source: liacs/coco/assignment3/ICGenerator.cc@ 364

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1/*
2 * ICGenerator.cc - Implementation of the ICGenerator class
3 *
4 * Part of the assignment of the Compiler Construction course
5 * LIACS, Leiden University
6 *
7 * This file will contain most of your work for assignment 3.
8 */
9
10#include "ICGenerator.h"
11
12#include <sstream>
13#include <cassert>
14#include <list>
15#include <iostream>
16
17extern bool bOptimize1;
18extern IntermediateCode *icode;
19extern SymbolTable *symtab;
20
21/* Macro to allow pretty display of parser tree calling stack debug print calls */
22#define picg(x) pmesg(100, "Parser: '"); pmesg(100, x); pmesg(100, "'\n")
23
24// Constructor
25ICGenerator::ICGenerator() {
26}
27
28
29// Destructor
30ICGenerator::~ICGenerator() {
31}
32
33
34// Preprocesses the syntax tree; this method is called before
35// GenerateIntermediateCode() if optimizations are enabled
36void ICGenerator::Preprocess (SyntaxTree * tree, SymbolTable * symtab) {
37}
38
39
40// Takes a SyntaxTree and converts it into an IntermediateCode structure
41IntermediateCode * ICGenerator::GenerateIntermediateCode (SyntaxTree * inputTree, SymbolTable * symtab) {
42 IStatement * istmt;
43
44 icode = new IntermediateCode;
45
46 /* Process program body */
47 /* Make sure temponary generated variables are added to the right scope */
48 symtab->SetCurrentScope(inputTree->GetProgramName());
49 icode->SetProgramName(inputTree->GetProgramName());
50 delete Treewalk(inputTree->GetProgramBody());
51
52 /* Indicate end of program body */
53 istmt = new IStatement (IOP_RETURN);
54 icode->AppendStatement(istmt);
55
56 /* Now walk through the list of subprograms, and process them one by one */
57 for (int i = 0; i < inputTree->GetSubprogramCount(); i++) {
58 // add subprogram code
59 Symbol *subprogram = symtab->GetSymbol(inputTree->GetSubprogramName(i));
60 /* Make sure temponary generated variables are added to the right scope */
61 symtab->SetCurrentScope(inputTree->GetSubprogramName(i));
62 icode->AppendStatement(new IStatement(IOP_SUBPROG, new IOperand_Symbol(subprogram), NULL, NULL));
63
64 // add subprogram body code
65 delete Treewalk(inputTree->GetSubprogram(i));
66
67 // add code for return value
68 IOperator op;
69 switch (subprogram->GetReturnType()) {
70 case RT_INT:
71 op = IOP_RETURN_I;
72 break;
73 case RT_REAL:
74 op = IOP_RETURN_R;
75 break;
76 case RT_VOID:
77 op = IOP_RETURN;
78 break;
79 default:
80 assert(0); // can't happen
81 }
82 icode->AppendStatement(new IStatement(op, (op == IOP_RETURN) ? NULL : new IOperand_Symbol(subprogram), NULL, NULL));
83 }
84
85 return icode;
86}
87
88
89// Postprocesses the intermediate code; this method is called after
90// GenerateIntermediateCode() if optimizations are enabled
91void ICGenerator::Postprocess (IntermediateCode * code, SymbolTable * symtab) {
92 /* Some trivial optimalisations which could be implemented */
93
94 /* 1) LABEL X
95 * 2) GOTO :Y
96 * Alter GOTO :X to GOTO :Y directly
97 */
98
99 /* 1) LABEL X
100 * 2) RETURN tX
101 * Alter GOTO :X to RETURN tX directly
102 */
103
104 /* 1) ASSIGN foo tX
105 * ... no use of tX, in the meantime ...
