1 //===-- ConstantRange.cpp - ConstantRange implementation ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Represent a range of possible values that may occur when the program is run
11 // for an integral value. This keeps track of a lower and upper bound for the
12 // constant, which MAY wrap around the end of the numeric range. To do this, it
13 // keeps track of a [lower, upper) bound, which specifies an interval just like
14 // STL iterators. When used with boolean values, the following are important
15 // ranges (other integral ranges use min/max values for special range values):
17 // [F, F) = {} = Empty set
20 // [T, T) = {F, T} = Full set
22 //===----------------------------------------------------------------------===//
24 #include "llvm/Constants.h"
25 #include "llvm/Support/ConstantRange.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include "llvm/Instructions.h"
31 /// Initialize a full (the default) or empty set for the specified type.
33 ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) {
35 Lower = Upper = APInt::getMaxValue(BitWidth);
37 Lower = Upper = APInt::getMinValue(BitWidth);
40 /// Initialize a range to hold the single specified value.
42 ConstantRange::ConstantRange(const APInt & V) : Lower(V), Upper(V + 1) {}
44 ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
46 assert(L.getBitWidth() == U.getBitWidth() &&
47 "ConstantRange with unequal bit widths");
48 assert((L != U || (L.isMaxValue() || L.isMinValue())) &&
49 "Lower == Upper, but they aren't min or max value!");
52 ConstantRange ConstantRange::makeICmpRegion(unsigned Pred,
53 const ConstantRange &CR) {
54 uint32_t W = CR.getBitWidth();
56 default: assert(!"Invalid ICmp predicate to makeICmpRegion()");
57 case ICmpInst::ICMP_EQ:
59 case ICmpInst::ICMP_NE:
60 if (CR.isSingleElement())
61 return ConstantRange(CR.getUpper(), CR.getLower());
62 return ConstantRange(W);
63 case ICmpInst::ICMP_ULT:
64 return ConstantRange(APInt::getMinValue(W), CR.getUnsignedMax());
65 case ICmpInst::ICMP_SLT:
66 return ConstantRange(APInt::getSignedMinValue(W), CR.getSignedMax());
67 case ICmpInst::ICMP_ULE: {
68 APInt UMax(CR.getUnsignedMax());
69 if (UMax.isMaxValue())
70 return ConstantRange(W);
71 return ConstantRange(APInt::getMinValue(W), UMax + 1);
73 case ICmpInst::ICMP_SLE: {
74 APInt SMax(CR.getSignedMax());
75 if (SMax.isMaxSignedValue() || (SMax+1).isMaxSignedValue())
76 return ConstantRange(W);
77 return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
79 case ICmpInst::ICMP_UGT:
80 return ConstantRange(CR.getUnsignedMin() + 1, APInt::getNullValue(W));
81 case ICmpInst::ICMP_SGT:
82 return ConstantRange(CR.getSignedMin() + 1,
83 APInt::getSignedMinValue(W));
84 case ICmpInst::ICMP_UGE: {
85 APInt UMin(CR.getUnsignedMin());
86 if (UMin.isMinValue())
87 return ConstantRange(W);
88 return ConstantRange(UMin, APInt::getNullValue(W));
90 case ICmpInst::ICMP_SGE: {
91 APInt SMin(CR.getSignedMin());
92 if (SMin.isMinSignedValue())
93 return ConstantRange(W);
94 return ConstantRange(SMin, APInt::getSignedMinValue(W));
99 /// isFullSet - Return true if this set contains all of the elements possible
100 /// for this data-type
101 bool ConstantRange::isFullSet() const {
102 return Lower == Upper && Lower.isMaxValue();
105 /// isEmptySet - Return true if this set contains no members.
107 bool ConstantRange::isEmptySet() const {
108 return Lower == Upper && Lower.isMinValue();
111 /// isWrappedSet - Return true if this set wraps around the top of the range,
112 /// for example: [100, 8)
114 bool ConstantRange::isWrappedSet() const {
115 return Lower.ugt(Upper);
118 /// getSetSize - Return the number of elements in this set.
