Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef ART_RUNTIME_SUBTYPE_CHECK_INFO_H_ |
| 18 | #define ART_RUNTIME_SUBTYPE_CHECK_INFO_H_ |
| 19 | |
| 20 | #include "base/bit_string.h" |
| 21 | #include "subtype_check_bits.h" |
| 22 | |
| 23 | // Forward-declare for testing purposes. |
| 24 | struct SubtypeCheckInfoTest; |
| 25 | |
| 26 | namespace art { |
| 27 | |
| 28 | /** |
| 29 | * SubtypeCheckInfo is a logical label for the class SubtypeCheck data, which is necessary to |
| 30 | * perform efficient O(1) subtype comparison checks. See also subtype_check.h |
| 31 | * for the more general explanation of how the labels are used overall. |
| 32 | * |
| 33 | * For convenience, we also store the class depth within an SubtypeCheckInfo, since nearly all |
| 34 | * calculations are dependent on knowing the depth of the class. |
| 35 | * |
| 36 | * A SubtypeCheckInfo logically has: |
| 37 | * * Depth - How many levels up to the root (j.l.Object)? |
| 38 | * * PathToRoot - Possibly truncated BitString that encodes path to root |
| 39 | * * Next - The value a newly inserted Child would get appended to its path. |
| 40 | * * Overflow - If this path can never become a full path. |
| 41 | * |
| 42 | * Depending on the values of the above, it can be in one of these logical states, |
| 43 | * which are introduced in subtype_check.h: |
| 44 | * |
| 45 | * Transient States Terminal States |
| 46 | * |
| 47 | * +-----------------+ +--------------------+ +-------------------+ |
| 48 | * | | | | | | |
| 49 | * | Uninitialized | +---> Initialized | +---> Assigned | |
| 50 | * | | | | | | |
| 51 | * +--------+--------+ +---------+----------+ +-------------------+ |
| 52 | * | | |
| 53 | * | | |
| 54 | * | | +-------------------+ |
| 55 | * | +----------------> | |
| 56 | * | | Overflowed | |
| 57 | * +-----------------------------------------> | |
| 58 | * +-------------------+ |
| 59 | * |
| 60 | * Invariants: |
| 61 | * |
| 62 | * Initialized => Parent >= Initialized |
| 63 | * |
| 64 | * Assigned => Parent == Assigned |
| 65 | * |
| 66 | * Overflowed => Parent == Overflowed || Parent.Next == Overflowed |
| 67 | * |
| 68 | * Thread-safety invariants: |
| 69 | * |
| 70 | * Initialized => Parent == Assigned |
| 71 | * // For a class that has an Initialized bitstring, its superclass needs to have an |
| 72 | * // Assigned bitstring since if its super class's bitstring is not Assigned yet, |
| 73 | * // once it becomes Assigned, we cannot update its children's bitstrings to maintain |
| 74 | * // all the tree invariants (below) atomically. |
| 75 | * |
| 76 | * -------------------------------------------------------------------------------------------- |
| 77 | * Knowing these transitions above, we can more closely define the various terms and operations: |
| 78 | * |
| 79 | * Definitions: |
| 80 | * (see also base/bit_string.h definitions). |
| 81 | * |
| 82 | * Depth := Distance(Root, Class) |
| 83 | * Safe(Depth) := Min(Depth, MaxBitstringLen) |
| 84 | * PathToRoot := Bitstring[0..Safe(Depth)) |
| 85 | * Next := Bitstring[Depth] |
| 86 | * OF ∈ {False, True} |
| 87 | * TruncPath(D) := PathToRoot[0..D) |
| 88 | * |
| 89 | * Local Invariants: |
| 90 | * |
| 91 | * Uninitialized <=> StrLen(PathToRoot) == 0 |
| 92 | * Next == 0 |
Hans Boehm | b91f9c1 | 2017-12-19 15:01:28 -0800 | [diff] [blame] | 93 | * OF == False |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 94 | * Initialized <=> StrLen(PathToRoot) < Depth |
Hans Boehm | b91f9c1 | 2017-12-19 15:01:28 -0800 | [diff] [blame] | 95 | * Next == 1 |
| 96 | * OF == False |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 97 | * Assigned <=> StrLen(PathToRoot) == Depth |