106 * X) ASSIGN bar tX
107 * Delete line 1)
108 */
109
110 /* Less trivials optimalisations which could be implemented*/
111
112 /* Unfold small for loops */
113
114 /* Delete/mangle branching code if TEST expression to always to be evaluated TRUE of FALSE */
115
116 /* Detect and remove useless IOP_ASSIGN_[IR] statements */
117
118 /* When parameters of function are not used, do not assign */
119
120 /* 1) ASSIGN int(1) tX
121 * 2) ASSIGN int(2) tY
122 * 3) ADD_I tX tY tZ
123 * Convert line 3) to ASSIGN int(3) tZ
124 */
125
126 /* 1) LABEL L_1
127 * 2) LABEL L_2
128 * Convert all GOTO L_2 to GOTO L_1 and delete L_2
129 */
130}
131
132
133// Generate a temporary symbol
134Symbol * ICGenerator::GenerateTempVar(ReturnType type) {
135 /* Keep track of variables given out, make all generated unique for the sake
136 * of debugging
137 */
138 static int count = 0;
139 count++;
140
141 Symbol *symbol = new Symbol();
142 symbol->SetSymbolType(ST_TEMPVAR);
143 symbol->SetReturnType(type);
144 std::stringstream ss;
145 ss << "t" << count;
146 symbol->SetName(ss.str());
147
148 /* Make sure to add it to the symbol table */
149 symtab->AddSymbol(symbol);
150 return symbol;
151}
152
153
154// Generates a Symbol for a label
155Symbol * ICGenerator::GenerateLabel() {
156 /* Keep track of variables given out, make all generated unique for the sake
157 * of debugging
158 */
159 static int count = 0;
160 count++;
161
162 Symbol *symbol = new Symbol();
163 symbol->SetSymbolType(ST_LABEL);
164 std::stringstream ss;
165 ss << "L_" << count;
166 symbol->SetName(ss.str());
167
168 /* Make sure to add it to the symbol table */
169 symtab->AddSymbol(symbol);
170 return symbol;
171}
172
173IOperand *ICGenerator::Treewalk (Node * node, IOperand *dest, IOperand *constant)
174{
175 switch (node->GetNodeType ())
176 {
177 case NODE_UNKNOWN: // Unknown (yet)
178 assert (0); // can't happen
179 break;
180 case NODE_ERROR: // Error
181 assert (0); // can't happen
182 break;
183
184 /*
185 * Statement list
186 * left child One of, NODE_ASSIGNMENT, NODE_IF, NODE_WHILE,
187 * NODE_PROCCALL, NODE_FUNCTIONCALL, NODE_STATEMENT_LIST.
188 * right child One of, NODE_ASSIGNMENT, NODE_IF, NODE_WHILE,
189 * NODE_PROCCALL, NODE_FUNCTIONCALL, NODE_STATEMENT_LIST, or
190 * NODE_EMPTY if no more statements follow.
191 */
192 case NODE_STATEMENT_LIST:
193 {
194 delete Treewalk(node->GetLeftChild());
195 delete Treewalk(node->GetRightChild());
196 return NULL;
197 }
198 break;
199
200 /*
201 * Assignment
202 * left child A NODE_ID that identifies the destination variable
203 * right child A subtree representing an expression
204 */
205 case NODE_ASSIGNMENT:
206 {
207 IOperand *result = Treewalk(node->GetLeftChild());
208 IOperand *operand = Treewalk(node->GetRightChild(), bOptimize1 ? result : NULL);
209 if (operand != result) {
210 IOperator op = ( (node->GetLeftChild()->GetReturnType() == RT_REAL) ? IOP_ASSIGN_R : IOP_ASSIGN_I );
211 icode->AppendStatement(new IStatement(op, operand, NULL, result));
212 }
213 return NULL;
214 }
215 break;
216
217 /*
218 * If statement
219 * left child A NODE_BOOLEXPR that provides the if condition
220 * right child A NODE_IF_TARGETS subtree (if there is an else clause) or
221 * a subtree consisting of statements (if there's no else)
222 */
223 case NODE_IF:
224 {
225 // generate labels
226 Symbol *false_label = GenerateLabel();
227 Symbol *end_label = GenerateLabel();
228
229 // add evaluation code
230 IOperand *evaluation = Treewalk(node->GetLeftChild());
231 icode->AppendStatement(new IStatement(IOP_BEQ_I, evaluation, new IOperand_Int(0), new IOperand_Symbol(false_label)));
232
233 // add code for true case
234 Node *rightchild = node->GetRightChild();
235 if (rightchild->GetNodeType() == NODE_IF_TARGETS) {
236 delete Treewalk(rightchild->GetLeftChild());
237 // there is a else part so skip over it
238 icode->AppendStatement(new IStatement(IOP_GOTO, new IOperand_Symbol(end_label), NULL, NULL));
239 } else {
240 delete Treewalk(rightchild);
241 }
242
243 // add label for false part
244 icode->AppendStatement(new IStatement(IOP_LABEL, new IOperand_Symbol(false_label), NULL, NULL));
245
246 // add code for false/else case if any
247 if (rightchild->GetNodeType() == NODE_IF_TARGETS) {
248 delete Treewalk(rightchild->GetRightChild ());
249 // add end label
250 icode->AppendStatement(new IStatement(IOP_LABEL, new IOperand_Symbol(end_label), NULL, NULL));
251 }
252
253 return NULL;
254 }
255 break;
256
257 /*
258 * Targets of an if-else-statement
259 * left child The statements that have to be executed when the condition
260 * of the parent if-statement is true.
261 * right child The statements that have to be executed when the condition
262 * of the parent if-statement is false: that is: the else
263 * part.