120 APInt ConstantRange::getSetSize() const {
122 return APInt(getBitWidth(), 0);
123 if (getBitWidth() == 1) {
124 if (Lower != Upper) // One of T or F in the set...
126 return APInt(2, 2); // Must be full set...
129 // Simply subtract the bounds...
130 return Upper - Lower;
133 /// getUnsignedMax - Return the largest unsigned value contained in the
136 APInt ConstantRange::getUnsignedMax() const {
137 if (isFullSet() || isWrappedSet())
138 return APInt::getMaxValue(getBitWidth());
140 return getUpper() - 1;
143 /// getUnsignedMin - Return the smallest unsigned value contained in the
146 APInt ConstantRange::getUnsignedMin() const {
147 if (isFullSet() || (isWrappedSet() && getUpper() != 0))
148 return APInt::getMinValue(getBitWidth());
153 /// getSignedMax - Return the largest signed value contained in the
156 APInt ConstantRange::getSignedMax() const {
157 APInt SignedMax(APInt::getSignedMaxValue(getBitWidth()));
158 if (!isWrappedSet()) {
159 if (getLower().sle(getUpper() - 1))
160 return getUpper() - 1;
164 if (getLower().isNegative() == getUpper().isNegative())
167 return getUpper() - 1;
171 /// getSignedMin - Return the smallest signed value contained in the
174 APInt ConstantRange::getSignedMin() const {
175 APInt SignedMin(APInt::getSignedMinValue(getBitWidth()));
176 if (!isWrappedSet()) {
177 if (getLower().sle(getUpper() - 1))
182 if ((getUpper() - 1).slt(getLower())) {
183 if (getUpper() != SignedMin)
193 /// contains - Return true if the specified value is in the set.
195 bool ConstantRange::contains(const APInt &V) const {
200 return Lower.ule(V) && V.ult(Upper);
202 return Lower.ule(V) || V.ult(Upper);
205 /// contains - Return true if the argument is a subset of this range.
206 /// Two equal set contain each other. The empty set is considered to be
207 /// contained by all other sets.
209 bool ConstantRange::contains(const ConstantRange &Other) const {
210 if (isFullSet()) return true;
211 if (Other.isFullSet()) return false;
212 if (Other.isEmptySet()) return true;
213 if (isEmptySet()) return false;
215 if (!isWrappedSet()) {
216 if (Other.isWrappedSet())
219 return Lower.ule(Other.getLower()) && Other.getUpper().ule(Upper);
222 if (!Other.isWrappedSet())
223 return Other.getUpper().ule(Upper) ||
224 Lower.ule(Other.getLower());
226 return Other.getUpper().ule(Upper) && Lower.ule(Other.getLower());
229 /// subtract - Subtract the specified constant from the endpoints of this
231 ConstantRange ConstantRange::subtract(const APInt &Val) const {
232 assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
233 // If the set is empty or full, don't modify the endpoints.
236 return ConstantRange(Lower - Val, Upper - Val);
240 // intersect1Wrapped - This helper function is used to intersect two ranges when
241 // it is known that LHS is wrapped and RHS isn't.
244 ConstantRange::intersect1Wrapped(const ConstantRange &LHS,
245 const ConstantRange &RHS) {
246 assert(LHS.isWrappedSet() && !RHS.isWrappedSet());
248 // Check to see if we overlap on the Left side of RHS...
250 if (RHS.Lower.ult(LHS.Upper)) {
251 // We do overlap on the left side of RHS, see if we overlap on the right of
253 if (RHS.Upper.ugt(LHS.Lower)) {
254 // Ok, the result overlaps on both the left and right sides. See if the
255 // resultant interval will be smaller if we wrap or not...
257 if (LHS.getSetSize().ult(RHS.getSetSize()))
263 // No overlap on the right, just on the left.
264 return ConstantRange(RHS.Lower, LHS.Upper);
267 // We don't overlap on the left side of RHS, see if we overlap on the right
269 if (RHS.Upper.ugt(LHS.Lower)) {
271 return ConstantRange(LHS.Lower, RHS.Upper);
274 return ConstantRange(LHS.getBitWidth(), false);
279 /// intersectWith - Return the range that results from the intersection of this
280 /// range with another range. The resultant range is guaranteed to include all
281 /// elements contained in both input ranges, and to have the smallest possible
282 /// set size that does so. Because there may be two intersections with the
283 /// same set size, A.intersectWith(B) might not be equal to B.intersectWith(A).
