1 // Copyright 2011 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #include "v8.h" 29 30 #if defined(V8_TARGET_ARCH_X64) 31 32 #include "x64/lithium-gap-resolver-x64.h" 33 #include "x64/lithium-codegen-x64.h" 34 35 namespace v8 { 36 namespace internal { 37 38 LGapResolver::LGapResolver(LCodeGen* owner) 39 : cgen_(owner), moves_(32) {} 40 41 42 void LGapResolver::Resolve(LParallelMove* parallel_move) { 43 ASSERT(moves_.is_empty()); 44 // Build up a worklist of moves. 45 BuildInitialMoveList(parallel_move); 46 47 for (int i = 0; i < moves_.length(); ++i) { 48 LMoveOperands move = moves_[i]; 49 // Skip constants to perform them last. They don't block other moves 50 // and skipping such moves with register destinations keeps those 51 // registers free for the whole algorithm. 52 if (!move.IsEliminated() && !move.source()->IsConstantOperand()) { 53 PerformMove(i); 54 } 55 } 56 57 // Perform the moves with constant sources. 58 for (int i = 0; i < moves_.length(); ++i) { 59 if (!moves_[i].IsEliminated()) { 60 ASSERT(moves_[i].source()->IsConstantOperand()); 61 EmitMove(i); 62 } 63 } 64 65 moves_.Rewind(0); 66 } 67 68 69 void LGapResolver::BuildInitialMoveList(LParallelMove* parallel_move) { 70 // Perform a linear sweep of the moves to add them to the initial list of 71 // moves to perform, ignoring any move that is redundant (the source is 72 // the same as the destination, the destination is ignored and 73 // unallocated, or the move was already eliminated). 74 const ZoneList<LMoveOperands>* moves = parallel_move->move_operands(); 75 for (int i = 0; i < moves->length(); ++i) { 76 LMoveOperands move = moves->at(i); 77 if (!move.IsRedundant()) moves_.Add(move); 78 } 79 Verify(); 80 } 81 82 83 void LGapResolver::PerformMove(int index) { 84 // Each call to this function performs a move and deletes it from the move 85 // graph. We first recursively perform any move blocking this one. We 86 // mark a move as "pending" on entry to PerformMove in order to detect 87 // cycles in the move graph. We use operand swaps to resolve cycles, 88 // which means that a call to PerformMove could change any source operand 89 // in the move graph. 90 91 ASSERT(!moves_[index].IsPending()); 92 ASSERT(!moves_[index].IsRedundant()); 93 94 // Clear this move's destination to indicate a pending move. The actual 95 // destination is saved in a stack-allocated local. Recursion may allow 96 // multiple moves to be pending. 97 ASSERT(moves_[index].source() != NULL); // Or else it will look eliminated. 98 LOperand* destination = moves_[index].destination(); 99 moves_[index].set_destination(NULL); 100 101 // Perform a depth-first traversal of the move graph to resolve 102 // dependencies. Any unperformed, unpending move with a source the same 103 // as this one's destination blocks this one so recursively perform all 104 // such moves. 105 for (int i = 0; i < moves_.length(); ++i) { 106 LMoveOperands other_move = moves_[i]; 107 if (other_move.Blocks(destination) && !other_move.IsPending()) { 108 // Though PerformMove can change any source operand in the move graph, 109 // this call cannot create a blocking move via a swap (this loop does 110 // not miss any). Assume there is a non-blocking move with source A 111 // and this move is blocked on source B and there is a swap of A and 112 // B. Then A and B must be involved in the same cycle (or they would 113 // not be swapped). Since this move's destination is B and there is 114 // only a single incoming edge to an operand, this move must also be 115 // involved in the same cycle. In that case, the blocking move will 116 // be created but will be "pending" when we return from PerformMove. 