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Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]6 <title>Kaleidoscope: Extending the Language: User-defined Operators</title>
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13
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]14<div class="doc_title">Kaleidoscope: Extending the Language: User-defined Operators</div>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]15
Chris Lattner128eb862007-11-05 19:06:59 +0000[diff] [blame]16<ul>
Chris Lattner0e555b12007-11-05 20:04:56 +0000[diff] [blame]17<li><a href="index.html">Up to Tutorial Index</a></li>
Chris Lattner128eb862007-11-05 19:06:59 +0000[diff] [blame]18<li>Chapter 6
19 <ol>
20 <li><a href="#intro">Chapter 6 Introduction</a></li>
21 <li><a href="#idea">User-defined Operators: the Idea</a></li>
22 <li><a href="#binary">User-defined Binary Operators</a></li>
23 <li><a href="#unary">User-defined Unary Operators</a></li>
24 <li><a href="#example">Kicking the Tires</a></li>
25 <li><a href="#code">Full Code Listing</a></li>
26 </ol>
27</li>
Chris Lattner0e555b12007-11-05 20:04:56 +0000[diff] [blame]28<li><a href="LangImpl7.html">Chapter 7</a>: Extending the Language: Mutable
29Variables / SSA Construction</li>
Chris Lattner128eb862007-11-05 19:06:59 +0000[diff] [blame]30</ul>
31
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]32<div class="doc_author">
33 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
34</div>
35
36<!-- *********************************************************************** -->
Chris Lattner128eb862007-11-05 19:06:59 +0000[diff] [blame]37<div class="doc_section"><a name="intro">Chapter 6 Introduction</a></div>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]38<!-- *********************************************************************** -->
39
40<div class="doc_text">
41
Chris Lattner128eb862007-11-05 19:06:59 +0000[diff] [blame]42<p>Welcome to Chapter 6 of the "<a href="index.html">Implementing a language
43with LLVM</a>" tutorial. At this point in our tutorial, we now have a fully
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]44functional language that is fairly minimal, but also useful. There
45is still one big problem with it, however. Our language doesn't have many
46useful operators (like division, logical negation, or even any comparisons
47besides less-than).</p>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]48
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]49<p>This chapter of the tutorial takes a wild digression into adding user-defined
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]50operators to the simple and beautiful Kaleidoscope language. This digression now gives
51us a simple and ugly language in some ways, but also a powerful one at the same time.
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]52One of the great things about creating your own language is that you get to
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]53decide what is good or bad. In this tutorial we'll assume that it is okay to
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]54use this as a way to show some interesting parsing techniques.</p>
55
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]56<p>At the end of this tutorial, we'll run through an example Kaleidoscope
57application that <a href="#example">renders the Mandelbrot set</a>. This gives
58an example of what you can build with Kaleidoscope and its feature set.</p>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]59
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]60</div>
61
62<!-- *********************************************************************** -->
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]63<div class="doc_section"><a name="idea">User-defined Operators: the Idea</a></div>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]64<!-- *********************************************************************** -->
65
66<div class="doc_text">
67
68<p>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]69The "operator overloading" that we will add to Kaleidoscope is more general than
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]70languages like C++. In C++, you are only allowed to redefine existing
71operators: you can't programatically change the grammar, introduce new
72operators, change precedence levels, etc. In this chapter, we will add this
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]73capability to Kaleidoscope, which will let the user round out the set of
74operators that are supported.</p>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]75
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]76<p>The point of going into user-defined operators in a tutorial like this is to
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]77show the power and flexibility of using a hand-written parser. Thus far, the parser
78we have been implementing uses recursive descent for most parts of the grammar and
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]79operator precedence parsing for the expressions. See <a
80href="LangImpl2.html">Chapter 2</a> for details. Without using operator
81precedence parsing, it would be very difficult to allow the programmer to
82introduce new operators into the grammar: the grammar is dynamically extensible
83as the JIT runs.</p>
84
85<p>The two specific features we'll add are programmable unary operators (right
86now, Kaleidoscope has no unary operators at all) as well as binary operators.
87An example of this is:</p>
88
89<div class="doc_code">
90<pre>
91# Logical unary not.
92def unary!(v)
93 if v then
94 0
95 else
96 1;
97
98# Define &gt; with the same precedence as &lt;.
99def binary&gt; 10 (LHS RHS)
Chris Lattner61ad4492007-11-23 22:19:33 +0000[diff] [blame]100 RHS &lt; LHS;
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]101
102# Binary "logical or", (note that it does not "short circuit")
103def binary| 5 (LHS RHS)
104 if LHS then
105 1
106 else if RHS then
107 1
108 else
109 0;
110
111# Define = with slightly lower precedence than relationals.
112def binary= 9 (LHS RHS)
113 !(LHS &lt; RHS | LHS &gt; RHS);
114</pre>
115</div>
116
117<p>Many languages aspire to being able to implement their standard runtime
118library in the language itself. In Kaleidoscope, we can implement significant
119parts of the language in the library!</p>
120
121<p>We will break down implementation of these features into two parts:
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]122implementing support for user-defined binary operators and adding unary
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]123operators.</p>
124
125</div>
126
127<!-- *********************************************************************** -->
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]128<div class="doc_section"><a name="binary">User-defined Binary Operators</a></div>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]129<!-- *********************************************************************** -->
130
131<div class="doc_text">
132
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]133<p>Adding support for user-defined binary operators is pretty simple with our
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]134current framework. We'll first add support for the unary/binary keywords:</p>
135
136<div class="doc_code">
137<pre>
138enum Token {
139 ...
140 <b>// operators
141 tok_binary = -11, tok_unary = -12</b>
142};
143...
144static int gettok() {
145...
146 if (IdentifierStr == "for") return tok_for;
147 if (IdentifierStr == "in") return tok_in;
148 <b>if (IdentifierStr == "binary") return tok_binary;
149 if (IdentifierStr == "unary") return tok_unary;</b>
150 return tok_identifier;
151</pre>
152</div>
153
154<p>This just adds lexer support for the unary and binary keywords, like we
155did in <a href="LangImpl5.html#iflexer">previous chapters</a>. One nice thing
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]156about our current AST, is that we represent binary operators with full generalisation
157by using their ASCII code as the opcode. For our extended operators, we'll use this
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]158same representation, so we don't need any new AST or parser support.</p>
159
160<p>On the other hand, we have to be able to represent the definitions of these
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]161new operators, in the "def binary| 5" part of the function definition. In our
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]162grammar so far, the "name" for the function definition is parsed as the
163"prototype" production and into the <tt>PrototypeAST</tt> AST node. To
164represent our new user-defined operators as prototypes, we have to extend
165the <tt>PrototypeAST</tt> AST node like this:</p>
166
167<div class="doc_code">
168<pre>
169/// PrototypeAST - This class represents the "prototype" for a function,
170/// which captures its argument names as well as if it is an operator.
171class PrototypeAST {
172 std::string Name;
173 std::vector&lt;std::string&gt; Args;
174 <b>bool isOperator;
175 unsigned Precedence; // Precedence if a binary op.</b>
176public:
177 PrototypeAST(const std::string &amp;name, const std::vector&lt;std::string&gt; &amp;args,
178 <b>bool isoperator = false, unsigned prec = 0</b>)
179 : Name(name), Args(args), <b>isOperator(isoperator), Precedence(prec)</b> {}
180
181 <b>bool isUnaryOp() const { return isOperator &amp;&amp; Args.size() == 1; }
182 bool isBinaryOp() const { return isOperator &amp;&amp; Args.size() == 2; }
183
184 char getOperatorName() const {
185 assert(isUnaryOp() || isBinaryOp());
186 return Name[Name.size()-1];
187 }
188
189 unsigned getBinaryPrecedence() const { return Precedence; }</b>
190
191 Function *Codegen();
192};
193</pre>
194</div>
195
196<p>Basically, in addition to knowing a name for the prototype, we now keep track
197of whether it was an operator, and if it was, what precedence level the operator
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]198is at. The precedence is only used for binary operators (as you'll see below,
199it just doesn't apply for unary operators). Now that we have a way to represent
200the prototype for a user-defined operator, we need to parse it:</p>
201
202<div class="doc_code">
203<pre>
204/// prototype
205/// ::= id '(' id* ')'
206<b>/// ::= binary LETTER number? (id, id)</b>
207static PrototypeAST *ParsePrototype() {
208 std::string FnName;
209
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]210 <b>unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]211 unsigned BinaryPrecedence = 30;</b>
212
213 switch (CurTok) {
214 default:
215 return ErrorP("Expected function name in prototype");
216 case tok_identifier:
217 FnName = IdentifierStr;
218 Kind = 0;
219 getNextToken();
220 break;
221 <b>case tok_binary:
222 getNextToken();
223 if (!isascii(CurTok))
224 return ErrorP("Expected binary operator");
225 FnName = "binary";
226 FnName += (char)CurTok;
227 Kind = 2;
228 getNextToken();
229
230 // Read the precedence if present.