284 ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
285 assert(getBitWidth() == CR.getBitWidth() &&
286 "ConstantRange types don't agree!");
288 // Handle common cases.
289 if ( isEmptySet() || CR.isFullSet()) return *this;
290 if (CR.isEmptySet() || isFullSet()) return CR;
292 if (!isWrappedSet() && CR.isWrappedSet())
293 return CR.intersectWith(*this);
295 if (!isWrappedSet() && !CR.isWrappedSet()) {
296 if (Lower.ult(CR.Lower)) {
297 if (Upper.ule(CR.Lower))
298 return ConstantRange(getBitWidth(), false);
300 if (Upper.ult(CR.Upper))
301 return ConstantRange(CR.Lower, Upper);
305 if (Upper.ult(CR.Upper))
308 if (Lower.ult(CR.Upper))
309 return ConstantRange(Lower, CR.Upper);
311 return ConstantRange(getBitWidth(), false);
315 if (isWrappedSet() && !CR.isWrappedSet()) {
316 if (CR.Lower.ult(Upper)) {
317 if (CR.Upper.ult(Upper))
320 if (CR.Upper.ult(Lower))
321 return ConstantRange(CR.Lower, Upper);
323 if (getSetSize().ult(CR.getSetSize()))
327 } else if (CR.Lower.ult(Lower)) {
328 if (CR.Upper.ule(Lower))
329 return ConstantRange(getBitWidth(), false);
331 return ConstantRange(Lower, CR.Upper);
336 if (CR.Upper.ult(Upper)) {
337 if (CR.Lower.ult(Upper)) {
338 if (getSetSize().ult(CR.getSetSize()))
344 if (CR.Lower.ult(Lower))
345 return ConstantRange(Lower, CR.Upper);
348 } else if (CR.Upper.ult(Lower)) {
349 if (CR.Lower.ult(Lower))
352 return ConstantRange(CR.Lower, Upper);
354 if (getSetSize().ult(CR.getSetSize()))
361 /// unionWith - Return the range that results from the union of this range with
362 /// another range. The resultant range is guaranteed to include the elements of
363 /// both sets, but may contain more. For example, [3, 9) union [12,15) is
364 /// [3, 15), which includes 9, 10, and 11, which were not included in either
367 ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
368 assert(getBitWidth() == CR.getBitWidth() &&
369 "ConstantRange types don't agree!");
371 if ( isFullSet() || CR.isEmptySet()) return *this;
372 if (CR.isFullSet() || isEmptySet()) return CR;
374 if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this);
376 if (!isWrappedSet() && !CR.isWrappedSet()) {
377 if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower)) {
378 // If the two ranges are disjoint, find the smaller gap and bridge it.