264 */
265 case NODE_IF_TARGETS:
266 assert(0); // handled in NODE_IF
267 break;
268
269 /*
270 * While loop
271 * left child A NODE_BOOLEXPR that provides the loop condition
272 * right child A subtree consisting of statements
273 */
274 case NODE_WHILE:
275 {
276 /* Method while tree
277 * :START
278 * if <expr> = 0 GOTO END
279 * <body>
280 * GOTO START
281 * :END
282 */
283 // generate labels
284 Symbol *start_label = GenerateLabel();
285 Symbol *end_label = GenerateLabel();
286
287 // add start label
288 icode->AppendStatement(new IStatement(IOP_LABEL, new IOperand_Symbol(start_label), NULL, NULL));
289
290 // add evaluation code
291 IOperand *evaluation = Treewalk(node->GetLeftChild());
292 icode->AppendStatement(new IStatement(IOP_BEQ_I, evaluation, new IOperand_Int(0), new IOperand_Symbol(end_label)));
293
294 // add code
295 delete Treewalk(node->GetLeftChild());
296
297 // add jump back to start
298 icode->AppendStatement(new IStatement(IOP_GOTO, new IOperand_Symbol(start_label), NULL, NULL));
299
300 // add end label
301 icode->AppendStatement(new IStatement(IOP_LABEL, new IOperand_Symbol(end_label), NULL, NULL));
302
303 return NULL;
304 }
305 break;
306
307 /*
308 * Subprogram calls
309 * left child A NODE_ID that identifies the called function/procedure
310 * right child A NODE_EXPRLIST that specifies the actual arguments: or
311 * NODE_EMPTY if no arguments required.
312 */
313 case NODE_PROCCALL:
314 {
315 // pass parameters
316 delete Treewalk(node->GetRightChild());
317
318 // add call statement
319 IOperand *id = Treewalk(node->GetLeftChild());
320 icode->AppendStatement(new IStatement(IOP_PROCCALL, id, NULL, NULL));
321
322 return NULL;
323 }
324 break;
325 case NODE_FUNCTIONCALL:
326 {
327 // pass parameters
328 delete Treewalk(node->GetRightChild());
329
330 // add call statement
331 IOperand *id = Treewalk(node->GetLeftChild());
332 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
333 icode->AppendStatement(new IStatement(IOP_FUNCCALL, id, NULL, result));
334
335 return (dest != NULL) ? dest : result->Clone();
336 }
337 break;
338
339 /*
340 * Expression list
341 * left child A subtree representing an expression
342 * right child A subtree representing an expression: another
343 * NODE_EXPRLIST: or NODE_EMPTY if no more expressions follow
344 * in the expression list.
345 */
346 case NODE_EXPRLIST:
347 {
348 // pass parameter
349 IOperand *parameter = Treewalk(node->GetLeftChild());
350 ReturnType type = node->GetLeftChild()->GetReturnType();
351 IOperator op = ( (type == RT_REAL) ? IOP_PARAM_R : IOP_PARAM_I );
352 icode->AppendStatement(new IStatement(op, parameter, NULL, NULL));
353
354 // pass any other parameters
355 delete Treewalk(node->GetRightChild());
356
357 return NULL;
358 }
359 break;
360
361 /*
362 * Boolean-like expression
363 * child A subtree with any NODE_REL_ node as parent
364 */
365 case NODE_BOOLEXPR:
366 {
367 return Treewalk(node->GetChild());
368 }
369 break;
370
371 /*
372 * Relational operators
373 * left child Left-hand side of the comparison
374 * right child Right-hand side of the comparison
375 */
376 case NODE_REL_EQUAL: // = operator
377 {
378 ReturnType type = node->GetLeftChild()->GetReturnType();
379 IOperator op = ((type == RT_INT) ? IOP_BEQ_I : IOP_BEQ_R);
380 return GenerateRelopCode(op, node);
381 }
382 break;
383 case NODE_REL_LT: // < operator
384 {
385 ReturnType type = node->GetLeftChild()->GetReturnType();
386 IOperator op = ((type == RT_INT) ? IOP_BLT_I : IOP_BLT_R);
387 return GenerateRelopCode(op, node);
388 }
389 break;
390 case NODE_REL_GT: // > operator
391 {
392 ReturnType type = node->GetLeftChild()->GetReturnType();
393 IOperator op = ((type == RT_INT) ? IOP_BGT_I : IOP_BGT_R);
394 return GenerateRelopCode(op, node);
395 }
396 break;
397 case NODE_REL_LTE: // <= operator
398 {
399 ReturnType type = node->GetLeftChild()->GetReturnType();
400 IOperator op = ((type == RT_INT) ? IOP_BLE_I : IOP_BLE_R);
401 return GenerateRelopCode(op, node);
402 }