Hans Boehm | b91f9c1 | 2017-12-19 15:01:28 -0800 | [diff] [blame] | 98 | * Next >= 1 |
| 99 | * OF == False |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 100 | * Overflowed <=> OF == True |
| 101 | * |
| 102 | * Tree Invariants: |
| 103 | * |
| 104 | * Uninitialized => |
| 105 | * forall child ∈ Children(Class): |
| 106 | * child.State == Uninitialized |
| 107 | * |
| 108 | * Assigned => |
| 109 | * forall child ∈ Children(Class): |
| 110 | * Next > Child.PathToRoot[Child.Depth-1] |
| 111 | * |
| 112 | * ! Uninitialized => |
| 113 | * forall ancestor ∈ Ancestors(Class): |
| 114 | * TruncPath(ancestor.Depth) == ancestor.PathToRoot |
| 115 | * forall unrelated ∈ (Classes - Ancestors(Class)) |
| 116 | * s.t. unrelated.State == Assigned: |
| 117 | * TruncPath(unrelated.Depth) != unrelated.PathToRoot |
| 118 | * |
| 119 | * Thread-safety invariants: |
| 120 | * |
| 121 | * Initialized <=> StrLen(PathToRoot) == Safe(Depth - 1) |
| 122 | * // Initialized State corresponds to exactly 1 bitstring. |
| 123 | * // Cannot transition from Initialized to Initialized. |
| 124 | */ |
| 125 | struct SubtypeCheckInfo { |
| 126 | // See above documentation for possible state transitions. |
| 127 | enum State { |
| 128 | kUninitialized, |
| 129 | kInitialized, |
| 130 | kAssigned, |
| 131 | kOverflowed |
| 132 | }; |
| 133 | |
| 134 | // The result of a "src IsSubType target" check: |
| 135 | enum Result { |
| 136 | kUnknownSubtypeOf, // Not enough data. Operand states weren't high enough. |
| 137 | kNotSubtypeOf, // Enough data. src is not a subchild of the target. |
| 138 | kSubtypeOf // Enough data. src is a subchild of the target. |
| 139 | }; |
| 140 | |
Vladimir Marko | 38b8b25 | 2018-01-02 19:07:06 +0000 | [diff] [blame] | 141 | // Get the raw depth. |
| 142 | size_t GetDepth() const { |
| 143 | return depth_; |
| 144 | } |
| 145 | |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 146 | // Chop off the depth, returning only the bitstring+of state. |
| 147 | // (Used to store into memory, since storing the depth would be redundant.) |
| 148 | SubtypeCheckBits GetSubtypeCheckBits() const { |
| 149 | return bitstring_and_of_; |
| 150 | } |
| 151 | |
| 152 | // Create from the depth and the bitstring+of state. |
| 153 | // This is done for convenience to avoid passing in "depth" everywhere, |
| 154 | // since our current state is almost always a function of depth. |
| 155 | static SubtypeCheckInfo Create(SubtypeCheckBits compressed_value, size_t depth) { |
| 156 | SubtypeCheckInfo io; |
| 157 | io.depth_ = depth; |
| 158 | io.bitstring_and_of_ = compressed_value; |
| 159 | io.DcheckInvariants(); |
| 160 | return io; |
| 161 | } |
| 162 | |
| 163 | // Is this a subtype of the target? |
| 164 | // |
| 165 | // The current state must be at least Initialized, and the target state |
| 166 | // must be Assigned, otherwise the result will return kUnknownSubtypeOf. |
| 167 | // |
| 168 | // Normally, return kSubtypeOf or kNotSubtypeOf. |
| 169 | Result IsSubtypeOf(const SubtypeCheckInfo& target) { |
| 170 | if (target.GetState() != SubtypeCheckInfo::kAssigned) { |
| 171 | return Result::kUnknownSubtypeOf; |
| 172 | } else if (GetState() == SubtypeCheckInfo::kUninitialized) { |
| 173 | return Result::kUnknownSubtypeOf; |
| 174 | } |
| 175 | |
| 176 | BitString::StorageType source_value = GetEncodedPathToRoot(); |
| 177 | BitString::StorageType target_value = target.GetEncodedPathToRoot(); |
| 178 | BitString::StorageType target_mask = target.GetEncodedPathToRootMask(); |
| 179 | |
| 180 | bool result = (source_value & target_mask) == (target_value); |
