Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 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 | #include "register_allocator.h" |
| 18 | |
| 19 | #include <iostream> |
| 20 | #include <sstream> |
| 21 | |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 22 | #include "base/scoped_arena_allocator.h" |
| 23 | #include "base/scoped_arena_containers.h" |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 24 | #include "base/bit_vector-inl.h" |
| 25 | #include "code_generator.h" |
Matthew Gharrity | d9ffd0d | 2016-06-22 10:27:55 -0700 | [diff] [blame] | 26 | #include "register_allocator_graph_color.h" |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 27 | #include "register_allocator_linear_scan.h" |
| 28 | #include "ssa_liveness_analysis.h" |
| 29 | |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 30 | namespace art { |
| 31 | |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 32 | RegisterAllocator::RegisterAllocator(ScopedArenaAllocator* allocator, |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 33 | CodeGenerator* codegen, |
| 34 | const SsaLivenessAnalysis& liveness) |
| 35 | : allocator_(allocator), |
| 36 | codegen_(codegen), |
| 37 | liveness_(liveness) {} |
| 38 | |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 39 | std::unique_ptr<RegisterAllocator> RegisterAllocator::Create(ScopedArenaAllocator* allocator, |
| 40 | CodeGenerator* codegen, |
| 41 | const SsaLivenessAnalysis& analysis, |
| 42 | Strategy strategy) { |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 43 | switch (strategy) { |
| 44 | case kRegisterAllocatorLinearScan: |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 45 | return std::unique_ptr<RegisterAllocator>( |
| 46 | new (allocator) RegisterAllocatorLinearScan(allocator, codegen, analysis)); |
Matthew Gharrity | d9ffd0d | 2016-06-22 10:27:55 -0700 | [diff] [blame] | 47 | case kRegisterAllocatorGraphColor: |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 48 | return std::unique_ptr<RegisterAllocator>( |
| 49 | new (allocator) RegisterAllocatorGraphColor(allocator, codegen, analysis)); |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 50 | default: |
| 51 | LOG(FATAL) << "Invalid register allocation strategy: " << strategy; |
| 52 | UNREACHABLE(); |
| 53 | } |
| 54 | } |
| 55 | |
Vladimir Marko | bea75ff | 2017-10-11 20:39:54 +0100 | [diff] [blame] | 56 | RegisterAllocator::~RegisterAllocator() { |
| 57 | if (kIsDebugBuild) { |
| 58 | // Poison live interval pointers with "Error: BAD 71ve1nt3rval." |
| 59 | LiveInterval* bad_live_interval = reinterpret_cast<LiveInterval*>(0xebad7113u); |
| 60 | for (HBasicBlock* block : codegen_->GetGraph()->GetLinearOrder()) { |
| 61 | for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) { |
| 62 | it.Current()->SetLiveInterval(bad_live_interval); |
| 63 | } |
| 64 | for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) { |
| 65 | it.Current()->SetLiveInterval(bad_live_interval); |
| 66 | } |
| 67 | } |
| 68 | } |
| 69 | } |
| 70 | |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 71 | bool RegisterAllocator::CanAllocateRegistersFor(const HGraph& graph ATTRIBUTE_UNUSED, |
| 72 | InstructionSet instruction_set) { |
Vladimir Marko | 33bff25 | 2017-11-01 14:35:42 +0000 | [diff] [blame] | 73 | return instruction_set == InstructionSet::kArm |
| 74 | || instruction_set == InstructionSet::kArm64 |
| 75 | || instruction_set == InstructionSet::kMips |
| 76 | || instruction_set == InstructionSet::kMips64 |
