From 169d2bd06003c39970bc94c99669a34b61bb7e45 Mon Sep 17 00:00:00 2001 From: dim Date: Mon, 8 Apr 2013 18:41:23 +0000 Subject: Vendor import of llvm trunk r178860: http://llvm.org/svn/llvm-project/llvm/trunk@178860 --- docs/tutorial/OCamlLangImpl6.html | 1574 ------------------------------------- 1 file changed, 1574 deletions(-) delete mode 100644 docs/tutorial/OCamlLangImpl6.html (limited to 'docs/tutorial/OCamlLangImpl6.html') diff --git a/docs/tutorial/OCamlLangImpl6.html b/docs/tutorial/OCamlLangImpl6.html deleted file mode 100644 index db25240..0000000 --- a/docs/tutorial/OCamlLangImpl6.html +++ /dev/null @@ -1,1574 +0,0 @@ - - - - - Kaleidoscope: Extending the Language: User-defined Operators - - - - - - - - -

Kaleidoscope: Extending the Language: User-defined Operators

- - - -
-

- Written by Chris Lattner - and Erick Tryzelaar -

-
- - -

Chapter 6 Introduction

- - -
- -

Welcome to Chapter 6 of the "Implementing a language -with LLVM" 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. 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 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:

- -
-
-type token =
-  ...
-  (* operators *)
-  | Binary | Unary
-
-...
-
-and lex_ident buffer = parser
-  ...
-      | "for" -> [< 'Token.For; stream >]
-      | "in" -> [< 'Token.In; stream >]
-      | "binary" -> [< 'Token.Binary; stream >]
-      | "unary" -> [< 'Token.Unary; stream >]
-
-
- -

This just adds lexer support for the unary and binary keywords, like we -did in previous chapters. 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 Ast.Prototype AST node. To -represent our new user-defined operators as prototypes, we have to extend -the Ast.Prototype AST node like this:

- -
-
-(* proto - This type represents the "prototype" for a function, which captures
- * its name, and its argument names (thus implicitly the number of arguments the
- * function takes). *)
-type proto =
-  | Prototype of string * string array
-  | BinOpPrototype of string * string array * int
-
-
- -

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:

- -
-
-(* prototype
- *   ::= id '(' id* ')'
- *   ::= binary LETTER number? (id, id)
- *   ::= unary LETTER number? (id) *)
-let parse_prototype =
-  let rec parse_args accumulator = parser
-    | [< 'Token.Ident id; e=parse_args (id::accumulator) >] -> e
-    | [< >] -> accumulator
-  in
-  let parse_operator = parser
-    | [< 'Token.Unary >] -> "unary", 1
-    | [< 'Token.Binary >] -> "binary", 2
-  in
-  let parse_binary_precedence = parser
-    | [< 'Token.Number n >] -> int_of_float n
-    | [< >] -> 30
-  in
-  parser
-  | [< 'Token.Ident id;
-       'Token.Kwd '(' ?? "expected '(' in prototype";
-       args=parse_args [];
-       'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
-      (* success. *)
-      Ast.Prototype (id, Array.of_list (List.rev args))
-  | [< (prefix, kind)=parse_operator;
-       'Token.Kwd op ?? "expected an operator";
-       (* Read the precedence if present. *)
-       binary_precedence=parse_binary_precedence;
-       'Token.Kwd '(' ?? "expected '(' in prototype";
-        args=parse_args [];
-       'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
-      let name = prefix ^ (String.make 1 op) in
-      let args = Array.of_list (List.rev args) in
-
-      (* Verify right number of arguments for operator. *)
-      if Array.length args != kind
-      then raise (Stream.Error "invalid number of operands for operator")
-      else
-        if kind == 1 then
-          Ast.Prototype (name, args)
-        else
-          Ast.BinOpPrototype (name, args, binary_precedence)
-  | [< >] ->
-      raise (Stream.Error "expected function name in prototype")
-
-
- -

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 name 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:

