterpreter();
 
             try {
                 final int i = matchData.getBackrefNumber(index.getByteList());
 
-                return getIndex(matchData, i, UndefinedPlaceholder.INSTANCE);
+                return getIndex(matchData, i, NotProvided.INSTANCE);
             }
             catch (final ValueException e) {
                 CompilerDirectives.transferToInterpreter();
@@ -98,19 +98,19 @@ public Object getIndex(RubyMatchData matchData, RubyString index, UndefinedPlace
         }
 
         @Specialization(guards = {"!isRubySymbol(index)", "!isRubyString(index)", "!isIntegerFixnumRange(index)"})
-        public Object getIndex(VirtualFrame frame, RubyMatchData matchData, Object index, UndefinedPlaceholder undefinedPlaceholder) {
+        public Object getIndex(VirtualFrame frame, RubyMatchData matchData, Object index, NotProvided length) {
             CompilerDirectives.transferToInterpreter();
 
             if (toIntNode == null) {
                 CompilerDirectives.transferToInterpreter();
                 toIntNode = insert(ToIntNodeGen.create(getContext(), getSourceSection(), null));
             }
 
-            return getIndex(matchData, toIntNode.doInt(frame, index), UndefinedPlaceholder.INSTANCE);
+            return getIndex(matchData, toIntNode.doInt(frame, index), NotProvided.INSTANCE);
         }
 
         @Specialization(guards = {"!isRubySymbol(range)", "!isRubyString(range)"})
-        public Object getIndex(VirtualFrame frame, RubyMatchData matchData, RubyRange.IntegerFixnumRange range, UndefinedPlaceholder undefinedPlaceholder) {
+        public Object getIndex(VirtualFrame frame, RubyMatchData matchData, RubyRange.IntegerFixnumRange range, NotProvided len) {
             final Object[] values = matchData.getValues();
             final int normalizedIndex = ArrayNodes.normalizeIndex(values.length, range.getBegin());
             final int end = ArrayNodes.normalizeIndex(values.length, range.getEnd());

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/MathNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/MathNodes.java
@@ -21,7 +21,7 @@
 import org.jruby.truffle.nodes.dispatch.MissingBehavior;
 import org.jruby.truffle.nodes.dispatch.UseMethodMissingException;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.RubyArray;
 import org.jruby.truffle.runtime.core.RubyBasicObject;
@@ -619,27 +619,27 @@ public LogNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public double function(int a, UndefinedPlaceholder b) {
+        public double function(int a, NotProvided b) {
             return doFunction(a);
         }
 
         @Specialization
-        public double function(long a, UndefinedPlaceholder b) {
+        public double function(long a, NotProvided b) {
             return doFunction(a);
         }
 
         @Specialization(guards = "isRubyBignum(a)")
-        public double function(RubyBasicObject a, UndefinedPlaceholder b) {
+        public double function(RubyBasicObject a, NotProvided b) {
             return doFunction(BignumNodes.getBigIntegerValue(a).doubleValue());
         }
 
         @Specialization
-        public double function(double a, UndefinedPlaceholder b) {
+        public double function(double a, NotProvided b) {
             return doFunction(a);
         }
 
         @Specialization
-        public double function(VirtualFrame frame, Object a, UndefinedPlaceholder b) {
+        public double function(VirtualFrame frame, Object a, NotProvided b) {
             if (isANode.executeIsA(frame, a, getContext().getCoreLibrary().getNumericClass())) {
                 try {
                     return doFunction(

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/MethodNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/MethodNodes.java
@@ -28,7 +28,7 @@
 import org.jruby.truffle.nodes.objects.ClassNodeGen;
 import org.jruby.truffle.runtime.RubyArguments;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.methods.InternalMethod;
 import org.jruby.truffle.runtime.object.BasicObjectType;
@@ -133,7 +133,7 @@ public CallNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object call(VirtualFrame frame, RubyBasicObject method, Object[] arguments, UndefinedPlaceholder block) {
+        public Object call(VirtualFrame frame, RubyBasicObject method, Object[] arguments, NotProvided block) {
             return doCall(frame, method, arguments, null);
         }
 

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
@@ -598,27 +598,27 @@ protected RubyString toStr(VirtualFrame frame, Object object) {
         }
 
         @Specialization
-        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, UndefinedPlaceholder file, UndefinedPlaceholder line, UndefinedPlaceholder block) {
+        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, NotProvided file, NotProvided line, NotProvided block) {
             return classEvalSource(frame, module, code, "(eval)");
         }
 
         @Specialization
-        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, RubyString file, UndefinedPlaceholder line, UndefinedPlaceholder block) {
+        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, RubyString file, NotProvided line, NotProvided block) {
             return classEvalSource(frame, module, code, file.toString());
         }
 
         @Specialization
-        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, RubyString file, int line, UndefinedPlaceholder block) {
+        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, RubyString file, int line, NotProvided block) {
             return classEvalSource(frame, module, code, file.toString());
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(code)")
-        public Object classEval(VirtualFrame frame, RubyModule module, Object code, UndefinedPlaceholder file, UndefinedPlaceholder line, UndefinedPlaceholder block) {
+        @Specialization(guards = "!isNotProvided(code)")
+        public Object classEval(VirtualFrame frame, RubyModule module, Object code, NotProvided file, NotProvided line, NotProvided block) {
             return classEvalSource(frame, module, toStr(frame, code), file.toString());
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(file)")
-        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, Object file, UndefinedPlaceholder line, UndefinedPlaceholder block) {
+        @Specialization(guards = "!isNotProvided(file)")
+        public Object classEval(VirtualFrame frame, RubyModule module, RubyString code, Object file, NotProvided line, NotProvided block) {
             return classEvalSource(frame, module, code, toStr(frame, file).toString());
         }
 
@@ -638,18 +638,18 @@ public RubyNode wrap(RubyNode node) {
         }
 
         @Specialization
-        public Object classEval(VirtualFrame frame, RubyModule self, UndefinedPlaceholder code, UndefinedPlaceholder file, UndefinedPlaceholder line, RubyProc block) {
+        public Object classEval(VirtualFrame frame, RubyModule self, NotProvided code, NotProvided file, NotProvided line, RubyProc block) {
             return yield.dispatchWithModifiedSelf(frame, block, self);
         }
 