231 if (CurTok == tok_number) {
232 if (NumVal &lt; 1 || NumVal &gt; 100)
233 return ErrorP("Invalid precedecnce: must be 1..100");
234 BinaryPrecedence = (unsigned)NumVal;
235 getNextToken();
236 }
237 break;</b>
238 }
239
240 if (CurTok != '(')
241 return ErrorP("Expected '(' in prototype");
242
243 std::vector&lt;std::string&gt; ArgNames;
244 while (getNextToken() == tok_identifier)
245 ArgNames.push_back(IdentifierStr);
246 if (CurTok != ')')
247 return ErrorP("Expected ')' in prototype");
248
249 // success.
250 getNextToken(); // eat ')'.
251
252 <b>// Verify right number of names for operator.
253 if (Kind &amp;&amp; ArgNames.size() != Kind)
254 return ErrorP("Invalid number of operands for operator");
255
256 return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);</b>
257}
258</pre>
259</div>
260
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]261<p>This is all fairly straightforward parsing code, and we have already seen
262a lot of similar code in the past. One interesting part about the code above is
263the couple lines that set up <tt>FnName</tt> for binary operators. This builds names
264like "binary@" for a newly defined "@" operator. This then takes advantage of the
265fact that symbol names in the LLVM symbol table are allowed to have any character in
266them, including embedded nul characters.</p>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]267
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]268<p>The next interesting thing to add, is codegen support for these binary operators.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]269Given our current structure, this is a simple addition of a default case for our
270existing binary operator node:</p>
271
272<div class="doc_code">
273<pre>
274Value *BinaryExprAST::Codegen() {
275 Value *L = LHS-&gt;Codegen();
276 Value *R = RHS-&gt;Codegen();
277 if (L == 0 || R == 0) return 0;
278
279 switch (Op) {
Eric Christopher2214b812010-06-14 06:09:39 +0000[diff] [blame]280 case '+': return Builder.CreateFAdd(L, R, "addtmp");
281 case '-': return Builder.CreateFSub(L, R, "subtmp");
282 case '*': return Builder.CreateFMul(L, R, "multmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]283 case '&lt;':
Chris Lattner71155212007-11-06 01:39:12 +0000[diff] [blame]284 L = Builder.CreateFCmpULT(L, R, "cmptmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]285 // Convert bool 0/1 to double 0.0 or 1.0
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]286 return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
287 "booltmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]288 <b>default: break;</b>
289 }
290
291 <b>// If it wasn't a builtin binary operator, it must be a user defined one. Emit
292 // a call to it.
293 Function *F = TheModule-&gt;getFunction(std::string("binary")+Op);
294 assert(F &amp;&amp; "binary operator not found!");
295
296 Value *Ops[] = { L, R };
297 return Builder.CreateCall(F, Ops, Ops+2, "binop");</b>
298}
299
300</pre>
301</div>
302
303<p>As you can see above, the new code is actually really simple. It just does
304a lookup for the appropriate operator in the symbol table and generates a
305function call to it. Since user-defined operators are just built as normal
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]306functions (because the "prototype" boils down to a function with the right
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]307name) everything falls into place.</p>
308
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]309<p>The final piece of code we are missing, is a bit of top-level magic:</p>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]310
311<div class="doc_code">
312<pre>
313Function *FunctionAST::Codegen() {
314 NamedValues.clear();
315
316 Function *TheFunction = Proto->Codegen();
317 if (TheFunction == 0)
318 return 0;
319
320 <b>// If this is an operator, install it.
321 if (Proto-&gt;isBinaryOp())
322 BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();</b>
323
324 // Create a new basic block to start insertion into.
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]325 BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]326 Builder.SetInsertPoint(BB);
327
328 if (Value *RetVal = Body-&gt;Codegen()) {
329 ...
330</pre>
331</div>
332
333<p>Basically, before codegening a function, if it is a user-defined operator, we
334register it in the precedence table. This allows the binary operator parsing
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]335logic 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>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]336
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]337<p>Now we have useful user-defined binary operators. This builds a lot
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]338on the previous framework we built for other operators. Adding unary operators
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]339is a bit more challenging, because we don't have any framework for it yet - lets
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]340see what it takes.</p>
341
342</div>
343
344<!-- *********************************************************************** -->
345<div class="doc_section"><a name="unary">User-defined Unary Operators</a></div>
346<!-- *********************************************************************** -->
347
348<div class="doc_text">
349
350<p>Since we don't currently support unary operators in the Kaleidoscope
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]351language, we'll need to add everything to support them. Above, we added simple
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]352support for the 'unary' keyword to the lexer. In addition to that, we need an
353AST node:</p>
354
355<div class="doc_code">
356<pre>
357/// UnaryExprAST - Expression class for a unary operator.
358class UnaryExprAST : public ExprAST {
359 char Opcode;
360 ExprAST *Operand;
361public:
362 UnaryExprAST(char opcode, ExprAST *operand)
363 : Opcode(opcode), Operand(operand) {}
364 virtual Value *Codegen();
365};
366</pre>
367</div>
368
369<p>This AST node is very simple and obvious by now. It directly mirrors the
370binary operator AST node, except that it only has one child. With this, we
371need to add the parsing logic. Parsing a unary operator is pretty simple: we'll
372add a new function to do it:</p>
373
374<div class="doc_code">
375<pre>
376/// unary
377/// ::= primary
378/// ::= '!' unary
379static ExprAST *ParseUnary() {
380 // If the current token is not an operator, it must be a primary expr.
381 if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
382 return ParsePrimary();
383
384 // If this is a unary operator, read it.
385 int Opc = CurTok;
386 getNextToken();
387 if (ExprAST *Operand = ParseUnary())
388 return new UnaryExprAST(Opc, Operand);
389 return 0;
390}
391</pre>
392</div>
393
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]394<p>The grammar we add is pretty straightforward here. If we see a unary
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]395operator when parsing a primary operator, we eat the operator as a prefix and
396parse the remaining piece as another unary operator. This allows us to handle
397multiple unary operators (e.g. "!!x"). Note that unary operators can't have
398ambiguous parses like binary operators can, so there is no need for precedence
399information.</p>
400
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]401<p>The problem with this function, is that we need to call ParseUnary from somewhere.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]402To do this, we change previous callers of ParsePrimary to call ParseUnary
403instead:</p>
404
405<div class="doc_code">
406<pre>
407/// binoprhs
408/// ::= ('+' unary)*
409static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
410 ...
411 <b>// Parse the unary expression after the binary operator.
412 ExprAST *RHS = ParseUnary();
413 if (!RHS) return 0;</b>
414 ...
415}
416/// expression
417/// ::= unary binoprhs
418///
419static ExprAST *ParseExpression() {
420 <b>ExprAST *LHS = ParseUnary();</b>
421 if (!LHS) return 0;
422
423 return ParseBinOpRHS(0, LHS);
424}
425</pre>
426</div>
427
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]428<p>With these two simple changes, we are now able to parse unary operators and build the
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]429AST for them. Next up, we need to add parser support for prototypes, to parse
430the unary operator prototype. We extend the binary operator code above
431with:</p>
432
433<div class="doc_code">
434<pre>
435/// prototype
436/// ::= id '(' id* ')'
437/// ::= binary LETTER number? (id, id)
438<b>/// ::= unary LETTER (id)</b>
439static PrototypeAST *ParsePrototype() {
440 std::string FnName;
441
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]442 unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]443 unsigned BinaryPrecedence = 30;
444
445 switch (CurTok) {
446 default:
447 return ErrorP("Expected function name in prototype");
448 case tok_identifier:
449 FnName = IdentifierStr;
450 Kind = 0;
451 getNextToken();
452 break;
453 <b>case tok_unary:
454 getNextToken();
455 if (!isascii(CurTok))
456 return ErrorP("Expected unary operator");
457 FnName = "unary";
458 FnName += (char)CurTok;
459 Kind = 1;
460 getNextToken();
461 break;</b>
462 case tok_binary:
463 ...
