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| author | mike-m <mikem.llvm@gmail.com> | 2010-05-06 23:45:43 +0000 |
|---|---|---|
| committer | mike-m <mikem.llvm@gmail.com> | 2010-05-06 23:45:43 +0000 |
| commit | 68cb31901c590cabceee6e6356d62c84142114cb (patch) | |
| tree | 6444bddc975b662fbe47d63cd98a7b776a407c1a /docs/tutorial/LangImpl6.html | |
| parent | c26ae5ab7e2d65b67c97524e66f50ce86445dec7 (diff) | |
| download | external_llvm-68cb31901c590cabceee6e6356d62c84142114cb.zip external_llvm-68cb31901c590cabceee6e6356d62c84142114cb.tar.gz external_llvm-68cb31901c590cabceee6e6356d62c84142114cb.tar.bz2 | |
Overhauled llvm/clang docs builds. Closes PR6613.
NOTE: 2nd part changeset for cfe trunk to follow.
*** PRE-PATCH ISSUES ADDRESSED
- clang api docs fail build from objdir
- clang/llvm api docs collide in install PREFIX/
- clang/llvm main docs collide in install
- clang/llvm main docs have full of hard coded destination
assumptions and make use of absolute root in static html files;
namely CommandGuide tools hard codes a website destination
for cross references and some html cross references assume
website root paths
*** IMPROVEMENTS
- bumped Doxygen from 1.4.x -> 1.6.3
- splits llvm/clang docs into 'main' and 'api' (doxygen) build trees
- provide consistent, reliable doc builds for both main+api docs
- support buid vs. install vs. website intentions
- support objdir builds
- document targets with 'make help'
- correct clean and uninstall operations
- use recursive dir delete only where absolutely necessary
- added call function fn.RMRF which safeguards against botched 'rm -rf';
if any target (or any variable is evaluated) which attempts
to remove any dirs which match a hard-coded 'safelist', a verbose
error will be printed and make will error-stop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103213 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/tutorial/LangImpl6.html')
| -rw-r--r-- | docs/tutorial/LangImpl6.html | 1814 |
1 files changed, 0 insertions, 1814 deletions
diff --git a/docs/tutorial/LangImpl6.html b/docs/tutorial/LangImpl6.html deleted file mode 100644 index 5fae906..0000000 --- a/docs/tutorial/LangImpl6.html +++ /dev/null @@ -1,1814 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" - "http://www.w3.org/TR/html4/strict.dtd"> - -<html> -<head> - <title>Kaleidoscope: Extending the Language: User-defined Operators</title> - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> - <meta name="author" content="Chris Lattner"> - <link rel="stylesheet" href="../llvm.css" type="text/css"> -</head> - -<body> - -<div class="doc_title">Kaleidoscope: Extending the Language: User-defined Operators</div> - -<ul> -<li><a href="index.html">Up to Tutorial Index</a></li> -<li>Chapter 6 - <ol> - <li><a href="#intro">Chapter 6 Introduction</a></li> - <li><a href="#idea">User-defined Operators: the Idea</a></li> - <li><a href="#binary">User-defined Binary Operators</a></li> - <li><a href="#unary">User-defined Unary Operators</a></li> - <li><a href="#example">Kicking the Tires</a></li> - <li><a href="#code">Full Code Listing</a></li> - </ol> -</li> -<li><a href="LangImpl7.html">Chapter 7</a>: Extending the Language: Mutable -Variables / SSA Construction</li> -</ul> - -<div class="doc_author"> - <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p> -</div> - -<!-- *********************************************************************** --> -<div class="doc_section"><a name="intro">Chapter 6 Introduction</a></div> -<!-- *********************************************************************** --> - -<div class="doc_text"> - -<p>Welcome to Chapter 6 of the "<a href="index.html">Implementing a language -with LLVM</a>" 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).</p> - -<p>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.</p> - -<p>At the end of this tutorial, we'll run through an example Kaleidoscope -application that <a href="#example">renders the Mandelbrot set</a>. This gives -an example of what you can build with Kaleidoscope and its feature set.</p> - -</div> - -<!-- *********************************************************************** --> -<div class="doc_section"><a name="idea">User-defined Operators: the Idea</a></div> -<!-- *********************************************************************** --> - -<div class="doc_text"> - -<p> -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.</p> - -<p>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 <a -href="LangImpl2.html">Chapter 2</a> 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.</p> - -<p>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:</p> - -<div class="doc_code"> -<pre> -# 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); -</pre> -</div> - -<p>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!</p> - -<p>We will break down implementation of these features into two parts: -implementing support for user-defined binary operators and adding unary -operators.</p> - -</div> - -<!-- *********************************************************************** --> -<div class="doc_section"><a name="binary">User-defined Binary Operators</a></div> -<!-- *********************************************************************** --> - -<div class="doc_text"> - -<p>Adding support for user-defined binary operators is pretty simple with our -current framework. We'll first add support for the unary/binary keywords:</p> - -<div class="doc_code"> -<pre> -enum Token { - ... - <b>// operators - tok_binary = -11, tok_unary = -12</b> -}; -... -static int gettok() { -... - if (IdentifierStr == "for") return tok_for; - if (IdentifierStr == "in") return tok_in; - <b>if (IdentifierStr == "binary") return tok_binary; - if (IdentifierStr == "unary") return tok_unary;</b> - return tok_identifier; -</pre> -</div> - -<p>This just adds lexer support for the unary and binary keywords, like we -did in <a href="LangImpl5.html#iflexer">previous chapters</a>. 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.</p> - -<p>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 <tt>PrototypeAST</tt> AST node. To -represent our new user-defined operators as prototypes, we have to extend -the <tt>PrototypeAST</tt> AST node like this:</p> - -<div class="doc_code"> -<pre> -/// PrototypeAST - This class represents the "prototype" for a function, -/// which captures its argument names as well as if it is an operator. -class PrototypeAST { - std::string Name; - std::vector<std::string> Args; - <b>bool isOperator; - unsigned Precedence; // Precedence if a binary op.