1 //
2 // Copyright 2016 The ANGLE Project Authors. All rights reserved.
3 // Use of this source code is governed by a BSD-style license that can be
4 // found in the LICENSE file.
5 //
6 // ConstantUnion: Constant folding helper class.
7
8 #include "compiler/translator/ConstantUnion.h"
9
10 #include "common/mathutil.h"
11 #include "compiler/translator/Diagnostics.h"
12 #include "compiler/translator/util.h"
13
14 namespace sh
15 {
16
17 namespace
18 {
19
CheckedSum(float lhs,float rhs,TDiagnostics * diag,const TSourceLoc & line)20 float CheckedSum(float lhs, float rhs, TDiagnostics *diag, const TSourceLoc &line)
21 {
22 float result = lhs + rhs;
23 if (gl::isNaN(result) && !gl::isNaN(lhs) && !gl::isNaN(rhs))
24 {
25 diag->warning(line, "Constant folded undefined addition generated NaN", "+");
26 }
27 else if (gl::isInf(result) && !gl::isInf(lhs) && !gl::isInf(rhs))
28 {
29 diag->warning(line, "Constant folded addition overflowed to infinity", "+");
30 }
31 return result;
32 }
33
CheckedDiff(float lhs,float rhs,TDiagnostics * diag,const TSourceLoc & line)34 float CheckedDiff(float lhs, float rhs, TDiagnostics *diag, const TSourceLoc &line)
35 {
36 float result = lhs - rhs;
37 if (gl::isNaN(result) && !gl::isNaN(lhs) && !gl::isNaN(rhs))
38 {
39 diag->warning(line, "Constant folded undefined subtraction generated NaN", "-");
40 }
41 else if (gl::isInf(result) && !gl::isInf(lhs) && !gl::isInf(rhs))
42 {
43 diag->warning(line, "Constant folded subtraction overflowed to infinity", "-");
44 }
45 return result;
46 }
47
CheckedMul(float lhs,float rhs,TDiagnostics * diag,const TSourceLoc & line)48 float CheckedMul(float lhs, float rhs, TDiagnostics *diag, const TSourceLoc &line)
49 {
50 float result = lhs * rhs;
51 if (gl::isNaN(result) && !gl::isNaN(lhs) && !gl::isNaN(rhs))
52 {
53 diag->warning(line, "Constant folded undefined multiplication generated NaN", "*");
54 }
55 else if (gl::isInf(result) && !gl::isInf(lhs) && !gl::isInf(rhs))
56 {
57 diag->warning(line, "Constant folded multiplication overflowed to infinity", "*");
58 }
59 return result;
60 }
61
IsValidShiftOffset(const TConstantUnion & rhs)62 bool IsValidShiftOffset(const TConstantUnion &rhs)
63 {
64 return (rhs.getType() == EbtInt && (rhs.getIConst() >= 0 && rhs.getIConst() <= 31)) ||
65 (rhs.getType() == EbtUInt && rhs.getUConst() <= 31u);
66 }
67
68 } // anonymous namespace
69
TConstantUnion()70 TConstantUnion::TConstantUnion() : iConst(0), type(EbtVoid) {}
71
TConstantUnion(int i)72 TConstantUnion::TConstantUnion(int i) : iConst(i), type(EbtInt) {}
73
TConstantUnion(unsigned int u)74 TConstantUnion::TConstantUnion(unsigned int u) : uConst(u), type(EbtUInt) {}
75
TConstantUnion(float f)76 TConstantUnion::TConstantUnion(float f) : fConst(f), type(EbtFloat) {}
77