| 181 | if (result) { |
| 182 | DCHECK_EQ(GetPathToRoot().Truncate(target.GetSafeDepth()), target.GetPathToRoot()) |
| 183 | << "Source: " << *this << ", Target: " << target; |
| 184 | } else { |
| 185 | DCHECK_NE(GetPathToRoot().Truncate(target.GetSafeDepth()), target.GetPathToRoot()) |
| 186 | << "Source: " << *this << ", Target: " << target; |
| 187 | } |
| 188 | |
| 189 | // Note: We could've also used shifts here, as described in subtype_check_bits.h, |
| 190 | // but it doesn't make much of a difference in the Runtime since we aren't trying to optimize |
| 191 | // for code size. |
| 192 | |
| 193 | return result ? Result::kSubtypeOf : Result::kNotSubtypeOf; |
| 194 | } |
| 195 | |
| 196 | // Returns a new root SubtypeCheckInfo with a blank PathToRoot. |
| 197 | // Post-condition: The return valued has an Assigned state. |
| 198 | static SubtypeCheckInfo CreateRoot() { |
Igor Murashkin | 5573c37 | 2017-11-16 13:34:30 -0800 | [diff] [blame] | 199 | SubtypeCheckInfo io{}; |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 200 | io.depth_ = 0u; |
| 201 | io.SetNext(io.GetNext() + 1u); |
| 202 | |
| 203 | // The root is always considered assigned once it is no longer Initialized. |
| 204 | DCHECK_EQ(SubtypeCheckInfo::kAssigned, io.GetState()); |
| 205 | return io; |
| 206 | } |
| 207 | |
| 208 | // Copies the current PathToRoot into the child. |
| 209 | // |
| 210 | // If assign_next is true, then also assign a new SubtypeCheckInfo for a child by |
| 211 | // assigning the current Next value to its PathToRoot[Depth] component. |
| 212 | // Updates the current Next value as a side effect. |
| 213 | // |
| 214 | // Preconditions: State is either Assigned or Overflowed. |
| 215 | // Returns: A new child >= Initialized state. |
| 216 | SubtypeCheckInfo CreateChild(bool assign_next) { |
| 217 | SubtypeCheckInfo child = *this; // Copy everything (path, next, of). |
| 218 | child.depth_ = depth_ + 1u; |
| 219 | |
| 220 | // Must be Assigned or Overflowed in order to create a subchild. |
| 221 | DCHECK(GetState() == kAssigned || GetState() == kOverflowed) |
| 222 | << "Unexpected bitstring state: " << GetState(); |
| 223 | |
| 224 | // Begin transition to >= Initialized. |
| 225 | |
| 226 | // Always attempt to re-initialize Child's Next value. |
| 227 | // Next must be non-0 to disambiguate it from Uninitialized. |
| 228 | child.MaybeInitNext(); |
| 229 | |
Hans Boehm | b91f9c1 | 2017-12-19 15:01:28 -0800 | [diff] [blame] | 230 | // Always clear the inherited Parent's next Value, i.e. the child's last path entry. |
Igor Murashkin | 5573c37 | 2017-11-16 13:34:30 -0800 | [diff] [blame] | 231 | OverwriteNextValueFromParent(/*inout*/&child, BitStringChar{}); |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 232 | |
| 233 | // The state is now Initialized | Overflowed. |
| 234 | DCHECK_NE(kAssigned, child.GetState()) << child.GetBitString(); |
| 235 | DCHECK_NE(kUninitialized, child.GetState()) << child.GetBitString(); |
| 236 | |
| 237 | if (assign_next == false) { |
| 238 | child.DcheckInvariants(); |
| 239 | return child; |
| 240 | } |
| 241 | |
| 242 | // Begin transition to >= Assigned. |
| 243 | |
| 244 | // Assign attempt. |
| 245 | if (HasNext() && !bitstring_and_of_.overflow_) { |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 246 | BitStringChar next = GetNext(); |
| 247 | if (next != next.MaximumValue()) { |
| 248 | // The parent's "next" value is now the child's latest path element. |
| 249 | OverwriteNextValueFromParent(/*inout*/&child, next); |
| 250 | // Update self next value, so that future CreateChild calls |