379 APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
381 return ConstantRange(Lower, CR.Upper);
383 return ConstantRange(CR.Lower, Upper);
386 APInt L = Lower, U = Upper;
389 if ((CR.Upper - 1).ugt(U - 1))
392 if (L == 0 && U == 0)
393 return ConstantRange(getBitWidth());
395 return ConstantRange(L, U);
398 if (!CR.isWrappedSet()) {
399 // ------U L----- and ------U L----- : this
401 if (CR.Upper.ule(Upper) || CR.Lower.uge(Lower))
404 // ------U L----- : this
406 if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper))
407 return ConstantRange(getBitWidth());
409 // ----U L---- : this
412 if (Upper.ule(CR.Lower) && CR.Upper.ule(Lower)) {
413 APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
415 return ConstantRange(Lower, CR.Upper);
417 return ConstantRange(CR.Lower, Upper);
420 // ----U L----- : this
422 if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper))
423 return ConstantRange(CR.Lower, Upper);
425 // ------U L---- : this
427 if (CR.Lower.ult(Upper) && CR.Upper.ult(Lower))
428 return ConstantRange(Lower, CR.Upper);
431 assert(isWrappedSet() && CR.isWrappedSet() &&
432 "ConstantRange::unionWith missed wrapped union unwrapped case");
434 // ------U L---- and ------U L---- : this
435 // -U L----------- and ------------U L : CR
436 if (CR.Lower.ule(Upper) || Lower.ule(CR.Upper))
437 return ConstantRange(getBitWidth());
439 APInt L = Lower, U = Upper;
445 return ConstantRange(L, U);
448 /// zeroExtend - Return a new range in the specified integer type, which must
449 /// be strictly larger than the current type. The returned range will
450 /// correspond to the possible range of values as if the source range had been
452 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
453 unsigned SrcTySize = getBitWidth();
454 assert(SrcTySize < DstTySize && "Not a value extension");
456 // Change a source full set into [0, 1 << 8*numbytes)
457 return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
459 APInt L = Lower; L.zext(DstTySize);
460 APInt U = Upper; U.zext(DstTySize);
461 return ConstantRange(L, U);
464 /// signExtend - Return a new range in the specified integer type, which must
465 /// be strictly larger than the current type. The returned range will
466 /// correspond to the possible range of values as if the source range had been
468 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
469 unsigned SrcTySize = getBitWidth();
470 assert(SrcTySize < DstTySize && "Not a value extension");
472 return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
473 APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
476 APInt L = Lower; L.sext(DstTySize);
477 APInt U = Upper; U.sext(DstTySize);
478 return ConstantRange(L, U);
481 /// truncate - Return a new range in the specified integer type, which must be
482 /// strictly smaller than the current type. The returned range will
483 /// correspond to the possible range of values as if the source range had been
484 /// truncated to the specified type.
485 ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
486 unsigned SrcTySize = getBitWidth();
487 assert(SrcTySize > DstTySize && "Not a value truncation");
488 APInt Size(APInt::getLowBitsSet(SrcTySize, DstTySize));
489 if (isFullSet() || getSetSize().ugt(Size))
490 return ConstantRange(DstTySize);
492 APInt L = Lower; L.trunc(DstTySize);
493 APInt U = Upper; U.trunc(DstTySize);
494 return ConstantRange(L, U);
497 /// zextOrTrunc - make this range have the bit width given by \p DstTySize. The
498 /// value is zero extended, truncated, or left alone to make it that width.
499 ConstantRange ConstantRange::zextOrTrunc(uint32_t DstTySize) const {
500 unsigned SrcTySize = getBitWidth();
501 if (SrcTySize > DstTySize)
502 return truncate(DstTySize);
503 else if (SrcTySize < DstTySize)
504 return zeroExtend(DstTySize);
509 /// sextOrTrunc - make this range have the bit width given by \p DstTySize. The
510 /// value is sign extended, truncated, or left alone to make it that width.
511 ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
512 unsigned SrcTySize = getBitWidth();
513 if (SrcTySize > DstTySize)
514 return truncate(DstTySize);
515 else if (SrcTySize < DstTySize)
516 return signExtend(DstTySize);
522 ConstantRange::add(const ConstantRange &Other) const {
523 if (isEmptySet() || Other.isEmptySet())
524 return ConstantRange(getBitWidth(), /*isFullSet=*/false);
525 if (isFullSet() || Other.isFullSet())
526 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
528 APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
529 APInt NewLower = getLower() + Other.getLower();
530 APInt NewUpper = getUpper() + Other.getUpper() - 1;
531 if (NewLower == NewUpper)
532 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
534 ConstantRange X = ConstantRange(NewLower, NewUpper);
535 if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
536 // We've wrapped, therefore, full set.
537 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
543 ConstantRange::multiply(const ConstantRange &Other) const {
544 // TODO: If either operand is a single element and the multiply is known to
545 // be non-wrapping, round the result min and max value to the appropriate
546 // multiple of that element. If wrapping is possible, at least adjust the
547 // range according to the greatest power-of-two factor of the single element.