464</pre>
465</div>
466
467<p>As with binary operators, we name unary operators with a name that includes
468the operator character. This assists us at code generation time. Speaking of,
469the final piece we need to add is codegen support for unary operators. It looks
470like this:</p>
471
472<div class="doc_code">
473<pre>
474Value *UnaryExprAST::Codegen() {
475 Value *OperandV = Operand->Codegen();
476 if (OperandV == 0) return 0;
477
478 Function *F = TheModule->getFunction(std::string("unary")+Opcode);
479 if (F == 0)
480 return ErrorV("Unknown unary operator");
481
482 return Builder.CreateCall(F, OperandV, "unop");
483}
484</pre>
485</div>
486
487<p>This code is similar to, but simpler than, the code for binary operators. It
488is simpler primarily because it doesn't need to handle any predefined operators.
489</p>
490
491</div>
492
493<!-- *********************************************************************** -->
494<div class="doc_section"><a name="example">Kicking the Tires</a></div>
495<!-- *********************************************************************** -->
496
497<div class="doc_text">
498
499<p>It is somewhat hard to believe, but with a few simple extensions we've
Chris Lattnerb5d81b32007-11-02 05:54:25 +0000[diff] [blame]500covered in the last chapters, we have grown a real-ish language. With this, we
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]501can do a lot of interesting things, including I/O, math, and a bunch of other
502things. For example, we can now add a nice sequencing operator (printd is
503defined to print out the specified value and a newline):</p>
504
505<div class="doc_code">
506<pre>
507ready&gt; <b>extern printd(x);</b>
508Read extern: declare double @printd(double)
509ready&gt; <b>def binary : 1 (x y) 0; # Low-precedence operator that ignores operands.</b>
510..
511ready&gt; <b>printd(123) : printd(456) : printd(789);</b>
512123.000000
513456.000000
514789.000000
515Evaluated to 0.000000
516</pre>
517</div>
518
Chris Lattnerb5d81b32007-11-02 05:54:25 +0000[diff] [blame]519<p>We can also define a bunch of other "primitive" operations, such as:</p>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]520
521<div class="doc_code">
522<pre>
523# Logical unary not.
524def unary!(v)
525 if v then
526 0
527 else
528 1;
529
530# Unary negate.
531def unary-(v)
532 0-v;
533
Chris Lattner6808cdc2010-06-21 20:31:30 +0000[diff] [blame]534# Define &gt; with the same precedence as &lt;.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]535def binary&gt; 10 (LHS RHS)
Chris Lattner61ad4492007-11-23 22:19:33 +0000[diff] [blame]536 RHS &lt; LHS;
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]537
538# Binary logical or, which does not short circuit.
539def binary| 5 (LHS RHS)
540 if LHS then
541 1
542 else if RHS then
543 1
544 else
545 0;
546
547# Binary logical and, which does not short circuit.
548def binary&amp; 6 (LHS RHS)
549 if !LHS then
550 0
551 else
552 !!RHS;
553
554# Define = with slightly lower precedence than relationals.
555def binary = 9 (LHS RHS)
556 !(LHS &lt; RHS | LHS &gt; RHS);
557
558</pre>
559</div>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]560
561
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]562<p>Given the previous if/then/else support, we can also define interesting
563functions for I/O. For example, the following prints out a character whose
564"density" reflects the value passed in: the lower the value, the denser the
565character:</p>
566
567<div class="doc_code">
568<pre>
569ready&gt;
570<b>
571extern putchard(char)
572def printdensity(d)
573 if d &gt; 8 then
574 putchard(32) # ' '
575 else if d &gt; 4 then
576 putchard(46) # '.'
577 else if d &gt; 2 then
578 putchard(43) # '+'
579 else
580 putchard(42); # '*'</b>
581...
582ready&gt; <b>printdensity(1): printdensity(2): printdensity(3) :
583 printdensity(4): printdensity(5): printdensity(9): putchard(10);</b>
584*++..
585Evaluated to 0.000000
586</pre>
587</div>
588
589<p>Based on these simple primitive operations, we can start to define more
590interesting things. For example, here's a little function that solves for the
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]591number of iterations it takes a function in the complex plane to
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]592converge:</p>
593
594<div class="doc_code">
595<pre>
596# determine whether the specific location diverges.
597# Solve for z = z^2 + c in the complex plane.
598def mandleconverger(real imag iters creal cimag)
599 if iters &gt; 255 | (real*real + imag*imag &gt; 4) then
600 iters
601 else
602 mandleconverger(real*real - imag*imag + creal,
603 2*real*imag + cimag,
604 iters+1, creal, cimag);
605
606# return the number of iterations required for the iteration to escape
607def mandleconverge(real imag)
608 mandleconverger(real, imag, 0, real, imag);
609</pre>
610</div>
611
Chris Lattnerb5d81b32007-11-02 05:54:25 +0000[diff] [blame]612<p>This "z = z<sup>2</sup> + c" function is a beautiful little creature that is the basis
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]613for computation of the <a
614href="http://en.wikipedia.org/wiki/Mandelbrot_set">Mandelbrot Set</a>. Our
615<tt>mandelconverge</tt> function returns the number of iterations that it takes
616for a complex orbit to escape, saturating to 255. This is not a very useful
617function by itself, but if you plot its value over a two-dimensional plane,
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]618you can see the Mandelbrot set. Given that we are limited to using putchard
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]619here, our amazing graphical output is limited, but we can whip together
620something using the density plotter above:</p>
621
622<div class="doc_code">
623<pre>
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]624# compute and plot the mandlebrot set with the specified 2 dimensional range
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]625# info.
626def mandelhelp(xmin xmax xstep ymin ymax ystep)
627 for y = ymin, y &lt; ymax, ystep in (
628 (for x = xmin, x &lt; xmax, xstep in
629 printdensity(mandleconverge(x,y)))
630 : putchard(10)
631 )
632
633# mandel - This is a convenient helper function for ploting the mandelbrot set
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]634# from the specified position with the specified Magnification.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]635def mandel(realstart imagstart realmag imagmag)
636 mandelhelp(realstart, realstart+realmag*78, realmag,
637 imagstart, imagstart+imagmag*40, imagmag);
638</pre>
639</div>
640
641<p>Given this, we can try plotting out the mandlebrot set! Lets try it out:</p>
642
643<div class="doc_code">
644<pre>
645ready&gt; <b>mandel(-2.3, -1.3, 0.05, 0.07);</b>
646*******************************+++++++++++*************************************
647*************************+++++++++++++++++++++++*******************************
648**********************+++++++++++++++++++++++++++++****************************
649*******************+++++++++++++++++++++.. ...++++++++*************************
650*****************++++++++++++++++++++++.... ...+++++++++***********************
651***************+++++++++++++++++++++++..... ...+++++++++*********************
652**************+++++++++++++++++++++++.... ....+++++++++********************
653*************++++++++++++++++++++++...... .....++++++++*******************
654************+++++++++++++++++++++....... .......+++++++******************
655***********+++++++++++++++++++.... ... .+++++++*****************
656**********+++++++++++++++++....... .+++++++****************
657*********++++++++++++++........... ...+++++++***************
658********++++++++++++............ ...++++++++**************
659********++++++++++... .......... .++++++++**************
660*******+++++++++..... .+++++++++*************
661*******++++++++...... ..+++++++++*************
662*******++++++....... ..+++++++++*************
663*******+++++...... ..+++++++++*************
664*******.... .... ...+++++++++*************
665*******.... . ...+++++++++*************
666*******+++++...... ...+++++++++*************
667*******++++++....... ..+++++++++*************
668*******++++++++...... .+++++++++*************
669*******+++++++++..... ..+++++++++*************
670********++++++++++... .......... .++++++++**************
671********++++++++++++............ ...++++++++**************
672*********++++++++++++++.......... ...+++++++***************
673**********++++++++++++++++........ .+++++++****************
674**********++++++++++++++++++++.... ... ..+++++++****************
675***********++++++++++++++++++++++....... .......++++++++*****************
676************+++++++++++++++++++++++...... ......++++++++******************
677**************+++++++++++++++++++++++.... ....++++++++********************
678***************+++++++++++++++++++++++..... ...+++++++++*********************
679*****************++++++++++++++++++++++.... ...++++++++***********************
680*******************+++++++++++++++++++++......++++++++*************************
681*********************++++++++++++++++++++++.++++++++***************************
682*************************+++++++++++++++++++++++*******************************
683******************************+++++++++++++************************************
684*******************************************************************************
685*******************************************************************************
686*******************************************************************************
687Evaluated to 0.000000
688ready&gt; <b>mandel(-2, -1, 0.02, 0.04);</b>
689**************************+++++++++++++++++++++++++++++++++++++++++++++++++++++
690***********************++++++++++++++++++++++++++++++++++++++++++++++++++++++++
691*********************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.
