Merge commit '1ad9253c9d34ccbce3e7e4ea5d87c266cbf93410'

deplib features commented out due to removal upstream;
will add back as a localmod

Conflicts:
	include/llvm/ADT/Triple.h
	include/llvm/MC/MCAssembler.h
	include/llvm/Target/TargetFrameLowering.h
	lib/CodeGen/AsmPrinter/DwarfDebug.cpp
	lib/CodeGen/AsmPrinter/DwarfDebug.h
	lib/CodeGen/BranchFolding.cpp
	lib/LLVMBuild.txt
	lib/Linker/LinkArchives.cpp
	lib/MC/MCAssembler.cpp
	lib/MC/MCELFStreamer.cpp
	lib/Makefile
	lib/Target/ARM/ARMExpandPseudoInsts.cpp
	lib/Target/ARM/ARMFrameLowering.cpp
	lib/Target/ARM/ARMISelLowering.cpp
	lib/Target/ARM/ARMSubtarget.h
	lib/Target/ARM/ARMTargetObjectFile.cpp
	lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
	lib/Target/Mips/MipsInstrFPU.td
	lib/Target/Mips/MipsInstrInfo.td
	lib/Target/X86/X86CodeEmitter.cpp
	lib/Target/X86/X86Subtarget.h
	lib/VMCore/Module.cpp
	test/MC/MachO/ARM/nop-armv4-padding.s
	tools/Makefile
	tools/llc/llc.cpp
	tools/lto/LTOModule.cpp
	tools/lto/lto.cpp

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diff --git a/docs/tutorial/LangImpl6.rst b/docs/tutorial/LangImpl6.rst
new file mode 100644
index 0000000000..30f4e90d03
--- /dev/null
+++ b/docs/tutorial/LangImpl6.rst
@@ -0,0 +1,1728 @@
+============================================================
+Kaleidoscope: Extending the Language: User-defined Operators
+============================================================
+
+.. contents::
+   :local:
+
+Written by `Chris Lattner <mailto:sabre@nondot.org>`_
+
+Chapter 6 Introduction
+======================
+
+Welcome to Chapter 6 of the "`Implementing a language with
+LLVM <index.html>`_" tutorial. At this point in our tutorial, we now
+have a fully functional language that is fairly minimal, but also
+useful. There is still one big problem with it, however. Our language
+doesn't have many useful operators (like division, logical negation, or
+even any comparisons besides less-than).
+
+This chapter of the tutorial takes a wild digression into adding
+user-defined operators to the simple and beautiful Kaleidoscope
+language. This digression now gives us a simple and ugly language in
+some ways, but also a powerful one at the same time. One of the great
+things about creating your own language is that you get to decide what
+is good or bad. In this tutorial we'll assume that it is okay to use
+this as a way to show some interesting parsing techniques.
+
+At the end of this tutorial, we'll run through an example Kaleidoscope
+application that `renders the Mandelbrot set <#example>`_. This gives an
+example of what you can build with Kaleidoscope and its feature set.
+
+User-defined Operators: the Idea
+================================
+
+The "operator overloading" that we will add to Kaleidoscope is more
+general than languages like C++. In C++, you are only allowed to
+redefine existing operators: you can't programatically change the
+grammar, introduce new operators, change precedence levels, etc. In this
+chapter, we will add this capability to Kaleidoscope, which will let the
+user round out the set of operators that are supported.
+
+The point of going into user-defined operators in a tutorial like this
+is to show the power and flexibility of using a hand-written parser.
+Thus far, the parser we have been implementing uses recursive descent
+for most parts of the grammar and operator precedence parsing for the
+expressions. See `Chapter 2 <LangImpl2.html>`_ for details. Without
+using operator precedence parsing, it would be very difficult to allow
+the programmer to introduce new operators into the grammar: the grammar
+is dynamically extensible as the JIT runs.
+
+The two specific features we'll add are programmable unary operators
+(right now, Kaleidoscope has no unary operators at all) as well as
+binary operators. An example of this is:
+
+::
+
+    # Logical unary not.
+    def unary!(v)
+      if v then
+        0
+      else
+        1;
+
+    # Define > with the same precedence as <.
+    def binary> 10 (LHS RHS)
+      RHS < LHS;
+
+    # Binary "logical or", (note that it does not "short circuit")
+    def binary| 5 (LHS RHS)
+      if LHS then
+        1
+      else if RHS then
+        1
+      else
+        0;
+
+    # Define = with slightly lower precedence than relationals.