- -
-
-let codegen_expr = function
-  ...
-  | Ast.Binary (op, lhs, rhs) ->
-      let lhs_val = codegen_expr lhs in
-      let rhs_val = codegen_expr rhs in
-      begin
-        match op with
-        | '+' -> build_add lhs_val rhs_val "addtmp" builder
-        | '-' -> build_sub lhs_val rhs_val "subtmp" builder
-        | '*' -> build_mul lhs_val rhs_val "multmp" builder
-        | '<' ->
-            (* Convert bool 0/1 to double 0.0 or 1.0 *)
-            let i = build_fcmp Fcmp.Ult lhs_val rhs_val "cmptmp" builder in
-            build_uitofp i double_type "booltmp" builder
-        | _ ->
-            (* If it wasn't a builtin binary operator, it must be a user defined
-             * one. Emit a call to it. *)
-            let callee = "binary" ^ (String.make 1 op) in
-            let callee =
-              match lookup_function callee the_module with
-              | Some callee -> callee
-              | None -> raise (Error "binary operator not found!")
-            in
-            build_call callee [|lhs_val; rhs_val|] "binop" builder
-      end
-
-
- -

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:

- -
-
-let codegen_func the_fpm = function
-  | Ast.Function (proto, body) ->
-      Hashtbl.clear named_values;
-      let the_function = codegen_proto proto in
-
-      (* If this is an operator, install it. *)
-      begin match proto with
-      | Ast.BinOpPrototype (name, args, prec) ->
-          let op = name.[String.length name - 1] in
-          Hashtbl.add Parser.binop_precedence op prec;
-      | _ -> ()
-      end;
-
-      (* Create a new basic block to start insertion into. *)
-      let bb = append_block context "entry" the_function in
-      position_at_end bb builder;
-      ...
-
-
- -

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:

- -
-
-type expr =
-  ...
-  (* variant for a unary operator. *)
-  | Unary of char * expr
-  ...
-
-
- -

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:

- -
-
-(* unary
- *   ::= primary
- *   ::= '!' unary *)
-and parse_unary = parser
-  (* If this is a unary operator, read it. *)
-  | [< 'Token.Kwd op when op != '(' && op != ')'; operand=parse_expr >] ->
-      Ast.Unary (op, operand)
-
-  (* If the current token is not an operator, it must be a primary expr. *)
-  | [< stream >] -> parse_primary stream
-
-
- -

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 -parse_unary instead:

- -
-
-(* binoprhs
- *   ::= ('+' primary)* *)
-and parse_bin_rhs expr_prec lhs stream =
-        ...
-        (* Parse the unary expression after the binary operator. *)
-        let rhs = parse_unary stream in
-        ...
-
-...
-
-(* expression
- *   ::= primary binoprhs *)
-and parse_expr = parser
-  | [< lhs=parse_unary; stream >] -> parse_bin_rhs 0 lhs stream
-
-
- -

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:

- -
-
-(* prototype
- *   ::= id '(' id* ')'
- *   ::= binary LETTER number? (id, id)
- *   ::= unary LETTER number? (id) *)
-let parse_prototype =
-  let rec parse_args accumulator = parser
-    | [< 'Token.Ident id; e=parse_args (id::accumulator) >] -> e
-    | [< >] -> accumulator
-  in
-  let parse_operator = parser
-    | [< 'Token.Unary >] -> "unary", 1
-    | [< 'Token.Binary >] -> "binary", 2
-  in
-  let parse_binary_precedence = parser
-    | [< 'Token.Number n >] -> int_of_float n
-    | [< >] -> 30
-  in
-  parser
-  | [< 'Token.Ident id;
-       'Token.Kwd '(' ?? "expected '(' in prototype";
-       args=parse_args [];
-       'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
-      (* success. *)
-      Ast.Prototype (id, Array.of_list (List.rev args))
-  | [< (prefix, kind)=parse_operator;
-       'Token.Kwd op ?? "expected an operator";
-       (* Read the precedence if present. *)
-       binary_precedence=parse_binary_precedence;
-       'Token.Kwd '(' ?? "expected '(' in prototype";
-        args=parse_args [];
-       'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
-      let name = prefix ^ (String.make 1 op) in
-      let args = Array.of_list (List.rev args) in
-
-      (* Verify right number of arguments for operator. *)
-      if Array.length args != kind
-      then raise (Stream.Error "invalid number of operands for operator")
-      else
-        if kind == 1 then
-          Ast.Prototype (name, args)
-        else
-          Ast.BinOpPrototype (name, args, binary_precedence)
-  | [< >] ->
-      raise (Stream.Error "expected function name in prototype")
-
-
- -

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:

- -
-
-let rec codegen_expr = function
-  ...
-  | Ast.Unary (op, operand) ->
-      let operand = codegen_expr operand in
-      let callee = "unary" ^ (String.make 1 op) in
-      let callee =
-        match lookup_function callee the_module with
-        | Some callee -> callee
-        | None -> raise (Error "unknown unary operator")
-      in
-      build_call callee [|operand|] "unop" builder
-
-
- -