</b> -public: - PrototypeAST(const std::string &name, const std::vector<std::string> &args, - <b>bool isoperator = false, unsigned prec = 0</b>) - : Name(name), Args(args), <b>isOperator(isoperator), Precedence(prec)</b> {} - - <b>bool isUnaryOp() const { return isOperator && Args.size() == 1; } - bool isBinaryOp() const { return isOperator && Args.size() == 2; } - - char getOperatorName() const { - assert(isUnaryOp() || isBinaryOp()); - return Name[Name.size()-1]; - } - - unsigned getBinaryPrecedence() const { return Precedence; }</b> - - Function *Codegen(); -}; -</pre> -</div> - -<p>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:</p> - -<div class="doc_code"> -<pre> -/// prototype -/// ::= id '(' id* ')' -<b>/// ::= binary LETTER number? (id, id)</b> -static PrototypeAST *ParsePrototype() { - std::string FnName; - - <b>unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary. - unsigned BinaryPrecedence = 30;</b> - - switch (CurTok) { - default: - return ErrorP("Expected function name in prototype"); - case tok_identifier: - FnName = IdentifierStr; - Kind = 0; - getNextToken(); - break; - <b>case tok_binary: - getNextToken(); - if (!isascii(CurTok)) - return ErrorP("Expected binary operator"); - FnName = "binary"; - FnName += (char)CurTok; - Kind = 2; - getNextToken(); - - // Read the precedence if present. - if (CurTok == tok_number) { - if (NumVal < 1 || NumVal > 100) - return ErrorP("Invalid precedecnce: must be 1..100"); - BinaryPrecedence = (unsigned)NumVal; - getNextToken(); - } - break;</b> - } - - if (CurTok != '(') - return ErrorP("Expected '(' in prototype"); - - std::vector<std::string> ArgNames; - while (getNextToken() == tok_identifier) - ArgNames.push_back(IdentifierStr); - if (CurTok != ')') - return ErrorP("Expected ')' in prototype"); - - // success. - getNextToken(); // eat ')'. - - <b>// Verify right number of names for operator. - if (Kind && ArgNames.size() != Kind) - return ErrorP("Invalid number of operands for operator"); - - return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);</b> -} -</pre> -</div> - -<p>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 <tt>FnName</tt> 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.</p> - -<p>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:</p> - -<div class="doc_code"> -<pre> -Value *BinaryExprAST::Codegen() { - Value *L = LHS->Codegen(); - Value *R = RHS->Codegen(); - if (L == 0 || R == 0) return 0; - - switch (Op) { - case '+': return Builder.CreateAdd(L, R, "addtmp"); - case '-': return Builder.CreateSub(L, R, "subtmp"); - case '*': return Builder.CreateMul(L, R, "multmp"); - case '<': - L = Builder.CreateFCmpULT(L, R, "cmptmp"); - // Convert bool 0/1 to double 0.0 or 1.0 - return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()), - "booltmp"); - <b>default: break;</b> - } - - <b>// If it wasn't a builtin binary operator, it must be a user defined one. Emit - // a call to it. - Function *F = TheModule->getFunction(std::string("binary")+Op); - assert(F && "binary operator not found!"); - - Value *Ops[] = { L, R }; - return Builder.CreateCall(F, Ops, Ops+2, "binop");</b> -} - -</pre> -</div> - -<p>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.</p> - -<p>The final piece of code we are missing, is a bit of top-level magic:</p> - -<div class="doc_code"> -<pre> -Function *FunctionAST::Codegen() { - NamedValues.clear(); - - Function *TheFunction = Proto->Codegen(); - if (TheFunction == 0) - return 0; - - <b>// If this is an operator, install it. - if (Proto->isBinaryOp()) - BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();</b> - - // Create a new basic block to start insertion into. - BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction); - Builder.SetInsertPoint(BB); - - if (Value *RetVal = Body->Codegen()) { - ... -</pre> -</div> - -<p>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".</p> - -<p>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.</p> - -</div> - -<!-- *********************************************************************** --> -<div class="doc_section"><a name="unary">User-defined Unary Operators</a></div> -<!-- *********************************************************************** --> - -<div class="doc_text"> - -<p>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:</p> - -<div class="doc_code"> -<pre> -/// UnaryExprAST - Expression class for a unary operator. -class UnaryExprAST : public ExprAST { - char Opcode; - ExprAST *Operand; -public: - UnaryExprAST(char opcode, ExprAST *operand) - : Opcode(opcode), Operand(operand) {} - virtual Value *Codegen(); -}; -</pre> -</div> - -<p>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:</p> - -<div class="doc_code"> -<pre> -/// unary -/// ::= primary -/// ::= '!' unary -static ExprAST *ParseUnary() { - // If the current token is not an operator, it must be a primary expr. - if (!isascii(CurTok) || CurTok == '(' || CurTok == ',') - return ParsePrimary(); - - // If this is a unary operator, read it. - int Opc = CurTok; - getNextToken(); - if (ExprAST *Operand = ParseUnary()) - return new UnaryExprAST(Opc, Operand); - return 0; -} -</pre> -</div> - -<p>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.</p> - -<p>The problem with this function, is that we need to call ParseUnary from somewhere. -To do this, we change previous callers of ParsePrimary to call ParseUnary -instead:</p> - -<div class="doc_code"> -<pre> -/// binoprhs -/// ::= ('+' unary)* -static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) { - ... - <b>// Parse the unary expression after the binary operator. - ExprAST *RHS = ParseUnary(); - if (!RHS) return 0;</b> - ... -} -/// expression -/// ::= unary binoprhs -/// -static ExprAST *ParseExpression() { - <b>ExprAST *LHS = ParseUnary();</b> - if (!LHS) return 0; - - return ParseBinOpRHS(0, LHS); -} -</pre> -</div> - -<p>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:</p> - -<div class="doc_code"> -<pre> -/// prototype -/// ::= id '(' id* ')' -/// ::= binary LETTER number? (id, id) -<b>/// ::= unary LETTER (id)</b> -static PrototypeAST *ParsePrototype() { - std::string FnName; - - unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary. - unsigned BinaryPrecedence = 30; - - switch (CurTok) { - default: - return ErrorP("Expected function name in prototype"); - case tok_identifier: - FnName = IdentifierStr; - Kind = 0; - getNextToken(); - break; - <b>case tok_unary: - getNextToken(); - if (!isascii(CurTok)) - return ErrorP("Expected unary operator"); - FnName = "unary"; - FnName += (char)CurTok; - Kind = 1; - getNextToken(); - break;</b> - case tok_binary: - ... -</pre> -</div> - -<p>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:</p> - -<div class="doc_code"> -<pre> -Value *UnaryExprAST::Codegen() { - Value *OperandV = Operand->Codegen(); - if (OperandV == 0) return 0; - - Function *F = TheModule->getFunction(std::string("unary")+Opcode); - if (F == 0) - return ErrorV("Unknown unary operator"); - - return Builder.CreateCall(F, OperandV, "unop"); -} -</pre> -</div> - -<p>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. -</p> - -</div> - -<!