         @Specialization
-        public Object classEval(RubyModule self, UndefinedPlaceholder code, UndefinedPlaceholder file, UndefinedPlaceholder line, UndefinedPlaceholder block) {
+        public Object classEval(RubyModule self, NotProvided code, NotProvided file, NotProvided line, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
             throw new RaiseException(getContext().getCoreLibrary().argumentError(0, 1, 2, this));
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(code)")
-        public Object classEval(RubyModule self, Object code, UndefinedPlaceholder file, UndefinedPlaceholder line, RubyProc block) {
+        @Specialization(guards = "!isNotProvided(code)")
+        public Object classEval(RubyModule self, Object code, NotProvided file, NotProvided line, RubyProc block) {
             CompilerDirectives.transferToInterpreter();
             throw new RaiseException(getContext().getCoreLibrary().argumentError(1, 0, this));
         }
@@ -674,7 +674,7 @@ public Object classExec(VirtualFrame frame, RubyModule self, Object[] args, Ruby
         }
 
         @Specialization
-        public Object classExec(VirtualFrame frame, RubyModule self, Object[] args, UndefinedPlaceholder block) {
+        public Object classExec(VirtualFrame frame, RubyModule self, Object[] args, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
             throw new RaiseException(getContext().getCoreLibrary().noBlockGiven(this));
         }
@@ -775,7 +775,7 @@ private boolean booleanCast(VirtualFrame frame, Object value) {
         }
 
         @Specialization
-        public RubyArray constants(RubyModule module, UndefinedPlaceholder inherit) {
+        public RubyArray constants(RubyModule module, NotProvided inherit) {
             return constants(module, true);
         }
 
@@ -801,7 +801,7 @@ public RubyArray constants(RubyModule module, boolean inherit) {
             return ArrayNodes.fromObjects(getContext().getCoreLibrary().getArrayClass(), constantsArray.toArray(new Object[constantsArray.size()]));
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(inherit)")
+        @Specialization(guards = "!isNotProvided(inherit)")
         public RubyArray constants(VirtualFrame frame, RubyModule module, Object inherit) {
             return constants(module, booleanCast(frame, inherit));
         }
@@ -826,7 +826,7 @@ public RubyNode coerceToString(RubyNode name) {
         }
 
         @Specialization
-        public boolean isConstDefined(RubyModule module, String name, UndefinedPlaceholder inherit) {
+        public boolean isConstDefined(RubyModule module, String name, NotProvided inherit) {
             return isConstDefined(module, name, true);
         }
 
@@ -861,7 +861,7 @@ public RubyNode coerceToString(RubyNode name) {
 
         // Symbol
         @Specialization
-        public Object getConstant(VirtualFrame frame, RubyModule module, RubySymbol name, UndefinedPlaceholder inherit) {
+        public Object getConstant(VirtualFrame frame, RubyModule module, RubySymbol name, NotProvided inherit) {
             return getConstant(frame, module, name, true);
         }
 
@@ -877,7 +877,7 @@ public Object getConstantNoInherit(VirtualFrame frame, RubyModule module, RubySy
 
         // String
         @Specialization(guards = "!isScoped(name)")
-        public Object getConstant(VirtualFrame frame, RubyModule module, RubyString name, UndefinedPlaceholder inherit) {
+        public Object getConstant(VirtualFrame frame, RubyModule module, RubyString name, NotProvided inherit) {
             return getConstant(frame, module, name, true);
         }
 
@@ -893,7 +893,7 @@ public Object getConstantNoInherit(VirtualFrame frame, RubyModule module, RubySt
 
         // Scoped String
         @Specialization(guards = "isScoped(fullName)")
-        public Object getConstantScoped(VirtualFrame frame, RubyModule module, RubyString fullName, UndefinedPlaceholder inherit) {
+        public Object getConstantScoped(VirtualFrame frame, RubyModule module, RubyString fullName, NotProvided inherit) {
             return getConstantScoped(frame, module, fullName, true);
         }
 
@@ -998,31 +998,31 @@ public RubyNode coerceToString(RubyNode name) {
 
         @TruffleBoundary
         @Specialization
-        public RubySymbol defineMethod(RubyModule module, String name, UndefinedPlaceholder proc, UndefinedPlaceholder block) {
+        public RubySymbol defineMethod(RubyModule module, String name, NotProvided proc, NotProvided block) {
             throw new RaiseException(getContext().getCoreLibrary().argumentError("needs either proc or block", this));
         }
 
         @TruffleBoundary
         @Specialization
-        public RubySymbol defineMethod(RubyModule module, String name, UndefinedPlaceholder proc, RubyProc block) {
-            return defineMethod(module, name, block, UndefinedPlaceholder.INSTANCE);
+        public RubySymbol defineMethod(RubyModule module, String name, NotProvided proc, RubyProc block) {
+            return defineMethod(module, name, block, NotProvided.INSTANCE);
         }
 
         @TruffleBoundary
         @Specialization
-        public RubySymbol defineMethod(RubyModule module, String name, RubyProc proc, UndefinedPlaceholder block) {
+        public RubySymbol defineMethod(RubyModule module, String name, RubyProc proc, NotProvided block) {
             return defineMethod(module, name, proc);
         }
 
         @TruffleBoundary
         @Specialization(guards = "isRubyMethod(method)")
-        public RubySymbol defineMethod(RubyModule module, String name, RubyBasicObject method, UndefinedPlaceholder block) {
+        public RubySymbol defineMethod(RubyModule module, String name, RubyBasicObject method, NotProvided block) {
             module.addMethod(this, MethodNodes.getMethod(method).withName(name));
             return getContext().getSymbolTable().getSymbol(name);
         }
 
         @Specialization(guards = "isRubyUnboundMethod(method)")
-        public RubySymbol defineMethod(VirtualFrame frame, RubyModule module, String name, RubyBasicObject method, UndefinedPlaceholder block) {
+        public RubySymbol defineMethod(VirtualFrame frame, RubyModule module, String name, RubyBasicObject method, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
 
             RubyModule origin = UnboundMethodNodes.getOrigin(method);
@@ -1102,7 +1102,7 @@ void classEval(VirtualFrame frame, RubyModule module, RubyProc block) {
         }
 
         @Specialization
-        public RubyModule initialize(RubyModule module, UndefinedPlaceholder block) {
+        public RubyModule initialize(RubyModule module, NotProvided block) {
             return module;
         }
 
@@ -1201,7 +1201,7 @@ public RubyNode coerceToString(RubyNode name) {
         }
 
         @Specialization
-        public boolean isMethodDefined(RubyModule module, String name, UndefinedPlaceholder inherit) {
+        public boolean isMethodDefined(RubyModule module, String name, NotProvided inherit) {
             return isMethodDefined(module, name, true);
         }
 
@@ -1411,7 +1411,7 @@ public ProtectedInstanceMethodsNode(RubyContext context, SourceSection sourceSec
         }
 