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);
-
-
-
- - -

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. 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 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: -

- -
-
-# Compile
-ocamlbuild toy.byte
-# Run
-./toy.byte
-
-
- -

Here is the code:

- -
-
_tags:
-
-
-<{lexer,parser}.ml>: use_camlp4, pp(camlp4of)
-<*.{byte,native}>: g++, use_llvm, use_llvm_analysis
-<*.{byte,native}>: use_llvm_executionengine, use_llvm_target
-<*.{byte,native}>: use_llvm_scalar_opts, use_bindings
-
-
- -
myocamlbuild.ml:
-
-
-open Ocamlbuild_plugin;;
-
-ocaml_lib ~extern:true "llvm";;
-ocaml_lib ~extern:true "llvm_analysis";;
-ocaml_lib ~extern:true "llvm_executionengine";;
-ocaml_lib ~extern:true "llvm_target";;
-ocaml_lib ~extern:true "llvm_scalar_opts";;
-
-flag ["link"; "ocaml"; "g++"] (S[A"-cc"; A"g++"; A"-cclib"; A"-rdynamic"]);;
-dep ["link"; "ocaml"; "use_bindings"] ["bindings.o"];;
-
-
- -
token.ml:
-
-
-(*===----------------------------------------------------------------------===
- * Lexer Tokens
- *===----------------------------------------------------------------------===*)
-
-(* The lexer returns these 'Kwd' if it is an unknown character, otherwise one of
- * these others for known things. *)
-type token =
-  (* commands *)
-  | Def | Extern
-
-  (* primary *)
-  | Ident of string | Number of float
-
-  (* unknown *)
-  | Kwd of char
-
-  (* control *)
-  | If | Then | Else
-  | For | In
-
-  (* operators *)
-  | Binary | Unary
-
-
- -
lexer.ml:
-
-
-(*===----------------------------------------------------------------------===
- * Lexer
- *===----------------------------------------------------------------------===*)
-
-let rec lex = parser
-  (* Skip any whitespace. *)
-  | [< ' (' ' | '\n' | '\r' | '\t'); stream >] -> lex stream
-
-  (* identifier: [a-zA-Z][a-zA-Z0-9] *)
-  | [< ' ('A' .. 'Z' | 'a' .. 'z' as c); stream >] ->
-      let buffer = Buffer.create 1 in
-      Buffer.add_char buffer c;
-      lex_ident buffer stream
-
-  (* number: [0-9.]+ *)
-  | [< ' ('0' .. '9' as c); stream >] ->
-      let buffer = Buffer.create 1 in
-      Buffer.add_char buffer c;
-      lex_number buffer stream
-
-  (* Comment until end of line. *)
-  | [< ' ('#'); stream >] ->
-      lex_comment stream
-
-  (* Otherwise, just return the character as its ascii value. *)
-  | [< 'c; stream >] ->
-      [< 'Token.Kwd c; lex stream >]
-
-  (* end of stream. *)
-  | [< >] -> [< >]
-
-and lex_number buffer = parser
-  | [< ' ('0' .. '9' | '.' as c); stream >] ->
-      Buffer.add_char buffer c;
-      lex_number buffer stream
-  | [< stream=lex >] ->
-      [< 'Token.Number (float_of_string (Buffer.contents buffer)); stream >]
-
-and lex_ident buffer = parser
-  | [< ' ('A' .. 'Z' | 'a' .. 'z' | '0' .. '9' as c); stream >] ->
-      Buffer.add_char buffer c;
-      lex_ident buffer stream
-  | [< stream=lex >] ->
-      match Buffer.contents buffer with
-      | "def" -> [< 'Token.Def; stream >]
-      | "extern" -> [< 'Token.Extern; stream >]
-      | "if" -> [< 'Token.If; stream >]
-      | "then" -> [< 'Token.Then; stream >]
-      | "else" -> [< 'Token.Else; stream >]
-      | "for" -> [< 'Token.For; stream >]
-      | "in" -> [< 'Token.In; stream >]
-      | "binary" -> [< 'Token.Binary; stream >]
-      | "unary" -> [< 'Token.Unary; stream >]
-      | id -> [< 'Token.Ident id; stream >]
-
-and lex_comment = parser
-  | [< ' ('\n'); stream=lex >] -> stream
-  | [< 'c; e=lex_comment >] -> e
-  | [< >] -> [< >]
-
-
- -
ast.ml:
-
-
-(*===----------------------------------------------------------------------===
- * Abstract Syntax Tree (aka Parse Tree)
- *===----------------------------------------------------------------------===*)
-
-(* expr - Base type for all expression nodes. *)
-type expr =
-  (* variant for numeric literals like "1.0". *)
-  | Number of float
-
-  (* variant for referencing a variable, like "a". *)
-  | Variable of string
-
-  (* variant for a unary operator. *)
-  | Unary of char * expr
-
-  (* variant for a binary operator. *)
-  | Binary of char * expr * expr
-
-  (* variant for function calls. *)
-  | Call of string * expr array
-
-  (* variant for if/then/else. *)
-  | If of expr * expr * expr
-