692*******************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++...
693*****************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.....
694***************++++++++++++++++++++++++++++++++++++++++++++++++++++++++........
695**************++++++++++++++++++++++++++++++++++++++++++++++++++++++...........
696************+++++++++++++++++++++++++++++++++++++++++++++++++++++..............
697***********++++++++++++++++++++++++++++++++++++++++++++++++++........ .
698**********++++++++++++++++++++++++++++++++++++++++++++++.............
699********+++++++++++++++++++++++++++++++++++++++++++..................
700*******+++++++++++++++++++++++++++++++++++++++.......................
701******+++++++++++++++++++++++++++++++++++...........................
702*****++++++++++++++++++++++++++++++++............................
703*****++++++++++++++++++++++++++++...............................
704****++++++++++++++++++++++++++...... .........................
705***++++++++++++++++++++++++......... ...... ...........
706***++++++++++++++++++++++............
707**+++++++++++++++++++++..............
708**+++++++++++++++++++................
709*++++++++++++++++++.................
710*++++++++++++++++............ ...
711*++++++++++++++..............
712*+++....++++................
713*.......... ...........
714*
715*.......... ...........
716*+++....++++................
717*++++++++++++++..............
718*++++++++++++++++............ ...
719*++++++++++++++++++.................
720**+++++++++++++++++++................
721**+++++++++++++++++++++..............
722***++++++++++++++++++++++............
723***++++++++++++++++++++++++......... ...... ...........
724****++++++++++++++++++++++++++...... .........................
725*****++++++++++++++++++++++++++++...............................
726*****++++++++++++++++++++++++++++++++............................
727******+++++++++++++++++++++++++++++++++++...........................
728*******+++++++++++++++++++++++++++++++++++++++.......................
729********+++++++++++++++++++++++++++++++++++++++++++..................
730Evaluated to 0.000000
731ready&gt; <b>mandel(-0.9, -1.4, 0.02, 0.03);</b>
732*******************************************************************************
733*******************************************************************************
734*******************************************************************************
735**********+++++++++++++++++++++************************************************
736*+++++++++++++++++++++++++++++++++++++++***************************************
737+++++++++++++++++++++++++++++++++++++++++++++**********************************
738++++++++++++++++++++++++++++++++++++++++++++++++++*****************************
739++++++++++++++++++++++++++++++++++++++++++++++++++++++*************************
740+++++++++++++++++++++++++++++++++++++++++++++++++++++++++**********************
741+++++++++++++++++++++++++++++++++.........++++++++++++++++++*******************
742+++++++++++++++++++++++++++++++.... ......+++++++++++++++++++****************
743+++++++++++++++++++++++++++++....... ........+++++++++++++++++++**************
744++++++++++++++++++++++++++++........ ........++++++++++++++++++++************
745+++++++++++++++++++++++++++......... .. ...+++++++++++++++++++++**********
746++++++++++++++++++++++++++........... ....++++++++++++++++++++++********
747++++++++++++++++++++++++............. .......++++++++++++++++++++++******
748+++++++++++++++++++++++............. ........+++++++++++++++++++++++****
749++++++++++++++++++++++........... ..........++++++++++++++++++++++***
750++++++++++++++++++++........... .........++++++++++++++++++++++*
751++++++++++++++++++............ ...........++++++++++++++++++++
752++++++++++++++++............... .............++++++++++++++++++
753++++++++++++++................. ...............++++++++++++++++
754++++++++++++.................. .................++++++++++++++
755+++++++++.................. .................+++++++++++++
756++++++........ . ......... ..++++++++++++
757++............ ...... ....++++++++++
758.............. ...++++++++++
759.............. ....+++++++++
760.............. .....++++++++
761............. ......++++++++
762........... .......++++++++
763......... ........+++++++
764......... ........+++++++
765......... ....+++++++
766........ ...+++++++
767....... ...+++++++
768 ....+++++++
769 .....+++++++
770 ....+++++++
771 ....+++++++
772 ....+++++++
773Evaluated to 0.000000
774ready&gt; <b>^D</b>
775</pre>
776</div>
777
778<p>At this point, you may be starting to realize that Kaleidoscope is a real
779and powerful language. It may not be self-similar :), but it can be used to
780plot things that are!</p>
781
782<p>With this, we conclude the "adding user-defined operators" chapter of the
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]783tutorial. We have successfully augmented our language, adding the ability to extend the
784language in the library, and we have shown how this can be used to build a simple but
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]785interesting end-user application in Kaleidoscope. At this point, Kaleidoscope
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]786can build a variety of applications that are functional and can call functions
Chris Lattnerb5d81b32007-11-02 05:54:25 +0000[diff] [blame]787with side-effects, but it can't actually define and mutate a variable itself.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]788</p>
789
Chris Lattner3616a8a2007-11-07 06:06:38 +0000[diff] [blame]790<p>Strikingly, variable mutation is an important feature of some
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]791languages, and it is not at all obvious how to <a href="LangImpl7.html">add
792support for mutable variables</a> without having to add an "SSA construction"
793phase to your front-end. In the next chapter, we will describe how you can
Chris Lattnerb7e6b1a2007-11-15 04:51:31 +0000[diff] [blame]794add variable mutation without building SSA in your front-end.</p>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]795
796</div>
797
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]798<!-- *********************************************************************** -->
799<div class="doc_section"><a name="code">Full Code Listing</a></div>
800<!-- *********************************************************************** -->
801
802<div class="doc_text">
803
804<p>
805Here is the complete code listing for our running example, enhanced with the
806if/then/else and for expressions.. To build this example, use:
807</p>
808
809<div class="doc_code">
810<pre>
811 # Compile
812 g++ -g toy.cpp `llvm-config --cppflags --ldflags --libs core jit native` -O3 -o toy
813 # Run
814 ./toy
815</pre>
816</div>
817
818<p>Here is the code:</p>
819
820<div class="doc_code">
821<pre>
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]822#include "llvm/DerivedTypes.h"
823#include "llvm/ExecutionEngine/ExecutionEngine.h"
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]824#include "llvm/ExecutionEngine/JIT.h"
Owen Andersond1fbd142009-07-08 20:50:47 +0000[diff] [blame]825#include "llvm/LLVMContext.h"
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]826#include "llvm/Module.h"
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]827#include "llvm/PassManager.h"
828#include "llvm/Analysis/Verifier.h"
829#include "llvm/Target/TargetData.h"
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]830#include "llvm/Target/TargetSelect.h"
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]831#include "llvm/Transforms/Scalar.h"
Duncan Sands89f6d882008-04-13 06:22:09 +0000[diff] [blame]832#include "llvm/Support/IRBuilder.h"
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]833#include &lt;cstdio&gt;
834#include &lt;string&gt;
835#include &lt;map&gt;
836#include &lt;vector&gt;
837using namespace llvm;
838
839//===----------------------------------------------------------------------===//
840// Lexer
841//===----------------------------------------------------------------------===//
842
843// The lexer returns tokens [0-255] if it is an unknown character, otherwise one
844// of these for known things.
845enum Token {
846 tok_eof = -1,
847
848 // commands
849 tok_def = -2, tok_extern = -3,
850
851 // primary
852 tok_identifier = -4, tok_number = -5,
853
854 // control
855 tok_if = -6, tok_then = -7, tok_else = -8,
856 tok_for = -9, tok_in = -10,
857
858 // operators
859 tok_binary = -11, tok_unary = -12
860};
861
862static std::string IdentifierStr; // Filled in if tok_identifier
863static double NumVal; // Filled in if tok_number
864
865/// gettok - Return the next token from standard input.
866static int gettok() {
867 static int LastChar = ' ';
868
869 // Skip any whitespace.
870 while (isspace(LastChar))
871 LastChar = getchar();
872
873 if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
874 IdentifierStr = LastChar;
875 while (isalnum((LastChar = getchar())))
876 IdentifierStr += LastChar;
877
878 if (IdentifierStr == "def") return tok_def;
879 if (IdentifierStr == "extern") return tok_extern;
880 if (IdentifierStr == "if") return tok_if;
881 if (IdentifierStr == "then") return tok_then;
882 if (IdentifierStr == "else") return tok_else;
883 if (IdentifierStr == "for") return tok_for;
884 if (IdentifierStr == "in") return tok_in;
885 if (IdentifierStr == "binary") return tok_binary;
886 if (IdentifierStr == "unary") return tok_unary;
887 return tok_identifier;
888 }
889
890 if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
891 std::string NumStr;
892 do {
893 NumStr += LastChar;
894 LastChar = getchar();
895 } while (isdigit(LastChar) || LastChar == '.');
896
897 NumVal = strtod(NumStr.c_str(), 0);
898 return tok_number;
899 }
900
901 if (LastChar == '#') {
902 // Comment until end of line.