| 77 | || instruction_set == InstructionSet::kThumb2 |
| 78 | || instruction_set == InstructionSet::kX86 |
| 79 | || instruction_set == InstructionSet::kX86_64; |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 80 | } |
| 81 | |
| 82 | class AllRangesIterator : public ValueObject { |
| 83 | public: |
| 84 | explicit AllRangesIterator(LiveInterval* interval) |
| 85 | : current_interval_(interval), |
| 86 | current_range_(interval->GetFirstRange()) {} |
| 87 | |
| 88 | bool Done() const { return current_interval_ == nullptr; } |
| 89 | LiveRange* CurrentRange() const { return current_range_; } |
| 90 | LiveInterval* CurrentInterval() const { return current_interval_; } |
| 91 | |
| 92 | void Advance() { |
| 93 | current_range_ = current_range_->GetNext(); |
| 94 | if (current_range_ == nullptr) { |
| 95 | current_interval_ = current_interval_->GetNextSibling(); |
| 96 | if (current_interval_ != nullptr) { |
| 97 | current_range_ = current_interval_->GetFirstRange(); |
| 98 | } |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | private: |
| 103 | LiveInterval* current_interval_; |
| 104 | LiveRange* current_range_; |
| 105 | |
| 106 | DISALLOW_COPY_AND_ASSIGN(AllRangesIterator); |
| 107 | }; |
| 108 | |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 109 | bool RegisterAllocator::ValidateIntervals(ArrayRef<LiveInterval* const> intervals, |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 110 | size_t number_of_spill_slots, |
| 111 | size_t number_of_out_slots, |
| 112 | const CodeGenerator& codegen, |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 113 | bool processing_core_registers, |
| 114 | bool log_fatal_on_failure) { |
| 115 | size_t number_of_registers = processing_core_registers |
| 116 | ? codegen.GetNumberOfCoreRegisters() |
| 117 | : codegen.GetNumberOfFloatingPointRegisters(); |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 118 | ScopedArenaAllocator allocator(codegen.GetGraph()->GetArenaStack()); |
| 119 | ScopedArenaVector<ArenaBitVector*> liveness_of_values( |
| 120 | allocator.Adapter(kArenaAllocRegisterAllocatorValidate)); |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 121 | liveness_of_values.reserve(number_of_registers + number_of_spill_slots); |
| 122 | |
| 123 | size_t max_end = 0u; |
| 124 | for (LiveInterval* start_interval : intervals) { |
| 125 | for (AllRangesIterator it(start_interval); !it.Done(); it.Advance()) { |
| 126 | max_end = std::max(max_end, it.CurrentRange()->GetEnd()); |
| 127 | } |
| 128 | } |
| 129 | |
| 130 | // Allocate a bit vector per register. A live interval that has a register |
| 131 | // allocated will populate the associated bit vector based on its live ranges. |
| 132 | for (size_t i = 0; i < number_of_registers + number_of_spill_slots; ++i) { |
| 133 | liveness_of_values.push_back( |
Vladimir Marko | e764d2e | 2017-10-05 14:35:55 +0100 | [diff] [blame] | 134 | ArenaBitVector::Create(&allocator, max_end, false, kArenaAllocRegisterAllocatorValidate)); |
| 135 | liveness_of_values.back()->ClearAllBits(); |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 136 | } |
| 137 | |
| 138 | for (LiveInterval* start_interval : intervals) { |
| 139 | for (AllRangesIterator it(start_interval); !it.Done(); it.Advance()) { |
| 140 | LiveInterval* current = it.CurrentInterval(); |
| 141 | HInstruction* defined_by = current->GetParent()->GetDefinedBy(); |
| 142 | if (current->GetParent()->HasSpillSlot() |
| 143 | // Parameters and current method have their own stack slot. |