+    def binary= 9 (LHS RHS)
+      !(LHS < RHS | LHS > RHS);
+
+Many languages aspire to being able to implement their standard runtime
+library in the language itself. In Kaleidoscope, we can implement
+significant parts of the language in the library!
+
+We will break down implementation of these features into two parts:
+implementing support for user-defined binary operators and adding unary
+operators.
+
+User-defined Binary Operators
+=============================
+
+Adding support for user-defined binary operators is pretty simple with
+our current framework. We'll first add support for the unary/binary
+keywords:
+
+.. code-block:: c++
+
+    enum Token {
+      ...
+      // operators
+      tok_binary = -11, tok_unary = -12
+    };
+    ...
+    static int gettok() {
+    ...
+        if (IdentifierStr == "for") return tok_for;
+        if (IdentifierStr == "in") return tok_in;
+        if (IdentifierStr == "binary") return tok_binary;
+        if (IdentifierStr == "unary") return tok_unary;
+        return tok_identifier;
+
+This just adds lexer support for the unary and binary keywords, like we
+did in `previous chapters <LangImpl5.html#iflexer>`_. One nice thing
+about our current AST, is that we represent binary operators with full
+generalisation by using their ASCII code as the opcode. For our extended
+operators, we'll use this same representation, so we don't need any new
+AST or parser support.
+
+On the other hand, we have to be able to represent the definitions of
+these new operators, in the "def binary\| 5" part of the function
+definition. In our grammar so far, the "name" for the function
+definition is parsed as the "prototype" production and into the
+``PrototypeAST`` AST node. To represent our new user-defined operators
+as prototypes, we have to extend the ``PrototypeAST`` AST node like
+this:
+
+.. code-block:: c++
+
+    /// PrototypeAST - This class represents the "prototype" for a function,
+    /// which captures its argument names as well as if it is an operator.
+    class PrototypeAST {
+      std::string Name;
+      std::vector<std::string> Args;
+      bool isOperator;
+      unsigned Precedence;  // Precedence if a binary op.
+    public:
+      PrototypeAST(const std::string &name, const std::vector<std::string> &args,
+                   bool isoperator = false, unsigned prec = 0)
+      : Name(name), Args(args), isOperator(isoperator), Precedence(prec) {}
+
+      bool isUnaryOp() const { return isOperator && Args.size() == 1; }
+      bool isBinaryOp() const { return isOperator && Args.size() == 2; }
+
+      char getOperatorName() const {
+        assert(isUnaryOp() || isBinaryOp());
+        return Name[Name.size()-1];
+      }
+
+      unsigned getBinaryPrecedence() const { return Precedence; }
+
+      Function *Codegen();
+    };
+
+Basically, in addition to knowing a name for the prototype, we now keep
+track of whether it was an operator, and if it was, what precedence
+level the operator is at. The precedence is only used for binary
+operators (as you'll see below, it just doesn't apply for unary
+operators). Now that we have a way to represent the prototype for a
+user-defined operator, we need to parse it:
+
+.. code-block:: c++
+
+    /// prototype
+    ///   ::= id '(' id* ')'
+    ///   ::= binary LETTER number? (id, id)
+    static PrototypeAST *ParsePrototype() {
+      std::string FnName;
+
+      unsigned Kind = 0;  // 0 = identifier, 1 = unary, 2 = binary.
+      unsigned BinaryPrecedence = 30;
+
+      switch (CurTok) {
+      default:
+        return ErrorP("Expected function name in prototype");
+      case tok_identifier:
+        FnName = IdentifierStr;
+        Kind = 0;
+        getNextToken();
+        break;
+      case tok_binary:
+        getNextToken();
+        if (!isascii(CurTok))
+          return ErrorP("Expected binary operator");
+        FnName = "binary";
+        FnName += (char)CurTok;
+        Kind = 2;
+        getNextToken();
+
+        // Read the precedence if present.
+        if (CurTok == tok_number) {
+          if (NumVal < 1 || NumVal > 100)
+            return ErrorP("Invalid precedecnce: must be 1..100");
+          BinaryPrecedence = (unsigned)NumVal;
+          getNextToken();
+        }
+        break;
+      }
+
+      if (CurTok != '(')
+        return ErrorP("Expected '(' in prototype");
+
+      std::vector<std::string> ArgNames;
+      while (getNextToken() == tok_identifier)
+        ArgNames.push_back(IdentifierStr);
+      if (CurTok != ')')
+        return ErrorP("Expected ')' in prototype");
+
+      // success.