903 do LastChar = getchar();
Chris Lattnerc80c23f2007-12-02 22:46:01 +0000[diff] [blame]904 while (LastChar != EOF &amp;&amp; LastChar != '\n' &amp;&amp; LastChar != '\r');
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]905
906 if (LastChar != EOF)
907 return gettok();
908 }
909
910 // Check for end of file. Don't eat the EOF.
911 if (LastChar == EOF)
912 return tok_eof;
913
914 // Otherwise, just return the character as its ascii value.
915 int ThisChar = LastChar;
916 LastChar = getchar();
917 return ThisChar;
918}
919
920//===----------------------------------------------------------------------===//
921// Abstract Syntax Tree (aka Parse Tree)
922//===----------------------------------------------------------------------===//
923
924/// ExprAST - Base class for all expression nodes.
925class ExprAST {
926public:
927 virtual ~ExprAST() {}
928 virtual Value *Codegen() = 0;
929};
930
931/// NumberExprAST - Expression class for numeric literals like "1.0".
932class NumberExprAST : public ExprAST {
933 double Val;
934public:
935 NumberExprAST(double val) : Val(val) {}
936 virtual Value *Codegen();
937};
938
939/// VariableExprAST - Expression class for referencing a variable, like "a".
940class VariableExprAST : public ExprAST {
941 std::string Name;
942public:
943 VariableExprAST(const std::string &amp;name) : Name(name) {}
944 virtual Value *Codegen();
945};
946
947/// UnaryExprAST - Expression class for a unary operator.
948class UnaryExprAST : public ExprAST {
949 char Opcode;
950 ExprAST *Operand;
951public:
952 UnaryExprAST(char opcode, ExprAST *operand)
953 : Opcode(opcode), Operand(operand) {}
954 virtual Value *Codegen();
955};
956
957/// BinaryExprAST - Expression class for a binary operator.
958class BinaryExprAST : public ExprAST {
959 char Op;
960 ExprAST *LHS, *RHS;
961public:
962 BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
963 : Op(op), LHS(lhs), RHS(rhs) {}
964 virtual Value *Codegen();
965};
966
967/// CallExprAST - Expression class for function calls.
968class CallExprAST : public ExprAST {
969 std::string Callee;
970 std::vector&lt;ExprAST*&gt; Args;
971public:
972 CallExprAST(const std::string &amp;callee, std::vector&lt;ExprAST*&gt; &amp;args)
973 : Callee(callee), Args(args) {}
974 virtual Value *Codegen();
975};
976
977/// IfExprAST - Expression class for if/then/else.
978class IfExprAST : public ExprAST {
979 ExprAST *Cond, *Then, *Else;
980public:
981 IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else)
982 : Cond(cond), Then(then), Else(_else) {}
983 virtual Value *Codegen();
984};
985
986/// ForExprAST - Expression class for for/in.
987class ForExprAST : public ExprAST {
988 std::string VarName;
989 ExprAST *Start, *End, *Step, *Body;
990public:
991 ForExprAST(const std::string &amp;varname, ExprAST *start, ExprAST *end,
992 ExprAST *step, ExprAST *body)
993 : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
994 virtual Value *Codegen();
995};
996
997/// PrototypeAST - This class represents the "prototype" for a function,
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]998/// which captures its name, and its argument names (thus implicitly the number
999/// of arguments the function takes), as well as if it is an operator.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1000class PrototypeAST {
1001 std::string Name;
1002 std::vector&lt;std::string&gt; Args;
1003 bool isOperator;
1004 unsigned Precedence; // Precedence if a binary op.
1005public:
1006 PrototypeAST(const std::string &amp;name, const std::vector&lt;std::string&gt; &amp;args,
1007 bool isoperator = false, unsigned prec = 0)
1008 : Name(name), Args(args), isOperator(isoperator), Precedence(prec) {}
1009
1010 bool isUnaryOp() const { return isOperator &amp;&amp; Args.size() == 1; }
1011 bool isBinaryOp() const { return isOperator &amp;&amp; Args.size() == 2; }
1012
1013 char getOperatorName() const {
1014 assert(isUnaryOp() || isBinaryOp());
1015 return Name[Name.size()-1];
1016 }
1017
1018 unsigned getBinaryPrecedence() const { return Precedence; }
1019
1020 Function *Codegen();
1021};
1022
1023/// FunctionAST - This class represents a function definition itself.
1024class FunctionAST {
1025 PrototypeAST *Proto;
1026 ExprAST *Body;
1027public:
1028 FunctionAST(PrototypeAST *proto, ExprAST *body)
1029 : Proto(proto), Body(body) {}
1030
1031 Function *Codegen();
1032};
1033
1034//===----------------------------------------------------------------------===//
1035// Parser
1036//===----------------------------------------------------------------------===//
1037
1038/// CurTok/getNextToken - Provide a simple token buffer. CurTok is the current
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1039/// token the parser is looking at. getNextToken reads another token from the
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1040/// lexer and updates CurTok with its results.
1041static int CurTok;
1042static int getNextToken() {
1043 return CurTok = gettok();
1044}
1045
1046/// BinopPrecedence - This holds the precedence for each binary operator that is
1047/// defined.
1048static std::map&lt;char, int&gt; BinopPrecedence;
1049
1050/// GetTokPrecedence - Get the precedence of the pending binary operator token.
1051static int GetTokPrecedence() {
1052 if (!isascii(CurTok))
1053 return -1;
1054
1055 // Make sure it's a declared binop.
1056 int TokPrec = BinopPrecedence[CurTok];
1057 if (TokPrec &lt;= 0) return -1;
1058 return TokPrec;
1059}
1060
1061/// Error* - These are little helper functions for error handling.
1062ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
1063PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
1064FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
1065
1066static ExprAST *ParseExpression();
1067
1068/// identifierexpr
Chris Lattner20a0c802007-11-05 17:54:34 +0000[diff] [blame]1069/// ::= identifier
1070/// ::= identifier '(' expression* ')'
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1071static ExprAST *ParseIdentifierExpr() {
1072 std::string IdName = IdentifierStr;
1073
Chris Lattner20a0c802007-11-05 17:54:34 +0000[diff] [blame]1074 getNextToken(); // eat identifier.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1075
1076 if (CurTok != '(') // Simple variable ref.
1077 return new VariableExprAST(IdName);
1078
1079 // Call.
1080 getNextToken(); // eat (
1081 std::vector&lt;ExprAST*&gt; Args;
1082 if (CurTok != ')') {
1083 while (1) {
1084 ExprAST *Arg = ParseExpression();
1085 if (!Arg) return 0;
1086 Args.push_back(Arg);
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1087
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1088 if (CurTok == ')') break;
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1089
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1090 if (CurTok != ',')
Chris Lattner6c4be9c2008-04-14 16:44:41 +0000[diff] [blame]1091 return Error("Expected ')' or ',' in argument list");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1092 getNextToken();
1093 }
1094 }
1095
1096 // Eat the ')'.
1097 getNextToken();
1098
1099 return new CallExprAST(IdName, Args);
1100}
1101
1102/// numberexpr ::= number
1103static ExprAST *ParseNumberExpr() {
1104 ExprAST *Result = new NumberExprAST(NumVal);
1105 getNextToken(); // consume the number
1106 return Result;
1107}
1108
1109/// parenexpr ::= '(' expression ')'
1110static ExprAST *ParseParenExpr() {
1111 getNextToken(); // eat (.
1112 ExprAST *V = ParseExpression();
1113 if (!V) return 0;
1114
1115 if (CurTok != ')')
1116 return Error("expected ')'");
1117 getNextToken(); // eat ).
1118 return V;
1119}
1120
1121/// ifexpr ::= 'if' expression 'then' expression 'else' expression
1122static ExprAST *ParseIfExpr() {
1123 getNextToken(); // eat the if.
1124
1125 // condition.
1126 ExprAST *Cond = ParseExpression();
1127 if (!Cond) return 0;
1128
1129 if (CurTok != tok_then)
1130 return Error("expected then");
1131 getNextToken(); // eat the then
1132
1133 ExprAST *Then = ParseExpression();
1134 if (Then == 0) return 0;
1135
1136 if (CurTok != tok_else)
1137 return Error("expected else");
1138
1139 getNextToken();
1140
1141 ExprAST *Else = ParseExpression();
1142 if (!Else) return 0;
1143
1144 return new IfExprAST(Cond, Then, Else);
1145}
1146
Chris Lattner20a0c802007-11-05 17:54:34 +0000[diff] [blame]1147/// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1148static ExprAST *ParseForExpr() {
1149 getNextToken(); // eat the for.