-- *********************************************************************** --> -<div class="doc_section"><a name="example">Kicking the Tires</a></div> -<!-- *********************************************************************** --> - -<div class="doc_text"> - -<p>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):</p> - -<div class="doc_code"> -<pre> -ready> <b>extern printd(x);</b> -Read extern: declare double @printd(double) -ready> <b>def binary : 1 (x y) 0; # Low-precedence operator that ignores operands.</b> -.. -ready> <b>printd(123) : printd(456) : printd(789);</b> -123.000000 -456.000000 -789.000000 -Evaluated to 0.000000 -</pre> -</div> - -<p>We can also define a bunch of other "primitive" operations, such as:</p> - -<div class="doc_code"> -<pre> -# 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); - -</pre> -</div> - - -<p>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:</p> - -<div class="doc_code"> -<pre> -ready> -<b> -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); # '*'</b> -... -ready> <b>printdensity(1): printdensity(2): printdensity(3) : - printdensity(4): printdensity(5): printdensity(9): putchard(10);</b> -*++.. -Evaluated to 0.000000 -</pre> -</div> - -<p>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:</p> - -<div class="doc_code"> -<pre> -# 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); -</pre> -</div> - -<p>This "z = z<sup>2</sup> + c" function is a beautiful little creature that is the basis -for computation of the <a -href="http://en.wikipedia.org/wiki/Mandelbrot_set">Mandelbrot Set</a>. Our -<tt>mandelconverge</tt> 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:</p> - -<div class="doc_code"> -<pre> -# 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 ploting 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); -</pre> -</div> - -<p>Given this, we can try plotting out the mandlebrot set! Lets try it out:</p> - -<div class="doc_code"> -<pre> -ready> <b>mandel(-2.3, -1.3, 0.05, 0.07);</b> -*******************************+++++++++++************************************* -*************************+++++++++++++++++++++++******************************* -**********************+++++++++++++++++++++++++++++**************************** -*******************+++++++++++++++++++++.. ...++++++++************************* -*****************++++++++++++++++++++++.... ...+++++++++*********************** -***************+++++++++++++++++++++++..... ...+++++++++********************* -**************+++++++++++++++++++++++.... ....+++++++++******************** -*************++++++++++++++++++++++...... .....++++++++******************* -************+++++++++++++++++++++....... .......+++++++****************** -***********+++++++++++++++++++.... ... .+++++++***************** -**********+++++++++++++++++....... .+++++++**************** -*********++++++++++++++........... ...+++++++*************** -********++++++++++++............ ...++++++++************** -********++++++++++... .......... .++++++++************** -*******+++++++++..... .+++++++++************* -*******++++++++...... ..+++++++++************* -*******++++++....... ..+++++++++************* -*******+++++...... ..+++++++++************* -*******.... .... ...+++++++++************* -*******.... . ...+++++++++************* -*******+++++...... ...+++++++++************* -*******++++++....... ..+++++++++************* -*******++++++++...... .+++++++++************* -*******+++++++++..... ..+++++++++************* -********++++++++++... .......... .++++++++************** -********++++++++++++............ ...++++++++************** -*********++++++++++++++.......... ...+++++++*************** -**********++++++++++++++++........ .+++++++**************** -**********++++++++++++++++++++.... ... ..+++++++**************** -***********++++++++++++++++++++++....... .......++++++++***************** -************+++++++++++++++++++++++...... ......++++++++****************** -**************+++++++++++++++++++++++.... ....++++++++******************** -***************+++++++++++++++++++++++..... ...+++++++++********************* -*****************++++++++++++++++++++++.... ...++++++++*********************** -*******************+++++++++++++++++++++......++++++++************************* -*********************++++++++++++++++++++++.++++++++*************************** -*************************+++++++++++++++++++++++******************************* -******************************+++++++++++++************************************ -******************************************************************************* -******************************************************************************* -******************************************************************************* -Evaluated to 0.000000 -ready> <b>mandel(-2, -1, 0.02, 0.04);</b> -**************************+++++++++++++++++++++++++++++++++++++++++++++++++++++ -***********************++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -*********************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++. -*******************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++... -*****************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++..... -***************++++++++++++++++++++++++++++++++++++++++++++++++++++++++........ -**************++++++++++++++++++++++++++++++++++++++++++++++++++++++........... -************+++++++++++++++++++++++++++++++++++++++++++++++++++++.............. -***********++++++++++++++++++++++++++++++++++++++++++++++++++........ . -**********++++++++++++++++++++++++++++++++++++++++++++++............. -********+++++++++++++++++++++++++++++++++++++++++++.................. -*******+++++++++++++++++++++++++++++++++++++++....................... -******+++++++++++++++++++++++++++++++++++........................... -*****++++++++++++++++++++++++++++++++............................ -*****++++++++++++++++++++++++++++............................... -****++++++++++++++++++++++++++...... ......................... -***++++++++++++++++++++++++......... ...... ........... -***++++++++++++++++++++++............ -**+++++++++++++++++++++.............. -**+++++++++++++++++++................ -*++++++++++++++++++................. -*++++++++++++++++............ ... -*++++++++++++++.............. -*+++....++++................ -*.......... ........... -* -*.......... ........... -*+++....++++................ -*++++++++++++++.............. -*++++++++++++++++............ ... -*++++++++++++++++++................. -**+++++++++++++++++++................ -**+++++++++++++++++++++.............. -***++++++++++++++++++++++............ -***++++++++++++++++++++++++......... ...... ........... -****++++++++++++++++++++++++++...... ......................... -*****++++++++++++++++++++++++++++............................... -*****++++++++++++++++++++++++++++++++............................ -******+++++++++++++++++++++++++++++++++++........................... -*******+++++++++++++++++++++++++++++++++++++++....................... -********+++++++++++++++++++++++++++++++++++++++++++.................. -Evaluated to 0.000000 -ready> <b>mandel(-0.9, -1.4, 0.02, 0.03);</b> -******************************************************************************* -******************************************************************************* -******************************************************************************* -**********+++++++++++++++++++++************************************************ -*+++++++++++++++++++++++++++++++++++++++*************************************** -+++++++++++++++++++++++++++++++++++++++++++++********************************** -++++++++++++++++++++++++++++++++++++++++++++++++++***************************** -++++++++++++++++++++++++++++++++++++++++++++++++++++++************************* -+++++++++++++++++++++++++++++++++++++++++++++++++++++++++********************** -+++++++++++++++++++++++++++++++++.........++++++++++++++++++******************* -+++++++++++++++++++++++++++++++.... ......+++++++++++++++++++**************** -+++++++++++++++++++++++++++++....... ........+++++++++++++++++++************** -++++++++++++++++++++++++++++........ ........++++++++++++++++++++************ -+++++++++++++++++++++++++++......... .. ...+++++++++++++++++++++********** -++++++++++++++++++++++++++........... ....++++++++++++++++++++++******** -++++++++++++++++++++++++............. .......++++++++++++++++++++++****** -+++++++++++++++++++++++............. ........+++++++++++++++++++++++**** -++++++++++++++++++++++........... ..........++++++++++++++++++++++*** -++++++++++++++++++++........... .........++++++++++++++++++++++* -++++++++++++++++++............ ...........++++++++++++++++++++ -++++++++++++++++............... .............++++++++++++++++++ -++++++++++++++................. ...............++++++++++++++++ -++++++++++++.................. .................++++++++++++++ -+++++++++.................. .................+++++++++++++ -++++++........ . ......... ..++++++++++++ -++............ ...... ....++++++++++ -.............. ...++++++++++ -.............. ....+++++++++ -.............. .....++++++++ -............. ......++++++++ -........... .......++++++++ -......... ........+++++++ -......... ........+++++++ -......... ....+++++++ -........ ...+++++++ -....... ...+++++++ - ....+++++++ - .....+++++++ - ....+++++++ - ....+++++++ - ....+++++++ -Evaluated to 0.000000 -ready> <b>^D</b> -</pre> -</div> - -<p>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!</p> - -<p>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. -</p> - -<p>Strikingly, variable mutation is an important feature of some -languages, and it is not at all obvious how to <a href="LangImpl7.html">add -support for mutable variables</a> 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.</p> - -</div> - -<!-- *********************************************************************** --> -<div class="doc_section"><a name="code">Full Code Listing</a></div> -<!-- *********************************************************************** --> - -<div class="doc_text"> - -<p> -Here is the complete code listing for our running example, enhanced with the -if/then/else and for expressions.. To build this example, use: -</p> - -<div class="doc_code"> -<pre> - # Compile - g++ -g toy.cpp `llvm-config --cppflags --ldflags --libs core jit native` -O3 -o toy - # Run - ./toy -</pre> -</div> - -<p>Here is the code:</p> - -<div class="doc_code"> -<pre> -#include "llvm/DerivedTypes.h" -#include "llvm/ExecutionEngine/ExecutionEngine.h" -#include "llvm/ExecutionEngine/JIT.h" -#include "llvm/LLVMContext.h" -#include "llvm/Module.h" -#include "llvm/PassManager.h" -#include "llvm/Analysis/Verifier.h" -#include "llvm/Target/TargetData.h" -#include "llvm/Target/TargetSelect.h" -#include "llvm/Transforms/Scalar.h" -#include "llvm/Support/IRBuilder.h" -#include <cstdio> -#include <string> -#include <map> -#include <vector> -using namespace llvm; - -//===----------------------------------------------------------------------===// -// Lexer -//===----------------------------------------------------------------------===// - -// The lexer returns tokens [0-255] if it is an unknown character, otherwise one -// of these for known things. -enum Token { - tok_eof = -1, - - // commands - tok_def = -2, tok_extern = -3, - - // primary - tok_identifier = -4, tok_number = -5, - - // control - tok_if = -6, tok_then = -7, tok_else = -8, - tok_for = -9, tok_in = -10, - - // operators - tok_binary = -11, tok_unary = -12 -}; - -static std::string IdentifierStr; // Filled in if tok_identifier -static double NumVal; // Filled in if tok_number - -/// gettok - Return the next token from standard input. -static int gettok() { - static int LastChar = ' '; - - // Skip any whitespace. - while (isspace(LastChar)) - LastChar = getchar(); - - if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]* - IdentifierStr = LastChar; - while (isalnum((LastChar = getchar()))) - IdentifierStr += LastChar; - - if (IdentifierStr == "def") return tok_def; - if (IdentifierStr == "extern") return tok_extern; - if (IdentifierStr == "if") return