+      getNextToken();  // eat ')'.
+
+      // Verify right number of names for operator.
+      if (Kind && ArgNames.size() != Kind)
+        return ErrorP("Invalid number of operands for operator");
+
+      return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);
+    }
+
+This is all fairly straightforward parsing code, and we have already
+seen a lot of similar code in the past. One interesting part about the
+code above is the couple lines that set up ``FnName`` for binary
+operators. This builds names like "binary@" for a newly defined "@"
+operator. This then takes advantage of the fact that symbol names in the
+LLVM symbol table are allowed to have any character in them, including
+embedded nul characters.
+
+The next interesting thing to add, is codegen support for these binary
+operators. Given our current structure, this is a simple addition of a
+default case for our existing binary operator node:
+
+.. code-block:: c++
+
+    Value *BinaryExprAST::Codegen() {
+      Value *L = LHS->Codegen();
+      Value *R = RHS->Codegen();
+      if (L == 0 || R == 0) return 0;
+
+      switch (Op) {
+      case '+': return Builder.CreateFAdd(L, R, "addtmp");
+      case '-': return Builder.CreateFSub(L, R, "subtmp");
+      case '*': return Builder.CreateFMul(L, R, "multmp");
+      case '<':
+        L = Builder.CreateFCmpULT(L, R, "cmptmp");
+        // Convert bool 0/1 to double 0.0 or 1.0
+        return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
+                                    "booltmp");
+      default: break;
+      }
+
+      // If it wasn't a builtin binary operator, it must be a user defined one. Emit
+      // a call to it.
+      Function *F = TheModule->getFunction(std::string("binary")+Op);
+      assert(F && "binary operator not found!");
+
+      Value *Ops[2] = { L, R };
+      return Builder.CreateCall(F, Ops, "binop");
+    }
+
+As you can see above, the new code is actually really simple. It just
+does a lookup for the appropriate operator in the symbol table and
+generates a function call to it. Since user-defined operators are just
+built as normal functions (because the "prototype" boils down to a
+function with the right name) everything falls into place.
+
+The final piece of code we are missing, is a bit of top-level magic:
+
+.. code-block:: c++
+
+    Function *FunctionAST::Codegen() {
+      NamedValues.clear();
+
+      Function *TheFunction = Proto->Codegen();
+      if (TheFunction == 0)
+        return 0;
+
+      // If this is an operator, install it.
+      if (Proto->isBinaryOp())
+        BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();
+
+      // Create a new basic block to start insertion into.
+      BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
+      Builder.SetInsertPoint(BB);
+
+      if (Value *RetVal = Body->Codegen()) {
+        ...
+
+Basically, before codegening a function, if it is a user-defined
+operator, we register it in the precedence table. This allows the binary
+operator parsing logic we already have in place to handle it. Since we
+are working on a fully-general operator precedence parser, this is all
+we need to do to "extend the grammar".
+
+Now we have useful user-defined binary operators. This builds a lot on
+the previous framework we built for other operators. Adding unary
+operators is a bit more challenging, because we don't have any framework
+for it yet - lets see what it takes.
+
+User-defined Unary Operators
+============================
+
+Since we don't currently support unary operators in the Kaleidoscope
+language, we'll need to add everything to support them. Above, we added
+simple support for the 'unary' keyword to the lexer. In addition to
+that, we need an AST node:
+
+.. code-block:: c++
+
+    /// UnaryExprAST - Expression class for a unary operator.
+    class UnaryExprAST : public ExprAST {
+      char Opcode;
+      ExprAST *Operand;
+    public:
+      UnaryExprAST(char opcode, ExprAST *operand)
+        : Opcode(opcode), Operand(operand) {}
+      virtual Value *Codegen();
+    };
+
+This AST node is very simple and obvious by now. It directly mirrors the
+binary operator AST node, except that it only has one child. With this,
+we need to add the parsing logic. Parsing a unary operator is pretty
+simple: we'll add a new function to do it:
+
+.. code-block:: c++
+
+    /// unary
+    ///   ::= primary
+    ///   ::= '!' unary
+    static ExprAST *ParseUnary() {
+      // If the current token is not an operator, it must be a primary expr.
