ConstantRange.cpp revision fc33d30446843009b0eadf63c0bfca35ae2baac6
1//===-- ConstantRange.cpp - ConstantRange implementation ------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 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. 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/Constants.h" 26#include "llvm/Instruction.h" 27#include "llvm/Type.h" 28using namespace llvm; 29 30static ConstantIntegral *Next(ConstantIntegral *CI) { 31 if (CI->getType() == Type::BoolTy) 32 return CI == ConstantBool::True ? ConstantBool::False : ConstantBool::True; 33 34 Constant *Result = ConstantExpr::getAdd(CI, 35 ConstantInt::get(CI->getType(), 1)); 36 return cast<ConstantIntegral>(Result); 37} 38 39static bool LT(ConstantIntegral *A, ConstantIntegral *B) { 40 Constant *C = ConstantExpr::getSetLT(A, B); 41 assert(isa<ConstantBool>(C) && "Constant folding of integrals not impl??"); 42 return cast<ConstantBool>(C)->getValue(); 43} 44 45static bool LTE(ConstantIntegral *A, ConstantIntegral *B) { 46 Constant *C = ConstantExpr::getSetLE(A, B); 47 assert(isa<ConstantBool>(C) && "Constant folding of integrals not impl??"); 48 return cast<ConstantBool>(C)->getValue(); 49} 50 51static bool GT(ConstantIntegral *A, ConstantIntegral *B) { return LT(B, A); } 52 53static ConstantIntegral *Min(ConstantIntegral *A, ConstantIntegral *B) { 54 return LT(A, B) ? A : B; 55} 56static ConstantIntegral *Max(ConstantIntegral *A, ConstantIntegral *B) { 57 return GT(A, B) ? A : B; 58} 59 60/// Initialize a full (the default) or empty set for the specified type. 61/// 62ConstantRange::ConstantRange(const Type *Ty, bool Full) { 63 assert(Ty->isIntegral() && 64 "Cannot make constant range of non-integral type!"); 65 if (Full) 66 Lower = Upper = ConstantIntegral::getMaxValue(Ty); 67 else 68 Lower = Upper = ConstantIntegral::getMinValue(Ty); 69} 70 71/// Initialize a range to hold the single specified value. 72/// 73ConstantRange::ConstantRange(Constant *V) 74 : Lower(cast<ConstantIntegral>(V)), Upper(Next(cast<ConstantIntegral>(V))) { 75} 76 77/// Initialize a range of values explicitly... this will assert out if 78/// Lower==Upper and Lower != Min or Max for its type (or if the two constants 79/// have different types) 80/// 81ConstantRange::ConstantRange(Constant *L, Constant *U) 82 : Lower(cast<ConstantIntegral>(L)), Upper(cast<ConstantIntegral>(U)) { 83 assert(Lower->getType() == Upper->getType() && 84 "Incompatible types for ConstantRange!"); 85 86 // Make sure that if L & U are equal that they are either Min or Max... 87 assert((L != U || (L == ConstantIntegral::getMaxValue(L->getType()) || 88 L == ConstantIntegral::getMinValue(L->getType()))) && 89 "Lower == Upper, but they aren't min or max for type!"); 90} 91 92/// Initialize a set of values that all satisfy the condition with C. 93/// 94ConstantRange::ConstantRange(unsigned SetCCOpcode, ConstantIntegral *C) { 95 switch (SetCCOpcode) { 96 default: assert(0 && "Invalid SetCC opcode to ConstantRange ctor!"); 97 case Instruction::SetEQ: Lower = C; Upper = Next(C); return; 98 case Instruction::SetNE: Upper = C; Lower = Next(C); return; 99 case Instruction::SetLT: 100 Lower = ConstantIntegral::getMinValue(C->getType()); 101 Upper = C; 102 return; 103 case Instruction::SetGT: 104 Lower = Next(C); 105 Upper = ConstantIntegral::getMinValue(C->getType()); // Min = Next(Max) 106 return; 107 case Instruction::SetLE: 108 Lower = ConstantIntegral::getMinValue(C->getType()); 109 Upper = Next(C); 110 return; 111 case Instruction::SetGE: 112 Lower = C; 113 Upper = ConstantIntegral::getMinValue(C->getType()); // Min = Next(Max) 114 return; 115 } 116} 117 118/// getType - Return the LLVM data type of this range. 