403 break;
404 case NODE_REL_GTE: // >= operator
405 {
406 ReturnType type = node->GetLeftChild()->GetReturnType();
407 IOperator op = ((type == RT_INT) ? IOP_BGE_I : IOP_BGE_R);
408 return GenerateRelopCode(op, node);
409 }
410 break;
411 case NODE_REL_NOTEQUAL: // <> operator
412 {
413 ReturnType type = node->GetLeftChild()->GetReturnType();
414 IOperator op = ((type == RT_INT) ? IOP_BNE_I : IOP_BNE_R);
415 return GenerateRelopCode(op, node);
416 }
417 break;
418
419 /*
420 * Binary arithmetic & logic operations
421 * left child Left-hand side of the operation
422 * right child Right-hand side of the operation
423 */
424 case NODE_ADD: // Add
425 {
426 IOperand *lhs = NULL;
427 IOperand *rhs = NULL;
428
429 // attempt optimizations
430 if (bOptimize1) {
431 /* reverse evaluation of operands, due to the fact the tree is always
432 * set to be on the left and we like to fold constants where ever
433 * possible
434 */
435 rhs = Treewalk(node->GetRightChild());
436 // check if we need to push any constant down the tree
437 if (node->GetLeftChild()->GetNodeType() == NODE_ADD ||
438 node->GetLeftChild()->GetNodeType() == NODE_SUB ) {
439 if (IsConstant(rhs)) {
440 // right hand side is also constant
441 if (constant != NULL) {
442 if (IsInt(rhs)) {
443 rhs->SetIntValue(rhs->GetIntValue() + constant->GetIntValue());
444 } else {
445 rhs->SetRealValue(rhs->GetRealValue() + constant->GetRealValue());
446 }
447 }
448 // evaluate left hand side passing constant value
449 lhs = Treewalk(node->GetLeftChild(), dest, rhs);
450 return lhs;
451 } else {
452 // generate add instruction for the right hand side
453 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_ADD_I : IOP_ADD_R );
454 lhs = Treewalk(node->GetLeftChild(), NULL, constant);
455 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
456 icode->AppendStatement(new IStatement(op, lhs, rhs, result));
457 return (dest != NULL) ? dest : result->Clone();
458 }
459 } else {
460 // can't push down constant
461 lhs = Treewalk(node->GetLeftChild());
462 }
463
464 // try to add the constant, if any, to any constant lhs or rhs
465 if (constant != NULL) {
466 if (IsConstant(lhs)) {
467 if (IsInt(lhs)) {
468 lhs->SetIntValue(lhs->GetIntValue() + constant->GetIntValue());
469 } else {
470 lhs->SetRealValue(lhs->GetRealValue() + constant->GetRealValue());
471 }
472 delete constant;
473 constant = NULL;
474 } else if (IsConstant(rhs)) {
475 if (IsInt(rhs)) {
476 rhs->SetIntValue(rhs->GetIntValue() + constant->GetIntValue());
477 } else {
478 rhs->SetRealValue(rhs->GetRealValue() + constant->GetRealValue());
479 }
480 delete constant;
481 constant = NULL;
482 }
483 }
484
485 // algebraic identity
486 if (IsZero(lhs)) {
487 delete lhs;
488 return rhs;
489 }
490 if (IsZero(rhs)) {
491 delete rhs;
492 return lhs;
493 }
494
495 // constant folding
496 if (IsConstant(lhs) && IsConstant(rhs)) {
497 IOperand *result = NULL;
498 if (IsInt(lhs)) {
499 result = new IOperand_Int(lhs->GetIntValue() + rhs->GetIntValue() + ((constant==NULL) ? 0 : constant->GetIntValue()));
500 } else {
501 result = new IOperand_Real(lhs->GetRealValue() + rhs->GetRealValue() + ((constant==NULL) ? 0 : constant->GetRealValue()));
502 }
503 delete lhs;
504 delete rhs;
505 return result;
506 }
507 } else {
508
509 // calculate operands for unoptimized case
510 lhs = Treewalk(node->GetLeftChild());
511 rhs = Treewalk(node->GetRightChild());
512 }
513
514 // generate add code
515 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
516 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_ADD_I : IOP_ADD_R );
517 if (constant == NULL) {
518 icode->AppendStatement(new IStatement(op, lhs, rhs, result));
519 } else {
520 IOperand *temp = new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
521 icode->AppendStatement(new IStatement(op, lhs, rhs, temp));
522 icode->AppendStatement(new IStatement(op, temp->Clone(), constant, result));
523 }
524 return (dest != NULL) ? dest : result->Clone();
525 }
526 break;
527 case NODE_SUB: // Substract
