Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 1 | // Copyright 2015 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/crankshaft/s390/lithium-gap-resolver-s390.h" |
| 6 | |
| 7 | #include "src/crankshaft/s390/lithium-codegen-s390.h" |
| 8 | |
| 9 | namespace v8 { |
| 10 | namespace internal { |
| 11 | |
| 12 | static const Register kSavedValueRegister = {1}; |
| 13 | |
| 14 | LGapResolver::LGapResolver(LCodeGen* owner) |
| 15 | : cgen_(owner), |
| 16 | moves_(32, owner->zone()), |
| 17 | root_index_(0), |
| 18 | in_cycle_(false), |
| 19 | saved_destination_(NULL) {} |
| 20 | |
| 21 | void LGapResolver::Resolve(LParallelMove* parallel_move) { |
| 22 | DCHECK(moves_.is_empty()); |
| 23 | // Build up a worklist of moves. |
| 24 | BuildInitialMoveList(parallel_move); |
| 25 | |
| 26 | for (int i = 0; i < moves_.length(); ++i) { |
| 27 | LMoveOperands move = moves_[i]; |
| 28 | // Skip constants to perform them last. They don't block other moves |
| 29 | // and skipping such moves with register destinations keeps those |
| 30 | // registers free for the whole algorithm. |
| 31 | if (!move.IsEliminated() && !move.source()->IsConstantOperand()) { |
| 32 | root_index_ = i; // Any cycle is found when by reaching this move again. |
| 33 | PerformMove(i); |
| 34 | if (in_cycle_) { |
| 35 | RestoreValue(); |
| 36 | } |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | // Perform the moves with constant sources. |
| 41 | for (int i = 0; i < moves_.length(); ++i) { |
| 42 | if (!moves_[i].IsEliminated()) { |
| 43 | DCHECK(moves_[i].source()->IsConstantOperand()); |
| 44 | EmitMove(i); |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | moves_.Rewind(0); |
| 49 | } |
| 50 | |
| 51 | void LGapResolver::BuildInitialMoveList(LParallelMove* parallel_move) { |
| 52 | // Perform a linear sweep of the moves to add them to the initial list of |
| 53 | // moves to perform, ignoring any move that is redundant (the source is |
| 54 | // the same as the destination, the destination is ignored and |
| 55 | // unallocated, or the move was already eliminated). |
| 56 | const ZoneList<LMoveOperands>* moves = parallel_move->move_operands(); |
| 57 | for (int i = 0; i < moves->length(); ++i) { |
| 58 | LMoveOperands move = moves->at(i); |
| 59 | if (!move.IsRedundant()) moves_.Add(move, cgen_->zone()); |
| 60 | } |
| 61 | Verify(); |
| 62 | } |
| 63 | |
| 64 | void LGapResolver::PerformMove(int index) { |
| 65 | // Each call to this function performs a move and deletes it from the move |
| 66 | // graph. We first recursively perform any move blocking this one. We |
| 67 | // mark a move as "pending" on entry to PerformMove in order to detect |
| 68 | // cycles in the move graph. |
| 69 | |
| 70 | // We can only find a cycle, when doing a depth-first traversal of moves, |
| 71 | // be encountering the starting move again. So by spilling the source of |
| 72 | // the starting move, we break the cycle. All moves are then unblocked, |
| 73 | // and the starting move is completed by writing the spilled value to |
| 74 | // its destination. All other moves from the spilled source have been |
| 75 | // completed prior to breaking the cycle. |
| 76 | // An additional complication is that moves to MemOperands with large |
| 77 | // offsets (more than 1K or 4K) require us to spill this spilled value to |
| 78 | // the stack, to free up the register. |
| 79 | DCHECK(!moves_[index].IsPending()); |
| 80 | DCHECK(!moves_[index].IsRedundant()); |
| 81 | |
| 82 | // Clear this move's destination to indicate a pending move. The actual |
| 83 | // destination is saved in a stack allocated local. Multiple moves can |
| 84 | // be pending because this function is recursive. |
| 85 | DCHECK(moves_[index].source() != NULL); // Or else it will look eliminated. |
| 86 | LOperand* destination = moves_[index].destination(); |
| 87 | moves_[index].set_destination(NULL); |
| 88 | |
| 89 | // Perform a depth-first traversal of the move graph to resolve |
| 90 | // dependencies. Any unperformed, unpending move with a source the same |
| 91 | // as this one's destination blocks this one so recursively perform all |