-  (* variant for for/in. *)
-  | For of string * expr * expr * expr option * expr
-
-(* proto - This type represents the "prototype" for a function, which captures
- * its name, and its argument names (thus implicitly the number of arguments the
- * function takes). *)
-type proto =
-  | Prototype of string * string array
-  | BinOpPrototype of string * string array * int
-
-(* func - This type represents a function definition itself. *)
-type func = Function of proto * expr
-
-
- -
parser.ml:
-
-
-(*===---------------------------------------------------------------------===
- * Parser
- *===---------------------------------------------------------------------===*)
-
-(* binop_precedence - This holds the precedence for each binary operator that is
- * defined *)
-let binop_precedence:(char, int) Hashtbl.t = Hashtbl.create 10
-
-(* precedence - Get the precedence of the pending binary operator token. *)
-let precedence c = try Hashtbl.find binop_precedence c with Not_found -> -1
-
-(* primary
- *   ::= identifier
- *   ::= numberexpr
- *   ::= parenexpr
- *   ::= ifexpr
- *   ::= forexpr *)
-let rec parse_primary = parser
-  (* numberexpr ::= number *)
-  | [< 'Token.Number n >] -> Ast.Number n
-
-  (* parenexpr ::= '(' expression ')' *)
-  | [< 'Token.Kwd '('; e=parse_expr; 'Token.Kwd ')' ?? "expected ')'" >] -> e
-
-  (* identifierexpr
-   *   ::= identifier
-   *   ::= identifier '(' argumentexpr ')' *)
-  | [< 'Token.Ident id; stream >] ->
-      let rec parse_args accumulator = parser
-        | [< e=parse_expr; stream >] ->
-            begin parser
-              | [< 'Token.Kwd ','; e=parse_args (e :: accumulator) >] -> e
-              | [< >] -> e :: accumulator
-            end stream
-        | [< >] -> accumulator
-      in
-      let rec parse_ident id = parser
-        (* Call. *)
-        | [< 'Token.Kwd '(';
-             args=parse_args [];
-             'Token.Kwd ')' ?? "expected ')'">] ->
-            Ast.Call (id, Array.of_list (List.rev args))
-
-        (* Simple variable ref. *)
-        | [< >] -> Ast.Variable id
-      in
-      parse_ident id stream
-
-  (* ifexpr ::= 'if' expr 'then' expr 'else' expr *)
-  | [< 'Token.If; c=parse_expr;
-       'Token.Then ?? "expected 'then'"; t=parse_expr;
-       'Token.Else ?? "expected 'else'"; e=parse_expr >] ->
-      Ast.If (c, t, e)
-
-  (* forexpr
-        ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression *)
-  | [< 'Token.For;
-       'Token.Ident id ?? "expected identifier after for";
-       'Token.Kwd '=' ?? "expected '=' after for";
-       stream >] ->
-      begin parser
-        | [<
-             start=parse_expr;
-             'Token.Kwd ',' ?? "expected ',' after for";
-             end_=parse_expr;
-             stream >] ->
-            let step =
-              begin parser
-              | [< 'Token.Kwd ','; step=parse_expr >] -> Some step
-              | [< >] -> None
-              end stream
-            in
-            begin parser
-            | [< 'Token.In; body=parse_expr >] ->
-                Ast.For (id, start, end_, step, body)
-            | [< >] ->
-                raise (Stream.Error "expected 'in' after for")
-            end stream
-        | [< >] ->
-            raise (Stream.Error "expected '=' after for")
-      end stream
-
-  | [< >] -> raise (Stream.Error "unknown token when expecting an expression.")
-
-(* unary
- *   ::= primary
- *   ::= '!' unary *)
-and parse_unary = parser
-  (* If this is a unary operator, read it. *)
-  | [< 'Token.Kwd op when op != '(' && op != ')'; operand=parse_expr >] ->
-      Ast.Unary (op, operand)
-
-  (* If the current token is not an operator, it must be a primary expr. *)
-  | [< stream >] -> parse_primary stream
-
-(* binoprhs
- *   ::= ('+' primary)* *)
-and parse_bin_rhs expr_prec lhs stream =
-  match Stream.peek stream with
-  (* If this is a binop, find its precedence. *)
-  | Some (Token.Kwd c) when Hashtbl.mem binop_precedence c ->
-      let token_prec = precedence c in
-
-      (* If this is a binop that binds at least as tightly as the current binop,
-       * consume it, otherwise we are done. *)
-      if token_prec < expr_prec then lhs else begin
-        (* Eat the binop. *)
-        Stream.junk stream;