528 {
529 // calculate operands
530 IOperand *lhs = NULL;
531 IOperand *rhs = NULL;
532
533 // attempt optimizations
534 if (bOptimize1) {
535 /* reverse evaluation of operands, due to the fact the tree is always
536 * set to be on the left and we like to fold constants where ever
537 * possible
538 */
539 rhs = Treewalk(node->GetRightChild());
540 // check if we need to push any constant down the tree
541 if (node->GetLeftChild()->GetNodeType() == NODE_ADD ||
542 node->GetLeftChild()->GetNodeType() == NODE_SUB ) {
543 if (IsConstant(rhs)) {
544 // right hand side is also constant
545 if (constant != NULL) {
546 if (IsInt(rhs)) {
547 rhs->SetIntValue((rhs->GetIntValue() * -1) + constant->GetIntValue());
548 } else {
549 rhs->SetRealValue((rhs->GetRealValue() * -1) + constant->GetRealValue());
550 }
551 } else {
552 /* Negate fresh new minus knob, if it is gonna be the first constant */
553 if (IsInt(rhs)) {
554 rhs->SetIntValue(rhs->GetIntValue() * -1);
555 } else {
556 rhs->SetRealValue(rhs->GetRealValue() * -1);
557 }
558 }
559
560 // evaluate left hand side passing constant value
561 lhs = Treewalk(node->GetLeftChild(), dest, rhs);
562 return lhs;
563 } else {
564 // generate add instruction for the right hand side
565 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_SUB_I : IOP_SUB_R );
566 lhs = Treewalk(node->GetLeftChild(), NULL, constant);
567 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
568 icode->AppendStatement(new IStatement(op, lhs, rhs, result));
569 return (dest != NULL) ? dest : result->Clone();
570 }
571 } else {
572 // can't push down constant
573 lhs = Treewalk(node->GetLeftChild());
574 }
575
576 // try to sub the constant, if any, to any constant lhs or rhs
577 if (constant != NULL) {
578 if (IsConstant(lhs)) {
579 if (IsInt(lhs)) {
580 lhs->SetIntValue(lhs->GetIntValue() + constant->GetIntValue());
581 } else {
582 lhs->SetRealValue(lhs->GetRealValue() + constant->GetRealValue());
583 }
584 delete constant;
585 constant = NULL;
586 } else if (IsConstant(rhs)) {
587 /* Negate right side as it is going to be negative constant value */
588 if (IsInt(rhs)) {
589 rhs->SetIntValue((rhs->GetIntValue() * -1) + constant->GetIntValue());
590 } else {
591 rhs->SetRealValue((rhs->GetRealValue() * -1) + constant->GetRealValue());
592 }
593 delete constant;
594 constant = NULL;
595 }
596 }
597
598 // algebraic identity right side
599 if (IsZero(rhs)) {
600 delete rhs;
601 return lhs;
602 }
603
604 // constant folding
605 if (IsConstant(lhs) && IsConstant(rhs)) {
606 IOperand *result = NULL;
607 if (IsInt(lhs)) {
608 result = new IOperand_Int(lhs->GetIntValue() - rhs->GetIntValue());
609 } else {
610 result = new IOperand_Real(lhs->GetRealValue() - rhs->GetRealValue());
611 }
612 delete lhs;
613 delete rhs;
614 return result;
615 }
616
617 // algebraic identity left side
618 if (IsZero(lhs)) {
619 delete lhs;
620
621 // generate unary minus code
622 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
623 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_UNARY_MINUS_I : IOP_UNARY_MINUS_R );
624 icode->AppendStatement(new IStatement(op, rhs, NULL, result));
625 return (dest != NULL) ? dest : result->Clone();
626 }
627 } else {
628
629 // calculate operands for unoptimized case
630 lhs = Treewalk(node->GetLeftChild());
631 rhs = Treewalk(node->GetRightChild());
632 }
633
634 // generate subtraction code
635 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
636 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_SUB_I : IOP_SUB_R );
637 if (constant == NULL) {
638 icode->AppendStatement(new IStatement(op, lhs, rhs, result));
639 } else {
640 IOperand *temp = new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
641 icode->AppendStatement(new IStatement(op, lhs, rhs, temp));
642 /* Constant could be negative, so always all value */
643 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_ADD_I : IOP_ADD_R );
644 icode->AppendStatement(new IStatement(op, temp->Clone(), constant, result));