| 92 | // such moves. |
| 93 | for (int i = 0; i < moves_.length(); ++i) { |
| 94 | LMoveOperands other_move = moves_[i]; |
| 95 | if (other_move.Blocks(destination) && !other_move.IsPending()) { |
| 96 | PerformMove(i); |
| 97 | // If there is a blocking, pending move it must be moves_[root_index_] |
| 98 | // and all other moves with the same source as moves_[root_index_] are |
| 99 | // sucessfully executed (because they are cycle-free) by this loop. |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | // We are about to resolve this move and don't need it marked as |
| 104 | // pending, so restore its destination. |
| 105 | moves_[index].set_destination(destination); |
| 106 | |
| 107 | // The move may be blocked on a pending move, which must be the starting move. |
| 108 | // In this case, we have a cycle, and we save the source of this move to |
| 109 | // a scratch register to break it. |
| 110 | LMoveOperands other_move = moves_[root_index_]; |
| 111 | if (other_move.Blocks(destination)) { |
| 112 | DCHECK(other_move.IsPending()); |
| 113 | BreakCycle(index); |
| 114 | return; |
| 115 | } |
| 116 | |
| 117 | // This move is no longer blocked. |
| 118 | EmitMove(index); |
| 119 | } |
| 120 | |
| 121 | void LGapResolver::Verify() { |
| 122 | #ifdef ENABLE_SLOW_DCHECKS |
| 123 | // No operand should be the destination for more than one move. |
| 124 | for (int i = 0; i < moves_.length(); ++i) { |
| 125 | LOperand* destination = moves_[i].destination(); |
| 126 | for (int j = i + 1; j < moves_.length(); ++j) { |
| 127 | SLOW_DCHECK(!destination->Equals(moves_[j].destination())); |
| 128 | } |
| 129 | } |
| 130 | #endif |
| 131 | } |
| 132 | |
| 133 | #define __ ACCESS_MASM(cgen_->masm()) |
| 134 | |
| 135 | void LGapResolver::BreakCycle(int index) { |
| 136 | // We save in a register the value that should end up in the source of |
| 137 | // moves_[root_index]. After performing all moves in the tree rooted |
| 138 | // in that move, we save the value to that source. |
| 139 | DCHECK(moves_[index].destination()->Equals(moves_[root_index_].source())); |
| 140 | DCHECK(!in_cycle_); |
| 141 | in_cycle_ = true; |
| 142 | LOperand* source = moves_[index].source(); |
| 143 | saved_destination_ = moves_[index].destination(); |
| 144 | if (source->IsRegister()) { |
| 145 | __ LoadRR(kSavedValueRegister, cgen_->ToRegister(source)); |
| 146 | } else if (source->IsStackSlot()) { |
| 147 | __ LoadP(kSavedValueRegister, cgen_->ToMemOperand(source)); |
| 148 | } else if (source->IsDoubleRegister()) { |
| 149 | __ ldr(kScratchDoubleReg, cgen_->ToDoubleRegister(source)); |
| 150 | } else if (source->IsDoubleStackSlot()) { |
| 151 | __ LoadDouble(kScratchDoubleReg, cgen_->ToMemOperand(source)); |
| 152 | } else { |
| 153 | UNREACHABLE(); |
| 154 | } |
| 155 | // This move will be done by restoring the saved value to the destination. |
| 156 | moves_[index].Eliminate(); |
| 157 | } |
| 158 | |
| 159 | void LGapResolver::RestoreValue() { |
| 160 | DCHECK(in_cycle_); |
| 161 | DCHECK(saved_destination_ != NULL); |
| 162 | |
| 163 | // Spilled value is in kSavedValueRegister or kSavedDoubleValueRegister. |
| 164 | if (saved_destination_->IsRegister()) { |
| 165 | __ LoadRR(cgen_->ToRegister(saved_destination_), kSavedValueRegister); |
| 166 | } else if (saved_destination_->IsStackSlot()) { |
| 167 | __ StoreP(kSavedValueRegister, cgen_->ToMemOperand(saved_destination_)); |
| 168 | } else if (saved_destination_->IsDoubleRegister()) { |
| 169 | __ ldr(cgen_->ToDoubleRegister(saved_destination_), kScratchDoubleReg); |
| 170 | } else if (saved_destination_->IsDoubleStackSlot()) { |
| 171 | __ StoreDouble(kScratchDoubleReg, cgen_->ToMemOperand(saved_destination_)); |
| 172 | } else { |
| 173 | UNREACHABLE(); |
| 174 | } |
| 175 | |
| 176 | in_cycle_ = false; |
| 177 | saved_destination_ = NULL; |
| 178 | } |
| 179 | |
| 180 | void LGapResolver::EmitMove(int index) { |
| 181 | LOperand* source = moves_[index].source(); |
| 182 | LOperand* destination = moves_[index].destination(); |
| 183 | |
| 184 | // Dispatch on the source and destination operand kinds. Not all |