TConstantUnion(bool b)78 TConstantUnion::TConstantUnion(bool b) : bConst(b), type(EbtBool) {}
79
getIConst() const80 int TConstantUnion::getIConst() const
81 {
82 ASSERT(type == EbtInt);
83 return iConst;
84 }
85
getUConst() const86 unsigned int TConstantUnion::getUConst() const
87 {
88 ASSERT(type == EbtUInt);
89 return uConst;
90 }
91
getFConst() const92 float TConstantUnion::getFConst() const
93 {
94 switch (type)
95 {
96 case EbtInt:
97 return static_cast<float>(iConst);
98 case EbtUInt:
99 return static_cast<float>(uConst);
100 default:
101 ASSERT(type == EbtFloat);
102 return fConst;
103 }
104 }
105
getBConst() const106 bool TConstantUnion::getBConst() const
107 {
108 ASSERT(type == EbtBool);
109 return bConst;
110 }
111
isZero() const112 bool TConstantUnion::isZero() const
113 {
114 switch (type)
115 {
116 case EbtInt:
117 return getIConst() == 0;
118 case EbtUInt:
119 return getUConst() == 0;
120 case EbtFloat:
121 return getFConst() == 0.0f;
122 case EbtBool:
123 return getBConst() == false;
124 default:
125 return false;
126 }
127 }
128
getYuvCscStandardEXTConst() const129 TYuvCscStandardEXT TConstantUnion::getYuvCscStandardEXTConst() const
130 {
131 ASSERT(type == EbtYuvCscStandardEXT);
132 return yuvCscStandardEXTConst;
133 }
134
cast(TBasicType newType,const TConstantUnion & constant)135 bool TConstantUnion::cast(TBasicType newType, const TConstantUnion &constant)
136 {
137 switch (newType)
138 {
139 case EbtFloat:
140 switch (constant.type)
141 {
142 case EbtInt:
143 setFConst(static_cast<float>(constant.getIConst()));
144 break;
145 case EbtUInt:
146 setFConst(static_cast<float>(constant.getUConst()));
147 break;
148 case EbtBool:
149 setFConst(static_cast<float>(constant.getBConst()));
150 break;
151 case EbtFloat:
152 setFConst(static_cast<float>(constant.getFConst()));
153 break;
154 default:
155 return false;
156 }
157 break;
158 case EbtInt:
159 switch (constant.type)
160 {
161 case EbtInt:
162 setIConst(static_cast<int>(constant.getIConst()));
163 break;
164 case EbtUInt:
165 setIConst(static_cast<int>(constant.getUConst()));
166 break;
167 case EbtBool:
168 setIConst(static_cast<int>(constant.getBConst()));
169 break;
170 case EbtFloat:
171 setIConst(static_cast<int>(constant.getFConst()));
172 break;
173 default:
174 return false;
175 }
176 break;
177 case EbtUInt:
178 switch (constant.type)
179 {
180 case EbtInt:
181 setUConst(static_cast<unsigned int>(constant.getIConst()));
182 break;
183 case EbtUInt:
184 setUConst(static_cast<unsigned int>(constant.getUConst()));
185 break;
186 case EbtBool:
187 setUConst(static_cast<unsigned int>(constant.getBConst()));
188 break;
189 case EbtFloat:
190 if (constant.getFConst() < 0.0f)
191 {
192 // Avoid undefined behavior in C++ by first casting to signed int.
