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diff --git a/gnu/llvm/docs/tutorial/OCamlLangImpl6.rst b/gnu/llvm/docs/tutorial/OCamlLangImpl6.rst deleted file mode 100644 index 4b3e1575adf..00000000000 --- a/gnu/llvm/docs/tutorial/OCamlLangImpl6.rst +++ /dev/null @@ -1,1441 +0,0 @@ -============================================================ -Kaleidoscope: Extending the Language: User-defined Operators -============================================================ - -.. contents:: - :local: - -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 <#kicking-the-tires>`_. 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 programmatically 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 <OCamlLangImpl2.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:: ocaml - - 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 <OCamlLangImpl5.html#lexer-extensions-for-if-then-else>`_. 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: - -.. code-block:: ocaml - - (* 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: - -.. code-block:: ocaml - - (* 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: - -.. code-block:: ocaml - - 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: - -.. code-block:: ocaml - - 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: - -.. code-block:: ocaml - - 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: - -.. code-block:: ocaml - - (* 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: - -.. code-block:: ocaml - - (* 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: - -.. code-block:: ocaml - - (* 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: - -.. code-block:: ocaml - - 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 mandelconverger(real imag iters creal cimag) - if iters > 255 | (real*real + imag*imag > 4) then - iters - else - mandelconverger(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 mandelconverge(real imag) - mandelconverger(real, imag, 0, real, imag); - -This "z = z\ :sup:`2`\ + 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 mandelbrot 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(mandelconverge(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 mandelbrot 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 <OCamlLangImpl7.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 - 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: - .. code-block:: ocaml - - 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: - .. code-block:: ocaml - - (*===----------------------------------------------------------------------=== - * 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: - .. code-block:: ocaml - - (*===----------------------------------------------------------------------=== - * 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: - .. code-block:: ocaml - - (*===----------------------------------------------------------------------=== - * 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: - .. code-block:: ocaml - - (*===---------------------------------------------------------------------=== - * 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-block:: ocaml - - (*===----------------------------------------------------------------------=== - * 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: - .. code-block:: ocaml - - (*===----------------------------------------------------------------------=== - * 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: - .. code-block:: ocaml - - (*===----------------------------------------------------------------------=== - * 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 - .. code-block:: 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 <OCamlLangImpl7.html>`_ - |