549 if (isEmptySet() || Other.isEmptySet())
550 return ConstantRange(getBitWidth(), /*isFullSet=*/false);
551 if (isFullSet() || Other.isFullSet())
552 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
554 APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
555 APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
556 APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
557 APInt Other_max = Other.getUnsignedMax().zext(getBitWidth() * 2);
559 ConstantRange Result_zext = ConstantRange(this_min * Other_min,
560 this_max * Other_max + 1);
561 return Result_zext.truncate(getBitWidth());
565 ConstantRange::smax(const ConstantRange &Other) const {
566 // X smax Y is: range(smax(X_smin, Y_smin),
567 // smax(X_smax, Y_smax))
568 if (isEmptySet() || Other.isEmptySet())
569 return ConstantRange(getBitWidth(), /*isFullSet=*/false);
570 APInt NewL = APIntOps::smax(getSignedMin(), Other.getSignedMin());
571 APInt NewU = APIntOps::smax(getSignedMax(), Other.getSignedMax()) + 1;
573 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
574 return ConstantRange(NewL, NewU);
578 ConstantRange::umax(const ConstantRange &Other) const {
579 // X umax Y is: range(umax(X_umin, Y_umin),
580 // umax(X_umax, Y_umax))
581 if (isEmptySet() || Other.isEmptySet())
582 return ConstantRange(getBitWidth(), /*isFullSet=*/false);
583 APInt NewL = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
584 APInt NewU = APIntOps::umax(getUnsignedMax(), Other.getUnsignedMax()) + 1;
586 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
587 return ConstantRange(NewL, NewU);
591 ConstantRange::udiv(const ConstantRange &RHS) const {
592 if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax() == 0)
593 return ConstantRange(getBitWidth(), /*isFullSet=*/false);
595 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
597 APInt Lower = getUnsignedMin().udiv(RHS.getUnsignedMax());
599 APInt RHS_umin = RHS.getUnsignedMin();
601 // We want the lowest value in RHS excluding zero. Usually that would be 1
602 // except for a range in the form of [X, 1) in which case it would be X.
603 if (RHS.getUpper() == 1)
604 RHS_umin = RHS.getLower();
606 RHS_umin = APInt(getBitWidth(), 1);
609 APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;
611 // If the LHS is Full and the RHS is a wrapped interval containing 1 then
614 return ConstantRange(getBitWidth(), /*isFullSet=*/true);
616 return ConstantRange(Lower, Upper);
620 ConstantRange::shl(const ConstantRange &Amount) const {
624 APInt min = getUnsignedMin() << Amount.getUnsignedMin();
625 APInt max = getUnsignedMax() << Amount.getUnsignedMax();
627 // there's no overflow!
628 APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
629 if (Zeros.uge(Amount.getUnsignedMax()))
630 return ConstantRange(min, max);
632 // FIXME: implement the other tricky cases
633 return ConstantRange(getBitWidth());
637 ConstantRange::ashr(const ConstantRange &Amount) const {
641 APInt min = getUnsignedMax().ashr(Amount.getUnsignedMin());
642 APInt max = getUnsignedMin().ashr(Amount.getUnsignedMax());
643 return ConstantRange(min, max);
647 ConstantRange::lshr(const ConstantRange &Amount) const {
651 APInt min = getUnsignedMax().lshr(Amount.getUnsignedMin());
652 APInt max = getUnsignedMin().lshr(Amount.getUnsignedMax());
653 return ConstantRange(min, max);
656 ConstantRange ConstantRange::inverse() const {
658 return ConstantRange(APInt::getNullValue(Lower.getBitWidth()),
659 APInt::getNullValue(Lower.getBitWidth()));
660 } else if (isEmptySet()) {
661 return ConstantRange(APInt::getAllOnesValue(Lower.getBitWidth()),
662 APInt::getAllOnesValue(Lower.getBitWidth()));
664 return ConstantRange(Upper, Lower);
667 /// print - Print out the bounds to a stream...
669 void ConstantRange::print(raw_ostream &OS) const {
672 else if (isEmptySet())
675 OS << "[" << Lower << "," << Upper << ")";
678 /// dump - Allow printing from a debugger easily...
680 void ConstantRange::dump() const {