| 144 | && !(defined_by != nullptr && (defined_by->IsParameterValue() |
| 145 | || defined_by->IsCurrentMethod()))) { |
| 146 | BitVector* liveness_of_spill_slot = liveness_of_values[number_of_registers |
| 147 | + current->GetParent()->GetSpillSlot() / kVRegSize |
| 148 | - number_of_out_slots]; |
| 149 | for (size_t j = it.CurrentRange()->GetStart(); j < it.CurrentRange()->GetEnd(); ++j) { |
| 150 | if (liveness_of_spill_slot->IsBitSet(j)) { |
| 151 | if (log_fatal_on_failure) { |
| 152 | std::ostringstream message; |
| 153 | message << "Spill slot conflict at " << j; |
| 154 | LOG(FATAL) << message.str(); |
| 155 | } else { |
| 156 | return false; |
| 157 | } |
| 158 | } else { |
| 159 | liveness_of_spill_slot->SetBit(j); |
| 160 | } |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | if (current->HasRegister()) { |
| 165 | if (kIsDebugBuild && log_fatal_on_failure && !current->IsFixed()) { |
| 166 | // Only check when an error is fatal. Only tests code ask for non-fatal failures |
| 167 | // and test code may not properly fill the right information to the code generator. |
| 168 | CHECK(codegen.HasAllocatedRegister(processing_core_registers, current->GetRegister())); |
| 169 | } |
| 170 | BitVector* liveness_of_register = liveness_of_values[current->GetRegister()]; |
| 171 | for (size_t j = it.CurrentRange()->GetStart(); j < it.CurrentRange()->GetEnd(); ++j) { |
| 172 | if (liveness_of_register->IsBitSet(j)) { |
| 173 | if (current->IsUsingInputRegister() && current->CanUseInputRegister()) { |
| 174 | continue; |
| 175 | } |
| 176 | if (log_fatal_on_failure) { |
| 177 | std::ostringstream message; |
| 178 | message << "Register conflict at " << j << " "; |
| 179 | if (defined_by != nullptr) { |
| 180 | message << "(" << defined_by->DebugName() << ")"; |
| 181 | } |
| 182 | message << "for "; |
| 183 | if (processing_core_registers) { |
| 184 | codegen.DumpCoreRegister(message, current->GetRegister()); |
| 185 | } else { |
| 186 | codegen.DumpFloatingPointRegister(message, current->GetRegister()); |
| 187 | } |
Matthew Gharrity | d9ffd0d | 2016-06-22 10:27:55 -0700 | [diff] [blame] | 188 | for (LiveInterval* interval : intervals) { |
| 189 | if (interval->HasRegister() |
| 190 | && interval->GetRegister() == current->GetRegister() |
| 191 | && interval->CoversSlow(j)) { |
| 192 | message << std::endl; |
| 193 | if (interval->GetDefinedBy() != nullptr) { |
| 194 | message << interval->GetDefinedBy()->GetKind() << " "; |
| 195 | } else { |
| 196 | message << "physical "; |
| 197 | } |
| 198 | interval->Dump(message); |
| 199 | } |
| 200 | } |
Matthew Gharrity | 8f49d4b | 2016-07-14 13:24:00 -0700 | [diff] [blame] | 201 | LOG(FATAL) << message.str(); |
| 202 | } else { |
| 203 | return false; |
| 204 | } |
| 205 | } else { |
| 206 | liveness_of_register->SetBit(j); |
| 207 | } |
| 208 | } |
| 209 | } |
| 210 | } |
| 211 | } |
| 212 | return true; |
| 213 | } |
| 214 | |
| 215 | LiveInterval* RegisterAllocator::Split(LiveInterval* interval, size_t position) { |
| 216 | DCHECK_GE(position, interval->GetStart()); |
| 217 | DCHECK(!interval->IsDeadAt(position)); |
| 218 | if (position == interval->GetStart()) { |
| 219 | // Spill slot will be allocated when handling `interval` again. |
| 220 | interval->ClearRegister(); |
| 221 | if (interval->HasHighInterval()) { |
| 222 | interval->GetHighInterval()->ClearRegister(); |
| 223 | } else if (interval->HasLowInterval()) { |
| 224 | interval->GetLowInterval()->ClearRegister(); |
