ConstantRange.cpp revision 193323
1//===-- ConstantRange.cpp - ConstantRange implementation ------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 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): 16// 17// [F, F) = {} = Empty set 18// [T, F) = {T} 19// [F, T) = {F} 20// [T, T) = {F, T} = Full set 21// 22//===----------------------------------------------------------------------===// 23 24#include "llvm/Support/ConstantRange.h" 25#include "llvm/Support/raw_ostream.h" 26using namespace llvm; 27 28/// Initialize a full (the default) or empty set for the specified type. 29/// 30ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) : 31 Lower(BitWidth, 0), Upper(BitWidth, 0) { 32 if (Full) 33 Lower = Upper = APInt::getMaxValue(BitWidth); 34 else 35 Lower = Upper = APInt::getMinValue(BitWidth); 36} 37 38/// Initialize a range to hold the single specified value. 39/// 40ConstantRange::ConstantRange(const APInt & V) : Lower(V), Upper(V + 1) { } 41 42ConstantRange::ConstantRange(const APInt &L, const APInt &U) : 43 Lower(L), Upper(U) { 44 assert(L.getBitWidth() == U.getBitWidth() && 45 "ConstantRange with unequal bit widths"); 46 assert((L != U || (L.isMaxValue() || L.isMinValue())) && 47 "Lower == Upper, but they aren't min or max value!"); 48} 49 50/// isFullSet - Return true if this set contains all of the elements possible 51/// for this data-type 52bool ConstantRange::isFullSet() const { 53 return Lower == Upper && Lower.isMaxValue(); 54} 55 56/// isEmptySet - Return true if this set contains no members. 57/// 58bool ConstantRange::isEmptySet() const { 59 return Lower == Upper && Lower.isMinValue(); 60} 61 62/// isWrappedSet - Return true if this set wraps around the top of the range, 63/// for example: [100, 8) 64/// 65bool ConstantRange::isWrappedSet() const { 66 return Lower.ugt(Upper); 67} 68 69/// getSetSize - Return the number of elements in this set. 70/// 71APInt ConstantRange::getSetSize() const { 72 if (isEmptySet()) 73 return APInt(getBitWidth(), 0); 74 if (getBitWidth() == 1) { 75 if (Lower != Upper) // One of T or F in the set... 76 return APInt(2, 1); 77 return APInt(2, 2); // Must be full set... 78 } 79 80 // Simply subtract the bounds... 81 return Upper - Lower; 82} 83 84/// getUnsignedMax - Return the largest unsigned value contained in the 85/// ConstantRange. 86/// 87APInt ConstantRange::getUnsignedMax() const { 88 if (isFullSet() || isWrappedSet()) 89 return APInt::getMaxValue(getBitWidth()); 90 else 91 return getUpper() - 1; 92} 93 94/// getUnsignedMin - Return the smallest unsigned value contained in the 95/// ConstantRange. 96/// 97APInt ConstantRange::getUnsignedMin() const { 98 if (isFullSet() || (isWrappedSet() && getUpper() != 0)) 99 return APInt::getMinValue(getBitWidth()); 100 else 101 return getLower(); 102} 103 104/// getSignedMax - Return the largest signed value contained in the 105/// ConstantRange. 106/// 107APInt ConstantRange::getSignedMax() const { 108 APInt SignedMax(APInt::getSignedMaxValue(getBitWidth())); 109 if (!isWrappedSet()) { 110 if (getLower().sle(getUpper() - 1)) 111 return getUpper() - 1; 112 else 113 return SignedMax; 114 } else { 115 if ((getUpper() - 1).slt(getLower())) { 116 if (getLower() != SignedMax) 117 return SignedMax; 118 else 119 return getUpper() - 1; 120 } else { 121 return getUpper() - 1; 122 } 123 } 124} 125 126/// getSignedMin - Return the smallest signed value contained in the 127/// ConstantRange. 