         @Specialization
-        public RubyArray protectedInstanceMethods(RubyModule module, UndefinedPlaceholder argument) {
+        public RubyArray protectedInstanceMethods(RubyModule module, NotProvided includeAncestors) {
             return protectedInstanceMethods(module, true);
         }
 
@@ -1459,7 +1459,7 @@ public PrivateInstanceMethodsNode(RubyContext context, SourceSection sourceSecti
         }
 
         @Specialization
-        public RubyArray privateInstanceMethods(RubyModule module, UndefinedPlaceholder argument) {
+        public RubyArray privateInstanceMethods(RubyModule module, NotProvided includeAncestors) {
             return privateInstanceMethods(module, true);
         }
 
@@ -1516,7 +1516,7 @@ public PublicInstanceMethodsNode(RubyContext context, SourceSection sourceSectio
         }
 
         @Specialization
-        public RubyArray publicInstanceMethods(RubyModule module, UndefinedPlaceholder argument) {
+        public RubyArray publicInstanceMethods(RubyModule module, NotProvided includeAncestors) {
             return publicInstanceMethods(module, true);
         }
 
@@ -1563,7 +1563,7 @@ public InstanceMethodsNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray instanceMethods(RubyModule module, UndefinedPlaceholder argument) {
+        public RubyArray instanceMethods(RubyModule module, NotProvided argument) {
             return instanceMethods(module, true);
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ObjectSpaceNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ObjectSpaceNodes.java
@@ -18,7 +18,7 @@
 import org.jruby.truffle.nodes.core.array.ArrayNodes;
 import org.jruby.truffle.runtime.ModuleOperations;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.object.ObjectIDOperations;
 
@@ -87,7 +87,7 @@ public EachObjectNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public int eachObject(VirtualFrame frame, UndefinedPlaceholder ofClass, RubyProc block) {
+        public int eachObject(VirtualFrame frame, NotProvided ofClass, RubyProc block) {
             CompilerDirectives.transferToInterpreter();
 
             int count = 0;

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ProcNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ProcNodes.java
@@ -27,7 +27,7 @@
 import org.jruby.truffle.nodes.yield.YieldDispatchHeadNode;
 import org.jruby.truffle.runtime.RubyArguments;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.util.Memo;
@@ -78,7 +78,7 @@ public CallNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object call(VirtualFrame frame, RubyProc proc, Object[] args, UndefinedPlaceholder block) {
+        public Object call(VirtualFrame frame, RubyProc proc, Object[] args, NotProvided block) {
             return yieldNode.dispatch(frame, proc, args);
         }
 
@@ -107,7 +107,7 @@ public RubyBasicObject initialize(RubyProc proc, RubyProc block) {
 
         @TruffleBoundary
         @Specialization
-        public RubyBasicObject initialize(RubyProc proc, UndefinedPlaceholder block) {
+        public RubyBasicObject initialize(RubyProc proc, NotProvided block) {
             final Memo<Integer> frameCount = new Memo<>(0);
 
             // The parent will be the Proc.new call.  We need to go an extra level up in order to get the parent

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ProcessNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ProcessNodes.java
@@ -15,7 +15,7 @@
 import com.oracle.truffle.api.source.SourceSection;
 
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.core.RubySymbol;
 import org.jruby.truffle.runtime.signal.SignalOperations;
 
@@ -40,12 +40,12 @@ public ClockGetTimeNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization(guards = "isMonotonic(clock_id)")
-        Object clock_gettime_monotonic(int clock_id, UndefinedPlaceholder unit) {
+        Object clock_gettime_monotonic(int clock_id, NotProvided unit) {
             return clock_gettime_monotonic(CLOCK_MONOTONIC, floatSecondSymbol);
         }
 
         @Specialization(guards = "isRealtime(clock_id)")
-        Object clock_gettime_realtime(int clock_id, UndefinedPlaceholder unit) {
+        Object clock_gettime_realtime(int clock_id, NotProvided unit) {
             return clock_gettime_realtime(CLOCK_REALTIME, floatSecondSymbol);
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/RangeNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/RangeNodes.java
@@ -16,7 +16,7 @@
 import com.oracle.truffle.api.utilities.BranchProfile;
 import org.jruby.truffle.nodes.core.array.ArrayBuilderNode;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.NextException;
 import org.jruby.truffle.runtime.control.RedoException;
 import org.jruby.truffle.runtime.core.RubyArray;
@@ -146,12 +146,12 @@ public Object each(VirtualFrame frame, RubyRange.LongFixnumRange range, RubyProc
         }
 
         @Specialization
-        public Object each(VirtualFrame frame, RubyRange.LongFixnumRange range, UndefinedPlaceholder proc) {
+        public Object each(VirtualFrame frame, RubyRange.LongFixnumRange range, NotProvided proc) {
             return ruby(frame, "each_internal(&block)", "block", nil());
         }
 
         @Specialization
-        public Object each(VirtualFrame frame, RubyRange.ObjectRange range, UndefinedPlaceholder proc) {
+        public Object each(VirtualFrame frame, RubyRange.ObjectRange range, NotProvided proc) {
             return ruby(frame, "each_internal(&block)", "block", nil());
         }
 
@@ -208,7 +208,7 @@ public InitializeNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyRange.ObjectRange initialize(RubyRange.ObjectRange range, Object begin, Object end, UndefinedPlaceholder undefined) {
+        public RubyRange.ObjectRange initialize(RubyRange.ObjectRange range, Object begin, Object end, NotProvided excludeEnd) {
             return initialize(range, begin, end, false);
         }
 
@@ -318,63 +318,63 @@ public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, int step
             return range;
         }
 
-        @Specialization(guards = {"!isStepValidInt(range, step, block)","!isUndefinedPlaceholder(step)"})
+        @Specialization(guards = { "!isStepValidInt(range, step, block)", "!isNotProvided(step)" })
         public Object stepFallback(VirtualFrame frame, RubyRange.IntegerFixnumRange range, Object step, RubyProc block) {
             return ruby(frame, "step_internal(step, &block)", "step", step, "block", block);
         }
 
-        @Specialization(guards = {"!isStepValidInt(range, step, block)","!isUndefinedPlaceholder(step)"})
+        @Specialization(guards = { "!isStepValidInt(range, step, block)", "!isNotProvided(step)" })
         public Object stepFallback(VirtualFrame frame, RubyRange.LongFixnumRange range, Object step, RubyProc block) {
             return ruby(frame, "step_internal(step, &block)", "step", step, "block", block);
         }
 
         @Specialization
-        public Object step(VirtualFrame frame, RubyRange.IntegerFixnumRange range, UndefinedPlaceholder step, UndefinedPlaceholder block) {
+        public Object step(VirtualFrame frame, RubyRange.IntegerFixnumRange range, NotProvided step, NotProvided block) {
             return ruby(frame, "step_internal");
         }
 