193 setUConst(
194 static_cast<unsigned int>(static_cast<int>(constant.getFConst())));
195 }
196 else
197 {
198 setUConst(static_cast<unsigned int>(constant.getFConst()));
199 }
200 break;
201 default:
202 return false;
203 }
204 break;
205 case EbtBool:
206 switch (constant.type)
207 {
208 case EbtInt:
209 setBConst(constant.getIConst() != 0);
210 break;
211 case EbtUInt:
212 setBConst(constant.getUConst() != 0);
213 break;
214 case EbtBool:
215 setBConst(constant.getBConst());
216 break;
217 case EbtFloat:
218 setBConst(constant.getFConst() != 0.0f);
219 break;
220 default:
221 return false;
222 }
223 break;
224 case EbtStruct: // Struct fields don't get cast
225 switch (constant.type)
226 {
227 case EbtInt:
228 setIConst(constant.getIConst());
229 break;
230 case EbtUInt:
231 setUConst(constant.getUConst());
232 break;
233 case EbtBool:
234 setBConst(constant.getBConst());
235 break;
236 case EbtFloat:
237 setFConst(constant.getFConst());
238 break;
239 default:
240 return false;
241 }
242 break;
243 case EbtYuvCscStandardEXT:
244 switch (constant.type)
245 {
246 case EbtYuvCscStandardEXT:
247 setYuvCscStandardEXTConst(constant.getYuvCscStandardEXTConst());
248 break;
249 default:
250 return false;
251 }
252 break;
253 default:
254 return false;
255 }
256
257 return true;
258 }
259
operator ==(const int i) const260 bool TConstantUnion::operator==(const int i) const
261 {
262 switch (type)
263 {
264 case EbtFloat:
265 return static_cast<float>(i) == fConst;
266 default:
267 return i == iConst;
268 }
269 }
270
operator ==(const unsigned int u) const271 bool TConstantUnion::operator==(const unsigned int u) const
272 {
273 switch (type)
274 {
275 case EbtFloat:
276 return static_cast<float>(u) == fConst;
277 default:
278 return u == uConst;
279 }
280 }
281
operator ==(const float f) const282 bool TConstantUnion::operator==(const float f) const
283 {
284 switch (type)
285 {
286 case EbtInt:
287 return f == static_cast<float>(iConst);
288 case EbtUInt:
289 return f == static_cast<float>(uConst);
290 default:
291 return f == fConst;
292 }
293 }
294
operator ==(const bool b) const295 bool TConstantUnion::operator==(const bool b) const
296 {
297 return b == bConst;
298 }
299
operator ==(const TYuvCscStandardEXT s) const300 bool TConstantUnion::operator==(const TYuvCscStandardEXT s) const
301 {
302 return s == yuvCscStandardEXTConst;
303 }
304
operator ==(const TConstantUnion & constant) const305 bool TConstantUnion::operator==(const TConstantUnion &constant) const
306 {
307 switch (type)
308 {
309 case EbtInt:
310 return constant.iConst == iConst;
311 case EbtUInt:
312 return constant.uConst == uConst;
313 case EbtFloat:
314 return constant.fConst == fConst;
315 case EbtBool:
316 return constant.bConst == bConst;
317 case EbtYuvCscStandardEXT:
318 return constant.yuvCscStandardEXTConst == yuvCscStandardEXTConst;
319 default:
320 return false;
321 }
322 }
323
operator !=(const int i) const324 bool TConstantUnion::operator!=(const int i) const
325 {
326 return !operator==(i);
327 }
328
operator !=(const unsigned int u) const329 bool TConstantUnion::operator!=(const unsigned int u) const
330 {
331 return !operator==(u);
332 }
333
operator !=(const float f) const334 bool TConstantUnion::operator!=(const float f) const
335 {
336 return !operator==(f);
337 }
338
