1 //===-- ConstantRange.cpp - ConstantRange implementation ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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/Support/ConstantRange.h"
25 #include "llvm/Support/Streams.h"
29 /// Initialize a full (the default) or empty set for the specified type.
31 ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) :
32 Lower(BitWidth, 0), Upper(BitWidth, 0) {
34 Lower = Upper = APInt::getMaxValue(BitWidth);
36 Lower = Upper = APInt::getMinValue(BitWidth);
39 /// Initialize a range to hold the single specified value.
41 ConstantRange::ConstantRange(const APInt & V) : Lower(V), Upper(V + 1) { }
43 ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
45 assert(L.getBitWidth() == U.getBitWidth() &&
46 "ConstantRange with unequal bit widths");
47 assert((L != U || (L.isMaxValue() || L.isMinValue())) &&
48 "Lower == Upper, but they aren't min or max value!");
51 /// isFullSet - Return true if this set contains all of the elements possible
52 /// for this data-type
53 bool ConstantRange::isFullSet() const {
54 return Lower == Upper && Lower.isMaxValue();
57 /// isEmptySet - Return true if this set contains no members.
59 bool ConstantRange::isEmptySet() const {
60 return Lower == Upper && Lower.isMinValue();
63 /// isWrappedSet - Return true if this set wraps around the top of the range,
64 /// for example: [100, 8)
66 bool ConstantRange::isWrappedSet() const {
67 return Lower.ugt(Upper);
70 /// getSetSize - Return the number of elements in this set.
72 APInt ConstantRange::getSetSize() const {
74 return APInt(getBitWidth(), 0);
75 if (getBitWidth() == 1) {
76 if (Lower != Upper) // One of T or F in the set...
78 return APInt(2, 2); // Must be full set...
81 // Simply subtract the bounds...
85 /// getUnsignedMax - Return the largest unsigned value contained in the
88 APInt ConstantRange::getUnsignedMax() const {
89 if (isFullSet() || isWrappedSet())
90 return APInt::getMaxValue(getBitWidth());
92 return getUpper() - 1;
95 /// getUnsignedMin - Return the smallest unsigned value contained in the
98 APInt ConstantRange::getUnsignedMin() const {
99 if (isFullSet() || (isWrappedSet() && getUpper() != 0))
100 return APInt::getMinValue(getBitWidth());
105 /// getSignedMax - Return the largest signed value contained in the
108 APInt ConstantRange::getSignedMax() const {
109 APInt SignedMax(APInt::getSignedMaxValue(getBitWidth()));
110 if (!isWrappedSet()) {
111 if (getLower().sle(getUpper() - 1))
112 return getUpper() - 1;
116 if ((getUpper() - 1).slt(getLower())) {
117 if (getLower() != SignedMax)
120 return getUpper() - 1;
122 return getUpper() - 1;
127 /// getSignedMin - Return the smallest signed value contained in the
130 APInt ConstantRange::getSignedMin() const {
131 APInt SignedMin(APInt::getSignedMinValue(getBitWidth()));
132 if (!isWrappedSet()) {
133 if (getLower().sle(getUpper() - 1))
138 if ((getUpper() - 1).slt(getLower())) {
139 if (getUpper() != SignedMin)
149 /// contains - Return true if the specified value is in the set.
151 bool ConstantRange::contains(const APInt &V) const {
156 return Lower.ule(V) && V.ult(Upper);
158 return Lower.ule(V) || V.ult(Upper);
161 /// subtract - Subtract the specified constant from the endpoints of this
163 ConstantRange ConstantRange::subtract(const APInt &Val) const {
164 assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
165 // If the set is empty or full, don't modify the endpoints.
168 return ConstantRange(Lower - Val, Upper - Val);
172 // intersect1Wrapped - This helper function is used to intersect two ranges when
173 // it is known that LHS is wrapped and RHS isn't.
176 ConstantRange::intersect1Wrapped(const ConstantRange &LHS,
177 const ConstantRange &RHS) {
178 assert(LHS.isWrappedSet() && !RHS.isWrappedSet());
180 // Check to see if we overlap on the Left side of RHS...
182 if (RHS.Lower.ult(LHS.Upper)) {
183 // We do overlap on the left side of RHS, see if we overlap on the right of
185 if (RHS.Upper.ugt(LHS.Lower)) {
186 // Ok, the result overlaps on both the left and right sides. See if the
187 // resultant interval will be smaller if we wrap or not...
189 if (LHS.getSetSize().ult(RHS.getSetSize()))
195 // No overlap on the right, just on the left.
196 return ConstantRange(RHS.Lower, LHS.Upper);
199 // We don't overlap on the left side of RHS, see if we overlap on the right
201 if (RHS.Upper.ugt(LHS.Lower)) {
203 return ConstantRange(LHS.Lower, RHS.Upper);
206 return ConstantRange(LHS.getBitWidth(), false);
211 /// intersectWith - Return the range that results from the intersection of this
212 /// range with another range.