         @Specialization
-        public Object step(VirtualFrame frame, RubyRange.IntegerFixnumRange range, UndefinedPlaceholder step, RubyProc block) {
+        public Object step(VirtualFrame frame, RubyRange.IntegerFixnumRange range, NotProvided step, RubyProc block) {
             return ruby(frame, "step_internal(&block)", "block", block);
         }
 
-        @Specialization(guards = {"!isInteger(step)","!isLong(step)","!isUndefinedPlaceholder(step)"})
-        public Object step(VirtualFrame frame, RubyRange.IntegerFixnumRange range, Object step, UndefinedPlaceholder block) {
+        @Specialization(guards = { "!isInteger(step)", "!isLong(step)", "!isNotProvided(step)" })
+        public Object step(VirtualFrame frame, RubyRange.IntegerFixnumRange range, Object step, NotProvided block) {
             return ruby(frame, "step_internal(step)", "step", step);
         }
 
         @Specialization
-        public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, UndefinedPlaceholder step, UndefinedPlaceholder block) {
+        public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, NotProvided step, NotProvided block) {
             return ruby(frame, "step_internal");
         }
 
         @Specialization
-        public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, UndefinedPlaceholder step, RubyProc block) {
+        public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, NotProvided step, RubyProc block) {
             return ruby(frame, "step_internal(&block)", "block", block);
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(step)")
-        public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, Object step, UndefinedPlaceholder block) {
+        @Specialization(guards = "!isNotProvided(step)")
+        public Object step(VirtualFrame frame, RubyRange.LongFixnumRange range, Object step, NotProvided block) {
             return ruby(frame, "step_internal(step)", "step", step);
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(step)")
+        @Specialization(guards = "!isNotProvided(step)")
         public Object step(VirtualFrame frame, RubyRange.ObjectRange range, Object step, RubyProc block) {
             return ruby(frame, "step_internal(step, &block)", "step", step, "block", block);
         }
 
         @Specialization
-        public Object step(VirtualFrame frame, RubyRange.ObjectRange range, UndefinedPlaceholder step, UndefinedPlaceholder block) {
+        public Object step(VirtualFrame frame, RubyRange.ObjectRange range, NotProvided step, NotProvided block) {
             return ruby(frame, "step_internal");
         }
 
         @Specialization
-        public Object step(VirtualFrame frame, RubyRange.ObjectRange range, UndefinedPlaceholder step, RubyProc block) {
+        public Object step(VirtualFrame frame, RubyRange.ObjectRange range, NotProvided step, RubyProc block) {
             return ruby(frame, "step_internal(&block)", "block", block);
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(step)")
-        public Object step(VirtualFrame frame, RubyRange.ObjectRange range, Object step, UndefinedPlaceholder block) {
+        @Specialization(guards = "!isNotProvided(step)")
+        public Object step(VirtualFrame frame, RubyRange.ObjectRange range, Object step, NotProvided block) {
             return ruby(frame, "step_internal(step)", "step", step);
         }
 

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
@@ -59,7 +59,7 @@
 import org.jruby.truffle.nodes.rubinius.StringPrimitiveNodes;
 import org.jruby.truffle.nodes.rubinius.StringPrimitiveNodesFactory;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.rubinius.RubiniusByteArray;
@@ -474,7 +474,7 @@ public GetIndexNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public Object getIndex(VirtualFrame frame, RubyString string, int index, UndefinedPlaceholder undefined) {
+        public Object getIndex(VirtualFrame frame, RubyString string, int index, NotProvided length) {
             int normalizedIndex = normalizeIndex(string, index);
             final ByteList bytes = string.getByteList();
 
@@ -487,23 +487,23 @@ public Object getIndex(VirtualFrame frame, RubyString string, int index, Undefin
         }
 
         @Specialization(guards = { "!isRubyRange(index)", "!isRubyRegexp(index)", "!isRubyString(index)" })
-        public Object getIndex(VirtualFrame frame, RubyString string, Object index, UndefinedPlaceholder undefined) {
-            return getIndex(frame, string, getToIntNode().doInt(frame, index), undefined);
+        public Object getIndex(VirtualFrame frame, RubyString string, Object index, NotProvided length) {
+            return getIndex(frame, string, getToIntNode().doInt(frame, index), length);
         }
 
         @Specialization
-        public Object sliceIntegerRange(VirtualFrame frame, RubyString string, RubyRange.IntegerFixnumRange range, UndefinedPlaceholder undefined) {
+        public Object sliceIntegerRange(VirtualFrame frame, RubyString string, RubyRange.IntegerFixnumRange range, NotProvided length) {
             return sliceRange(frame, string, range.getBegin(), range.getEnd(), range.doesExcludeEnd());
         }
 
         @Specialization
-        public Object sliceLongRange(VirtualFrame frame, RubyString string, RubyRange.LongFixnumRange range, UndefinedPlaceholder undefined) {
+        public Object sliceLongRange(VirtualFrame frame, RubyString string, RubyRange.LongFixnumRange range, NotProvided length) {
             // TODO (nirvdrum 31-Mar-15) The begin and end values should be properly lowered, only if possible.
             return sliceRange(frame, string, (int) range.getBegin(), (int) range.getEnd(), range.doesExcludeEnd());
         }
 
         @Specialization
-        public Object sliceObjectRange(VirtualFrame frame, RubyString string, RubyRange.ObjectRange range, UndefinedPlaceholder undefined) {
+        public Object sliceObjectRange(VirtualFrame frame, RubyString string, RubyRange.ObjectRange range, NotProvided length) {
             // TODO (nirvdrum 31-Mar-15) The begin and end values may return Fixnums beyond int boundaries and we should handle that -- Bignums are always errors.
             final int coercedBegin = getToIntNode().doInt(frame, range.getBegin());
             final int coercedEnd = getToIntNode().doInt(frame, range.getEnd());
@@ -551,29 +551,29 @@ public Object slice(VirtualFrame frame, RubyString string, int start, int length
             return getSubstringNode().execute(frame, string, start, length);
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(length)")
+        @Specialization(guards = "!isNotProvided(length)")
         public Object slice(VirtualFrame frame, RubyString string, int start, Object length) {
             return slice(frame, string, start, getToIntNode().doInt(frame, length));
         }
 
-        @Specialization(guards = { "!isRubyRange(start)", "!isRubyRegexp(start)", "!isRubyString(start)", "!isUndefinedPlaceholder(length)" })
+        @Specialization(guards = { "!isRubyRange(start)", "!isRubyRegexp(start)", "!isRubyString(start)", "!isNotProvided(length)" })
         public Object slice(VirtualFrame frame, RubyString string, Object start, Object length) {
             return slice(frame, string, getToIntNode().doInt(frame, start), getToIntNode().doInt(frame, length));
         }
 