1150
1151 if (CurTok != tok_identifier)
1152 return Error("expected identifier after for");
1153
1154 std::string IdName = IdentifierStr;
Chris Lattner20a0c802007-11-05 17:54:34 +0000[diff] [blame]1155 getNextToken(); // eat identifier.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1156
1157 if (CurTok != '=')
1158 return Error("expected '=' after for");
1159 getNextToken(); // eat '='.
1160
1161
1162 ExprAST *Start = ParseExpression();
1163 if (Start == 0) return 0;
1164 if (CurTok != ',')
1165 return Error("expected ',' after for start value");
1166 getNextToken();
1167
1168 ExprAST *End = ParseExpression();
1169 if (End == 0) return 0;
1170
1171 // The step value is optional.
1172 ExprAST *Step = 0;
1173 if (CurTok == ',') {
1174 getNextToken();
1175 Step = ParseExpression();
1176 if (Step == 0) return 0;
1177 }
1178
1179 if (CurTok != tok_in)
1180 return Error("expected 'in' after for");
1181 getNextToken(); // eat 'in'.
1182
1183 ExprAST *Body = ParseExpression();
1184 if (Body == 0) return 0;
1185
1186 return new ForExprAST(IdName, Start, End, Step, Body);
1187}
1188
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1189/// primary
1190/// ::= identifierexpr
1191/// ::= numberexpr
1192/// ::= parenexpr
1193/// ::= ifexpr
1194/// ::= forexpr
1195static ExprAST *ParsePrimary() {
1196 switch (CurTok) {
1197 default: return Error("unknown token when expecting an expression");
1198 case tok_identifier: return ParseIdentifierExpr();
1199 case tok_number: return ParseNumberExpr();
1200 case '(': return ParseParenExpr();
1201 case tok_if: return ParseIfExpr();
1202 case tok_for: return ParseForExpr();
1203 }
1204}
1205
1206/// unary
1207/// ::= primary
1208/// ::= '!' unary
1209static ExprAST *ParseUnary() {
1210 // If the current token is not an operator, it must be a primary expr.
1211 if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
1212 return ParsePrimary();
1213
1214 // If this is a unary operator, read it.
1215 int Opc = CurTok;
1216 getNextToken();
1217 if (ExprAST *Operand = ParseUnary())
1218 return new UnaryExprAST(Opc, Operand);
1219 return 0;
1220}
1221
1222/// binoprhs
1223/// ::= ('+' unary)*
1224static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
1225 // If this is a binop, find its precedence.
1226 while (1) {
1227 int TokPrec = GetTokPrecedence();
1228
1229 // If this is a binop that binds at least as tightly as the current binop,
1230 // consume it, otherwise we are done.
1231 if (TokPrec &lt; ExprPrec)
1232 return LHS;
1233
1234 // Okay, we know this is a binop.
1235 int BinOp = CurTok;
1236 getNextToken(); // eat binop
1237
1238 // Parse the unary expression after the binary operator.
1239 ExprAST *RHS = ParseUnary();
1240 if (!RHS) return 0;
1241
1242 // If BinOp binds less tightly with RHS than the operator after RHS, let
1243 // the pending operator take RHS as its LHS.
1244 int NextPrec = GetTokPrecedence();
1245 if (TokPrec &lt; NextPrec) {
1246 RHS = ParseBinOpRHS(TokPrec+1, RHS);
1247 if (RHS == 0) return 0;
1248 }
1249
1250 // Merge LHS/RHS.
1251 LHS = new BinaryExprAST(BinOp, LHS, RHS);
1252 }
1253}
1254
1255/// expression
1256/// ::= unary binoprhs
1257///
1258static ExprAST *ParseExpression() {
1259 ExprAST *LHS = ParseUnary();
1260 if (!LHS) return 0;
1261
1262 return ParseBinOpRHS(0, LHS);
1263}
1264
1265/// prototype
1266/// ::= id '(' id* ')'
1267/// ::= binary LETTER number? (id, id)
1268/// ::= unary LETTER (id)
1269static PrototypeAST *ParsePrototype() {
1270 std::string FnName;
1271
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1272 unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1273 unsigned BinaryPrecedence = 30;
1274
1275 switch (CurTok) {
1276 default:
1277 return ErrorP("Expected function name in prototype");
1278 case tok_identifier:
1279 FnName = IdentifierStr;
1280 Kind = 0;
1281 getNextToken();
1282 break;
1283 case tok_unary:
1284 getNextToken();
1285 if (!isascii(CurTok))
1286 return ErrorP("Expected unary operator");
1287 FnName = "unary";
1288 FnName += (char)CurTok;
1289 Kind = 1;
1290 getNextToken();
1291 break;
1292 case tok_binary:
1293 getNextToken();
1294 if (!isascii(CurTok))
1295 return ErrorP("Expected binary operator");
1296 FnName = "binary";
1297 FnName += (char)CurTok;
1298 Kind = 2;
1299 getNextToken();
1300
1301 // Read the precedence if present.
1302 if (CurTok == tok_number) {
1303 if (NumVal &lt; 1 || NumVal &gt; 100)
1304 return ErrorP("Invalid precedecnce: must be 1..100");
1305 BinaryPrecedence = (unsigned)NumVal;
1306 getNextToken();
1307 }
1308 break;
1309 }
1310
1311 if (CurTok != '(')
1312 return ErrorP("Expected '(' in prototype");
1313
1314 std::vector&lt;std::string&gt; ArgNames;
1315 while (getNextToken() == tok_identifier)
1316 ArgNames.push_back(IdentifierStr);
1317 if (CurTok != ')')
1318 return ErrorP("Expected ')' in prototype");
1319
1320 // success.
1321 getNextToken(); // eat ')'.
1322
1323 // Verify right number of names for operator.
1324 if (Kind &amp;&amp; ArgNames.size() != Kind)
1325 return ErrorP("Invalid number of operands for operator");
1326
1327 return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);
1328}
1329
1330/// definition ::= 'def' prototype expression
1331static FunctionAST *ParseDefinition() {
1332 getNextToken(); // eat def.
1333 PrototypeAST *Proto = ParsePrototype();
1334 if (Proto == 0) return 0;
1335
1336 if (ExprAST *E = ParseExpression())
1337 return new FunctionAST(Proto, E);
1338 return 0;
1339}
1340
1341/// toplevelexpr ::= expression
1342static FunctionAST *ParseTopLevelExpr() {
1343 if (ExprAST *E = ParseExpression()) {
1344 // Make an anonymous proto.
1345 PrototypeAST *Proto = new PrototypeAST("", std::vector&lt;std::string&gt;());
1346 return new FunctionAST(Proto, E);
1347 }
1348 return 0;
1349}
1350
1351/// external ::= 'extern' prototype
1352static PrototypeAST *ParseExtern() {
1353 getNextToken(); // eat extern.
1354 return ParsePrototype();
1355}
1356
1357//===----------------------------------------------------------------------===//
1358// Code Generation
1359//===----------------------------------------------------------------------===//
1360
1361static Module *TheModule;
Owen Andersond1fbd142009-07-08 20:50:47 +0000[diff] [blame]1362static IRBuilder&lt;&gt; Builder(getGlobalContext());
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1363static std::map&lt;std::string, Value*&gt; NamedValues;
1364static FunctionPassManager *TheFPM;
1365
1366Value *ErrorV(const char *Str) { Error(Str); return 0; }
1367
1368Value *NumberExprAST::Codegen() {
Owen Anderson6f83c9c2009-07-27 20:59:43 +0000[diff] [blame]1369 return ConstantFP::get(getGlobalContext(), APFloat(Val));
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1370}
1371
1372Value *VariableExprAST::Codegen() {
1373 // Look this variable up in the function.