128/// 129APInt ConstantRange::getSignedMin() const { 130 APInt SignedMin(APInt::getSignedMinValue(getBitWidth())); 131 if (!isWrappedSet()) { 132 if (getLower().sle(getUpper() - 1)) 133 return getLower(); 134 else 135 return SignedMin; 136 } else { 137 if ((getUpper() - 1).slt(getLower())) { 138 if (getUpper() != SignedMin) 139 return SignedMin; 140 else 141 return getLower(); 142 } else { 143 return getLower(); 144 } 145 } 146} 147 148/// contains - Return true if the specified value is in the set. 149/// 150bool ConstantRange::contains(const APInt &V) const { 151 if (Lower == Upper) 152 return isFullSet(); 153 154 if (!isWrappedSet()) 155 return Lower.ule(V) && V.ult(Upper); 156 else 157 return Lower.ule(V) || V.ult(Upper); 158} 159 160/// subtract - Subtract the specified constant from the endpoints of this 161/// constant range. 162ConstantRange ConstantRange::subtract(const APInt &Val) const { 163 assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width"); 164 // If the set is empty or full, don't modify the endpoints. 165 if (Lower == Upper) 166 return *this; 167 return ConstantRange(Lower - Val, Upper - Val); 168} 169 170 171// intersect1Wrapped - This helper function is used to intersect two ranges when 172// it is known that LHS is wrapped and RHS isn't. 173// 174ConstantRange 175ConstantRange::intersect1Wrapped(const ConstantRange &LHS, 176 const ConstantRange &RHS) { 177 assert(LHS.isWrappedSet() && !RHS.isWrappedSet()); 178 179 // Check to see if we overlap on the Left side of RHS... 180 // 181 if (RHS.Lower.ult(LHS.Upper)) { 182 // We do overlap on the left side of RHS, see if we overlap on the right of 183 // RHS... 184 if (RHS.Upper.ugt(LHS.Lower)) { 185 // Ok, the result overlaps on both the left and right sides. See if the 186 // resultant interval will be smaller if we wrap or not... 187 // 188 if (LHS.getSetSize().ult(RHS.getSetSize())) 189 return LHS; 190 else 191 return RHS; 192 193 } else { 194 // No overlap on the right, just on the left. 195 return ConstantRange(RHS.Lower, LHS.Upper); 196 } 197 } else { 198 // We don't overlap on the left side of RHS, see if we overlap on the right 199 // of RHS... 200 if (RHS.Upper.ugt(LHS.Lower)) { 201 // Simple overlap... 202 return ConstantRange(LHS.Lower, RHS.Upper); 203 } else { 204 // No overlap... 205 return ConstantRange(LHS.getBitWidth(), false); 206 } 207 } 208} 209 210/// intersectWith - Return the range that results from the intersection of this 211/// range with another range. 212/// 213ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const { 214 assert(getBitWidth() == CR.getBitWidth() && 215 "ConstantRange types don't agree!"); 216 // Handle common special cases 217 if (isEmptySet() || CR.isFullSet()) 218 return *this; 219 if (isFullSet() || CR.isEmptySet()) 220 return CR; 221 222 if (!isWrappedSet()) { 223 if (!CR.isWrappedSet()) { 224 using namespace APIntOps; 225 APInt L = umax(Lower, CR.Lower); 226 APInt U = umin(Upper, CR.Upper); 227 228 if (L.ult(U)) // If range isn't empty... 229 return ConstantRange(L, U); 230 else 231 return ConstantRange(getBitWidth(), false);// Otherwise, empty set 232 } else 233 return intersect1Wrapped(CR, *this); 234 } else { // We know "this" is wrapped... 235 if (!CR.isWrappedSet()) 236 return intersect1Wrapped(*this, CR); 237 else { 238 // Both ranges are wrapped... 