operator !=(const bool b) const339 bool TConstantUnion::operator!=(const bool b) const
340 {
341 return !operator==(b);
342 }
343
operator !=(const TYuvCscStandardEXT s) const344 bool TConstantUnion::operator!=(const TYuvCscStandardEXT s) const
345 {
346 return !operator==(s);
347 }
348
operator !=(const TConstantUnion & constant) const349 bool TConstantUnion::operator!=(const TConstantUnion &constant) const
350 {
351 return !operator==(constant);
352 }
353
operator >(const TConstantUnion & constant) const354 bool TConstantUnion::operator>(const TConstantUnion &constant) const
355 {
356
357 switch (type)
358 {
359 case EbtInt:
360 return iConst > constant.iConst;
361 case EbtUInt:
362 return uConst > constant.uConst;
363 case EbtFloat:
364 return fConst > constant.fConst;
365 default:
366 return false; // Invalid operation, handled at semantic analysis
367 }
368 }
369
operator <(const TConstantUnion & constant) const370 bool TConstantUnion::operator<(const TConstantUnion &constant) const
371 {
372 switch (type)
373 {
374 case EbtInt:
375 return iConst < constant.iConst;
376 case EbtUInt:
377 return uConst < constant.uConst;
378 case EbtFloat:
379 return fConst < constant.fConst;
380 default:
381 return false; // Invalid operation, handled at semantic analysis
382 }
383 }
384
385 // static
add(const TConstantUnion & lhs,const TConstantUnion & rhs,TDiagnostics * diag,const TSourceLoc & line)386 TConstantUnion TConstantUnion::add(const TConstantUnion &lhs,
387 const TConstantUnion &rhs,
388 TDiagnostics *diag,
389 const TSourceLoc &line)
390 {
391 TConstantUnion returnValue;
392
393 switch (lhs.type)
394 {
395 case EbtInt:
396 returnValue.setIConst(gl::WrappingSum<int>(lhs.iConst, rhs.iConst));
397 break;
398 case EbtUInt:
399 returnValue.setUConst(gl::WrappingSum<unsigned int>(lhs.uConst, rhs.uConst));
400 break;
401 case EbtFloat:
402 returnValue.setFConst(CheckedSum(lhs.fConst, rhs.fConst, diag, line));
403 break;
404 default:
405 UNREACHABLE();
406 }
407
408 return returnValue;
409 }
410
411 // static
sub(const TConstantUnion & lhs,const TConstantUnion & rhs,TDiagnostics * diag,const TSourceLoc & line)412 TConstantUnion TConstantUnion::sub(const TConstantUnion &lhs,
413 const TConstantUnion &rhs,
414 TDiagnostics *diag,
415 const TSourceLoc &line)
416 {
417 TConstantUnion returnValue;
418
419 switch (lhs.type)
420 {
421 case EbtInt:
422 returnValue.setIConst(gl::WrappingDiff<int>(lhs.iConst, rhs.iConst));
423 break;
424 case EbtUInt:
425 returnValue.setUConst(gl::WrappingDiff<unsigned int>(lhs.uConst, rhs.uConst));
426 break;
427 case EbtFloat:
428 returnValue.setFConst(CheckedDiff(lhs.fConst, rhs.fConst, diag, line));
429 break;
430 default:
431 UNREACHABLE();
432 }
433
434 return returnValue;
435 }
436
437 // static
mul(const TConstantUnion & lhs,const TConstantUnion & rhs,TDiagnostics * diag,const TSourceLoc & line)438 TConstantUnion TConstantUnion::mul(const TConstantUnion &lhs,
439 const TConstantUnion &rhs,
440 TDiagnostics *diag,
441 const TSourceLoc &line)
442 {
443 TConstantUnion returnValue;
444
445 switch (lhs.type)
446 {
447 case EbtInt:
448 returnValue.setIConst(gl::WrappingMul(lhs.iConst, rhs.iConst));
449 break;
450 case EbtUInt:
451 // Unsigned integer math in C++ is defined to be done in modulo 2^n, so we rely
452 // on that to implement wrapping multiplication.