tok_if; - if (IdentifierStr == "then") return tok_then; - if (IdentifierStr == "else") return tok_else; - if (IdentifierStr == "for") return tok_for; - if (IdentifierStr == "in") return tok_in; - if (IdentifierStr == "binary") return tok_binary; - if (IdentifierStr == "unary") return tok_unary; - return tok_identifier; - } - - if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+ - std::string NumStr; - do { - NumStr += LastChar; - LastChar = getchar(); - } while (isdigit(LastChar) || LastChar == '.'); - - NumVal = strtod(NumStr.c_str(), 0); - return tok_number; - } - - if (LastChar == '#') { - // Comment until end of line. - do LastChar = getchar(); - while (LastChar != EOF && LastChar != '\n' && LastChar != '\r'); - - if (LastChar != EOF) - return gettok(); - } - - // Check for end of file. Don't eat the EOF. - if (LastChar == EOF) - return tok_eof; - - // Otherwise, just return the character as its ascii value. - int ThisChar = LastChar; - LastChar = getchar(); - return ThisChar; -} - -//===----------------------------------------------------------------------===// -// Abstract Syntax Tree (aka Parse Tree) -//===----------------------------------------------------------------------===// - -/// ExprAST - Base class for all expression nodes. -class ExprAST { -public: - virtual ~ExprAST() {} - virtual Value *Codegen() = 0; -}; - -/// NumberExprAST - Expression class for numeric literals like "1.0". -class NumberExprAST : public ExprAST { - double Val; -public: - NumberExprAST(double val) : Val(val) {} - virtual Value *Codegen(); -}; - -/// VariableExprAST - Expression class for referencing a variable, like "a". -class VariableExprAST : public ExprAST { - std::string Name; -public: - VariableExprAST(const std::string &name) : Name(name) {} - virtual Value *Codegen(); -}; - -/// UnaryExprAST - Expression class for a unary operator. -class UnaryExprAST : public ExprAST { - char Opcode; - ExprAST *Operand; -public: - UnaryExprAST(char opcode, ExprAST *operand) - : Opcode(opcode), Operand(operand) {} - virtual Value *Codegen(); -}; - -/// BinaryExprAST - Expression class for a binary operator. -class BinaryExprAST : public ExprAST { - char Op; - ExprAST *LHS, *RHS; -public: - BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs) - : Op(op), LHS(lhs), RHS(rhs) {} - virtual Value *Codegen(); -}; - -/// CallExprAST - Expression class for function calls. -class CallExprAST : public ExprAST { - std::string Callee; - std::vector<ExprAST*> Args; -public: - CallExprAST(const std::string &callee, std::vector<ExprAST*> &args) - : Callee(callee), Args(args) {} - virtual Value *Codegen(); -}; - -/// IfExprAST - Expression class for if/then/else. -class IfExprAST : public ExprAST { - ExprAST *Cond, *Then, *Else; -public: - IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else) - : Cond(cond), Then(then), Else(_else) {} - virtual Value *Codegen(); -}; - -/// ForExprAST - Expression class for for/in. -class ForExprAST : public ExprAST { - std::string VarName; - ExprAST *Start, *End, *Step, *Body; -public: - ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end, - ExprAST *step, ExprAST *body) - : VarName(varname), Start(start), End(end), Step(step), Body(body) {} - virtual Value *Codegen(); -}; - -/// PrototypeAST - This class represents the "prototype" for a function, -/// which captures its name, and its argument names (thus implicitly the number -/// of arguments the function takes), as well as if it is an operator. -class PrototypeAST { - std::string Name; - std::vector<std::string> Args; - bool isOperator; - unsigned Precedence; // Precedence if a binary op. -public: - PrototypeAST(const std::string &name, const std::vector<std::string> &args, - bool isoperator = false, unsigned prec = 0) - : Name(name), Args(args), isOperator(isoperator), Precedence(prec) {} - - bool isUnaryOp() const { return isOperator && Args.size() == 1; } - bool isBinaryOp() const { return isOperator && Args.size() == 2; } - - char getOperatorName() const { - assert(isUnaryOp() || isBinaryOp()); - return Name[Name.size()-1]; - } - - unsigned getBinaryPrecedence() const { return Precedence; } - - Function *Codegen(); -}; - -/// FunctionAST - This class represents a function definition itself. -class FunctionAST { - PrototypeAST *Proto; - ExprAST *Body; -public: - FunctionAST(PrototypeAST *proto, ExprAST *body) - : Proto(proto), Body(body) {} - - Function *Codegen(); -}; - -//===----------------------------------------------------------------------===// -// Parser -//===----------------------------------------------------------------------===// - -/// CurTok/getNextToken - Provide a simple token buffer. CurTok is the current -/// token the parser is looking at. getNextToken reads another token from the -/// lexer and updates CurTok with its results. -static int CurTok; -static int getNextToken() { - return CurTok = gettok(); -} - -/// BinopPrecedence - This holds the precedence for each binary operator that is -/// defined. -static std::map<char, int> BinopPrecedence; - -/// GetTokPrecedence - Get the precedence of the pending binary operator token. -static int GetTokPrecedence() { - if (!isascii(CurTok)) - return -1; - - // Make sure it's a declared binop. - int TokPrec = BinopPrecedence[CurTok]; - if (TokPrec <= 0) return -1; - return TokPrec; -} - -/// Error* - These are little helper functions for error handling. -ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;} -PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; } -FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; } - -static ExprAST *ParseExpression(); - -/// identifierexpr -/// ::= identifier -/// ::= identifier '(' expression* ')' -static ExprAST *ParseIdentifierExpr() { - std::string IdName = IdentifierStr; - - getNextToken(); // eat identifier. - - if (CurTok != '(') // Simple variable ref. - return new VariableExprAST(IdName); - - // Call. - getNextToken(); // eat ( - std::vector<ExprAST*> Args; - if (CurTok != ')') { - while (1) { - ExprAST *Arg = ParseExpression(); - if (!Arg) return 0; - Args.push_back(Arg); - - if (CurTok == ')') break; - - if (CurTok != ',') - return Error("Expected ')' or ',' in argument list"); - getNextToken(); - } - } - - // Eat the ')'. - getNextToken(); - - return new CallExprAST(IdName, Args); -} - -/// numberexpr ::= number -static ExprAST *ParseNumberExpr() { - ExprAST *Result = new NumberExprAST(NumVal); - getNextToken(); // consume the