239 using namespace APIntOps; 240 APInt L = umax(Lower, CR.Lower); 241 APInt U = umin(Upper, CR.Upper); 242 return ConstantRange(L, U); 243 } 244 } 245 return *this; 246} 247 248/// maximalIntersectWith - Return the range that results from the intersection 249/// of this range with another range. The resultant range is guaranteed to 250/// include all elements contained in both input ranges, and to have the 251/// smallest possible set size that does so. Because there may be two 252/// intersections with the same set size, A.maximalIntersectWith(B) might not 253/// be equal to B.maximalIntersect(A). 254ConstantRange ConstantRange::maximalIntersectWith(const ConstantRange &CR) const { 255 assert(getBitWidth() == CR.getBitWidth() && 256 "ConstantRange types don't agree!"); 257 258 // Handle common cases. 259 if ( isEmptySet() || CR.isFullSet()) return *this; 260 if (CR.isEmptySet() || isFullSet()) return CR; 261 262 if (!isWrappedSet() && CR.isWrappedSet()) 263 return CR.maximalIntersectWith(*this); 264 265 if (!isWrappedSet() && !CR.isWrappedSet()) { 266 if (Lower.ult(CR.Lower)) { 267 if (Upper.ule(CR.Lower)) 268 return ConstantRange(getBitWidth(), false); 269 270 if (Upper.ult(CR.Upper)) 271 return ConstantRange(CR.Lower, Upper); 272 273 return CR; 274 } else { 275 if (Upper.ult(CR.Upper)) 276 return *this; 277 278 if (Lower.ult(CR.Upper)) 279 return ConstantRange(Lower, CR.Upper); 280 281 return ConstantRange(getBitWidth(), false); 282 } 283 } 284 285 if (isWrappedSet() && !CR.isWrappedSet()) { 286 if (CR.Lower.ult(Upper)) { 287 if (CR.Upper.ult(Upper)) 288 return CR; 289 290 if (CR.Upper.ult(Lower)) 291 return ConstantRange(CR.Lower, Upper); 292 293 if (getSetSize().ult(CR.getSetSize())) 294 return *this; 295 else 296 return CR; 297 } else if (CR.Lower.ult(Lower)) { 298 if (CR.Upper.ule(Lower)) 299 return ConstantRange(getBitWidth(), false); 300 301 return ConstantRange(Lower, CR.Upper); 302 } 303 return CR; 304 } 305 306 if (CR.Upper.ult(Upper)) { 307 if (CR.Lower.ult(Upper)) { 308 if (getSetSize().ult(CR.getSetSize())) 309 return *this; 310 else 311 return CR; 312 } 313 314 if (CR.Lower.ult(Lower)) 315 return ConstantRange(Lower, CR.Upper); 316 317 return CR; 318 } else if (CR.Upper.ult(Lower)) { 319 if (CR.Lower.ult(Lower)) 320 return *this; 321 322 return ConstantRange(CR.Lower, Upper); 323 } 324 if (getSetSize().ult(CR.getSetSize())) 325 return *this; 326 else 327 return CR; 328} 329 330 331/// unionWith - Return the range that results from the union of this range with 332/// another range. The resultant range is guaranteed to include the elements of 333/// both sets, but may contain more. For example, [3, 9) union [12,15) is 334/// [3, 15), which includes 9, 10, and 11, which were not included in either 335/// set before. 336/// 337ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const { 338 assert(getBitWidth() == CR.getBitWidth() && 339 "ConstantRange types don't agree!"); 340 341 if ( isFullSet() || CR.isEmptySet()) return *this; 342 if (CR.isFullSet() || isEmptySet()) return CR; 343 344 if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this); 345 346 APInt L = Lower, U = Upper; 347 348 if (!isWrappedSet() && !CR.isWrappedSet()) { 349 if (CR.Lower.ult(L)) 350 L = CR.Lower; 351 352 if (CR.Upper.ugt(U)) 353 U = CR.Upper; 354 } 355 356 if (isWrappedSet() && !CR.isWrappedSet()) { 357 if ((CR.Lower.ult(Upper) && CR.Upper.ult(Upper)) || 358 (CR.Lower.ugt(Lower) && CR.Upper.ugt(Lower))) { 359 return *this; 360 } 361 362 if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper)) { 363 return