117 PerformMove(i); 118 } 119 } 120 121 // We are about to resolve this move and don't need it marked as 122 // pending, so restore its destination. 123 moves_[index].set_destination(destination); 124 125 // This move's source may have changed due to swaps to resolve cycles and 126 // so it may now be the last move in the cycle. If so remove it. 127 if (moves_[index].source()->Equals(destination)) { 128 moves_[index].Eliminate(); 129 return; 130 } 131 132 // The move may be blocked on a (at most one) pending move, in which case 133 // we have a cycle. Search for such a blocking move and perform a swap to 134 // resolve it. 135 for (int i = 0; i < moves_.length(); ++i) { 136 LMoveOperands other_move = moves_[i]; 137 if (other_move.Blocks(destination)) { 138 ASSERT(other_move.IsPending()); 139 EmitSwap(index); 140 return; 141 } 142 } 143 144 // This move is not blocked. 145 EmitMove(index); 146 } 147 148 149 void LGapResolver::Verify() { 150 #ifdef ENABLE_SLOW_ASSERTS 151 // No operand should be the destination for more than one move. 152 for (int i = 0; i < moves_.length(); ++i) { 153 LOperand* destination = moves_[i].destination(); 154 for (int j = i + 1; j < moves_.length(); ++j) { 155 SLOW_ASSERT(!destination->Equals(moves_[j].destination())); 156 } 157 } 158 #endif 159 } 160 161 162 #define __ ACCESS_MASM(cgen_->masm()) 163 164 165 void LGapResolver::EmitMove(int index) { 166 LOperand* source = moves_[index].source(); 167 LOperand* destination = moves_[index].destination(); 168 169 // Dispatch on the source and destination operand kinds. Not all 170 // combinations are possible. 171 if (source->IsRegister()) { 172 Register src = cgen_->ToRegister(source); 173 if (destination->IsRegister()) { 174 Register dst = cgen_->ToRegister(destination); 175 __ movq(dst, src); 176 } else { 177 ASSERT(destination->IsStackSlot()); 178 Operand dst = cgen_->ToOperand(destination); 179 __ movq(dst, src); 180 } 181 182 } else if (source->IsStackSlot()) { 183 Operand src = cgen_->ToOperand(source); 184 if (destination->IsRegister()) { 185 Register dst = cgen_->ToRegister(destination); 186 __ movq(dst, src); 187 } else { 188 ASSERT(destination->IsStackSlot()); 189 Operand dst = cgen_->ToOperand(destination); 190 __ movq(kScratchRegister, src); 191 __ movq(dst, kScratchRegister); 192 } 193 194 } else if (source->IsConstantOperand()) { 195 LConstantOperand* constant_source = LConstantOperand::cast(source); 196 if (destination->IsRegister()) { 197 Register dst = cgen_->ToRegister(destination); 198 if (cgen_->IsInteger32Constant(constant_source)) { 199 __ movl(dst, Immediate(cgen_->ToInteger32(constant_source))); 200 } else { 201 __ Move(dst, cgen_->ToHandle(constant_source)); 202 } 203 } else { 204 ASSERT(destination->IsStackSlot()); 205 Operand dst = cgen_->ToOperand(destination); 206 if (cgen_->IsInteger32Constant(constant_source)) { 207 // Allow top 32 bits of an untagged Integer32 to be arbitrary. 