1374 Value *V = NamedValues[Name];
1375 return V ? V : ErrorV("Unknown variable name");
1376}
1377
1378Value *UnaryExprAST::Codegen() {
1379 Value *OperandV = Operand-&gt;Codegen();
1380 if (OperandV == 0) return 0;
1381
1382 Function *F = TheModule-&gt;getFunction(std::string("unary")+Opcode);
1383 if (F == 0)
1384 return ErrorV("Unknown unary operator");
1385
1386 return Builder.CreateCall(F, OperandV, "unop");
1387}
1388
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1389Value *BinaryExprAST::Codegen() {
1390 Value *L = LHS-&gt;Codegen();
1391 Value *R = RHS-&gt;Codegen();
1392 if (L == 0 || R == 0) return 0;
1393
1394 switch (Op) {
Eric Christopher2214b812010-06-14 06:09:39 +0000[diff] [blame]1395 case '+': return Builder.CreateFAdd(L, R, "addtmp");
1396 case '-': return Builder.CreateFSub(L, R, "subtmp");
1397 case '*': return Builder.CreateFMul(L, R, "multmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1398 case '&lt;':
Chris Lattner71155212007-11-06 01:39:12 +0000[diff] [blame]1399 L = Builder.CreateFCmpULT(L, R, "cmptmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1400 // Convert bool 0/1 to double 0.0 or 1.0
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1401 return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
1402 "booltmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1403 default: break;
1404 }
1405
1406 // If it wasn't a builtin binary operator, it must be a user defined one. Emit
1407 // a call to it.
1408 Function *F = TheModule-&gt;getFunction(std::string("binary")+Op);
1409 assert(F &amp;&amp; "binary operator not found!");
1410
1411 Value *Ops[] = { L, R };
1412 return Builder.CreateCall(F, Ops, Ops+2, "binop");
1413}
1414
1415Value *CallExprAST::Codegen() {
1416 // Look up the name in the global module table.
1417 Function *CalleeF = TheModule-&gt;getFunction(Callee);
1418 if (CalleeF == 0)
1419 return ErrorV("Unknown function referenced");
1420
1421 // If argument mismatch error.
1422 if (CalleeF-&gt;arg_size() != Args.size())
1423 return ErrorV("Incorrect # arguments passed");
1424
1425 std::vector&lt;Value*&gt; ArgsV;
1426 for (unsigned i = 0, e = Args.size(); i != e; ++i) {
1427 ArgsV.push_back(Args[i]-&gt;Codegen());
1428 if (ArgsV.back() == 0) return 0;
1429 }
1430
1431 return Builder.CreateCall(CalleeF, ArgsV.begin(), ArgsV.end(), "calltmp");
1432}
1433
1434Value *IfExprAST::Codegen() {
1435 Value *CondV = Cond-&gt;Codegen();
1436 if (CondV == 0) return 0;
1437
1438 // Convert condition to a bool by comparing equal to 0.0.
1439 CondV = Builder.CreateFCmpONE(CondV,
Owen Anderson6f83c9c2009-07-27 20:59:43 +0000[diff] [blame]1440 ConstantFP::get(getGlobalContext(), APFloat(0.0)),
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1441 "ifcond");
1442
1443 Function *TheFunction = Builder.GetInsertBlock()-&gt;getParent();
1444
1445 // Create blocks for the then and else cases. Insert the 'then' block at the
1446 // end of the function.
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]1447 BasicBlock *ThenBB = BasicBlock::Create(getGlobalContext(), "then", TheFunction);
1448 BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else");
1449 BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1450
1451 Builder.CreateCondBr(CondV, ThenBB, ElseBB);
1452
1453 // Emit then value.
1454 Builder.SetInsertPoint(ThenBB);
1455
1456 Value *ThenV = Then-&gt;Codegen();
1457 if (ThenV == 0) return 0;
1458
1459 Builder.CreateBr(MergeBB);
1460 // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
1461 ThenBB = Builder.GetInsertBlock();
1462
1463 // Emit else block.
1464 TheFunction-&gt;getBasicBlockList().push_back(ElseBB);
1465 Builder.SetInsertPoint(ElseBB);
1466
1467 Value *ElseV = Else-&gt;Codegen();
1468 if (ElseV == 0) return 0;
1469
1470 Builder.CreateBr(MergeBB);
1471 // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
1472 ElseBB = Builder.GetInsertBlock();
1473
1474 // Emit merge block.
1475 TheFunction-&gt;getBasicBlockList().push_back(MergeBB);
1476 Builder.SetInsertPoint(MergeBB);
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]1477 PHINode *PN = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()),
1478 "iftmp");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1479
1480 PN-&gt;addIncoming(ThenV, ThenBB);
1481 PN-&gt;addIncoming(ElseV, ElseBB);
1482 return PN;
1483}
1484
1485Value *ForExprAST::Codegen() {
1486 // Output this as:
1487 // ...
1488 // start = startexpr
1489 // goto loop
1490 // loop:
1491 // variable = phi [start, loopheader], [nextvariable, loopend]
1492 // ...
1493 // bodyexpr
1494 // ...
1495 // loopend:
1496 // step = stepexpr
1497 // nextvariable = variable + step
1498 // endcond = endexpr
1499 // br endcond, loop, endloop
1500 // outloop:
1501
1502 // Emit the start code first, without 'variable' in scope.
1503 Value *StartVal = Start-&gt;Codegen();
1504 if (StartVal == 0) return 0;
1505
1506 // Make the new basic block for the loop header, inserting after current
1507 // block.
1508 Function *TheFunction = Builder.GetInsertBlock()-&gt;getParent();
1509 BasicBlock *PreheaderBB = Builder.GetInsertBlock();
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]1510 BasicBlock *LoopBB = BasicBlock::Create(getGlobalContext(), "loop", TheFunction);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1511
1512 // Insert an explicit fall through from the current block to the LoopBB.
1513 Builder.CreateBr(LoopBB);
1514
1515 // Start insertion in LoopBB.
1516 Builder.SetInsertPoint(LoopBB);
1517
1518 // Start the PHI node with an entry for Start.
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]1519 PHINode *Variable = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), VarName.c_str());
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1520 Variable-&gt;addIncoming(StartVal, PreheaderBB);
1521
1522 // Within the loop, the variable is defined equal to the PHI node. If it
1523 // shadows an existing variable, we have to restore it, so save it now.
1524 Value *OldVal = NamedValues[VarName];
1525 NamedValues[VarName] = Variable;
1526
1527 // Emit the body of the loop. This, like any other expr, can change the
1528 // current BB. Note that we ignore the value computed by the body, but don't
1529 // allow an error.
1530 if (Body-&gt;Codegen() == 0)
1531 return 0;
1532
1533 // Emit the step value.
1534 Value *StepVal;
1535 if (Step) {
1536 StepVal = Step-&gt;Codegen();
1537 if (StepVal == 0) return 0;
1538 } else {
1539 // If not specified, use 1.0.
Owen Anderson6f83c9c2009-07-27 20:59:43 +0000[diff] [blame]1540 StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0));
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1541 }
1542
Chris Lattnerf57fcf72010-09-01 20:09:20 +0000[diff] [blame]1543 Value *NextVar = Builder.CreateFAdd(Variable, StepVal, "nextvar");
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1544
1545 // Compute the end condition.
1546 Value *EndCond = End-&gt;Codegen();
1547 if (EndCond == 0) return EndCond;
1548
1549 // Convert condition to a bool by comparing equal to 0.0.
1550 EndCond = Builder.CreateFCmpONE(EndCond,
Owen Anderson6f83c9c2009-07-27 20:59:43 +0000[diff] [blame]1551 ConstantFP::get(getGlobalContext(), APFloat(0.0)),
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1552 "loopcond");
1553
1554 // Create the "after loop" block and insert it.
1555 BasicBlock *LoopEndBB = Builder.GetInsertBlock();
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]1556 BasicBlock *AfterBB = BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1557
1558 // Insert the conditional branch into the end of LoopEndBB.
1559 Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
1560
1561 // Any new code will be inserted in AfterBB.
1562 Builder.SetInsertPoint(AfterBB);
1563
1564 // Add a new entry to the PHI node for the backedge.
1565 Variable-&gt;addIncoming(NextVar, LoopEndBB);
1566
1567 // Restore the unshadowed variable.
1568 if (OldVal)
1569 NamedValues[VarName] = OldVal;
1570 else
1571 NamedValues.erase(VarName);
1572
1573
1574 // for expr always returns 0.0.
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]1575 return Constant::getNullValue(Type::getDoubleTy(getGlobalContext()));
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1576}
1577
1578Function *PrototypeAST::Codegen() {
1579 // Make the function type: double(double,double) etc.
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]1580 std::vector&lt;const Type*&gt; Doubles(Args.size(),
1581 Type::getDoubleTy(getGlobalContext()));
1582 FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()),
1583 Doubles, false);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1584
Gabor Greifdf7d2b42008-04-19 22:25:09 +0000[diff] [blame]1585 Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1586
1587 // If F conflicted, there was already something named 'Name'. If it has a
1588 // body, don't allow redefinition or reextern.