         @Specialization
-        public Object slice(VirtualFrame frame, RubyString string, RubyRegexp regexp, UndefinedPlaceholder capture) {
+        public Object slice(VirtualFrame frame, RubyString string, RubyRegexp regexp, NotProvided capture) {
             return slice(frame, string, regexp, 0);
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(capture)")
+        @Specialization(guards = "!isNotProvided(capture)")
         public Object slice(VirtualFrame frame, RubyString string, RubyRegexp regexp, Object capture) {
             // Extracted from Rubinius's definition of String#[].
             return ruby(frame, "match, str = subpattern(index, other); Regexp.last_match = match; str", "index", regexp, "other", capture);
         }
 
         @Specialization
-        public Object slice(VirtualFrame frame, RubyString string, RubyString matchStr, UndefinedPlaceholder undefined) {
+        public Object slice(VirtualFrame frame, RubyString string, RubyString matchStr, NotProvided length) {
             if (includeNode == null) {
                 CompilerDirectives.transferToInterpreter();
                 includeNode = insert(DispatchHeadNodeFactory.createMethodCall(getContext()));
@@ -1226,7 +1226,7 @@ public InitializeNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyString initialize(RubyString self, UndefinedPlaceholder from) {
+        public RubyString initialize(RubyString self, NotProvided from) {
             return self;
         }
 
@@ -1250,7 +1250,7 @@ public RubyString initialize(RubyString self, RubyString from) {
             return self;
         }
 
-        @Specialization(guards = { "!isRubyString(from)", "!isUndefinedPlaceholder(from)" })
+        @Specialization(guards = { "!isRubyString(from)", "!isNotProvided(from)" })
         public RubyString initialize(VirtualFrame frame, RubyString self, Object from) {
             if (toStrNode == null) {
                 CompilerDirectives.transferToInterpreter();
@@ -1679,7 +1679,7 @@ public ScanNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyArray scan(RubyString string, RubyString regexpString, UndefinedPlaceholder block) {
+        public RubyArray scan(RubyString string, RubyString regexpString, NotProvided block) {
             final RubyRegexp regexp = new RubyRegexp(this, getContext().getCoreLibrary().getRegexpClass(), regexpString.getByteList(), Option.DEFAULT);
             return scan(string, regexp, block);
         }
@@ -1691,7 +1691,7 @@ public RubyString scan(VirtualFrame frame, RubyString string, RubyString regexpS
         }
 
         @Specialization
-        public RubyArray scan(RubyString string, RubyRegexp regexp, UndefinedPlaceholder block) {
+        public RubyArray scan(RubyString string, RubyRegexp regexp, NotProvided block) {
             return ArrayNodes.fromObjects(getContext().getCoreLibrary().getArrayClass(), (Object[]) regexp.scan(string));
         }
 
@@ -1993,11 +1993,11 @@ public Object sum(VirtualFrame frame, RubyString string, long bits) {
         }
 
         @Specialization
-        public Object sum(VirtualFrame frame, RubyString string, UndefinedPlaceholder bits) {
+        public Object sum(VirtualFrame frame, RubyString string, NotProvided bits) {
             return sum(frame, string, 16);
         }
 
-        @Specialization(guards = {"!isInteger(bits)", "!isLong(bits)", "!isUndefinedPlaceholder(bits)"})
+        @Specialization(guards = { "!isInteger(bits)", "!isLong(bits)", "!isNotProvided(bits)" })
         public Object sum(VirtualFrame frame, RubyString string, Object bits) {
             return ruby(frame, "sum Rubinius::Type.coerce_to(bits, Fixnum, :to_int)", "bits", bits);
         }

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/ThreadNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/ThreadNodes.java
@@ -18,7 +18,7 @@
 import org.jruby.truffle.nodes.dispatch.CallDispatchHeadNode;
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.subsystems.SafepointAction;
@@ -100,14 +100,14 @@ public JoinNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyThread join(RubyThread thread, UndefinedPlaceholder timeout) {
+        public RubyThread join(RubyThread thread, NotProvided timeout) {
             thread.join();
             return thread;
         }
 
         @Specialization(guards = "isNil(nil)")
         public RubyThread join(RubyThread thread, Object nil) {
-            return join(thread, UndefinedPlaceholder.INSTANCE);
+            return join(thread, NotProvided.INSTANCE);
         }
 
         @Specialization
@@ -173,12 +173,12 @@ public RaiseNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyBasicObject raise(VirtualFrame frame, RubyThread thread, RubyString message, UndefinedPlaceholder undefined) {
+        public RubyBasicObject raise(VirtualFrame frame, RubyThread thread, RubyString message, NotProvided unused) {
             return raise(frame, thread, getContext().getCoreLibrary().getRuntimeErrorClass(), message);
         }
 
         @Specialization
-        public RubyBasicObject raise(VirtualFrame frame, RubyThread thread, RubyClass exceptionClass, UndefinedPlaceholder message) {
+        public RubyBasicObject raise(VirtualFrame frame, RubyThread thread, RubyClass exceptionClass, NotProvided message) {
             return raise(frame, thread, exceptionClass, getContext().makeString(""));
         }
 

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
diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/fixnum/FixnumLowerNode.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/fixnum/FixnumLowerNode.java
@@ -13,7 +13,7 @@
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.UnexpectedResultException;
 import org.jruby.truffle.nodes.RubyNode;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.core.CoreLibrary;
 import org.jruby.truffle.runtime.core.RubyBasicObject;
 import org.jruby.truffle.runtime.core.RubyRange;
@@ -69,7 +69,7 @@ public Object execute(VirtualFrame frame) {
             }
         }
 
-        if (hasSeenUndefined && value instanceof UndefinedPlaceholder) {
+        if (hasSeenUndefined && value instanceof NotProvided) {
             return value;
         }
 
@@ -103,7 +103,7 @@ public Object execute(VirtualFrame frame) {
             }
         }
 
-        if (value instanceof UndefinedPlaceholder) {
+        if (value instanceof NotProvided) {
             hasSeenUndefined = true;
             return value;
         }
@@ -177,9 +177,9 @@ public RubyRange.LongFixnumRange executeLongFixnumRange(VirtualFrame frame) thro
     }
 