-
-        (* Parse the unary expression after the binary operator. *)
-        let rhs = parse_unary stream in
-
-        (* Okay, we know this is a binop. *)
-        let rhs =
-          match Stream.peek stream with
-          | Some (Token.Kwd c2) ->
-              (* If BinOp binds less tightly with rhs than the operator after
-               * rhs, let the pending operator take rhs as its lhs. *)
-              let next_prec = precedence c2 in
-              if token_prec < next_prec
-              then parse_bin_rhs (token_prec + 1) rhs stream
-              else rhs
-          | _ -> rhs
-        in
-
-        (* Merge lhs/rhs. *)
-        let lhs = Ast.Binary (c, lhs, rhs) in
-        parse_bin_rhs expr_prec lhs stream
-      end
-  | _ -> lhs
-
-(* expression
- *   ::= primary binoprhs *)
-and parse_expr = parser
-  | [< lhs=parse_unary; stream >] -> parse_bin_rhs 0 lhs stream
-
-(* prototype
- *   ::= id '(' id* ')'
- *   ::= binary LETTER number? (id, id)
- *   ::= unary LETTER number? (id) *)
-let parse_prototype =
-  let rec parse_args accumulator = parser
-    | [< 'Token.Ident id; e=parse_args (id::accumulator) >] -> e
-    | [< >] -> accumulator
-  in
-  let parse_operator = parser
-    | [< 'Token.Unary >] -> "unary", 1
-    | [< 'Token.Binary >] -> "binary", 2
-  in
-  let parse_binary_precedence = parser
-    | [< 'Token.Number n >] -> int_of_float n
-    | [< >] -> 30
-  in
-  parser
-  | [< 'Token.Ident id;
-       'Token.Kwd '(' ?? "expected '(' in prototype";
-       args=parse_args [];
-       'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
-      (* success. *)
-      Ast.Prototype (id, Array.of_list (List.rev args))
-  | [< (prefix, kind)=parse_operator;
-       'Token.Kwd op ?? "expected an operator";
-       (* Read the precedence if present. *)
-       binary_precedence=parse_binary_precedence;
-       'Token.Kwd '(' ?? "expected '(' in prototype";
-        args=parse_args [];
-       'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
-      let name = prefix ^ (String.make 1 op) in
-      let args = Array.of_list (List.rev args) in
-
-      (* Verify right number of arguments for operator. *)
-      if Array.length args != kind
-      then raise (Stream.Error "invalid number of operands for operator")
-      else
-        if kind == 1 then
-          Ast.Prototype (name, args)
-        else
-          Ast.BinOpPrototype (name, args, binary_precedence)
-  | [< >] ->
-      raise (Stream.Error "expected function name in prototype")
-
-(* definition ::= 'def' prototype expression *)
-let parse_definition = parser
-  | [< 'Token.Def; p=parse_prototype; e=parse_expr >] ->
-      Ast.Function (p, e)
-
-(* toplevelexpr ::= expression *)
-let parse_toplevel = parser
-  | [< e=parse_expr >] ->
-      (* Make an anonymous proto. *)
-      Ast.Function (Ast.Prototype ("", [||]), e)
-
-(*  external ::= 'extern' prototype *)
-let parse_extern = parser
-  | [< 'Token.Extern; e=parse_prototype >] -> e
-
-
- -
codegen.ml:
-
-
-(*===----------------------------------------------------------------------===
- * Code Generation
- *===----------------------------------------------------------------------===*)
-
-open Llvm
-
-exception Error of string
-
-let context = global_context ()
-let the_module = create_module context "my cool jit"
-let builder = builder context
-let named_values:(string, llvalue) Hashtbl.t = Hashtbl.create 10
-let double_type = double_type context
-
-let rec codegen_expr = function
-  | Ast.Number n -> const_float double_type n
-  | Ast.Variable name ->
-      (try Hashtbl.find named_values name with
-        | Not_found -> raise (Error "unknown variable name"))
-  | Ast.Unary (op, operand) ->
-      let operand = codegen_expr operand in
-      let callee = "unary" ^ (String.make 1 op) in
-      let callee =
-        match lookup_function callee the_module with
-        | Some callee -> callee
-        | None -> raise (Error "unknown unary operator")
-      in
-      build_call callee [|operand|] "unop" builder
-  | Ast.Binary (op, lhs, rhs) ->
-      let lhs_val = codegen_expr lhs in
-      let rhs_val = codegen_expr rhs in
-      begin
-        match op with
-        | '+' -> build_add lhs_val rhs_val "addtmp" builder