number - return Result; -} - -/// parenexpr ::= '(' expression ')' -static ExprAST *ParseParenExpr() { - getNextToken(); // eat (. - ExprAST *V = ParseExpression(); - if (!V) return 0; - - if (CurTok != ')') - return Error("expected ')'"); - getNextToken(); // eat ). - return V; -} - -/// ifexpr ::= 'if' expression 'then' expression 'else' expression -static ExprAST *ParseIfExpr() { - getNextToken(); // eat the if. - - // condition. - ExprAST *Cond = ParseExpression(); - if (!Cond) return 0; - - if (CurTok != tok_then) - return Error("expected then"); - getNextToken(); // eat the then - - ExprAST *Then = ParseExpression(); - if (Then == 0) return 0; - - if (CurTok != tok_else) - return Error("expected else"); - - getNextToken(); - - ExprAST *Else = ParseExpression(); - if (!Else) return 0; - - return new IfExprAST(Cond, Then, Else); -} - -/// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression -static ExprAST *ParseForExpr() { - getNextToken(); // eat the for. - - if (CurTok != tok_identifier) - return Error("expected identifier after for"); - - std::string IdName = IdentifierStr; - getNextToken(); // eat identifier. - - if (CurTok != '=') - return Error("expected '=' after for"); - getNextToken(); // eat '='. - - - ExprAST *Start = ParseExpression(); - if (Start == 0) return 0; - if (CurTok != ',') - return Error("expected ',' after for start value"); - getNextToken(); - - ExprAST *End = ParseExpression(); - if (End == 0) return 0; - - // The step value is optional. - ExprAST *Step = 0; - if (CurTok == ',') { - getNextToken(); - Step = ParseExpression(); - if (Step == 0) return 0; - } - - if (CurTok != tok_in) - return Error("expected 'in' after for"); - getNextToken(); // eat 'in'. - - ExprAST *Body = ParseExpression(); - if (Body == 0) return 0; - - return new ForExprAST(IdName, Start, End, Step, Body); -} - -/// primary -/// ::= identifierexpr -/// ::= numberexpr -/// ::= parenexpr -/// ::= ifexpr -/// ::= forexpr -static ExprAST *ParsePrimary() { - switch (CurTok) { - default: return Error("unknown token when expecting an expression"); - case tok_identifier: return ParseIdentifierExpr(); - case tok_number: return ParseNumberExpr(); - case '(': return ParseParenExpr(); - case tok_if: return ParseIfExpr(); - case tok_for: return ParseForExpr(); - } -} - -/// unary -/// ::= primary -/// ::= '!' unary -static ExprAST *ParseUnary() { - // If the current token is not an operator, it must be a primary expr. - if (!isascii(CurTok) || CurTok == '(' || CurTok == ',') - return ParsePrimary(); - - // If this is a unary operator, read it. - int Opc = CurTok; - getNextToken(); - if (ExprAST *Operand = ParseUnary()) - return new UnaryExprAST(Opc, Operand); - return 0; -} - -/// binoprhs -/// ::= ('+' unary)* -static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) { - // If this is a binop, find its precedence. - while (1) { - int TokPrec = GetTokPrecedence(); - - // If this is a binop that binds at least as tightly as the current binop, - // consume it, otherwise we are done. - if (TokPrec < ExprPrec) - return LHS; - - // Okay, we know this is a binop. - int BinOp = CurTok; - getNextToken(); // eat binop - - // Parse the unary expression after the binary operator. - ExprAST *RHS = ParseUnary(); - if (!RHS) return 0; - - // If BinOp binds less tightly with RHS than the operator after RHS, let - // the pending operator take RHS as its LHS. - int NextPrec = GetTokPrecedence(); - if (TokPrec < NextPrec) { - RHS = ParseBinOpRHS(TokPrec+1, RHS); - if (RHS == 0) return 0; - } - - // Merge LHS/RHS. - LHS = new BinaryExprAST(BinOp, LHS, RHS); - } -} - -/// expression -/// ::= unary binoprhs -/// -static ExprAST *ParseExpression() { - ExprAST *LHS = ParseUnary(); - if (!LHS) return 0; - - return ParseBinOpRHS(0, LHS); -} - -/// prototype -/// ::= id '(' id* ')' -/// ::= binary LETTER number? (id, id) -/// ::= unary LETTER (id) -static PrototypeAST *ParsePrototype() { - std::string FnName; - - unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary. - unsigned BinaryPrecedence = 30; - - switch (CurTok) { - default: - return ErrorP("Expected function name in prototype"); - case tok_identifier: - FnName = IdentifierStr; - Kind = 0; - getNextToken(); - break; - case tok_unary: - getNextToken(); - if (!isascii(CurTok)) - return ErrorP("Expected unary operator"); - FnName = "unary"; - FnName += (char)CurTok; - Kind = 1; - getNextToken(); - break; - case tok_binary: - getNextToken(); - if (!isascii(CurTok)) - return ErrorP("Expected binary operator"); - FnName = "binary"; - FnName += (char)CurTok; - Kind = 2; - getNextToken(); - - // Read the precedence if present. - if (CurTok == tok_number) { - if (NumVal < 1 || NumVal > 100) - return ErrorP("Invalid precedecnce: must be 1..100"); - BinaryPrecedence = (unsigned)NumVal; - getNextToken(); - } - break; - } - - if (CurTok != '(') - return ErrorP("Expected '(' in prototype"); - - std::vector<std::string> ArgNames; - while (getNextToken() == tok_identifier) - ArgNames.push_back(IdentifierStr); - if (CurTok != ')') - return ErrorP("Expected ')' in prototype"); - - // success. - getNextToken(); // eat ')'. - - // Verify right number of names for operator. - if (Kind && ArgNames.size() != Kind) - return ErrorP("Invalid number of operands for operator"); - - return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence); -} - -/// definition ::= 'def' prototype expression -static FunctionAST *ParseDefinition() { - getNextToken(); // eat def. - PrototypeAST *Proto = ParsePrototype(); - if (Proto == 0) return 0; - - if (ExprAST *E = ParseExpression()) - return new FunctionAST(Proto, E); - return 0; -} - -/// toplevelexpr ::= expression -static FunctionAST *ParseTopLevelExpr() { - if (ExprAST *E = ParseExpression()) { - // Make an anonymous proto. - PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>()); - return new FunctionAST(Proto, E); - } - return 0; -} - -/// external ::= 'extern' prototype -static PrototypeAST *ParseExtern() { - getNextToken(); // eat extern. - return ParsePrototype(); -} - -//===----------------------------------------------------------------------===// -// Code Generation -//===----------------------------------------------------------------------===// - -static Module *TheModule; -static IRBuilder<> Builder(getGlobalContext()); -static std::map<std::string, Value*> NamedValues; -static FunctionPassManager *TheFPM; - -Value *ErrorV(const char *Str) { Error(Str); return 