| 251 | // do not get the same path value. |
| 252 | SetNext(next + 1u); |
| 253 | } else { |
| 254 | child.MarkOverflowed(); // Too wide. |
| 255 | } |
| 256 | } else { |
| 257 | child.MarkOverflowed(); // Too deep, or parent was already overflowed. |
| 258 | } |
| 259 | |
| 260 | // The state is now Assigned | Overflowed. |
| 261 | DCHECK(child.GetState() == kAssigned || child.GetState() == kOverflowed); |
| 262 | |
| 263 | child.DcheckInvariants(); |
| 264 | return child; |
| 265 | } |
| 266 | |
| 267 | // Get the current state (Uninitialized, Initialized, Assigned, or Overflowed). |
| 268 | // See the "SubtypeCheckInfo" documentation above which explains how a state is determined. |
| 269 | State GetState() const { |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 270 | if (bitstring_and_of_.overflow_) { |
| 271 | // Overflowed if and only if the OF bit was set. |
| 272 | return kOverflowed; |
| 273 | } |
| 274 | |
Hans Boehm | b91f9c1 | 2017-12-19 15:01:28 -0800 | [diff] [blame] | 275 | if (GetBitString().IsEmpty()) { |
| 276 | // Empty bitstring (all 0s) -> uninitialized. |
| 277 | return kUninitialized; |
| 278 | } |
| 279 | |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 280 | // Either Assigned or Initialized. |
| 281 | BitString path_to_root = GetPathToRoot(); |
| 282 | |
Igor Murashkin | 86083f7 | 2017-10-27 10:59:04 -0700 | [diff] [blame] | 283 | DCHECK(!HasNext() || GetNext() != 0u) |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 284 | << "Expected (Assigned|Initialized) state to have >0 Next value: " |
| 285 | << GetNext() << " path: " << path_to_root; |
| 286 | |
| 287 | if (path_to_root.Length() == depth_) { |
| 288 | return kAssigned; |
| 289 | } |
| 290 | |
| 291 | return kInitialized; |
| 292 | } |
| 293 | |
| 294 | // Retrieve the path to root bitstring as a plain uintN_t value that is amenable to |
| 295 | // be used by a fast check "encoded_src & mask_target == encoded_target". |
| 296 | BitString::StorageType GetEncodedPathToRoot() const { |
| 297 | BitString::StorageType data = static_cast<BitString::StorageType>(GetPathToRoot()); |
| 298 | // Bit strings are logically in the least-significant memory. |
Vladimir Marko | dc682aa | 2018-01-04 18:42:57 +0000 | [diff] [blame] | 299 | return data; |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 300 | } |
| 301 | |
| 302 | // Retrieve the path to root bitstring mask as a plain uintN_t that is amenable to |
| 303 | // be used by a fast check "encoded_src & mask_target == encoded_target". |
| 304 | BitString::StorageType GetEncodedPathToRootMask() const { |
| 305 | size_t num_bitchars = GetSafeDepth(); |
| 306 | size_t bitlength = BitString::GetBitLengthTotalAtPosition(num_bitchars); |
Vladimir Marko | dc682aa | 2018-01-04 18:42:57 +0000 | [diff] [blame] | 307 | return MaskLeastSignificant<BitString::StorageType>(bitlength); |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 308 | } |
| 309 | |
| 310 | // Get the "Next" bitchar, assuming that there is one to get. |
| 311 | BitStringChar GetNext() const { |
| 312 | DCHECK(HasNext()); |
| 313 | return GetBitString()[depth_]; |
| 314 | } |
| 315 | |
| 316 | // Try to get the Next value, if there is one. |
| 317 | // Returns: Whether or not there was a Next value. |
| 318 | bool MaybeGetNext(/*out*/BitStringChar* next) const { |
| 319 | DCHECK(next != nullptr); |
| 320 | |
| 321 | if (HasNext()) { |
| 322 | *next = GetBitString()[depth_]; |
| 323 | return true; |
| 324 | } |
| 325 | return false; |
| 326 | } |
| 327 | |
| 328 | private: |
| 329 | // Constructor intended for testing. Runs all invariant checks. |