| 225 | } |
| 226 | return interval; |
| 227 | } else { |
| 228 | LiveInterval* new_interval = interval->SplitAt(position); |
| 229 | if (interval->HasHighInterval()) { |
| 230 | LiveInterval* high = interval->GetHighInterval()->SplitAt(position); |
| 231 | new_interval->SetHighInterval(high); |
| 232 | high->SetLowInterval(new_interval); |
| 233 | } else if (interval->HasLowInterval()) { |
| 234 | LiveInterval* low = interval->GetLowInterval()->SplitAt(position); |
| 235 | new_interval->SetLowInterval(low); |
| 236 | low->SetHighInterval(new_interval); |
| 237 | } |
| 238 | return new_interval; |
| 239 | } |
| 240 | } |
| 241 | |
| 242 | LiveInterval* RegisterAllocator::SplitBetween(LiveInterval* interval, size_t from, size_t to) { |
| 243 | HBasicBlock* block_from = liveness_.GetBlockFromPosition(from / 2); |
| 244 | HBasicBlock* block_to = liveness_.GetBlockFromPosition(to / 2); |
| 245 | DCHECK(block_from != nullptr); |
| 246 | DCHECK(block_to != nullptr); |
| 247 | |
| 248 | // Both locations are in the same block. We split at the given location. |
| 249 | if (block_from == block_to) { |
| 250 | return Split(interval, to); |
| 251 | } |
| 252 | |
| 253 | /* |
| 254 | * Non-linear control flow will force moves at every branch instruction to the new location. |
| 255 | * To avoid having all branches doing the moves, we find the next non-linear position and |
| 256 | * split the interval at this position. Take the following example (block number is the linear |
| 257 | * order position): |
| 258 | * |
| 259 | * B1 |
| 260 | * / \ |
| 261 | * B2 B3 |
| 262 | * \ / |
| 263 | * B4 |
| 264 | * |
| 265 | * B2 needs to split an interval, whose next use is in B4. If we were to split at the |
| 266 | * beginning of B4, B3 would need to do a move between B3 and B4 to ensure the interval |
| 267 | * is now in the correct location. It makes performance worst if the interval is spilled |
| 268 | * and both B2 and B3 need to reload it before entering B4. |
| 269 | * |
| 270 | * By splitting at B3, we give a chance to the register allocator to allocate the |
| 271 | * interval to the same register as in B1, and therefore avoid doing any |
| 272 | * moves in B3. |
| 273 | */ |
| 274 | if (block_from->GetDominator() != nullptr) { |
| 275 | for (HBasicBlock* dominated : block_from->GetDominator()->GetDominatedBlocks()) { |
| 276 | size_t position = dominated->GetLifetimeStart(); |
| 277 | if ((position > from) && (block_to->GetLifetimeStart() > position)) { |
| 278 | // Even if we found a better block, we continue iterating in case |
| 279 | // a dominated block is closer. |
| 280 | // Note that dominated blocks are not sorted in liveness order. |
| 281 | block_to = dominated; |
| 282 | DCHECK_NE(block_to, block_from); |
| 283 | } |
| 284 | } |
| 285 | } |
| 286 | |
| 287 | // If `to` is in a loop, find the outermost loop header which does not contain `from`. |
| 288 | for (HLoopInformationOutwardIterator it(*block_to); !it.Done(); it.Advance()) { |
| 289 | HBasicBlock* header = it.Current()->GetHeader(); |
| 290 | if (block_from->GetLifetimeStart() >= header->GetLifetimeStart()) { |
| 291 | break; |
| 292 | } |
| 293 | block_to = header; |
| 294 | } |
| 295 | |
| 296 | // Split at the start of the found block, to piggy back on existing moves |
| 297 | // due to resolution if non-linear control flow (see `ConnectSplitSiblings`). |
| 298 | return Split(interval, block_to->GetLifetimeStart()); |
| 299 | } |
| 300 | |
| 301 | } // namespace art |