+      if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
+        return ParsePrimary();
+
+      // If this is a unary operator, read it.
+      int Opc = CurTok;
+      getNextToken();
+      if (ExprAST *Operand = ParseUnary())
+        return new UnaryExprAST(Opc, Operand);
+      return 0;
+    }
+
+The grammar we add is pretty straightforward here. If we see a unary
+operator when parsing a primary operator, we eat the operator as a
+prefix and parse the remaining piece as another unary operator. This
+allows us to handle multiple unary operators (e.g. "!!x"). Note that
+unary operators can't have ambiguous parses like binary operators can,
+so there is no need for precedence information.
+
+The problem with this function, is that we need to call ParseUnary from
+somewhere. To do this, we change previous callers of ParsePrimary to
+call ParseUnary instead:
+
+.. code-block:: c++
+
+    /// binoprhs
+    ///   ::= ('+' unary)*
+    static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
+      ...
+        // Parse the unary expression after the binary operator.
+        ExprAST *RHS = ParseUnary();
+        if (!RHS) return 0;
+      ...
+    }
+    /// expression
+    ///   ::= unary binoprhs
+    ///
+    static ExprAST *ParseExpression() {
+      ExprAST *LHS = ParseUnary();
+      if (!LHS) return 0;
+
+      return ParseBinOpRHS(0, LHS);
+    }
+
+With these two simple changes, we are now able to parse unary operators
+and build the AST for them. Next up, we need to add parser support for
+prototypes, to parse the unary operator prototype. We extend the binary
+operator code above with:
+
+.. code-block:: c++
+
+    /// prototype
+    ///   ::= id '(' id* ')'
+    ///   ::= binary LETTER number? (id, id)
+    ///   ::= unary LETTER (id)
+    static PrototypeAST *ParsePrototype() {
+      std::string FnName;
+
+      unsigned Kind = 0;  // 0 = identifier, 1 = unary, 2 = binary.
+      unsigned BinaryPrecedence = 30;
+
+      switch (CurTok) {
+      default:
+        return ErrorP("Expected function name in prototype");
+      case tok_identifier:
+        FnName = IdentifierStr;
+        Kind = 0;
+        getNextToken();
+        break;
+      case tok_unary:
+        getNextToken();
+        if (!isascii(CurTok))
+          return ErrorP("Expected unary operator");
+        FnName = "unary";
+        FnName += (char)CurTok;
+        Kind = 1;
+        getNextToken();
+        break;
+      case tok_binary:
+        ...
+
+As with binary operators, we name unary operators with a name that
+includes the operator character. This assists us at code generation
+time. Speaking of, the final piece we need to add is codegen support for
+unary operators. It looks like this:
+
+.. code-block:: c++
+
+    Value *UnaryExprAST::Codegen() {
+      Value *OperandV = Operand->Codegen();
+      if (OperandV == 0) return 0;
+
+      Function *F = TheModule->getFunction(std::string("unary")+Opcode);
+      if (F == 0)
+        return ErrorV("Unknown unary operator");
+
+      return Builder.CreateCall(F, OperandV, "unop");
+    }
+
+This code is similar to, but simpler than, the code for binary
+operators. It is simpler primarily because it doesn't need to handle any
+predefined operators.
+
+Kicking the Tires
+=================
+
+It is somewhat hard to believe, but with a few simple extensions we've
+covered in the last chapters, we have grown a real-ish language. With
+this, we can do a lot of interesting things, including I/O, math, and a
+bunch of other things. For example, we can now add a nice sequencing
+operator (printd is defined to print out the specified value and a
+newline):
+
+::
+
+    ready> extern printd(x);
+    Read extern:
+    declare double @printd(double)
+
+    ready> def binary : 1 (x y) 0;  # Low-precedence operator that ignores operands.
+    ..
+    ready> printd(123) : printd(456) : printd(789);
+    123.000000
+    456.000000
+    789.000000
+    Evaluated to 0.000000
+
+We can also define a bunch of other "primitive" operations, such as:
+
+::
+
+    # Logical unary not.
+    def unary!(v)
+      if v then
+        0
+      else
+        1;
+
+    # Unary negate.
+    def unary-(v)
+      0-v;
+
+    # Define > with the same precedence as <.