0; } - -Value *NumberExprAST::Codegen() { - return ConstantFP::get(getGlobalContext(), APFloat(Val)); -} - -Value *VariableExprAST::Codegen() { - // Look this variable up in the function. - Value *V = NamedValues[Name]; - return V ? V : ErrorV("Unknown variable name"); -} - -Value *UnaryExprAST::Codegen() { - Value *OperandV = Operand->Codegen(); - if (OperandV == 0) return 0; - - Function *F = TheModule->getFunction(std::string("unary")+Opcode); - if (F == 0) - return ErrorV("Unknown unary operator"); - - return Builder.CreateCall(F, OperandV, "unop"); -} - -Value *BinaryExprAST::Codegen() { - Value *L = LHS->Codegen(); - Value *R = RHS->Codegen(); - if (L == 0 || R == 0) return 0; - - switch (Op) { - case '+': return Builder.CreateAdd(L, R, "addtmp"); - case '-': return Builder.CreateSub(L, R, "subtmp"); - case '*': return Builder.CreateMul(L, R, "multmp"); - case '<': - L = Builder.CreateFCmpULT(L, R, "cmptmp"); - // Convert bool 0/1 to double 0.0 or 1.0 - return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()), - "booltmp"); - default: break; - } - - // If it wasn't a builtin binary operator, it must be a user defined one. Emit - // a call to it. - Function *F = TheModule->getFunction(std::string("binary")+Op); - assert(F && "binary operator not found!"); - - Value *Ops[] = { L, R }; - return Builder.CreateCall(F, Ops, Ops+2, "binop"); -} - -Value *CallExprAST::Codegen() { - // Look up the name in the global module table. - Function *CalleeF = TheModule->getFunction(Callee); - if (CalleeF == 0) - return ErrorV("Unknown function referenced"); - - // If argument mismatch error. - if (CalleeF->arg_size() != Args.size()) - return ErrorV("Incorrect # arguments passed"); - - std::vector<Value*> ArgsV; - for (unsigned i = 0, e = Args.size(); i != e; ++i) { - ArgsV.push_back(Args[i]->Codegen()); - if (ArgsV.back() == 0) return 0; - } - - return Builder.CreateCall(CalleeF, ArgsV.begin(), ArgsV.end(), "calltmp"); -} - -Value *IfExprAST::Codegen() { - Value *CondV = Cond->Codegen(); - if (CondV == 0) return 0; - - // Convert condition to a bool by comparing equal to 0.0. - CondV = Builder.CreateFCmpONE(CondV, - ConstantFP::get(getGlobalContext(), APFloat(0.0)), - "ifcond"); - - Function *TheFunction = Builder.GetInsertBlock()->getParent(); - - // Create blocks for the then and else cases. Insert the 'then' block at the - // end of the function. - BasicBlock *ThenBB = BasicBlock::Create(getGlobalContext(), "then", TheFunction); - BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else"); - BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont"); - - Builder.CreateCondBr(CondV, ThenBB, ElseBB); - - // Emit then value. - Builder.SetInsertPoint(ThenBB); - - Value *ThenV = Then->Codegen(); - if (ThenV == 0) return 0; - - Builder.CreateBr(MergeBB); - // Codegen of 'Then' can change the current block, update ThenBB for the PHI. - ThenBB = Builder.GetInsertBlock(); - - // Emit else block. - TheFunction->getBasicBlockList().push_back(ElseBB); - Builder.SetInsertPoint(ElseBB); - - Value *ElseV = Else->Codegen(); - if (ElseV == 0) return 0; - - Builder.CreateBr(MergeBB); - // Codegen of 'Else' can change the current block, update ElseBB for the PHI. - ElseBB = Builder.GetInsertBlock(); - - // Emit merge block. - TheFunction->getBasicBlockList().push_back(MergeBB); - Builder.SetInsertPoint(MergeBB); - PHINode *PN = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), - "iftmp"); - - PN->addIncoming(ThenV, ThenBB); - PN->addIncoming(ElseV, ElseBB); - return PN; -} - -Value *ForExprAST::Codegen() { - // Output this as: - // ... - // start = startexpr - // goto loop - // loop: - // variable = phi [start, loopheader], [nextvariable, loopend] - // ... - // bodyexpr - // ... - // loopend: - // step = stepexpr - // nextvariable = variable + step - // endcond = endexpr - // br endcond, loop, endloop - // outloop: - - // Emit the start code first, without 'variable' in scope. - Value *StartVal = Start->Codegen(); - if (StartVal == 0) return 0; - - // Make the new basic block for the loop header, inserting after current - // block. - Function *TheFunction = Builder.GetInsertBlock()->getParent(); - BasicBlock *PreheaderBB = Builder.GetInsertBlock(); - BasicBlock *LoopBB = BasicBlock::Create(getGlobalContext(), "loop", TheFunction); - - // Insert an explicit fall through from the current block to the LoopBB. - Builder.CreateBr(LoopBB); - - // Start insertion in LoopBB. - Builder.SetInsertPoint(LoopBB); - - // Start the PHI node with an entry for Start. - PHINode *Variable = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), VarName.c_str()); - Variable->addIncoming(StartVal, PreheaderBB); - - // 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. - Value *OldVal = NamedValues[VarName]; - NamedValues[VarName] = 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. - if (Body->Codegen() == 0) - return 0; - - // Emit the step value. - Value *StepVal; - if (Step) { - StepVal = Step->Codegen(); - if (StepVal == 0) return 0; - } else { - // If not specified, use 1.0. - StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0)); - } - - Value *NextVar = Builder.CreateAdd(Variable, StepVal, "nextvar"); - - // Compute the end condition. - Value *EndCond = End->Codegen(); - if (EndCond == 0) return EndCond; - - // Convert condition to a bool by comparing equal to 0.0. - EndCond = Builder.CreateFCmpONE(EndCond, - ConstantFP::get(getGlobalContext(), APFloat(0.0)), - "loopcond"); - - // Create the "after loop" block and insert it. - BasicBlock *LoopEndBB = Builder.GetInsertBlock(); - BasicBlock *AfterBB = BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction); - - // Insert the conditional branch into the end of LoopEndBB. - Builder.CreateCondBr(EndCond, LoopBB, AfterBB); - - // Any new code will be inserted in AfterBB. - Builder.SetInsertPoint(AfterBB); - - // Add a new entry to the PHI node for the backedge. - Variable->addIncoming(NextVar, LoopEndBB); - - // Restore the unshadowed variable. - if (OldVal) - NamedValues[VarName] = OldVal; - else - NamedValues.erase(VarName); - - - // for expr always returns 0.0. - return Constant::getNullValue(Type::getDoubleTy(getGlobalContext())); -} - -Function *PrototypeAST::Codegen() { - // Make the function type: double(double,double) etc. - std::vector<const Type*> Doubles(Args.size(), - Type::getDoubleTy(getGlobalContext())); - FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()), - Doubles, false); - - Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule); - - // If