453 returnValue.setUConst(lhs.uConst * rhs.uConst);
454 break;
455 case EbtFloat:
456 returnValue.setFConst(CheckedMul(lhs.fConst, rhs.fConst, diag, line));
457 break;
458 default:
459 UNREACHABLE();
460 }
461
462 return returnValue;
463 }
464
operator %(const TConstantUnion & constant) const465 TConstantUnion TConstantUnion::operator%(const TConstantUnion &constant) const
466 {
467 TConstantUnion returnValue;
468 ASSERT(type == constant.type);
469 switch (type)
470 {
471 case EbtInt:
472 returnValue.setIConst(iConst % constant.iConst);
473 break;
474 case EbtUInt:
475 returnValue.setUConst(uConst % constant.uConst);
476 break;
477 default:
478 UNREACHABLE();
479 }
480
481 return returnValue;
482 }
483
484 // static
rshift(const TConstantUnion & lhs,const TConstantUnion & rhs,TDiagnostics * diag,const TSourceLoc & line)485 TConstantUnion TConstantUnion::rshift(const TConstantUnion &lhs,
486 const TConstantUnion &rhs,
487 TDiagnostics *diag,
488 const TSourceLoc &line)
489 {
490 TConstantUnion returnValue;
491 ASSERT(lhs.type == EbtInt || lhs.type == EbtUInt);
492 ASSERT(rhs.type == EbtInt || rhs.type == EbtUInt);
493 if (!IsValidShiftOffset(rhs))
494 {
495 diag->warning(line, "Undefined shift (operand out of range)", ">>");
496 switch (lhs.type)
497 {
498 case EbtInt:
499 returnValue.setIConst(0);
500 break;
501 case EbtUInt:
502 returnValue.setUConst(0u);
503 break;
504 default:
505 UNREACHABLE();
506 }
507 return returnValue;
508 }
509
510 switch (lhs.type)
511 {
512 case EbtInt:
513 {
514 unsigned int shiftOffset = 0;
515 switch (rhs.type)
516 {
517 case EbtInt:
518 shiftOffset = static_cast<unsigned int>(rhs.iConst);
519 break;
520 case EbtUInt:
521 shiftOffset = rhs.uConst;
522 break;
523 default:
524 UNREACHABLE();
525 }
526 if (shiftOffset > 0)
527 {
528 // ESSL 3.00.6 section 5.9: "If E1 is a signed integer, the right-shift will extend
529 // the sign bit." In C++ shifting negative integers is undefined, so we implement
530 // extending the sign bit manually.
531 int lhsSafe = lhs.iConst;
532 if (lhsSafe == std::numeric_limits<int>::min())
533 {
534 // The min integer needs special treatment because only bit it has set is the
535 // sign bit, which we clear later to implement safe right shift of negative
536 // numbers.
537 lhsSafe = -0x40000000;
538 --shiftOffset;
539 }
540 if (shiftOffset > 0)
541 {
542 bool extendSignBit = false;
543 if (lhsSafe < 0)
544 {
545 extendSignBit = true;
546 // Clear the sign bit so that bitshift right is defined in C++.
547 lhsSafe &= 0x7fffffff;
548 ASSERT(lhsSafe > 0);
549 }
550 returnValue.setIConst(lhsSafe >> shiftOffset);
551
552 // Manually fill in the extended sign bit if necessary.
553 if (extendSignBit)
554 {
555 int extendedSignBit = static_cast<int>(0xffffffffu << (31 - shiftOffset));
556 returnValue.setIConst(returnValue.getIConst() | extendedSignBit);
557 }
558 }
559 else
560 {
561 returnValue.setIConst(lhsSafe);
562 }
563 }
564 else
565 {
566 returnValue.setIConst(lhs.iConst);
567 }
568 break;
569 }
570 case EbtUInt:
571 switch (rhs.type)
572 {
573 case EbtInt:
574 returnValue.setUConst(lhs.uConst >> rhs.iConst);
575 break;
576 case EbtUInt:
577 returnValue.setUConst(lhs.uConst >> rhs.uConst);
578 break;
579 default:
580 UNREACHABLE();
581 }
582 break;
583
584 default:
585 UNREACHABLE();
586 }
587 return returnValue;
588 }
589
590 // static
lshift(const TConstantUnion & lhs,const TConstantUnion & rhs,TDiagnostics * diag,const TSourceLoc & line)591 TConstantUnion TConstantUnion::lshift(const TConstantUnion &lhs,
592 const TConstantUnion &rhs,
593 TDiagnostics *diag,
594 const TSourceLoc &line)
595 {
596 TConstantUnion returnValue;
597 ASSERT(lhs.type == EbtInt || lhs.type == EbtUInt);
598 ASSERT(rhs.type == EbtInt || rhs.type == EbtUInt);
599 if (!IsValidShiftOffset(rhs))
600 {
601 diag->warning(line, "Undefined shift (operand out of range)", "<<");
602 switch (lhs.type)
603 {
604 case EbtInt:
605 returnValue.setIConst(0);
606 break;
607 case EbtUInt:
608 returnValue.setUConst(0u);
609 break;
610 default:
611 UNREACHABLE();
612 }
613 return returnValue;
614 }
615
616 switch (lhs.type)
617 {
618 case EbtInt:
619 switch (rhs.type)
620 {
621 // Cast to unsigned integer before shifting, since ESSL 3.00.6 section 5.9 says that
622 // lhs is "interpreted as a bit pattern". This also avoids the possibility of signed
623 // integer overflow or undefined shift of a negative integer.