+    def binary> 10 (LHS RHS)
+      RHS < LHS;
+
+    # Binary logical or, which does not short circuit.
+    def binary| 5 (LHS RHS)
+      if LHS then
+        1
+      else if RHS then
+        1
+      else
+        0;
+
+    # Binary logical and, which does not short circuit.
+    def binary& 6 (LHS RHS)
+      if !LHS then
+        0
+      else
+        !!RHS;
+
+    # Define = with slightly lower precedence than relationals.
+    def binary = 9 (LHS RHS)
+      !(LHS < RHS | LHS > RHS);
+
+    # Define ':' for sequencing: as a low-precedence operator that ignores operands
+    # and just returns the RHS.
+    def binary : 1 (x y) y;
+
+Given the previous if/then/else support, we can also define interesting
+functions for I/O. For example, the following prints out a character
+whose "density" reflects the value passed in: the lower the value, the
+denser the character:
+
+::
+
+    ready>
+
+    extern putchard(char)
+    def printdensity(d)
+      if d > 8 then
+        putchard(32)  # ' '
+      else if d > 4 then
+        putchard(46)  # '.'
+      else if d > 2 then
+        putchard(43)  # '+'
+      else
+        putchard(42); # '*'
+    ...
+    ready> printdensity(1): printdensity(2): printdensity(3):
+           printdensity(4): printdensity(5): printdensity(9):
+           putchard(10);
+    **++.
+    Evaluated to 0.000000
+
+Based on these simple primitive operations, we can start to define more
+interesting things. For example, here's a little function that solves
+for the number of iterations it takes a function in the complex plane to
+converge:
+
+::
+
+    # Determine whether the specific location diverges.
+    # Solve for z = z^2 + c in the complex plane.
+    def mandleconverger(real imag iters creal cimag)
+      if iters > 255 | (real*real + imag*imag > 4) then
+        iters
+      else
+        mandleconverger(real*real - imag*imag + creal,
+                        2*real*imag + cimag,
+                        iters+1, creal, cimag);
+
+    # Return the number of iterations required for the iteration to escape
+    def mandleconverge(real imag)
+      mandleconverger(real, imag, 0, real, imag);
+
+This "``z = z2 + c``" function is a beautiful little creature that is
+the basis for computation of the `Mandelbrot
+Set <http://en.wikipedia.org/wiki/Mandelbrot_set>`_. Our
+``mandelconverge`` function returns the number of iterations that it
+takes for a complex orbit to escape, saturating to 255. This is not a
+very useful function by itself, but if you plot its value over a
+two-dimensional plane, you can see the Mandelbrot set. Given that we are
+limited to using putchard here, our amazing graphical output is limited,
+but we can whip together something using the density plotter above:
+
+::
+
+    # Compute and plot the mandlebrot set with the specified 2 dimensional range
+    # info.
+    def mandelhelp(xmin xmax xstep   ymin ymax ystep)
+      for y = ymin, y < ymax, ystep in (
+        (for x = xmin, x < xmax, xstep in
+           printdensity(mandleconverge(x,y)))
+        : putchard(10)
+      )
+
+    # mandel - This is a convenient helper function for plotting the mandelbrot set
+    # from the specified position with the specified Magnification.
