| // Copyright 2012 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #include "v8.h" |
| |
| #include "arm/lithium-gap-resolver-arm.h" |
| #include "arm/lithium-codegen-arm.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| static const Register kSavedValueRegister = { 9 }; |
| |
| LGapResolver::LGapResolver(LCodeGen* owner) |
| : cgen_(owner), moves_(32), root_index_(0), in_cycle_(false), |
| saved_destination_(NULL) { } |
| |
| |
| void LGapResolver::Resolve(LParallelMove* parallel_move) { |
| ASSERT(moves_.is_empty()); |
| // Build up a worklist of moves. |
| BuildInitialMoveList(parallel_move); |
| |
| for (int i = 0; i < moves_.length(); ++i) { |
| LMoveOperands move = moves_[i]; |
| // Skip constants to perform them last. They don't block other moves |
| // and skipping such moves with register destinations keeps those |
| // registers free for the whole algorithm. |
| if (!move.IsEliminated() && !move.source()->IsConstantOperand()) { |
| root_index_ = i; // Any cycle is found when by reaching this move again. |
| PerformMove(i); |
| if (in_cycle_) { |
| RestoreValue(); |
| } |
| } |
| } |
| |
| // Perform the moves with constant sources. |
| for (int i = 0; i < moves_.length(); ++i) { |
| if (!moves_[i].IsEliminated()) { |
| ASSERT(moves_[i].source()->IsConstantOperand()); |
| EmitMove(i); |
| } |
| } |
| |
| moves_.Rewind(0); |
| } |
| |
| |
| void LGapResolver::BuildInitialMoveList(LParallelMove* parallel_move) { |
| // Perform a linear sweep of the moves to add them to the initial list of |
| // moves to perform, ignoring any move that is redundant (the source is |
| // the same as the destination, the destination is ignored and |
| // unallocated, or the move was already eliminated). |
| const ZoneList<LMoveOperands>* moves = parallel_move->move_operands(); |
| for (int i = 0; i < moves->length(); ++i) { |
| LMoveOperands move = moves->at(i); |
| if (!move.IsRedundant()) moves_.Add(move); |
| } |
| Verify(); |
| } |
| |
| |
| void LGapResolver::PerformMove(int index) { |
| // Each call to this function performs a move and deletes it from the move |
| // graph. We first recursively perform any move blocking this one. We |
| // mark a move as "pending" on entry to PerformMove in order to detect |
| // cycles in the move graph. |
| |
| // We can only find a cycle, when doing a depth-first traversal of moves, |
| // be encountering the starting move again. So by spilling the source of |
| // the starting move, we break the cycle. All moves are then unblocked, |
| // and the starting move is completed by writing the spilled value to |
| // its destination. All other moves from the spilled source have been |
| // completed prior to breaking the cycle. |
| // An additional complication is that moves to MemOperands with large |
| // offsets (more than 1K or 4K) require us to spill this spilled value to |
| // the stack, to free up the register. |
| ASSERT(!moves_[index].IsPending()); |
| ASSERT(!moves_[index].IsRedundant()); |
| |
| // Clear this move's destination to indicate a pending move. The actual |
| // destination is saved in a stack allocated local. Multiple moves can |
| // be pending because this function is recursive. |
| ASSERT(moves_[index].source() != NULL); // Or else it will look eliminated. |
| LOperand* destination = moves_[index].destination(); |
| moves_[index].set_destination(NULL); |
| |
| // Perform a depth-first traversal of the move graph to resolve |
| // dependencies. Any unperformed, unpending move with a source the same |
| // as this one's destination blocks this one so recursively perform all |
| // such moves. |
| for (int i = 0; i < moves_.length(); ++i) { |
| LMoveOperands other_move = moves_[i]; |
| if (other_move.Blocks(destination) && !other_move.IsPending()) { |
| PerformMove(i); |
| // If there is a blocking, pending move it must be moves_[root_index_] |
| // and all other moves with the same source as moves_[root_index_] are |
| // sucessfully executed (because they are cycle-free) by this loop. |
| } |
| } |
| |
| // We are about to resolve this move and don't need it marked as |
| // pending, so restore its destination. |
| moves_[index].set_destination(destination); |
| |
| // The move may be blocked on a pending move, which must be the starting move. |
| // In this case, we have a cycle, and we save the source of this move to |
| // a scratch register to break it. |
| LMoveOperands other_move = moves_[root_index_]; |
| if (other_move.Blocks(destination)) { |
| ASSERT(other_move.IsPending()); |
| BreakCycle(index); |
| return; |
| } |
| |
| // This move is no longer blocked. |
| EmitMove(index); |
| } |
| |
| |
| void LGapResolver::Verify() { |
| #ifdef ENABLE_SLOW_ASSERTS |
| // No operand should be the destination for more than one move. |
| for (int i = 0; i < moves_.length(); ++i) { |