645 }
646
647 return (dest != NULL) ? dest : result->Clone();
648 }
649 break;
650 case NODE_OR: // Bitwise OR operation
651 {
652 // calculate operands
653 IOperand *lhs = Treewalk(node->GetLeftChild());
654 IOperand *rhs = Treewalk(node->GetRightChild());
655
656 // attempt optimizations
657 if (bOptimize1) {
658 // 0 or X will always evaluate to X
659 if (IsZero(lhs)) {
660 delete lhs;
661 return rhs;
662 }
663
664 // X or 0 will always evaluate to X
665 if (IsZero(rhs)) {
666 delete rhs;
667 return lhs;
668 }
669
670 // constant folding
671 if (IsConstant(lhs) && IsConstant(rhs)) {
672 IOperand *result = new IOperand_Int(lhs->GetIntValue() | rhs->GetIntValue());
673 delete lhs;
674 delete rhs;
675 return result;
676 }
677 }
678
679 // generate bitwise or code
680 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(RT_INT));
681 icode->AppendStatement(new IStatement(IOP_OR, lhs, rhs, result));
682 return (dest != NULL) ? dest : result->Clone();
683 }
684 break;
685 case NODE_MUL: // Multiply
686 {
687 // calculate operands
688 IOperand *lhs = Treewalk(node->GetLeftChild());
689 IOperand *rhs = Treewalk(node->GetRightChild());
690
691 // attempt optimizations
692 if (bOptimize1) {
693 // zero product
694 if (IsZero(lhs) || IsZero(rhs)) {
695 delete lhs;
696 delete rhs;
697 return new IOperand_Int(0);
698 }
699
700 // algebraic identity
701 if (IsOne(lhs)) {
702 delete lhs;
703 return rhs;
704 }
705 if (IsOne(rhs)) {
706 delete rhs;
707 return lhs;
708 }
709
710 // constant folding
711 if (IsConstant(lhs) && IsConstant(rhs)) {
712 IOperand *result = NULL;
713 if (IsInt(lhs)) {
714 result = new IOperand_Int(lhs->GetIntValue() * rhs->GetIntValue());
715 } else {
716 result = new IOperand_Real(lhs->GetRealValue() * rhs->GetRealValue());
717 }
718 delete lhs;
719 delete rhs;
720 return result;
721 }
722 }
723
724 // generate multiply code
725 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
726 IOperator op = ( (node->GetReturnType() == RT_INT) ? IOP_MUL_I : IOP_MUL_R );
727 icode->AppendStatement(new IStatement(op, lhs, rhs, result));
728 return (dest != NULL) ? dest : result->Clone();
729 }
730 break;
731 case NODE_DIV: // Divide
732 {
733 // calculate operands
734 IOperand *lhs = Treewalk(node->GetLeftChild());
735 IOperand *rhs = Treewalk(node->GetRightChild());
736
737 // attempt optimizations
738 if (bOptimize1) {
739 // 0 / X will always evaluate to zero
740 if (IsZero(lhs)) {
741 delete lhs;
742 delete rhs;
743 return new IOperand_Real(0);
744 }
745
746 // X / 1 will always evuluate to X
747 if (IsOne(rhs)) {
748 delete rhs;
749 return lhs;
750 }
751
752 // XXX: How to act on X / 0, which should not be possible
753
754 // constant folding
755 if (IsConstant(lhs) && IsConstant(rhs)) {
756 IOperand *result = NULL;
757 result = new IOperand_Real(lhs->GetRealValue() / rhs->GetRealValue());
758 delete lhs;
759 delete rhs;
760 return result;
761 }
762 }
763
764 // generate division code
765 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
766 icode->AppendStatement(new IStatement(IOP_DIV_R, lhs, rhs, result));
767 return (dest != NULL) ? dest : result->Clone();
768 }
769 break;
770 case NODE_IDIV: // Integer division
771 {
772 // calculate operands
773 IOperand *lhs = Treewalk(node->GetLeftChild());
774 IOperand *rhs = Treewalk(node->GetRightChild());
775
776 // attempt optimizations
777 if (bOptimize1) {
778 // 0 / X will always evaluate to zero
779 if (IsZero(lhs)) {
780 delete lhs;
781 delete rhs;
782 return new IOperand_Int(0);
783 }
784
785 // X / 1 will always evuluate to X
786 if (IsOne(rhs)) {
787 delete rhs;
788 return lhs;
789 }
790
791 // XXX: How to act on X / 0, which should not be possible
792
793 // constant folding
794 if (IsConstant(lhs) && IsConstant(rhs)) {
795 IOperand *result = NULL;
796 result = new IOperand_Int(lhs->GetIntValue() / rhs->GetIntValue());
797 delete lhs;
798 delete rhs;
799 return result;
800 }
801 }
802
803 // generate division code
804 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