-        | '-' -> build_sub lhs_val rhs_val "subtmp" builder
-        | '*' -> build_mul lhs_val rhs_val "multmp" builder
-        | '<' ->
-            (* Convert bool 0/1 to double 0.0 or 1.0 *)
-            let i = build_fcmp Fcmp.Ult lhs_val rhs_val "cmptmp" builder in
-            build_uitofp i double_type "booltmp" builder
-        | _ ->
-            (* If it wasn't a builtin binary operator, it must be a user defined
-             * one. Emit a call to it. *)
-            let callee = "binary" ^ (String.make 1 op) in
-            let callee =
-              match lookup_function callee the_module with
-              | Some callee -> callee
-              | None -> raise (Error "binary operator not found!")
-            in
-            build_call callee [|lhs_val; rhs_val|] "binop" builder
-      end
-  | Ast.Call (callee, args) ->
-      (* Look up the name in the module table. *)
-      let callee =
-        match lookup_function callee the_module with
-        | Some callee -> callee
-        | None -> raise (Error "unknown function referenced")
-      in
-      let params = params callee in
-
-      (* If argument mismatch error. *)
-      if Array.length params == Array.length args then () else
-        raise (Error "incorrect # arguments passed");
-      let args = Array.map codegen_expr args in
-      build_call callee args "calltmp" builder
-  | Ast.If (cond, then_, else_) ->
-      let cond = codegen_expr cond in
-
-      (* Convert condition to a bool by comparing equal to 0.0 *)
-      let zero = const_float double_type 0.0 in
-      let cond_val = build_fcmp Fcmp.One cond zero "ifcond" builder in
-
-      (* Grab the first block so that we might later add the conditional branch
-       * to it at the end of the function. *)
-      let start_bb = insertion_block builder in
-      let the_function = block_parent start_bb in
-
-      let then_bb = append_block context "then" the_function in
-
-      (* Emit 'then' value. *)
-      position_at_end then_bb builder;
-      let then_val = codegen_expr then_ in
-
-      (* Codegen of 'then' can change the current block, update then_bb for the
-       * phi. We create a new name because one is used for the phi node, and the
-       * other is used for the conditional branch. *)
-      let new_then_bb = insertion_block builder in
-
-      (* Emit 'else' value. *)
-      let else_bb = append_block context "else" the_function in
-      position_at_end else_bb builder;
-      let else_val = codegen_expr else_ in
-
-      (* Codegen of 'else' can change the current block, update else_bb for the
-       * phi. *)
-      let new_else_bb = insertion_block builder in
-
-      (* Emit merge block. *)
-      let merge_bb = append_block context "ifcont" the_function in
-      position_at_end merge_bb builder;
-      let incoming = [(then_val, new_then_bb); (else_val, new_else_bb)] in
-      let phi = build_phi incoming "iftmp" builder in
-
-      (* Return to the start block to add the conditional branch. *)
-      position_at_end start_bb builder;
-      ignore (build_cond_br cond_val then_bb else_bb builder);
-
-      (* Set a unconditional branch at the end of the 'then' block and the
-       * 'else' block to the 'merge' block. *)
-      position_at_end new_then_bb builder; ignore (build_br merge_bb builder);
-      position_at_end new_else_bb builder; ignore (build_br merge_bb builder);
-
-      (* Finally, set the builder to the end of the merge block. *)
-      position_at_end merge_bb builder;
-
-      phi
-  | Ast.For (var_name, start, end_, step, body) ->
-      (* Emit the start code first, without 'variable' in scope. *)
-      let start_val = codegen_expr start in
-
-      (* Make the new basic block for the loop header, inserting after current
-       * block. *)
-      let preheader_bb = insertion_block builder in
-      let the_function = block_parent preheader_bb in
-      let loop_bb = append_block context "loop" the_function in
-
-      (* Insert an explicit fall through from the current block to the
-       * loop_bb. *)
-      ignore (build_br loop_bb builder);
-
-      (* Start insertion in loop_bb. *)
-      position_at_end loop_bb builder;
-
-      (* Start the PHI node with an entry for start. *)