+    def mandel(realstart imagstart realmag imagmag)
+      mandelhelp(realstart, realstart+realmag*78, realmag,
+                 imagstart, imagstart+imagmag*40, imagmag);
+
+Given this, we can try plotting out the mandlebrot set! Lets try it out:
+
+::
+
+    ready> mandel(-2.3, -1.3, 0.05, 0.07);
+    *******************************+++++++++++*************************************
+    *************************+++++++++++++++++++++++*******************************
+    **********************+++++++++++++++++++++++++++++****************************
+    *******************+++++++++++++++++++++.. ...++++++++*************************
+    *****************++++++++++++++++++++++.... ...+++++++++***********************
+    ***************+++++++++++++++++++++++.....   ...+++++++++*********************
+    **************+++++++++++++++++++++++....     ....+++++++++********************
+    *************++++++++++++++++++++++......      .....++++++++*******************
+    ************+++++++++++++++++++++.......       .......+++++++******************
+    ***********+++++++++++++++++++....                ... .+++++++*****************
+    **********+++++++++++++++++.......                     .+++++++****************
+    *********++++++++++++++...........                    ...+++++++***************
+    ********++++++++++++............                      ...++++++++**************
+    ********++++++++++... ..........                        .++++++++**************
+    *******+++++++++.....                                   .+++++++++*************
+    *******++++++++......                                  ..+++++++++*************
+    *******++++++.......                                   ..+++++++++*************
+    *******+++++......                                     ..+++++++++*************
+    *******.... ....                                      ...+++++++++*************
+    *******.... .                                         ...+++++++++*************
+    *******+++++......                                    ...+++++++++*************
+    *******++++++.......                                   ..+++++++++*************
+    *******++++++++......                                   .+++++++++*************
+    *******+++++++++.....                                  ..+++++++++*************
+    ********++++++++++... ..........                        .++++++++**************
+    ********++++++++++++............                      ...++++++++**************
+    *********++++++++++++++..........                     ...+++++++***************
+    **********++++++++++++++++........                     .+++++++****************
+    **********++++++++++++++++++++....                ... ..+++++++****************
+    ***********++++++++++++++++++++++.......       .......++++++++*****************
+    ************+++++++++++++++++++++++......      ......++++++++******************
+    **************+++++++++++++++++++++++....      ....++++++++********************
+    ***************+++++++++++++++++++++++.....   ...+++++++++*********************
+    *****************++++++++++++++++++++++....  ...++++++++***********************
+    *******************+++++++++++++++++++++......++++++++*************************
+    *********************++++++++++++++++++++++.++++++++***************************
+    *************************+++++++++++++++++++++++*******************************
+    ******************************+++++++++++++************************************
+    *******************************************************************************
+    *******************************************************************************
+    *******************************************************************************
+    Evaluated to 0.000000
+    ready> mandel(-2, -1, 0.02, 0.04);
+    **************************+++++++++++++++++++++++++++++++++++++++++++++++++++++
+    ***********************++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    *********************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.
+    *******************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++...
+    *****************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.....
+    ***************++++++++++++++++++++++++++++++++++++++++++++++++++++++++........
+    **************++++++++++++++++++++++++++++++++++++++++++++++++++++++...........
+    ************+++++++++++++++++++++++++++++++++++++++++++++++++++++..............
+    ***********++++++++++++++++++++++++++++++++++++++++++++++++++........        .
+    **********++++++++++++++++++++++++++++++++++++++++++++++.............
+    ********+++++++++++++++++++++++++++++++++++++++++++..................
+    *******+++++++++++++++++++++++++++++++++++++++.......................
+    ******+++++++++++++++++++++++++++++++++++...........................
+    *****++++++++++++++++++++++++++++++++............................
+    *****++++++++++++++++++++++++++++...............................
+    ****++++++++++++++++++++++++++......   .........................
+    ***++++++++++++++++++++++++.........     ......    ...........
+    ***++++++++++++++++++++++............
+    **+++++++++++++++++++++..............
+    **+++++++++++++++++++................
+    *++++++++++++++++++.................
+    *++++++++++++++++............ ...
+    *++++++++++++++..............
+    *+++....++++................
+    *..........  ...........
+    *
+    *..........  ...........
+    *+++....++++................
+    *++++++++++++++..............
+    *++++++++++++++++............ ...
+    *++++++++++++++++++.................
+    **+++++++++++++++++++................
+    **+++++++++++++++++++++..............
+    ***++++++++++++++++++++++............
+    ***++++++++++++++++++++++++.........     ......    ...........
+    ****++++++++++++++++++++++++++......   .........................
+    *****++++++++++++++++++++++++++++...............................
+    *****++++++++++++++++++++++++++++++++............................
+    ******+++++++++++++++++++++++++++++++++++...........................
+    *******+++++++++++++++++++++++++++++++++++++++.......................
+    ********+++++++++++++++++++++++++++++++++++++++++++..................