805 icode->AppendStatement(new IStatement(IOP_DIV_I, lhs, rhs, result));
806 return (dest != NULL) ? dest : result->Clone();
807 }
808 break;
809 case NODE_MOD: // Modulo
810 {
811 // calculate operands
812 IOperand *lhs = Treewalk (node->GetLeftChild ());
813 IOperand *rhs = Treewalk (node->GetRightChild ());
814
815 // attempt optimizations
816 if (bOptimize1) {
817 // 0 mod X will always evaluate to zero
818 if (IsZero (lhs)) {
819 delete lhs;
820 delete rhs;
821 return new IOperand_Int (0);
822 }
823
824 // X mod 1 will always evaluate to zero
825 if (IsOne (rhs)) {
826 delete lhs;
827 delete rhs;
828 return new IOperand_Int (0);
829 }
830 // X mod -1 will always evaluate to zero
831 if (IsMinusOne (rhs)) {
832 delete lhs;
833 delete rhs;
834 return new IOperand_Int (0);
835 }
836 }
837
838 // generate modulus code
839 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
840 icode->AppendStatement (new IStatement (IOP_MOD, lhs, rhs, result));
841 return (dest != NULL) ? dest : result->Clone();
842 }
843 break;
844 case NODE_AND: // Bitwise AND operation
845 {
846 // calculate operands
847 IOperand *lhs = Treewalk (node->GetLeftChild ());
848 IOperand *rhs = Treewalk (node->GetRightChild ());
849
850 // attempt optimizations
851 if (bOptimize1) {
852 // X and 0 will always evaluate to zero
853 if (IsZero (lhs) || IsZero (rhs)) {
854 delete lhs;
855 delete rhs;
856 return new IOperand_Int (0);
857 }
858 }
859
860 // generate bitwise and code
861 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
862 icode->AppendStatement (new IStatement (IOP_AND, lhs, rhs, result));
863 return (dest != NULL) ? dest : result->Clone();
864 }
865 break;
866
867 /*
868 * Leafs
869 * these nodes have no child nodes
870 */
871 case NODE_NUM_INT: // Integer number
872 {
873 /* return the integer value */
874 return new IOperand_Int(node->GetIntValue());
875 }
876 break;
877 case NODE_NUM_REAL: // Real number
878 {
879 /* return the real value */
880 return new IOperand_Real(node->GetRealValue());
881 }
882 break;
883 case NODE_ID: // Identifier
884 {
885 /* ID requires returning its symbol */
886 return new IOperand_Symbol(node->GetSymbol());
887 }
888 break;
889 case NODE_EMPTY: // Empty leaf (terminates lists etc.)
890 {
891 return (NULL);
892 }
893 break;
894
895 /*
896 * Unary nodes
897 * child The subtree to which the operation has to be applied
898 */
899 case NODE_NOT: // NOT operation
900 {
901 IOperand *operand = ICGenerator::Treewalk (node->GetChild ());
902
903 // attempt optimizations
904 if (bOptimize1) {
905 // constant folding
906 if (IsConstant(operand)) {
907 IOperand *result = new IOperand_Int(~operand->GetIntValue());
908 delete operand;
909 return result;
910 }
911 }
912
913 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(node->GetReturnType()));
914 icode->AppendStatement (new IStatement (IOP_NOT, operand, NULL, result));
915
916 return (dest != NULL) ? dest : result->Clone();
917 }
918 break;
919 case NODE_SIGNPLUS: // Unary plus
920 {
921 /* Unary plus does not require any work, direct pass trough */
922 IOperand *operand = ICGenerator::Treewalk (node->GetChild ());
923 return (operand);
924 }
925 break;
926 case NODE_SIGNMINUS: // Unary minus
927 {
928 IOperand *operand = ICGenerator::Treewalk (node->GetChild ());
929
930 // attempt optimizations
931 if (bOptimize1) {
932 // constant folding
933 if (IsConstant(operand)) {
934 IOperand *result = NULL;
935 if (IsInt(operand)) {
936 result = new IOperand_Int(-operand->GetIntValue());
937 } else {
938 result = new IOperand_Real(-operand->GetRealValue());
939 }
940 delete operand;
941 return result;
942 }
943 }
944
945 ReturnType type = node->GetReturnType();
946 IOperator op = ( (type == RT_REAL) ? IOP_UNARY_MINUS_R : IOP_UNARY_MINUS_I );
947 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(type));
948 icode->AppendStatement (new IStatement (op, operand, NULL, result));
949 return (dest != NULL) ? dest : result->Clone();
950 }
951 break;