214 ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
215 assert(getBitWidth() == CR.getBitWidth() &&
216 "ConstantRange types don't agree!");
217 // Handle common special cases
218 if (isEmptySet() || CR.isFullSet())
220 if (isFullSet() || CR.isEmptySet())
223 if (!isWrappedSet()) {
224 if (!CR.isWrappedSet()) {
225 using namespace APIntOps;
226 APInt L = umax(Lower, CR.Lower);
227 APInt U = umin(Upper, CR.Upper);
229 if (L.ult(U)) // If range isn't empty...
230 return ConstantRange(L, U);
232 return ConstantRange(getBitWidth(), false);// Otherwise, empty set
234 return intersect1Wrapped(CR, *this);
235 } else { // We know "this" is wrapped...
236 if (!CR.isWrappedSet())
237 return intersect1Wrapped(*this, CR);
239 // Both ranges are wrapped...
240 using namespace APIntOps;
241 APInt L = umax(Lower, CR.Lower);
242 APInt U = umin(Upper, CR.Upper);
243 return ConstantRange(L, U);
249 /// unionWith - Return the range that results from the union of this range with
250 /// another range. The resultant range is guaranteed to include the elements of
251 /// both sets, but may contain more. For example, [3, 9) union [12,15) is
252 /// [3, 15), which includes 9, 10, and 11, which were not included in either
255 ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
256 assert(getBitWidth() == CR.getBitWidth() &&
257 "ConstantRange types don't agree!");
259 if ( isFullSet() || CR.isEmptySet()) return *this;
260 if (CR.isFullSet() || isEmptySet()) return CR;
262 if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this);
264 APInt L = Lower, U = Upper;
266 if (!isWrappedSet() && !CR.isWrappedSet()) {
274 if (isWrappedSet() && !CR.isWrappedSet()) {
275 if ((CR.Lower.ult(Upper) && CR.Upper.ult(Upper)) ||
276 (CR.Lower.ugt(Lower) && CR.Upper.ugt(Lower))) {
280 if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper)) {
281 return ConstantRange(getBitWidth());
284 if (CR.Lower.ule(Upper) && CR.Upper.ule(Lower)) {
285 APInt d1 = CR.Upper - Upper, d2 = Lower - CR.Upper;
293 if (Upper.ult(CR.Lower) && CR.Upper.ult(Lower)) {
294 APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
302 if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper)) {
303 APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Lower;
313 if (isWrappedSet() && CR.isWrappedSet()) {
314 if (Lower.ult(CR.Upper) || CR.Lower.ult(Upper))
315 return ConstantRange(getBitWidth());
317 if (CR.Upper.ugt(U)) {
321 if (CR.Lower.ult(L)) {
325 if (L == U) return ConstantRange(getBitWidth());
328 return ConstantRange(L, U);
331 /// zeroExtend - Return a new range in the specified integer type, which must
332 /// be strictly larger than the current type. The returned range will
333 /// correspond to the possible range of values as if the source range had been
335 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
336 unsigned SrcTySize = getBitWidth();
337 assert(SrcTySize < DstTySize && "Not a value extension");
339 // Change a source full set into [0, 1 << 8*numbytes)
340 return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
342 APInt L = Lower; L.zext(DstTySize);
343 APInt U = Upper; U.zext(DstTySize);
344 return ConstantRange(L, U);
347 /// signExtend - Return a new range in the specified integer type, which must
348 /// be strictly larger than the current type. The returned range will
349 /// correspond to the possible range of values as if the source range had been
351 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
352 unsigned SrcTySize = getBitWidth();
353 assert(SrcTySize < DstTySize && "Not a value extension");
355 return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
356 APInt::getLowBitsSet(DstTySize, SrcTySize-1));
359 APInt L = Lower; L.sext(DstTySize);
360 APInt U = Upper; U.sext(DstTySize);
361 return ConstantRange(L, U);
364 /// truncate - Return a new range in the specified integer type, which must be
365 /// strictly smaller than the current type. The returned range will
366 /// correspond to the possible range of values as if the source range had been
367 /// truncated to the specified type.
368 ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
369 unsigned SrcTySize = getBitWidth();
370 assert(SrcTySize > DstTySize && "Not a value truncation");
371 APInt Size(APInt::getLowBitsSet(SrcTySize, DstTySize));
372 if (isFullSet() || getSetSize().ugt(Size))
373 return ConstantRange(DstTySize);
375 APInt L = Lower; L.trunc(DstTySize);
376 APInt U = Upper; U.trunc(DstTySize);
377 return ConstantRange(L, U);
380 /// print - Print out the bounds to a stream...
382 void ConstantRange::print(std::ostream &OS) const {
383 OS << "[" << Lower.toStringSigned(10) << ","
384 << Upper.toStringSigned(10) << " )";
387 /// dump - Allow printing from a debugger easily...
389 void ConstantRange::dump() const {