-      let variable = build_phi [(start_val, preheader_bb)] var_name builder in
-
-      (* Within the loop, the variable is defined equal to the PHI node. If it
-       * shadows an existing variable, we have to restore it, so save it
-       * now. *)
-      let old_val =
-        try Some (Hashtbl.find named_values var_name) with Not_found -> None
-      in
-      Hashtbl.add named_values var_name variable;
-
-      (* Emit the body of the loop.  This, like any other expr, can change the
-       * current BB.  Note that we ignore the value computed by the body, but
-       * don't allow an error *)
-      ignore (codegen_expr body);
-
-      (* Emit the step value. *)
-      let step_val =
-        match step with
-        | Some step -> codegen_expr step
-        (* If not specified, use 1.0. *)
-        | None -> const_float double_type 1.0
-      in
-
-      let next_var = build_add variable step_val "nextvar" builder in
-
-      (* Compute the end condition. *)
-      let end_cond = codegen_expr end_ in
-
-      (* Convert condition to a bool by comparing equal to 0.0. *)
-      let zero = const_float double_type 0.0 in
-      let end_cond = build_fcmp Fcmp.One end_cond zero "loopcond" builder in
-
-      (* Create the "after loop" block and insert it. *)
-      let loop_end_bb = insertion_block builder in
-      let after_bb = append_block context "afterloop" the_function in
-
-      (* Insert the conditional branch into the end of loop_end_bb. *)
-      ignore (build_cond_br end_cond loop_bb after_bb builder);
-
-      (* Any new code will be inserted in after_bb. *)
-      position_at_end after_bb builder;
-
-      (* Add a new entry to the PHI node for the backedge. *)
-      add_incoming (next_var, loop_end_bb) variable;
-
-      (* Restore the unshadowed variable. *)
-      begin match old_val with
-      | Some old_val -> Hashtbl.add named_values var_name old_val
-      | None -> ()
-      end;
-
-      (* for expr always returns 0.0. *)
-      const_null double_type
-
-let codegen_proto = function
-  | Ast.Prototype (name, args) | Ast.BinOpPrototype (name, args, _) ->
-      (* Make the function type: double(double,double) etc. *)
-      let doubles = Array.make (Array.length args) double_type in
-      let ft = function_type double_type doubles in
-      let f =
-        match lookup_function name the_module with
-        | None -> declare_function name ft the_module
-
-        (* If 'f' conflicted, there was already something named 'name'. If it
-         * has a body, don't allow redefinition or reextern. *)
-        | Some f ->
-            (* If 'f' already has a body, reject this. *)
-            if block_begin f <> At_end f then
-              raise (Error "redefinition of function");
-
-            (* If 'f' took a different number of arguments, reject. *)
-            if element_type (type_of f) <> ft then
-              raise (Error "redefinition of function with different # args");
-            f
-      in
-
-      (* Set names for all arguments. *)
-      Array.iteri (fun i a ->
-        let n = args.(i) in
-        set_value_name n a;
-        Hashtbl.add named_values n a;
-      ) (params f);
-      f
-
-let codegen_func the_fpm = function
-  | Ast.Function (proto, body) ->
-      Hashtbl.clear named_values;
-      let the_function = codegen_proto proto in
-
-      (* If this is an operator, install it. *)
-      begin match proto with
-      | Ast.BinOpPrototype (name, args, prec) ->
-          let op = name.[String.length name - 1] in
-          Hashtbl.add Parser.binop_precedence op prec;
-      | _ -> ()
-      end;
-
-      (* Create a new basic block to start insertion into. *)
-      let bb = append_block context "entry" the_function in
-      position_at_end bb builder;
-
-      try
-        let ret_val = codegen_expr body in
-
-        (* Finish off the function. *)
-        let _ = build_ret ret_val builder in
-
-        (* Validate the generated code, checking for consistency. *)
-        Llvm_analysis.assert_valid_function the_function;
-
-        (* Optimize the function. *)
-        let _ = PassManager.run_function the_function the_fpm in
-
-        the_function
-      with e ->
-        delete_function the_function;
-        raise e
-
-
- -