952 case NODE_COERCION: // Int to Real coercion
953 {
954 IOperand *operand = ICGenerator::Treewalk (node->GetChild ());
955
956 // attempt optimizations
957 if (bOptimize1) {
958 // constant folding
959 if (IsConstant(operand)) {
960 IOperand *result = new IOperand_Real(operand->GetIntValue());
961 delete operand;
962 return result;
963 }
964 }
965
966 IOperand *result = (dest != NULL) ? dest : new IOperand_Symbol(GenerateTempVar(RT_REAL));
967 icode->AppendStatement (new IStatement (IOP_INT_TO_REAL, operand, NULL, result));
968 return (dest != NULL) ? dest : result->Clone();
969 }
970 break;
971 default:
972 assert (0); // can't happen
973
974 }
975 return NULL; // silences warning
976}
977
978IOperand * ICGenerator::GenerateRelopCode(IOperator op, Node *node)
979{
980 // generate labels
981 Symbol *true_label = GenerateLabel();
982
983 // get operands
984 IOperand *lhs = Treewalk(node->GetLeftChild());
985 IOperand *rhs = Treewalk(node->GetRightChild());
986
987 // attempt optimizations
988 if (bOptimize1) {
989 // constant folding
990 if (IsConstant(lhs) && IsConstant(rhs)) {
991 int value;
992 switch (op) {
993 case IOP_BEQ_I: value = lhs->GetIntValue() == rhs->GetIntValue(); break;
994 case IOP_BLT_I: value = lhs->GetIntValue() < rhs->GetIntValue(); break;
995 case IOP_BGT_I: value = lhs->GetIntValue() > rhs->GetIntValue(); break;
996 case IOP_BLE_I: value = lhs->GetIntValue() <= rhs->GetIntValue(); break;
997 case IOP_BGE_I: value = lhs->GetIntValue() >= rhs->GetIntValue(); break;
998 case IOP_BNE_I: value = lhs->GetIntValue() != rhs->GetIntValue(); break;
999 case IOP_BEQ_R: value = lhs->GetRealValue() == rhs->GetRealValue(); break;
1000 case IOP_BLT_R: value = lhs->GetRealValue() < rhs->GetRealValue(); break;
1001 case IOP_BGT_R: value = lhs->GetRealValue() > rhs->GetRealValue(); break;
1002 case IOP_BLE_R: value = lhs->GetRealValue() <= rhs->GetRealValue(); break;
1003 case IOP_BGE_R: value = lhs->GetRealValue() >= rhs->GetRealValue(); break;
1004 case IOP_BNE_R: value = lhs->GetRealValue() != rhs->GetRealValue(); break;
1005 default:
1006 assert(0); // can't happen
1007 }
1008 IOperand *result = new IOperand_Int(value);
1009 delete lhs;
1010 delete rhs;
1011 return result;
1012 }
1013 }
1014
1015 /* generate code */
1016 /* Methode 1 | Methode 2
1017 * -------------------------------------
1018 * b = 0 goto TRUE | ret = 1
1019 * ret = 0 | b = 0 GOTO TRUE
1020 * goto END | ret = 0
1021 * :TRUE | :TRUE
1022 * ret = 1 |
1023 * :END |
1024 */
1025 /* Method 2 used */
1026 IOperand *result = new IOperand_Symbol(GenerateTempVar(RT_INT));
1027 icode->AppendStatement(new IStatement(IOP_ASSIGN_I, new IOperand_Int(1), NULL, result));
1028 icode->AppendStatement(new IStatement(op, lhs, rhs, new IOperand_Symbol(true_label)));
1029 icode->AppendStatement(new IStatement(IOP_ASSIGN_I, new IOperand_Int(0), NULL, result->Clone()));
1030 icode->AppendStatement(new IStatement(IOP_LABEL, new IOperand_Symbol(true_label), NULL, NULL));
1031 return result->Clone();
1032}
1033
1034bool ICGenerator::IsZero(IOperand *operand) const
1035{
1036 return (IsInt(operand) && operand->GetIntValue() == 0) ||
1037 (IsReal(operand) && operand->GetRealValue() == 0.0);
1038}
1039
1040bool ICGenerator::IsOne(IOperand *operand) const
1041{
1042 return (IsInt(operand) && operand->GetIntValue() == 1) ||
1043 (IsReal(operand) && operand->GetRealValue() == 1.0);
1044}
1045
1046bool ICGenerator::IsMinusOne(IOperand *operand) const
1047{
1048 return (IsInt(operand) && operand->GetIntValue() == -1) ||
1049 (IsReal(operand) && operand->GetRealValue() == -1.0);
1050}
1051
1052bool ICGenerator::IsConstant(IOperand *operand) const
1053{
1054 return IsInt(operand) || IsReal(operand);
1055}
1056
1057bool ICGenerator::IsInt(IOperand *operand) const
1058{
1059 return operand->GetOperandType() == OT_INT;
1060}
1061
1062bool ICGenerator::IsReal(IOperand *operand) const
1063{
1064 return operand->GetOperandType() == OT_REAL;
1065}
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