119/// 120const Type *ConstantRange::getType() const { return Lower->getType(); } 121 122/// isFullSet - Return true if this set contains all of the elements possible 123/// for this data-type 124bool ConstantRange::isFullSet() const { 125 return Lower == Upper && Lower == ConstantIntegral::getMaxValue(getType()); 126} 127 128/// isEmptySet - Return true if this set contains no members. 129/// 130bool ConstantRange::isEmptySet() const { 131 return Lower == Upper && Lower == ConstantIntegral::getMinValue(getType()); 132} 133 134/// isWrappedSet - Return true if this set wraps around the top of the range, 135/// for example: [100, 8) 136/// 137bool ConstantRange::isWrappedSet() const { 138 return GT(Lower, Upper); 139} 140 141 142/// getSingleElement - If this set contains a single element, return it, 143/// otherwise return null. 144ConstantIntegral *ConstantRange::getSingleElement() const { 145 if (Upper == Next(Lower)) // Is it a single element range? 146 return Lower; 147 return 0; 148} 149 150/// getSetSize - Return the number of elements in this set. 151/// 152uint64_t ConstantRange::getSetSize() const { 153 if (isEmptySet()) return 0; 154 if (getType() == Type::BoolTy) { 155 if (Lower != Upper) // One of T or F in the set... 156 return 1; 157 return 2; // Must be full set... 158 } 159 160 // Simply subtract the bounds... 161 Constant *Result = ConstantExpr::getSub(Upper, Lower); 162 return cast<ConstantInt>(Result)->getRawValue(); 163} 164 165/// contains - Return true if the specified value is in the set. 166/// 167bool ConstantRange::contains(ConstantInt *Val) const { 168 if (Lower == Upper) { 169 if (isFullSet()) return true; 170 return false; 171 } 172 173 if (!isWrappedSet()) 174 return LTE(Lower, Val) && LT(Val, Upper); 175 return LTE(Lower, Val) || LT(Val, Upper); 176} 177 178 179 180/// subtract - Subtract the specified constant from the endpoints of this 181/// constant range. 182ConstantRange ConstantRange::subtract(ConstantInt *CI) const { 183 assert(CI->getType() == getType() && getType()->isInteger() && 184 "Cannot subtract from different type range or non-integer!"); 185 // If the set is empty or full, don't modify the endpoints. 186 if (Lower == Upper) return *this; 187 return ConstantRange(ConstantExpr::getSub(Lower, CI), 188 ConstantExpr::getSub(Upper, CI)); 189} 190 191 192// intersect1Wrapped - This helper function is used to intersect two ranges when 193// it is known that LHS is wrapped and RHS isn't. 194// 195static ConstantRange intersect1Wrapped(const ConstantRange &LHS, 196 const ConstantRange &RHS) { 197 assert(LHS.isWrappedSet() && !RHS.isWrappedSet()); 198 199 // Check to see if we overlap on the Left side of RHS... 200 // 201 if (LT(RHS.getLower(), LHS.getUpper())) { 202 // We do overlap on the left side of RHS, see if we overlap on the right of 203 // RHS... 204 if (GT(RHS.getUpper(), LHS.getLower())) { 205 // Ok, the result overlaps on both the left and right sides. See if the 206 // resultant interval will be smaller if we wrap or not... 207 // 208 if (LHS.getSetSize() < RHS.getSetSize()) 209 return LHS; 210 else 211 return RHS; 212 213 } else { 214 // No overlap on the right, just on the left. 215 return ConstantRange(RHS.getLower(), LHS.getUpper()); 216 } 217 218 } else { 219 // We don't overlap on the left side of RHS, see if we overlap on the right 220 // of RHS... 221 if (GT(RHS.getUpper(), LHS.getLower())) { 222 // Simple overlap... 223 return ConstantRange(LHS.getLower(), RHS.getUpper()); 224 } else { 225 // No overlap... 226 return ConstantRange(LHS.getType(), false); 227 } 228 } 229} 230 231/// intersect - Return the range that results from the intersection of this 232/// range with another range. 