| 330 | SubtypeCheckInfo(BitString path_to_root, BitStringChar next, bool overflow, size_t depth) { |
| 331 | SubtypeCheckBits iod; |
| 332 | iod.bitstring_ = path_to_root; |
| 333 | iod.overflow_ = overflow; |
| 334 | |
| 335 | bitstring_and_of_ = iod; |
| 336 | depth_ = depth; |
| 337 | |
| 338 | // Len(Path-to-root) <= Depth. |
| 339 | DCHECK_GE(depth_, path_to_root.Length()) |
| 340 | << "Path was too long for the depth, path: " << path_to_root; |
| 341 | |
| 342 | bool did_overlap = false; |
| 343 | if (HasNext()) { |
| 344 | if (kIsDebugBuild) { |
Igor Murashkin | 86083f7 | 2017-10-27 10:59:04 -0700 | [diff] [blame] | 345 | did_overlap = (GetNext() != 0u); |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 346 | } |
| 347 | |
| 348 | SetNext(next); |
| 349 | |
| 350 | DCHECK_EQ(next, GetNext()); |
| 351 | } |
| 352 | // "Next" must be set before we can check the invariants. |
| 353 | DcheckInvariants(); |
| 354 | DCHECK(!did_overlap) |
| 355 | << "Path to root overlapped with Next value, path: " << path_to_root; |
| 356 | DCHECK_EQ(path_to_root, GetPathToRoot()); |
| 357 | } |
| 358 | |
| 359 | // Factory intended for testing. Skips DcheckInvariants. |
| 360 | static SubtypeCheckInfo MakeUnchecked(BitString bitstring, bool overflow, size_t depth) { |
| 361 | SubtypeCheckBits iod; |
| 362 | iod.bitstring_ = bitstring; |
| 363 | iod.overflow_ = overflow; |
| 364 | |
| 365 | SubtypeCheckInfo io; |
| 366 | io.depth_ = depth; |
| 367 | io.bitstring_and_of_ = iod; |
| 368 | |
| 369 | return io; |
| 370 | } |
| 371 | |
| 372 | void SetNext(BitStringChar next) { |
| 373 | DCHECK(HasNext()); |
| 374 | BitString bs = GetBitString(); |
| 375 | bs.SetAt(depth_, next); |
| 376 | SetBitString(bs); |
| 377 | } |
| 378 | |
| 379 | void SetNextUnchecked(BitStringChar next) { |
| 380 | BitString bs = GetBitString(); |
| 381 | bs.SetAt(depth_, next); |
| 382 | SetBitStringUnchecked(bs); |
| 383 | } |
| 384 | |
Hans Boehm | b91f9c1 | 2017-12-19 15:01:28 -0800 | [diff] [blame] | 385 | // If there is a next field, set it to 1. |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 386 | void MaybeInitNext() { |
| 387 | if (HasNext()) { |
| 388 | // Clearing out the "Next" value like this |
| 389 | // is often an intermediate operation which temporarily |
| 390 | // violates the invariants. Do not do the extra dchecks. |
Igor Murashkin | 5573c37 | 2017-11-16 13:34:30 -0800 | [diff] [blame] | 391 | SetNextUnchecked(BitStringChar{}); |
Igor Murashkin | f31a00c | 2017-10-27 10:52:07 -0700 | [diff] [blame] | 392 | SetNextUnchecked(GetNext()+1u); |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | BitString GetPathToRoot() const { |
| 397 | size_t end = GetSafeDepth(); |
| 398 | return GetBitString().Truncate(end); |
| 399 | } |
| 400 | |
| 401 | bool HasNext() const { |
| 402 | return depth_ < BitString::kCapacity; |
| 403 | } |
| 404 | |
| 405 | void MarkOverflowed() { |
| 406 | bitstring_and_of_.overflow_ = true; |
| 407 | } |
| 408 | |
| 409 | static constexpr bool HasBitStringCharStorage(size_t idx) { |
| 410 | return idx < BitString::kCapacity; |
| 411 | } |
| 412 | |
| 413 | size_t GetSafeDepth() const { |
| 414 | return GetSafeDepth(depth_); |
| 415 | } |
| 416 | |
| 417 | // Get a "safe" depth, one that is truncated to the bitstring max capacity. |
| 418 | // Using a value larger than this will cause undefined behavior. |
| 419 | static size_t GetSafeDepth(size_t depth) { |
| 420 | return std::min(depth, BitString::kCapacity); |
| 421 | } |
| 422 | |
| 423 | BitString GetBitString() const { |
| 424 | return bitstring_and_of_.bitstring_; |
| 425 | } |
| 426 | |