+    Evaluated to 0.000000
+    ready> mandel(-0.9, -1.4, 0.02, 0.03);
+    *******************************************************************************
+    *******************************************************************************
+    *******************************************************************************
+    **********+++++++++++++++++++++************************************************
+    *+++++++++++++++++++++++++++++++++++++++***************************************
+    +++++++++++++++++++++++++++++++++++++++++++++**********************************
+    ++++++++++++++++++++++++++++++++++++++++++++++++++*****************************
+    ++++++++++++++++++++++++++++++++++++++++++++++++++++++*************************
+    +++++++++++++++++++++++++++++++++++++++++++++++++++++++++**********************
+    +++++++++++++++++++++++++++++++++.........++++++++++++++++++*******************
+    +++++++++++++++++++++++++++++++....   ......+++++++++++++++++++****************
+    +++++++++++++++++++++++++++++.......  ........+++++++++++++++++++**************
+    ++++++++++++++++++++++++++++........   ........++++++++++++++++++++************
+    +++++++++++++++++++++++++++.........     ..  ...+++++++++++++++++++++**********
+    ++++++++++++++++++++++++++...........        ....++++++++++++++++++++++********
+    ++++++++++++++++++++++++.............       .......++++++++++++++++++++++******
+    +++++++++++++++++++++++.............        ........+++++++++++++++++++++++****
+    ++++++++++++++++++++++...........           ..........++++++++++++++++++++++***
+    ++++++++++++++++++++...........                .........++++++++++++++++++++++*
+    ++++++++++++++++++............                  ...........++++++++++++++++++++
+    ++++++++++++++++...............                 .............++++++++++++++++++
+    ++++++++++++++.................                 ...............++++++++++++++++
+    ++++++++++++..................                  .................++++++++++++++
+    +++++++++..................                      .................+++++++++++++
+    ++++++........        .                               .........  ..++++++++++++
+    ++............                                         ......    ....++++++++++
+    ..............                                                    ...++++++++++
+    ..............                                                    ....+++++++++
+    ..............                                                    .....++++++++
+    .............                                                    ......++++++++
+    ...........                                                     .......++++++++
+    .........                                                       ........+++++++
+    .........                                                       ........+++++++
+    .........                                                           ....+++++++
+    ........                                                             ...+++++++
+    .......                                                              ...+++++++
+                                                                        ....+++++++
+                                                                       .....+++++++
+                                                                        ....+++++++
+                                                                        ....+++++++
+                                                                        ....+++++++
+    Evaluated to 0.000000
+    ready> ^D
+
+At this point, you may be starting to realize that Kaleidoscope is a
+real and powerful language. It may not be self-similar :), but it can be
+used to plot things that are!
+
+With this, we conclude the "adding user-defined operators" chapter of
+the tutorial. We have successfully augmented our language, adding the
+ability to extend the language in the library, and we have shown how
+this can be used to build a simple but interesting end-user application
+in Kaleidoscope. At this point, Kaleidoscope can build a variety of
+applications that are functional and can call functions with
+side-effects, but it can't actually define and mutate a variable itself.
+
+Strikingly, variable mutation is an important feature of some languages,
+and it is not at all obvious how to `add support for mutable
+variables <LangImpl7.html>`_ without having to add an "SSA construction"
+phase to your front-end. In the next chapter, we will describe how you
+can add variable mutation without building SSA in your front-end.
+
+Full Code Listing
+=================
+
+Here is the complete code listing for our running example, enhanced with
+the if/then/else and for expressions.. To build this example, use:
+
+.. code-block:: bash
+
+    # Compile
+    clang++ -g toy.cpp `llvm-config --cppflags --ldflags --libs core jit native` -O3 -o toy
+    # Run
+    ./toy
+
+On some platforms, you will need to specify -rdynamic or
+-Wl,--export-dynamic when linking. This ensures that symbols defined in
+the main executable are exported to the dynamic linker and so are
+available for symbol resolution at run time. This is not needed if you
+compile your support code into a shared library, although doing that
+will cause problems on Windows.
+
+Here is the code:
+
+.. code-block:: c++
+
+    #include "llvm/DerivedTypes.h"
+    #include "llvm/ExecutionEngine/ExecutionEngine.h"
+    #include "llvm/ExecutionEngine/JIT.h"
+    #include "llvm/IRBuilder.h"
+    #include "llvm/LLVMContext.h"
+    #include "llvm/Module.h"
+    #include "llvm/PassManager.h"
+    #include "llvm/Analysis/Verifier.h"
+    #include "llvm/Analysis/Passes.h"
+    #include "llvm/DataLayout.h"
+    #include "llvm/Transforms/Scalar.h"
+    #include "llvm/Support/TargetSelect.h"
+    #include <cstdio>
+    #include <string>
+    #include <map>
+    #include <vector>
+    using namespace llvm;
+
+    //===----------------------------------------------------------------------===//
+    // Lexer
+    //===----------------------------------------------------------------------===//
+
+    // The lexer returns tokens [0-255] if it is an unknown character, otherwise one
+    // of these for known things.