624 case EbtInt:
625 returnValue.setIConst(
626 static_cast<int>(static_cast<uint32_t>(lhs.iConst) << rhs.iConst));
627 break;
628 case EbtUInt:
629 returnValue.setIConst(
630 static_cast<int>(static_cast<uint32_t>(lhs.iConst) << rhs.uConst));
631 break;
632 default:
633 UNREACHABLE();
634 }
635 break;
636
637 case EbtUInt:
638 switch (rhs.type)
639 {
640 case EbtInt:
641 returnValue.setUConst(lhs.uConst << rhs.iConst);
642 break;
643 case EbtUInt:
644 returnValue.setUConst(lhs.uConst << rhs.uConst);
645 break;
646 default:
647 UNREACHABLE();
648 }
649 break;
650
651 default:
652 UNREACHABLE();
653 }
654 return returnValue;
655 }
656
operator &(const TConstantUnion & constant) const657 TConstantUnion TConstantUnion::operator&(const TConstantUnion &constant) const
658 {
659 TConstantUnion returnValue;
660 ASSERT(constant.type == EbtInt || constant.type == EbtUInt);
661 switch (type)
662 {
663 case EbtInt:
664 returnValue.setIConst(iConst & constant.iConst);
665 break;
666 case EbtUInt:
667 returnValue.setUConst(uConst & constant.uConst);
668 break;
669 default:
670 UNREACHABLE();
671 }
672
673 return returnValue;
674 }
675
operator |(const TConstantUnion & constant) const676 TConstantUnion TConstantUnion::operator|(const TConstantUnion &constant) const
677 {
678 TConstantUnion returnValue;
679 ASSERT(type == constant.type);
680 switch (type)
681 {
682 case EbtInt:
683 returnValue.setIConst(iConst | constant.iConst);
684 break;
685 case EbtUInt:
686 returnValue.setUConst(uConst | constant.uConst);
687 break;
688 default:
689 UNREACHABLE();
690 }
691
692 return returnValue;
693 }
694
operator ^(const TConstantUnion & constant) const695 TConstantUnion TConstantUnion::operator^(const TConstantUnion &constant) const
696 {
697 TConstantUnion returnValue;
698 ASSERT(type == constant.type);
699 switch (type)
700 {
701 case EbtInt:
702 returnValue.setIConst(iConst ^ constant.iConst);
703 break;
704 case EbtUInt:
705 returnValue.setUConst(uConst ^ constant.uConst);
706 break;
707 default:
708 UNREACHABLE();
709 }
710
711 return returnValue;
712 }
713
operator &&(const TConstantUnion & constant) const714 TConstantUnion TConstantUnion::operator&&(const TConstantUnion &constant) const
715 {
716 TConstantUnion returnValue;
717 ASSERT(type == constant.type);
718 switch (type)
719 {
720 case EbtBool:
721 returnValue.setBConst(bConst && constant.bConst);
722 break;
723 default:
724 UNREACHABLE();
725 }
726
727 return returnValue;
728 }
729
operator ||(const TConstantUnion & constant) const730 TConstantUnion TConstantUnion::operator||(const TConstantUnion &constant) const
731 {
732 TConstantUnion returnValue;
733 ASSERT(type == constant.type);
734 switch (type)
735 {
736 case EbtBool:
737 returnValue.setBConst(bConst || constant.bConst);
738 break;
739 default:
740 UNREACHABLE();
741 }
742
743 return returnValue;
744 }
745
746 } // namespace sh
747