| 427 | void SetBitString(const BitString& val) { |
| 428 | SetBitStringUnchecked(val); |
| 429 | DcheckInvariants(); |
| 430 | } |
| 431 | |
| 432 | void SetBitStringUnchecked(const BitString& val) { |
| 433 | bitstring_and_of_.bitstring_ = val; |
| 434 | } |
| 435 | |
| 436 | void OverwriteNextValueFromParent(/*inout*/SubtypeCheckInfo* child, BitStringChar value) const { |
| 437 | // Helper function for CreateChild. |
| 438 | if (HasNext()) { |
| 439 | // When we copied the "Next" value, it is now our |
| 440 | // last path component in the child. |
| 441 | // Always overwrite it with either a cleared value or the parent's Next value. |
| 442 | BitString bs = child->GetBitString(); |
| 443 | |
| 444 | // Safe write. This.Next always occupies same slot as Child[Depth_]. |
| 445 | DCHECK(child->HasBitStringCharStorage(depth_)); |
| 446 | |
| 447 | bs.SetAt(depth_, value); |
| 448 | |
| 449 | // The child is temporarily in a bad state until it is fixed up further. |
| 450 | // Do not do the normal dchecks which do not allow transient badness. |
| 451 | child->SetBitStringUnchecked(bs); |
| 452 | } |
| 453 | } |
| 454 | |
| 455 | void DcheckInvariants() const { |
| 456 | if (kIsDebugBuild) { |
| 457 | CHECK_GE(GetSafeDepth(depth_ + 1u), GetBitString().Length()) |
| 458 | << "Bitstring too long for depth, bitstring: " << GetBitString() << ", depth: " << depth_; |
| 459 | |
| 460 | BitString path_to_root = GetPathToRoot(); |
| 461 | |
| 462 | // A 'null' (\0) character in path-to-root must be followed only |
| 463 | // by other null characters. |
| 464 | size_t i; |
| 465 | for (i = 0; i < BitString::kCapacity; ++i) { |
| 466 | BitStringChar bc = path_to_root[i]; |
| 467 | if (bc == 0u) { |
| 468 | break; |
| 469 | } |
| 470 | } |
| 471 | |
| 472 | // All characters following a 0 must also be 0. |
| 473 | for (; i < BitString::kCapacity; ++i) { |
| 474 | BitStringChar bc = path_to_root[i]; |
| 475 | if (bc != 0u) { |
| 476 | LOG(FATAL) << "Path to root had non-0s following 0s: " << path_to_root; |
| 477 | } |
| 478 | } |
| 479 | |
| 480 | // Trigger any dchecks in GetState. |
| 481 | (void)GetState(); |
| 482 | } |
| 483 | } |
| 484 | |
| 485 | SubtypeCheckInfo() = default; |
| 486 | size_t depth_; |
| 487 | SubtypeCheckBits bitstring_and_of_; |
| 488 | |
| 489 | friend struct ::SubtypeCheckInfoTest; |
| 490 | friend std::ostream& operator<<(std::ostream& os, const SubtypeCheckInfo& io); |
| 491 | }; |
| 492 | |
| 493 | // Prints the SubtypeCheckInfo::State, e.g. "kUnitialized". |
| 494 | inline std::ostream& operator<<(std::ostream& os, const SubtypeCheckInfo::State& state) { |
| 495 | switch (state) { |
| 496 | case SubtypeCheckInfo::kUninitialized: |
| 497 | os << "kUninitialized"; |
| 498 | break; |
| 499 | case SubtypeCheckInfo::kInitialized: |
| 500 | os << "kInitialized"; |
| 501 | break; |
| 502 | case SubtypeCheckInfo::kAssigned: |
| 503 | os << "kAssigned"; |
| 504 | break; |
| 505 | case SubtypeCheckInfo::kOverflowed: |
| 506 | os << "kOverflowed"; |
| 507 | break; |
| 508 | default: |
| 509 | os << "(Invalid SubtypeCheckInfo::State " << static_cast<int>(state) << ")"; |
| 510 | } |
| 511 | return os; |
| 512 | } |
| 513 | |
| 514 | // Prints e.g. "SubtypeCheckInfo{BitString[1,2,3], depth: 3, of:1}" |
| 515 | inline std::ostream& operator<<(std::ostream& os, const SubtypeCheckInfo& io) { |
| 516 | os << "SubtypeCheckInfo{" << io.GetBitString() << ", " |
| 517 | << "depth: " << io.depth_ << ", of:" << io.bitstring_and_of_.overflow_ << "}"; |
| 518 | return os; |
| 519 | } |
| 520 | |
| 521 | } // namespace art |
| 522 | |
| 523 | #endif // ART_RUNTIME_SUBTYPE_CHECK_INFO_H_ |