F conflicted, there was already something named 'Name'. If it has a - // body, don't allow redefinition or reextern. - if (F->getName() != Name) { - // Delete the one we just made and get the existing one. - F->eraseFromParent(); - F = TheModule->getFunction(Name); - - // If F already has a body, reject this. - if (!F->empty()) { - ErrorF("redefinition of function"); - return 0; - } - - // If F took a different number of args, reject. - if (F->arg_size() != Args.size()) { - ErrorF("redefinition of function with different # args"); - return 0; - } - } - - // Set names for all arguments. - unsigned Idx = 0; - for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size(); - ++AI, ++Idx) { - AI->setName(Args[Idx]); - - // Add arguments to variable symbol table. - NamedValues[Args[Idx]] = AI; - } - - return F; -} - -Function *FunctionAST::Codegen() { - NamedValues.clear(); - - Function *TheFunction = Proto->Codegen(); - if (TheFunction == 0) - return 0; - - // If this is an operator, install it. - if (Proto->isBinaryOp()) - BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence(); - - // Create a new basic block to start insertion into. - BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction); - Builder.SetInsertPoint(BB); - - if (Value *RetVal = Body->Codegen()) { - // Finish off the function. - Builder.CreateRet(RetVal); - - // Validate the generated code, checking for consistency. - verifyFunction(*TheFunction); - - // Optimize the function. - TheFPM->run(*TheFunction); - - return TheFunction; - } - - // Error reading body, remove function. - TheFunction->eraseFromParent(); - - if (Proto->isBinaryOp()) - BinopPrecedence.erase(Proto->getOperatorName()); - return 0; -} - -//===----------------------------------------------------------------------===// -// Top-Level parsing and JIT Driver -//===----------------------------------------------------------------------===// - -static ExecutionEngine *TheExecutionEngine; - -static void HandleDefinition() { - if (FunctionAST *F = ParseDefinition()) { - if (Function *LF = F->Codegen()) { - fprintf(stderr, "Read function definition:"); - LF->dump(); - } - } else { - // Skip token for error recovery. - getNextToken(); - } -} - -static void HandleExtern() { - if (PrototypeAST *P = ParseExtern()) { - if (Function *F = P->Codegen()) { - fprintf(stderr, "Read extern: "); - F->dump(); - } - } else { - // Skip token for error recovery. - getNextToken(); - } -} - -static void HandleTopLevelExpression() { - // Evaluate a top-level expression into an anonymous function. - if (FunctionAST *F = ParseTopLevelExpr()) { - if (Function *LF = F->Codegen()) { - // JIT the function, returning a function pointer. - void *FPtr = TheExecutionEngine->getPointerToFunction(LF); - - // Cast it to the right type (takes no arguments, returns a double) so we - // can call it as a native function. - double (*FP)() = (double (*)())(intptr_t)FPtr; - fprintf(stderr, "Evaluated to %f\n", FP()); - } - } else { - // Skip token for error recovery. - getNextToken(); - } -} - -/// top ::= definition | external | expression | ';' -static void MainLoop() { - while (1) { - fprintf(stderr, "ready> "); - switch (CurTok) { - case tok_eof: return; - case ';': getNextToken(); break; // ignore top-level semicolons. - case tok_def: HandleDefinition(); break; - case tok_extern: HandleExtern(); break; - default: HandleTopLevelExpression(); break; - } - } -} - -//===----------------------------------------------------------------------===// -// "Library" functions that can be "extern'd" from user code. -//===----------------------------------------------------------------------===// - -/// putchard - putchar that takes a double and returns 0. -extern "C" -double putchard(double X) { - putchar((char)X); - return 0; -} - -/// printd - printf that takes a double prints it as "%f\n", returning 0. -extern "C" -double printd(double X) { - printf("%f\n", X); - return 0; -} - -//===----------------------------------------------------------------------===// -// Main driver code. -//===----------------------------------------------------------------------===// - -int main() { - InitializeNativeTarget(); - LLVMContext &Context = getGlobalContext(); - - // Install standard binary operators. - // 1 is lowest precedence. - BinopPrecedence['<'] = 10; - BinopPrecedence['+'] = 20; - BinopPrecedence['-'] = 20; - BinopPrecedence['*'] = 40; // highest. - - // Prime the first token. - fprintf(stderr, "ready> "); - getNextToken(); - - // Make the module, which holds all the code. - TheModule = new Module("my cool jit", Context); - - // Create the JIT. This takes ownership of the module. - std::string ErrStr; - TheExecutionEngine = EngineBuilder(TheModule).setErrorStr(&ErrStr).create(); - if (!TheExecutionEngine) { - fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str()); - exit(1); - } - - FunctionPassManager OurFPM(TheModule); - - // Set up the optimizer pipeline. Start with registering info about how the - // target lays out data structures. - OurFPM.add(new TargetData(*TheExecutionEngine->getTargetData())); - // Do simple "peephole" optimizations and bit-twiddling optzns. - OurFPM.add(createInstructionCombiningPass()); - // Reassociate expressions. - OurFPM.add(createReassociatePass()); - // Eliminate Common SubExpressions. - OurFPM.add(createGVNPass()); - // Simplify the control flow graph (deleting unreachable blocks, etc). - OurFPM.add(createCFGSimplificationPass()); - - OurFPM.doInitialization(); - - // Set the global so the code gen can use this. - TheFPM = &OurFPM; - - // Run the main "interpreter loop" now. - MainLoop(); - - TheFPM = 0; - - // Print out all of the generated code. - TheModule->dump(); - - return 0; -} -</pre> -</div> - -<a href="LangImpl7.html">Next: Extending the language: mutable variables / SSA construction</a> -</div> - -<!-- *********************************************************************** --> -<hr> -<address> - <a href="http://jigsaw.w3.org/css-validator/check/referer"><img - src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a> - <a href="http://validator.w3.org/check/referer"><img - src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a> - - <a href="mailto:sabre@nondot.org">Chris Lattner</a><br> - <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br> - Last modified: $Date$ -</address> -</body> -</html> |