     @Override
-    public UndefinedPlaceholder executeUndefinedPlaceholder(VirtualFrame frame) throws UnexpectedResultException {
+    public NotProvided executeNotProvided(VirtualFrame frame) throws UnexpectedResultException {
         try {
-            return super.executeUndefinedPlaceholder(frame);
+            return super.executeNotProvided(frame);
         } catch (UnexpectedResultException e) {
             if (e.getResult() instanceof Long && canLower((long) e.getResult())) {
                 hasNeededToLowerLongFixnum = true;

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/fixnum/FixnumNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/fixnum/FixnumNodes.java
@@ -23,7 +23,7 @@
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.nodes.methods.UnsupportedOperationBehavior;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.RubyArray;
 import org.jruby.truffle.runtime.core.RubyBasicObject;
@@ -92,11 +92,6 @@ public long addWithOverflow(int a, int b) {
             return (long) a + (long) b;
         }
 
-        @Specialization
-        public double add(int a, double b) {
-            return a + b;
-        }
-
         @Specialization(guards = "!isRubyBignum(b)")
         public Object addCoerced(VirtualFrame frame, int a, RubyBasicObject b) {
             return ruby(frame, "redo_coerced :+, b", "b", b);
@@ -146,11 +141,6 @@ public long subWithOverflow(int a, int b) {
             return (long) a - (long) b;
         }
 
-        @Specialization
-        public double sub(int a, double b) {
-            return a - b;
-        }
-
         @Specialization(guards = "!isRubyBignum(b)")
         public Object subCoerced(VirtualFrame frame, int a, RubyBasicObject b) {
             return ruby(frame, "redo_coerced :-, b", "b", b);
@@ -200,11 +190,6 @@ public long mulWithOverflow(int a, int b) {
             return (long) a * (long) b;
         }
 
-        @Specialization
-        public double mul(int a, double b) {
-            return a * b;
-        }
-
         @Specialization(guards = "!isRubyBignum(b)")
         public Object mulCoerced(VirtualFrame frame, int a, RubyBasicObject b) {
             return ruby(frame, "redo_coerced :*, b", "b", b);
@@ -312,11 +297,6 @@ public Object divEdgeCase(int a, int b) {
             }
         }
 
-        @Specialization
-        public double div(int a, double b) {
-            return a / b;
-        }
-
         @Specialization(guards = "!isRubyBignum(b)")
         public Object divCoerced(VirtualFrame frame, int a, RubyBasicObject b) {
             return ruby(frame, "redo_coerced :/, b", "b", b);
@@ -474,11 +454,6 @@ public DivModNode(RubyContext context, SourceSection sourceSection) {
             divModNode = new GeneralDivModNode(context, sourceSection);
         }
 
-        @Specialization
-        public RubyArray divMod(int a, double b) {
-            return divModNode.execute(a, b);
-        }
-
         @Specialization
         public RubyArray divMod(long a, long b) {
             return divModNode.execute(a, b);
@@ -508,11 +483,6 @@ public boolean less(int a, int b) {
             return a < b;
         }
 
-        @Specialization
-        public boolean less(int a, double b) {
-            return a < b;
-        }
-
         @Specialization(guards = "isRubyBignum(b)")
         public boolean less(int a, RubyBasicObject b) {
             return BigInteger.valueOf(a).compareTo(BignumNodes.getBigIntegerValue(b)) < 0;
@@ -552,11 +522,6 @@ public boolean lessEqual(int a, int b) {
             return a <= b;
         }
 
-        @Specialization
-        public boolean lessEqual(int a, double b) {
-            return a <= b;
-        }
-
         @Specialization(guards = "isRubyBignum(b)")
         public boolean lessEqual(int a, RubyBasicObject b) {
             return BigInteger.valueOf(a).compareTo(BignumNodes.getBigIntegerValue(b)) <= 0;
@@ -593,11 +558,6 @@ public boolean equal(int a, int b) {
             return a == b;
         }
 
-        @Specialization
-        public boolean equal(int a, double b) {
-            return a == b;
-        }
-
         @Specialization(guards = "isRubyBignum(b)")
         public boolean equal(int a, RubyBasicObject b) {
             return false;
@@ -641,11 +601,6 @@ public int compare(int a, int b) {
             return Integer.compare(a, b);
         }
 
-        @Specialization
-        public int compare(int a, double b) {
-            return Double.compare(a, b);
-        }
-
         @Specialization(guards = "isRubyBignum(b)")
         public int compare(int a, RubyBasicObject b) {
             return BigInteger.valueOf(a).compareTo(BignumNodes.getBigIntegerValue(b));
@@ -689,11 +644,6 @@ public boolean greaterEqual(int a, int b) {
             return a >= b;
         }
 
-        @Specialization
-        public boolean greaterEqual(int a, double b) {
-            return a >= b;
-        }
-
         @Specialization(guards = "isRubyBignum(b)")
         public boolean greaterEqual(int a, RubyBasicObject b) {
             return BigInteger.valueOf(a).compareTo(BignumNodes.getBigIntegerValue(b)) >= 0;
@@ -727,11 +677,6 @@ public boolean greater(int a, int b) {
             return a > b;
         }
 
-        @Specialization
-        public boolean greater(int a, double b) {
-            return a > b;
-        }
-
         @Specialization(guards = "isRubyBignum(b)")
         public boolean greater(int a, RubyBasicObject b) {
             return BigInteger.valueOf(a).compareTo(BignumNodes.getBigIntegerValue(b)
@@ -1195,13 +1140,13 @@ public ToSNode(RubyContext context, SourceSection sourceSection) {
 
         @TruffleBoundary
         @Specialization
-        public RubyString toS(int n, UndefinedPlaceholder undefined) {
+        public RubyString toS(int n, NotProvided base) {
             return getContext().makeString(Integer.toString(n));
         }
 
         @TruffleBoundary
         @Specialization
-        public RubyString toS(long n, UndefinedPlaceholder undefined) {
+        public RubyString toS(long n, NotProvided base) {
             return getContext().makeString(Long.toString(n));
         }
 

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/core/hash/HashNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/core/hash/HashNodes.java
@@ -28,7 +28,7 @@
 import org.jruby.truffle.nodes.yield.YieldDispatchHeadNode;
 import org.jruby.truffle.runtime.RubyArguments;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.hash.*;
@@ -555,7 +555,7 @@ public DeleteNode(RubyContext context, SourceSection sourceSection) {
         public Object deleteNull(VirtualFrame frame, RubyHash hash, Object key, Object block) {
             assert HashOperations.verifyStore(hash);
 
-            if (block == UndefinedPlaceholder.INSTANCE) {
+            if (block == NotProvided.INSTANCE) {
                 return nil();
             } else {
                 return yieldNode.dispatch(frame, (RubyProc) block, key);
@@ -587,7 +587,7 @@ public Object deletePackedArray(VirtualFrame frame, RubyHash hash, Object key, O
 
             assert HashOperations.verifyStore(hash);
 