| 185 | // combinations are possible. |
| 186 | |
| 187 | if (source->IsRegister()) { |
| 188 | Register source_register = cgen_->ToRegister(source); |
| 189 | if (destination->IsRegister()) { |
| 190 | __ LoadRR(cgen_->ToRegister(destination), source_register); |
| 191 | } else { |
| 192 | DCHECK(destination->IsStackSlot()); |
| 193 | __ StoreP(source_register, cgen_->ToMemOperand(destination)); |
| 194 | } |
| 195 | } else if (source->IsStackSlot()) { |
| 196 | MemOperand source_operand = cgen_->ToMemOperand(source); |
| 197 | if (destination->IsRegister()) { |
| 198 | __ LoadP(cgen_->ToRegister(destination), source_operand); |
| 199 | } else { |
| 200 | DCHECK(destination->IsStackSlot()); |
| 201 | MemOperand destination_operand = cgen_->ToMemOperand(destination); |
| 202 | if (in_cycle_) { |
| 203 | __ LoadP(ip, source_operand); |
| 204 | __ StoreP(ip, destination_operand); |
| 205 | } else { |
| 206 | __ LoadP(kSavedValueRegister, source_operand); |
| 207 | __ StoreP(kSavedValueRegister, destination_operand); |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | } else if (source->IsConstantOperand()) { |
| 212 | LConstantOperand* constant_source = LConstantOperand::cast(source); |
| 213 | if (destination->IsRegister()) { |
| 214 | Register dst = cgen_->ToRegister(destination); |
| 215 | if (cgen_->IsInteger32(constant_source)) { |
| 216 | cgen_->EmitLoadIntegerConstant(constant_source, dst); |
| 217 | } else { |
| 218 | __ Move(dst, cgen_->ToHandle(constant_source)); |
| 219 | } |
| 220 | } else if (destination->IsDoubleRegister()) { |
| 221 | DoubleRegister result = cgen_->ToDoubleRegister(destination); |
| 222 | double v = cgen_->ToDouble(constant_source); |
| 223 | __ LoadDoubleLiteral(result, v, ip); |
| 224 | } else { |
| 225 | DCHECK(destination->IsStackSlot()); |
| 226 | DCHECK(!in_cycle_); // Constant moves happen after all cycles are gone. |
| 227 | if (cgen_->IsInteger32(constant_source)) { |
| 228 | cgen_->EmitLoadIntegerConstant(constant_source, kSavedValueRegister); |
| 229 | } else { |
| 230 | __ Move(kSavedValueRegister, cgen_->ToHandle(constant_source)); |
| 231 | } |
| 232 | __ StoreP(kSavedValueRegister, cgen_->ToMemOperand(destination)); |
| 233 | } |
| 234 | |
| 235 | } else if (source->IsDoubleRegister()) { |
| 236 | DoubleRegister source_register = cgen_->ToDoubleRegister(source); |
| 237 | if (destination->IsDoubleRegister()) { |
| 238 | __ ldr(cgen_->ToDoubleRegister(destination), source_register); |
| 239 | } else { |
| 240 | DCHECK(destination->IsDoubleStackSlot()); |
| 241 | __ StoreDouble(source_register, cgen_->ToMemOperand(destination)); |
| 242 | } |
| 243 | |
| 244 | } else if (source->IsDoubleStackSlot()) { |
| 245 | MemOperand source_operand = cgen_->ToMemOperand(source); |
| 246 | if (destination->IsDoubleRegister()) { |
| 247 | __ LoadDouble(cgen_->ToDoubleRegister(destination), source_operand); |
| 248 | } else { |
| 249 | DCHECK(destination->IsDoubleStackSlot()); |
| 250 | MemOperand destination_operand = cgen_->ToMemOperand(destination); |
| 251 | if (in_cycle_) { |
| 252 | // kSavedDoubleValueRegister was used to break the cycle, |
| 253 | // but kSavedValueRegister is free. |
| 254 | #if V8_TARGET_ARCH_S390X |
| 255 | __ lg(kSavedValueRegister, source_operand); |
| 256 | __ stg(kSavedValueRegister, destination_operand); |
| 257 | #else |
| 258 | MemOperand source_high_operand = cgen_->ToHighMemOperand(source); |
| 259 | MemOperand destination_high_operand = |
| 260 | cgen_->ToHighMemOperand(destination); |
| 261 | __ LoadlW(kSavedValueRegister, source_operand); |
| 262 | __ StoreW(kSavedValueRegister, destination_operand); |
| 263 | __ LoadlW(kSavedValueRegister, source_high_operand); |
| 264 | __ StoreW(kSavedValueRegister, destination_high_operand); |
| 265 | #endif |
| 266 | } else { |
| 267 | __ LoadDouble(kScratchDoubleReg, source_operand); |
| 268 | __ StoreDouble(kScratchDoubleReg, destination_operand); |
| 269 | } |
| 270 | } |
| 271 | } else { |
| 272 | UNREACHABLE(); |
| 273 | } |
| 274 | |
| 275 | moves_[index].Eliminate(); |
| 276 | } |
| 277 | |
| 278 | #undef __ |
| 279 | } // namespace internal |
| 280 | } // namespace v8 |