208 __ movl(dst, Immediate(cgen_->ToInteger32(constant_source))); 209 } else { 210 __ Move(dst, cgen_->ToHandle(constant_source)); 211 } 212 } 213 214 } else if (source->IsDoubleRegister()) { 215 XMMRegister src = cgen_->ToDoubleRegister(source); 216 if (destination->IsDoubleRegister()) { 217 __ movsd(cgen_->ToDoubleRegister(destination), src); 218 } else { 219 ASSERT(destination->IsDoubleStackSlot()); 220 __ movsd(cgen_->ToOperand(destination), src); 221 } 222 } else if (source->IsDoubleStackSlot()) { 223 Operand src = cgen_->ToOperand(source); 224 if (destination->IsDoubleRegister()) { 225 __ movsd(cgen_->ToDoubleRegister(destination), src); 226 } else { 227 ASSERT(destination->IsDoubleStackSlot()); 228 __ movsd(xmm0, src); 229 __ movsd(cgen_->ToOperand(destination), xmm0); 230 } 231 } else { 232 UNREACHABLE(); 233 } 234 235 moves_[index].Eliminate(); 236 } 237 238 239 void LGapResolver::EmitSwap(int index) { 240 LOperand* source = moves_[index].source(); 241 LOperand* destination = moves_[index].destination(); 242 243 // Dispatch on the source and destination operand kinds. Not all 244 // combinations are possible. 245 if (source->IsRegister() && destination->IsRegister()) { 246 // Swap two general-purpose registers. 247 Register src = cgen_->ToRegister(source); 248 Register dst = cgen_->ToRegister(destination); 249 __ xchg(dst, src); 250 251 } else if ((source->IsRegister() && destination->IsStackSlot()) || 252 (source->IsStackSlot() && destination->IsRegister())) { 253 // Swap a general-purpose register and a stack slot. 254 Register reg = 255 cgen_->ToRegister(source->IsRegister() ? source : destination); 256 Operand mem = 257 cgen_->ToOperand(source->IsRegister() ? destination : source); 258 __ movq(kScratchRegister, mem); 259 __ movq(mem, reg); 260 __ movq(reg, kScratchRegister); 261 262 } else if ((source->IsStackSlot() && destination->IsStackSlot()) || 263 (source->IsDoubleStackSlot() && destination->IsDoubleStackSlot())) { 264 // Swap two stack slots or two double stack slots. 265 Operand src = cgen_->ToOperand(source); 266 Operand dst = cgen_->ToOperand(destination); 267 __ movsd(xmm0, src); 268 __ movq(kScratchRegister, dst); 269 __ movsd(dst, xmm0); 270 __ movq(src, kScratchRegister); 271 272 } else if (source->IsDoubleRegister() && destination->IsDoubleRegister()) { 273 // Swap two double registers. 274 XMMRegister source_reg = cgen_->ToDoubleRegister(source); 275 XMMRegister destination_reg = cgen_->ToDoubleRegister(destination); 276 __ movsd(xmm0, source_reg); 277 __ movsd(source_reg, destination_reg); 278 __ movsd(destination_reg, xmm0); 279 280 } else if (source->IsDoubleRegister() || destination->IsDoubleRegister()) { 281 // Swap a double register and a double stack slot. 282 ASSERT((source->IsDoubleRegister() && destination->IsDoubleStackSlot()) || 283 (source->IsDoubleStackSlot() && destination->IsDoubleRegister())); 284 XMMRegister reg = cgen_->ToDoubleRegister(source->IsDoubleRegister() 285 ? source 286 : destination); 287 LOperand* other = source->IsDoubleRegister() ? destination : source; 288 ASSERT(other->IsDoubleStackSlot()); 289 Operand other_operand = cgen_->ToOperand(other); 290 __ movsd(xmm0, other_operand); 291 __ movsd(other_operand, reg); 292 __ movsd(reg, xmm0); 293 294 } else { 295 // No other combinations are possible. 296 UNREACHABLE(); 297 } 298 299 // The swap of source and destination has executed a move from source to 300 // destination. 301 moves_[index].Eliminate(); 302 303 // Any unperformed (including pending) move with a source of either 304 // this move's source or destination needs to have their source 305 // changed to reflect the state of affairs after the swap. 306 for (int i = 0; i < moves_.length(); ++i) { 307 LMoveOperands other_move = moves_[i]; 308 if (other_move.Blocks(source)) { 309 moves_[i].set_source(destination); 310 } else if (other_move.Blocks(destination)) { 311 moves_[i].set_source(source); 312 } 313 } 314 } 315 316 #undef __ 317 318 } } // namespace v8::internal 319 320 #endif // V8_TARGET_ARCH_X64 321