-            if (block == UndefinedPlaceholder.INSTANCE) {
+            if (block == NotProvided.INSTANCE) {
                 return nil();
             } else {
                 return yieldNode.dispatch(frame, (RubyProc) block, key);
@@ -601,7 +601,7 @@ public Object delete(VirtualFrame frame, RubyHash hash, Object key, Object block
             final HashLookupResult hashLookupResult = lookupEntryNode.lookup(frame, hash, key);
 
             if (hashLookupResult.getEntry() == null) {
-                if (block == UndefinedPlaceholder.INSTANCE) {
+                if (block == NotProvided.INSTANCE) {
                     return nil();
                 } else {
                     return yieldNode.dispatch(frame, (RubyProc) block, key);
@@ -704,7 +704,7 @@ private Collection<KeyValue> verySlowToKeyValues(RubyHash hash) {
         }
 
         @Specialization
-        public Object each(VirtualFrame frame, RubyHash hash, UndefinedPlaceholder block) {
+        public Object each(VirtualFrame frame, RubyHash hash, NotProvided block) {
             if (toEnumNode == null) {
                 CompilerDirectives.transferToInterpreter();
                 toEnumNode = insert(DispatchHeadNodeFactory.createMethodCallOnSelf(getContext()));
@@ -745,30 +745,30 @@ public InitializeNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public RubyHash initialize(RubyHash hash, UndefinedPlaceholder defaultValue, UndefinedPlaceholder block) {
+        public RubyHash initialize(RubyHash hash, NotProvided defaultValue, NotProvided block) {
             setStore(hash, null, 0, null, null);
             setDefaultValue(hash, null);
             setDefaultBlock(hash, null);
             return hash;
         }
 
         @Specialization
-        public RubyHash initialize(RubyHash hash, UndefinedPlaceholder defaultValue, RubyProc block) {
+        public RubyHash initialize(RubyHash hash, NotProvided defaultValue, RubyProc block) {
             setStore(hash, null, 0, null, null);
             setDefaultValue(hash, null);
             setDefaultBlock(hash, block);
             return hash;
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(defaultValue)")
-        public RubyHash initialize(RubyHash hash, Object defaultValue, UndefinedPlaceholder block) {
+        @Specialization(guards = "!isNotProvided(defaultValue)")
+        public RubyHash initialize(RubyHash hash, Object defaultValue, NotProvided block) {
             setStore(hash, null, 0, null, null);
             setDefaultValue(hash, defaultValue);
             setDefaultBlock(hash, null);
             return hash;
         }
 
-        @Specialization(guards = "!isUndefinedPlaceholder(defaultValue)")
+        @Specialization(guards = "!isNotProvided(defaultValue)")
         public Object initialize(RubyHash hash, Object defaultValue, RubyProc block) {
             CompilerDirectives.transferToInterpreter();
             throw new RaiseException(getContext().getCoreLibrary().argumentError("wrong number of arguments (1 for 0)", this));
@@ -925,15 +925,15 @@ public MergeNode(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization(guards = {"isPackedArrayStorage(hash)", "isNullStorage(other)", "!isCompareByIdentity(hash)"})
-        public RubyHash mergePackedArrayNull(RubyHash hash, RubyHash other, UndefinedPlaceholder block) {
+        public RubyHash mergePackedArrayNull(RubyHash hash, RubyHash other, NotProvided block) {
             final Object[] store = (Object[]) getStore(hash);
             final Object[] copy = PackedArrayStrategy.copyStore(store);
             return new RubyHash(hash.getLogicalClass(), getDefaultBlock(hash), getDefaultValue(hash), copy, getSize(hash), null);
         }
 
         @ExplodeLoop
         @Specialization(guards = {"isPackedArrayStorage(hash)", "isPackedArrayStorage(other)", "!isCompareByIdentity(hash)"})
-        public RubyHash mergePackedArrayPackedArray(VirtualFrame frame, RubyHash hash, RubyHash other, UndefinedPlaceholder block) {
+        public RubyHash mergePackedArrayPackedArray(VirtualFrame frame, RubyHash hash, RubyHash other, NotProvided block) {
             // TODO(CS): what happens with the default block here? Which side does it get merged from?
             assert HashOperations.verifyStore(hash);
             assert HashOperations.verifyStore(other);
@@ -1022,7 +1022,7 @@ public RubyHash mergePackedArrayPackedArray(VirtualFrame frame, RubyHash hash, R
 
         // TODO CS 3-Mar-15 need negative guards on this
         @Specialization(guards = "!isCompareByIdentity(hash)")
-        public RubyHash mergeBucketsBuckets(RubyHash hash, RubyHash other, UndefinedPlaceholder block) {
+        public RubyHash mergeBucketsBuckets(RubyHash hash, RubyHash other, NotProvided block) {
             CompilerDirectives.transferToInterpreter();
 
             final RubyHash merged = new RubyHash(hash.getLogicalClass(), null, null, new Entry[BucketsStrategy.capacityGreaterThan(getSize(hash) + getSize(other))], 0, null);
@@ -1091,7 +1091,7 @@ public Object merge(VirtualFrame frame, RubyHash hash, Object other, Object bloc
 
             final RubyProc blockProc;
 
-            if (block == UndefinedPlaceholder.INSTANCE) {
+            if (block == NotProvided.INSTANCE) {
                 blockProc = null;
             } else {
                 blockProc = (RubyProc) block;

diff --git a/truffle/src/main/java/org/jruby/truffle/nodes/ext/ZlibNodes.java b/truffle/src/main/java/org/jruby/truffle/nodes/ext/ZlibNodes.java
@@ -21,7 +21,7 @@
 import org.jruby.truffle.nodes.core.CoreMethod;
 import org.jruby.truffle.nodes.core.CoreMethodArrayArgumentsNode;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.RubyBasicObject;
 import org.jruby.truffle.runtime.core.RubyString;
@@ -48,13 +48,13 @@ public CRC32Node(RubyContext context, SourceSection sourceSection) {
         }
 
         @Specialization
-        public int crc32(UndefinedPlaceholder message, UndefinedPlaceholder initial) {
+        public int crc32(NotProvided message, NotProvided initial) {
             return 0;
         }
 
         @TruffleBoundary
         @Specialization
-        public long crc32(RubyString message, UndefinedPlaceholder initial) {
+        public long crc32(RubyString message, NotProvided initial) {
             final ByteList bytes = message.getByteList();
             final CRC32 crc32 = new CRC32();
             crc32.update(bytes.unsafeBytes(), bytes.begin(), bytes.length());