toplevel.ml:
-
-
-(*===----------------------------------------------------------------------===
- * Top-Level parsing and JIT Driver
- *===----------------------------------------------------------------------===*)
-
-open Llvm
-open Llvm_executionengine
-
-(* top ::= definition | external | expression | ';' *)
-let rec main_loop the_fpm the_execution_engine stream =
-  match Stream.peek stream with
-  | None -> ()
-
-  (* ignore top-level semicolons. *)
-  | Some (Token.Kwd ';') ->
-      Stream.junk stream;
-      main_loop the_fpm the_execution_engine stream
-
-  | Some token ->
-      begin
-        try match token with
-        | Token.Def ->
-            let e = Parser.parse_definition stream in
-            print_endline "parsed a function definition.";
-            dump_value (Codegen.codegen_func the_fpm e);
-        | Token.Extern ->
-            let e = Parser.parse_extern stream in
-            print_endline "parsed an extern.";
-            dump_value (Codegen.codegen_proto e);
-        | _ ->
-            (* Evaluate a top-level expression into an anonymous function. *)
-            let e = Parser.parse_toplevel stream in
-            print_endline "parsed a top-level expr";
-            let the_function = Codegen.codegen_func the_fpm e in
-            dump_value the_function;
-
-            (* JIT the function, returning a function pointer. *)
-            let result = ExecutionEngine.run_function the_function [||]
-              the_execution_engine in
-
-            print_string "Evaluated to ";
-            print_float (GenericValue.as_float Codegen.double_type result);
-            print_newline ();
-        with Stream.Error s | Codegen.Error s ->
-          (* Skip token for error recovery. *)
-          Stream.junk stream;
-          print_endline s;
-      end;
-      print_string "ready> "; flush stdout;
-      main_loop the_fpm the_execution_engine stream
-
-
- -
toy.ml:
-
-
-(*===----------------------------------------------------------------------===
- * Main driver code.
- *===----------------------------------------------------------------------===*)
-
-open Llvm
-open Llvm_executionengine
-open Llvm_target
-open Llvm_scalar_opts
-
-let main () =
-  ignore (initialize_native_target ());
-
-  (* Install standard binary operators.
-   * 1 is the lowest precedence. *)
-  Hashtbl.add Parser.binop_precedence '<' 10;
-  Hashtbl.add Parser.binop_precedence '+' 20;
-  Hashtbl.add Parser.binop_precedence '-' 20;
-  Hashtbl.add Parser.binop_precedence '*' 40;    (* highest. *)
-
-  (* Prime the first token. *)
-  print_string "ready> "; flush stdout;
-  let stream = Lexer.lex (Stream.of_channel stdin) in
-
-  (* Create the JIT. *)
-  let the_execution_engine = ExecutionEngine.create Codegen.the_module in
-  let the_fpm = PassManager.create_function Codegen.the_module in
-
-  (* Set up the optimizer pipeline.  Start with registering info about how the
-   * target lays out data structures. *)
-  DataLayout.add (ExecutionEngine.target_data the_execution_engine) the_fpm;
-
-  (* Do simple "peephole" optimizations and bit-twiddling optzn. *)
-  add_instruction_combination the_fpm;
-
-  (* reassociate expressions. *)
-  add_reassociation the_fpm;
-
-  (* Eliminate Common SubExpressions. *)
-  add_gvn the_fpm;
-
-  (* Simplify the control flow graph (deleting unreachable blocks, etc). *)
-  add_cfg_simplification the_fpm;
-
-  ignore (PassManager.initialize the_fpm);
-
-  (* Run the main "interpreter loop" now. *)
-  Toplevel.main_loop the_fpm the_execution_engine stream;
-
-  (* Print out all the generated code. *)
-  dump_module Codegen.the_module
-;;
-
-main ()
-
-
- -
bindings.c
-
-
-#include <stdio.h>
-
-/* putchard - putchar that takes a double and returns 0. */
-extern double putchard(double X) {
-  putchar((char)X);
-  return 0;
-}
-
-/* printd - printf that takes a double prints it as "%f\n", returning 0. */
-extern double printd(double X) {
-  printf("%f\n", X);
-  return 0;
-}
-
-
-
- -Next: Extending the language: mutable variables / -SSA construction -
- - -
-
- Valid CSS! - Valid HTML 4.01! - - Chris Lattner
- Erick Tryzelaar
- The LLVM Compiler Infrastructure
- Last modified: $Date: 2012-10-08 18:39:34 +0200 (Mon, 08 Oct 2012) $ -
- - -- cgit v1.1