1589 if (F-&gt;getName() != Name) {
1590 // Delete the one we just made and get the existing one.
1591 F-&gt;eraseFromParent();
1592 F = TheModule-&gt;getFunction(Name);
1593
1594 // If F already has a body, reject this.
1595 if (!F-&gt;empty()) {
1596 ErrorF("redefinition of function");
1597 return 0;
1598 }
1599
1600 // If F took a different number of args, reject.
1601 if (F-&gt;arg_size() != Args.size()) {
1602 ErrorF("redefinition of function with different # args");
1603 return 0;
1604 }
1605 }
1606
1607 // Set names for all arguments.
1608 unsigned Idx = 0;
1609 for (Function::arg_iterator AI = F-&gt;arg_begin(); Idx != Args.size();
1610 ++AI, ++Idx) {
1611 AI-&gt;setName(Args[Idx]);
1612
1613 // Add arguments to variable symbol table.
1614 NamedValues[Args[Idx]] = AI;
1615 }
1616
1617 return F;
1618}
1619
1620Function *FunctionAST::Codegen() {
1621 NamedValues.clear();
1622
1623 Function *TheFunction = Proto-&gt;Codegen();
1624 if (TheFunction == 0)
1625 return 0;
1626
1627 // If this is an operator, install it.
1628 if (Proto-&gt;isBinaryOp())
1629 BinopPrecedence[Proto-&gt;getOperatorName()] = Proto-&gt;getBinaryPrecedence();
1630
1631 // Create a new basic block to start insertion into.
Owen Anderson1d0be152009-08-13 21:58:54 +0000[diff] [blame]1632 BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1633 Builder.SetInsertPoint(BB);
1634
1635 if (Value *RetVal = Body-&gt;Codegen()) {
1636 // Finish off the function.
1637 Builder.CreateRet(RetVal);
1638
1639 // Validate the generated code, checking for consistency.
1640 verifyFunction(*TheFunction);
1641
1642 // Optimize the function.
1643 TheFPM-&gt;run(*TheFunction);
1644
1645 return TheFunction;
1646 }
1647
1648 // Error reading body, remove function.
1649 TheFunction-&gt;eraseFromParent();
1650
1651 if (Proto-&gt;isBinaryOp())
1652 BinopPrecedence.erase(Proto-&gt;getOperatorName());
1653 return 0;
1654}
1655
1656//===----------------------------------------------------------------------===//
1657// Top-Level parsing and JIT Driver
1658//===----------------------------------------------------------------------===//
1659
1660static ExecutionEngine *TheExecutionEngine;
1661
1662static void HandleDefinition() {
1663 if (FunctionAST *F = ParseDefinition()) {
1664 if (Function *LF = F-&gt;Codegen()) {
1665 fprintf(stderr, "Read function definition:");
1666 LF-&gt;dump();
1667 }
1668 } else {
1669 // Skip token for error recovery.
1670 getNextToken();
1671 }
1672}
1673
1674static void HandleExtern() {
1675 if (PrototypeAST *P = ParseExtern()) {
1676 if (Function *F = P-&gt;Codegen()) {
1677 fprintf(stderr, "Read extern: ");
1678 F-&gt;dump();
1679 }
1680 } else {
1681 // Skip token for error recovery.
1682 getNextToken();
1683 }
1684}
1685
1686static void HandleTopLevelExpression() {
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1687 // Evaluate a top-level expression into an anonymous function.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1688 if (FunctionAST *F = ParseTopLevelExpr()) {
1689 if (Function *LF = F-&gt;Codegen()) {
1690 // JIT the function, returning a function pointer.
1691 void *FPtr = TheExecutionEngine-&gt;getPointerToFunction(LF);
1692
1693 // Cast it to the right type (takes no arguments, returns a double) so we
1694 // can call it as a native function.
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]1695 double (*FP)() = (double (*)())(intptr_t)FPtr;
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1696 fprintf(stderr, "Evaluated to %f\n", FP());
1697 }
1698 } else {
1699 // Skip token for error recovery.
1700 getNextToken();
1701 }
1702}
1703
1704/// top ::= definition | external | expression | ';'
1705static void MainLoop() {
1706 while (1) {
1707 fprintf(stderr, "ready&gt; ");
1708 switch (CurTok) {
1709 case tok_eof: return;
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1710 case ';': getNextToken(); break; // ignore top-level semicolons.
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1711 case tok_def: HandleDefinition(); break;
1712 case tok_extern: HandleExtern(); break;
1713 default: HandleTopLevelExpression(); break;
1714 }
1715 }
1716}
1717
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1718//===----------------------------------------------------------------------===//
1719// "Library" functions that can be "extern'd" from user code.
1720//===----------------------------------------------------------------------===//
1721
1722/// putchard - putchar that takes a double and returns 0.
1723extern "C"
1724double putchard(double X) {
1725 putchar((char)X);
1726 return 0;
1727}
1728
1729/// printd - printf that takes a double prints it as "%f\n", returning 0.
1730extern "C"
1731double printd(double X) {
1732 printf("%f\n", X);
1733 return 0;
1734}
1735
1736//===----------------------------------------------------------------------===//
1737// Main driver code.
1738//===----------------------------------------------------------------------===//
1739
1740int main() {
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1741 InitializeNativeTarget();
1742 LLVMContext &amp;Context = getGlobalContext();
1743
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1744 // Install standard binary operators.
1745 // 1 is lowest precedence.
1746 BinopPrecedence['&lt;'] = 10;
1747 BinopPrecedence['+'] = 20;
1748 BinopPrecedence['-'] = 20;
1749 BinopPrecedence['*'] = 40; // highest.
1750
1751 // Prime the first token.
1752 fprintf(stderr, "ready&gt; ");
1753 getNextToken();
1754
1755 // Make the module, which holds all the code.
Erick Tryzelaarfd1ec5e2009-09-22 21:14:49 +0000[diff] [blame]1756 TheModule = new Module("my cool jit", Context);
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1757
Jeffrey Yasskinf0356fe2010-01-27 20:34:15 +0000[diff] [blame]1758 // Create the JIT. This takes ownership of the module.
Jeffrey Yasskin42fc5582010-02-11 19:15:20 +0000[diff] [blame]1759 std::string ErrStr;
1760 TheExecutionEngine = EngineBuilder(TheModule).setErrorStr(&ErrStr).create();
1761 if (!TheExecutionEngine) {
1762 fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
1763 exit(1);
1764 }
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1765
Jeffrey Yasskinf0356fe2010-01-27 20:34:15 +0000[diff] [blame]1766 FunctionPassManager OurFPM(TheModule);
Reid Kleckner60130f02009-08-26 20:58:25 +0000[diff] [blame]1767
1768 // Set up the optimizer pipeline. Start with registering info about how the
1769 // target lays out data structures.
1770 OurFPM.add(new TargetData(*TheExecutionEngine-&gt;getTargetData()));
Dan Gohmandfa1a792010-11-15 18:41:10 +0000[diff] [blame^]1771 // Provide basic AliasAnalysis support for GVN.
1772 OurFPM.add(createBasicAliasAnalysisPass());
Reid Kleckner60130f02009-08-26 20:58:25 +0000[diff] [blame]1773 // Do simple "peephole" optimizations and bit-twiddling optzns.
1774 OurFPM.add(createInstructionCombiningPass());
1775 // Reassociate expressions.
1776 OurFPM.add(createReassociatePass());
1777 // Eliminate Common SubExpressions.
1778 OurFPM.add(createGVNPass());
1779 // Simplify the control flow graph (deleting unreachable blocks, etc).
1780 OurFPM.add(createCFGSimplificationPass());
1781
Nick Lewycky422094c2009-09-13 21:38:54 +0000[diff] [blame]1782 OurFPM.doInitialization();
1783
Reid Kleckner60130f02009-08-26 20:58:25 +0000[diff] [blame]1784 // Set the global so the code gen can use this.
1785 TheFPM = &amp;OurFPM;
1786
1787 // Run the main "interpreter loop" now.
1788 MainLoop();
1789
1790 TheFPM = 0;
1791
1792 // Print out all of the generated code.
1793 TheModule-&gt;dump();
1794
Chris Lattner58f2c872007-11-02 05:42:52 +0000[diff] [blame]1795 return 0;
1796}
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]1797</pre>
1798</div>
1799
Chris Lattner729eb142008-02-10 19:11:04 +0000[diff] [blame]1800<a href="LangImpl7.html">Next: Extending the language: mutable variables / SSA construction</a>
Chris Lattnerc9d5d2c2007-11-01 06:49:54 +0000[diff] [blame]1801</div>
1802
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