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
@@ -21,7 +21,7 @@
 import org.jruby.truffle.nodes.dispatch.CallDispatchHeadNode;
 import org.jruby.truffle.nodes.dispatch.DispatchHeadNodeFactory;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.util.ByteList;
@@ -39,7 +39,7 @@ public EncodingConverterAllocateNode(RubyContext context, SourceSection sourceSe
         }
 
         @Specialization
-        public Object encodingConverterAllocate(RubyClass encodingConverterClass, UndefinedPlaceholder undefined1, UndefinedPlaceholder undefined2) {
+        public Object encodingConverterAllocate(RubyClass encodingConverterClass, NotProvided unused1, NotProvided unused2) {
             return new RubyEncodingConverter(encodingConverterClass, null);
         }
 
@@ -160,7 +160,7 @@ public RubyString encodingConverterPutback(RubyEncodingConverter encodingConvert
         }
 
         @Specialization
-        public RubyString encodingConverterPutback(RubyEncodingConverter encodingConverter, UndefinedPlaceholder maxBytes) {
+        public RubyString encodingConverterPutback(RubyEncodingConverter encodingConverter, NotProvided maxBytes) {
             // Taken from org.jruby.RubyConverter#putback.
 
             final EConv ec = encodingConverter.getEConv();

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
@@ -72,7 +72,7 @@
 import org.jruby.truffle.nodes.core.StringNodesFactory;
 import org.jruby.truffle.nodes.core.array.ArrayNodes;
 import org.jruby.truffle.runtime.RubyContext;
-import org.jruby.truffle.runtime.UndefinedPlaceholder;
+import org.jruby.truffle.runtime.NotProvided;
 import org.jruby.truffle.runtime.control.RaiseException;
 import org.jruby.truffle.runtime.core.*;
 import org.jruby.truffle.runtime.rubinius.RubiniusByteArray;
@@ -200,7 +200,7 @@ public StringByteSubstringPrimitiveNode(RubyContext context, SourceSection sourc
         }
 
         @Specialization
-        public Object stringByteSubstring(RubyString string, int index, UndefinedPlaceholder length) {
+        public Object stringByteSubstring(RubyString string, int index, NotProvided length) {
             final Object subString = stringByteSubstring(string, index, 1);
 
             if (subString == nil()) {
@@ -249,7 +249,7 @@ public Object stringByteSubstring(RubyString string, int index, double length) {
         }
 
         @Specialization
-        public Object stringByteSubstring(RubyString string, double index, UndefinedPlaceholder length) {
+        public Object stringByteSubstring(RubyString string, double index, NotProvided length) {
             return stringByteSubstring(string, (int) index, 1);
         }
 
@@ -287,7 +287,7 @@ public Object stringByteSubstring(RubyString string, double index, int length) {
         }
 
         @Specialization
-        public Object stringByteSubstring(RubyString string, RubyRange range, UndefinedPlaceholder unused) {
+        public Object stringByteSubstring(RubyString string, RubyRange range, NotProvided length) {
             return null;
         }
 

diff --git a/...truffle/runtime/UndefinedPlaceholder.java → ...rg/jruby/truffle/runtime/NotProvided.java b/...truffle/runtime/UndefinedPlaceholder.java → ...rg/jruby/truffle/runtime/NotProvided.java
@@ -10,15 +10,15 @@
 package org.jruby.truffle.runtime;
 
 /**
- * The {@link UndefinedPlaceholder} is a value that represents an undefined value in Ruby. This is
- * used to differentiate between nil and the true absence of a value, such as an argument that has
- * not been passed.
+ * The {@link NotProvided} instance represents an argument which was <i>not provided</i>. 
+ * This is necessary as we need to differentiate based on the number of passed arguments
+ * and there is not a single default value that fits for omitted arguments.
  */
-public final class UndefinedPlaceholder {
+public final class NotProvided {
 
-    public static final UndefinedPlaceholder INSTANCE = new UndefinedPlaceholder();
+    public static final NotProvided INSTANCE = new NotProvided();
 
-    private UndefinedPlaceholder() {
+    private NotProvided() {
     }
 
 }
diff --git a/truffle/src/main/ruby/core/truffle/cext/require.rb b/truffle/src/main/ruby/core/truffle/cext/require.rb
@@ -7,39 +7,45 @@
 # GNU Lesser General Public License version 2.1
 
 if Truffle::CExt.supported?
+  module Kernel
+    # Monkey patch #require, similar to how RubyGems does,
+    # in order to load C extensions.
+    alias_method :truffle_cext_original_require, :require
+
+    # Normally a Ruby method in core is not allowed to replace one defined in Java.
+    # But here we really want it.
+    remove_method :require
+
+    def require(name)
+      # We're getting quite hacky here. A lot of C extensions are required
+      # using the format foo/foo, so we need to guess that the real name is
+      # foo from that.
+
+      if name =~ /(.+?)\/\1/
+        cext_name = $1
+      else
+        cext_name = name
+      end
 
-  # Monkey patch #require, similar to how RubyGems does, in order to load
-  # C extensions.
-
-  def require(name)
-    # We're getting quite hacky here. A lot of C extensions are required
-    # using the format foo/foo, so we need to guess that the real name is
-    # foo from that.
-
-    if name =~ /(.+?)\/\1/
-      cext_name = $1
-    else
-      cext_name = name
-    end
-
-    # Look in each $JRUBY_TRUFFLE_CEXT_PATH directory for
-    # cext_name/ext/cext_name/extconf.rb
+      # Look in each $JRUBY_TRUFFLE_CEXT_PATH directory for
+      # cext_name/ext/cext_name/extconf.rb
 
-    if ENV.include? 'JRUBY_TRUFFLE_CEXT_PATH'
-      cext_path = ENV['JRUBY_TRUFFLE_CEXT_PATH'].split(':')
-    else
-      cext_path = [Dir.pwd]
-    end
+      if ENV.include? 'JRUBY_TRUFFLE_CEXT_PATH'
+        cext_path = ENV['JRUBY_TRUFFLE_CEXT_PATH'].split(':')
+      else
+        cext_path = [Dir.pwd]
+      end
 
-    cext_path.each do |dir|
-      extconf = File.join(dir, cext_name, 'ext', cext_name, 'extconf.rb')
+      cext_path.each do |dir|
+        extconf = File.join(dir, cext_name, 'ext', cext_name, 'extconf.rb')
 
-      if File.exist? extconf
-        return Truffle::CExt::load_extconf(extconf)
+        if File.exist? extconf
+          return Truffle::CExt::load_extconf(extconf)
+        end
       end
-    end
 
-    Kernel.require name
+      truffle_cext_original_require name
+    end
+    module_function :require
   end
-
 end