ConstantRange(getBitWidth()); 364 } 365 366 if (CR.Lower.ule(Upper) && CR.Upper.ule(Lower)) { 367 APInt d1 = CR.Upper - Upper, d2 = Lower - CR.Upper; 368 if (d1.ult(d2)) { 369 U = CR.Upper; 370 } else { 371 L = CR.Upper; 372 } 373 } 374 375 if (Upper.ult(CR.Lower) && CR.Upper.ult(Lower)) { 376 APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper; 377 if (d1.ult(d2)) { 378 U = CR.Lower + 1; 379 } else { 380 L = CR.Upper - 1; 381 } 382 } 383 384 if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper)) { 385 APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Lower; 386 387 if (d1.ult(d2)) { 388 U = CR.Lower + 1; 389 } else { 390 L = CR.Lower; 391 } 392 } 393 } 394 395 if (isWrappedSet() && CR.isWrappedSet()) { 396 if (Lower.ult(CR.Upper) || CR.Lower.ult(Upper)) 397 return ConstantRange(getBitWidth()); 398 399 if (CR.Upper.ugt(U)) { 400 U = CR.Upper; 401 } 402 403 if (CR.Lower.ult(L)) { 404 L = CR.Lower; 405 } 406 407 if (L == U) return ConstantRange(getBitWidth()); 408 } 409 410 return ConstantRange(L, U); 411} 412 413/// zeroExtend - Return a new range in the specified integer type, which must 414/// be strictly larger than the current type. The returned range will 415/// correspond to the possible range of values as if the source range had been 416/// zero extended. 417ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const { 418 unsigned SrcTySize = getBitWidth(); 419 assert(SrcTySize < DstTySize && "Not a value extension"); 420 if (isFullSet()) 421 // Change a source full set into [0, 1 << 8*numbytes) 422 return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize)); 423 424 APInt L = Lower; L.zext(DstTySize); 425 APInt U = Upper; U.zext(DstTySize); 426 return ConstantRange(L, U); 427} 428 429/// signExtend - Return a new range in the specified integer type, which must 430/// be strictly larger than the current type. The returned range will 431/// correspond to the possible range of values as if the source range had been 432/// sign extended. 433ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const { 434 unsigned SrcTySize = getBitWidth(); 435 assert(SrcTySize < DstTySize && "Not a value extension"); 436 if (isFullSet()) { 437 return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1), 438 APInt::getLowBitsSet(DstTySize, SrcTySize-1)); 439 } 440 441 APInt L = Lower; L.sext(DstTySize); 442 APInt U = Upper; U.sext(DstTySize); 443 return ConstantRange(L, U); 444} 445 446/// truncate - Return a new range in the specified integer type, which must be 447/// strictly smaller than the current type. The returned range will 448/// correspond to the possible range of values as if the source range had been 449/// truncated to the specified type. 450ConstantRange ConstantRange::truncate(uint32_t DstTySize) const { 451 unsigned SrcTySize = getBitWidth(); 452 assert(SrcTySize > DstTySize && "Not a value truncation"); 453 APInt Size(APInt::getLowBitsSet(SrcTySize, DstTySize)); 454 if (isFullSet() || getSetSize().ugt(Size)) 455 return ConstantRange(DstTySize); 456 457 APInt L = Lower; L.trunc(DstTySize); 458 APInt U = Upper; U.trunc(DstTySize); 459 return ConstantRange(L, U); 460} 461 462/// print - Print out the bounds to a stream... 463/// 464void ConstantRange::print(raw_ostream &OS) const { 465 OS << "[" << Lower << "," << Upper << ")"; 466} 467 468/// dump - Allow printing from a debugger easily... 469/// 470void ConstantRange::dump() const { 471 print(errs()); 472} 473