233/// 234ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const { 235 assert(getType() == CR.getType() && "ConstantRange types don't agree!"); 236 // Handle common special cases 237 if (isEmptySet() || CR.isFullSet()) return *this; 238 if (isFullSet() || CR.isEmptySet()) return CR; 239 240 if (!isWrappedSet()) { 241 if (!CR.isWrappedSet()) { 242 ConstantIntegral *L = Max(Lower, CR.Lower); 243 ConstantIntegral *U = Min(Upper, CR.Upper); 244 245 if (LT(L, U)) // If range isn't empty... 246 return ConstantRange(L, U); 247 else 248 return ConstantRange(getType(), false); // Otherwise, return empty set 249 } else 250 return intersect1Wrapped(CR, *this); 251 } else { // We know "this" is wrapped... 252 if (!CR.isWrappedSet()) 253 return intersect1Wrapped(*this, CR); 254 else { 255 // Both ranges are wrapped... 256 ConstantIntegral *L = Max(Lower, CR.Lower); 257 ConstantIntegral *U = Min(Upper, CR.Upper); 258 return ConstantRange(L, U); 259 } 260 } 261 return *this; 262} 263 264/// union - Return the range that results from the union of this range with 265/// another range. The resultant range is guaranteed to include the elements of 266/// both sets, but may contain more. For example, [3, 9) union [12,15) is [3, 267/// 15), which includes 9, 10, and 11, which were not included in either set 268/// before. 269/// 270ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const { 271 assert(getType() == CR.getType() && "ConstantRange types don't agree!"); 272 273 assert(0 && "Range union not implemented yet!"); 274 275 return *this; 276} 277 278/// zeroExtend - Return a new range in the specified integer type, which must 279/// be strictly larger than the current type. The returned range will 280/// correspond to the possible range of values if the source range had been 281/// zero extended. 282ConstantRange ConstantRange::zeroExtend(const Type *Ty) const { 283 assert(getLower()->getType()->getPrimitiveSize() < Ty->getPrimitiveSize() && 284 "Not a value extension"); 285 if (isFullSet()) { 286 // Change a source full set into [0, 1 << 8*numbytes) 287 unsigned SrcTySize = getLower()->getType()->getPrimitiveSize(); 288 return ConstantRange(Constant::getNullValue(Ty), 289 ConstantUInt::get(Ty, 1ULL << SrcTySize*8)); 290 } 291 292 Constant *Lower = getLower(); 293 Constant *Upper = getUpper(); 294 if (Lower->getType()->isInteger() && !Lower->getType()->isUnsigned()) { 295 // Ensure we are doing a ZERO extension even if the input range is signed. 296 Lower = ConstantExpr::getCast(Lower, Ty->getUnsignedVersion()); 297 Upper = ConstantExpr::getCast(Upper, Ty->getUnsignedVersion()); 298 } 299 300 return ConstantRange(ConstantExpr::getCast(Lower, Ty), 301 ConstantExpr::getCast(Upper, Ty)); 302} 303 304/// truncate - Return a new range in the specified integer type, which must be 305/// strictly smaller than the current type. The returned range will 306/// correspond to the possible range of values if the source range had been 307/// truncated to the specified type. 308ConstantRange ConstantRange::truncate(const Type *Ty) const { 309 assert(getLower()->getType()->getPrimitiveSize() > Ty->getPrimitiveSize() && 310 "Not a value truncation"); 311 uint64_t Size = 1ULL << Ty->getPrimitiveSize()*8; 312 if (isFullSet() || getSetSize() >= Size) 313 return ConstantRange(getType()); 314 315 return ConstantRange(ConstantExpr::getCast(getLower(), Ty), 316 ConstantExpr::getCast(getUpper(), Ty)); 317} 318 319 320/// print - Print out the bounds to a stream... 321/// 322void ConstantRange::print(std::ostream &OS) const { 323 OS << "[" << Lower << "," << Upper << " )"; 324} 325 326/// dump - Allow printing from a debugger easily... 327/// 328void ConstantRange::dump() const { 329 print(std::cerr); 330} 331