+    enum Token {
+      tok_eof = -1,
+
+      // commands
+      tok_def = -2, tok_extern = -3,
+
+      // primary
+      tok_identifier = -4, tok_number = -5,
+
+      // control
+      tok_if = -6, tok_then = -7, tok_else = -8,
+      tok_for = -9, tok_in = -10,
+
+      // operators
+      tok_binary = -11, tok_unary = -12
+    };
+
+    static std::string IdentifierStr;  // Filled in if tok_identifier
+    static double NumVal;              // Filled in if tok_number
+
+    /// gettok - Return the next token from standard input.
+    static int gettok() {
+      static int LastChar = ' ';
+
+      // Skip any whitespace.
+      while (isspace(LastChar))
+        LastChar = getchar();
+
+      if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
+        IdentifierStr = LastChar;
+        while (isalnum((LastChar = getchar())))
+          IdentifierStr += LastChar;
+
+        if (IdentifierStr == "def") return tok_def;
+        if (IdentifierStr == "extern") return tok_extern;
+        if (IdentifierStr == "if") return tok_if;
+        if (IdentifierStr == "then") return tok_then;
+        if (IdentifierStr == "else") return tok_else;
+        if (IdentifierStr == "for") return tok_for;
+        if (IdentifierStr == "in") return tok_in;
+        if (IdentifierStr == "binary") return tok_binary;
+        if (IdentifierStr == "unary") return tok_unary;
+        return tok_identifier;
+      }
+
+      if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
+        std::string NumStr;
+        do {
+          NumStr += LastChar;
+          LastChar = getchar();
+        } while (isdigit(LastChar) || LastChar == '.');
+
+        NumVal = strtod(NumStr.c_str(), 0);
+        return tok_number;
+      }
+
+      if (LastChar == '#') {
+        // Comment until end of line.
+        do LastChar = getchar();
+        while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
+
+        if (LastChar != EOF)
+          return gettok();
+      }
+
+      // Check for end of file.  Don't eat the EOF.
+      if (LastChar == EOF)
+        return tok_eof;
+
+      // Otherwise, just return the character as its ascii value.
+      int ThisChar = LastChar;
+      LastChar = getchar();
+      return ThisChar;
+    }
+
+    //===----------------------------------------------------------------------===//
+    // Abstract Syntax Tree (aka Parse Tree)
+    //===----------------------------------------------------------------------===//
+
+    /// ExprAST - Base class for all expression nodes.
+    class ExprAST {
+    public:
+      virtual ~ExprAST() {}
+      virtual Value *Codegen() = 0;
+    };
+
+    /// NumberExprAST - Expression class for numeric literals like "1.0".
+    class NumberExprAST : public ExprAST {
+      double Val;
+    public:
+      NumberExprAST(double val) : Val(val) {}
+      virtual Value *Codegen();
+    };
+
+    /// VariableExprAST - Expression class for referencing a variable, like "a".
+    class VariableExprAST : public ExprAST {
+      std::string Name;
+    public:
+      VariableExprAST(const std::string &name) : Name(name) {}
+      virtual Value *Codegen();
+    };
+
+    /// UnaryExprAST - Expression class for a unary operator.
+    class UnaryExprAST : public ExprAST {
+      char Opcode;
+      ExprAST *Operand;
+    public:
+      UnaryExprAST(char opcode, ExprAST *operand)
+        : Opcode(opcode), Operand(operand) {}
+      virtual Value *Codegen();
+    };
+
+    /// BinaryExprAST - Expression class for a binary operator.
+    class BinaryExprAST : public ExprAST {
+      char Op;
+      ExprAST *LHS, *RHS;
+    public:
+      BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
+        : Op(op), LHS(lhs), RHS(rhs) {}
+      virtual Value *Codegen();
+    };
+
+    /// CallExprAST - Expression class for function calls.
+    class CallExprAST : public ExprAST {
+      std::string Callee;
+      std::vector<ExprAST*> Args;
+    public:
+      CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
+        : Callee(callee), Args(args) {}
+      virtual Value *Codegen();
+    };
+
+    /// IfExprAST - Expression class for if/then/else.
+    class IfExprAST : public ExprAST {
+      ExprAST *Cond, *Then, *Else;