| LOperand* destination = moves_[i].destination(); |
| for (int j = i + 1; j < moves_.length(); ++j) { |
| SLOW_ASSERT(!destination->Equals(moves_[j].destination())); |
| } |
| } |
| #endif |
| } |
| |
| #define __ ACCESS_MASM(cgen_->masm()) |
| |
| void LGapResolver::BreakCycle(int index) { |
| // We save in a register the value that should end up in the source of |
| // moves_[root_index]. After performing all moves in the tree rooted |
| // in that move, we save the value to that source. |
| ASSERT(moves_[index].destination()->Equals(moves_[root_index_].source())); |
| ASSERT(!in_cycle_); |
| in_cycle_ = true; |
| LOperand* source = moves_[index].source(); |
| saved_destination_ = moves_[index].destination(); |
| if (source->IsRegister()) { |
| __ mov(kSavedValueRegister, cgen_->ToRegister(source)); |
| } else if (source->IsStackSlot()) { |
| __ ldr(kSavedValueRegister, cgen_->ToMemOperand(source)); |
| } else if (source->IsDoubleRegister()) { |
| __ vmov(kScratchDoubleReg, cgen_->ToDoubleRegister(source)); |
| } else if (source->IsDoubleStackSlot()) { |
| __ vldr(kScratchDoubleReg, cgen_->ToMemOperand(source)); |
| } else { |
| UNREACHABLE(); |
| } |
| // This move will be done by restoring the saved value to the destination. |
| moves_[index].Eliminate(); |
| } |
| |
| |
| void LGapResolver::RestoreValue() { |
| ASSERT(in_cycle_); |
| ASSERT(saved_destination_ != NULL); |
| |
| // Spilled value is in kSavedValueRegister or kSavedDoubleValueRegister. |
| if (saved_destination_->IsRegister()) { |
| __ mov(cgen_->ToRegister(saved_destination_), kSavedValueRegister); |
| } else if (saved_destination_->IsStackSlot()) { |
| __ str(kSavedValueRegister, cgen_->ToMemOperand(saved_destination_)); |
| } else if (saved_destination_->IsDoubleRegister()) { |
| __ vmov(cgen_->ToDoubleRegister(saved_destination_), kScratchDoubleReg); |
| } else if (saved_destination_->IsDoubleStackSlot()) { |
| __ vstr(kScratchDoubleReg, cgen_->ToMemOperand(saved_destination_)); |
| } else { |
| UNREACHABLE(); |
| } |
| |
| in_cycle_ = false; |
| saved_destination_ = NULL; |
| } |
| |
| |
| void LGapResolver::EmitMove(int index) { |
| LOperand* source = moves_[index].source(); |
| LOperand* destination = moves_[index].destination(); |
| |
| // Dispatch on the source and destination operand kinds. Not all |
| // combinations are possible. |
| |
| if (source->IsRegister()) { |
| Register source_register = cgen_->ToRegister(source); |
| if (destination->IsRegister()) { |
| __ mov(cgen_->ToRegister(destination), source_register); |
| } else { |
| ASSERT(destination->IsStackSlot()); |
| __ str(source_register, cgen_->ToMemOperand(destination)); |
| } |
| |
| } else if (source->IsStackSlot()) { |
| MemOperand source_operand = cgen_->ToMemOperand(source); |
| if (destination->IsRegister()) { |
| __ ldr(cgen_->ToRegister(destination), source_operand); |
| } else { |
| ASSERT(destination->IsStackSlot()); |
| MemOperand destination_operand = cgen_->ToMemOperand(destination); |
| if (in_cycle_) { |
| if (!destination_operand.OffsetIsUint12Encodable()) { |
| // ip is overwritten while saving the value to the destination. |
| // Therefore we can't use ip. It is OK if the read from the source |
| // destroys ip, since that happens before the value is read. |
| __ vldr(kScratchDoubleReg.low(), source_operand); |
| __ vstr(kScratchDoubleReg.low(), destination_operand); |
| } else { |
| __ ldr(ip, source_operand); |
| __ str(ip, destination_operand); |
| } |
| } else { |
| __ ldr(kSavedValueRegister, source_operand); |
| __ str(kSavedValueRegister, destination_operand); |
| } |
| } |
| |
| } else if (source->IsConstantOperand()) { |
| LConstantOperand* constant_source = LConstantOperand::cast(source); |
| if (destination->IsRegister()) { |
| Register dst = cgen_->ToRegister(destination); |
| if (cgen_->IsInteger32(constant_source)) { |
| __ mov(dst, Operand(cgen_->ToInteger32(constant_source))); |
| } else { |
| __ LoadObject(dst, cgen_->ToHandle(constant_source)); |
| } |
| } else { |
| ASSERT(destination->IsStackSlot()); |
| ASSERT(!in_cycle_); // Constant moves happen after all cycles are gone. |
| if (cgen_->IsInteger32(constant_source)) { |
| __ mov(kSavedValueRegister, |
| Operand(cgen_->ToInteger32(constant_source))); |
| } else { |
| __ LoadObject(kSavedValueRegister, |
| cgen_->ToHandle(constant_source)); |
| } |
| __ str(kSavedValueRegister, cgen_->ToMemOperand(destination)); |
| } |
| |
| } else if (source->IsDoubleRegister()) { |
| DoubleRegister source_register = cgen_->ToDoubleRegister(source); |
| if (destination->IsDoubleRegister()) { |
| __ vmov(cgen_->ToDoubleRegister(destination), source_register); |
| } else { |
| ASSERT(destination->IsDoubleStackSlot()); |
| __ vstr(source_register, cgen_->ToMemOperand(destination)); |
| } |
| |
| } else if (source->IsDoubleStackSlot()) { |
| MemOperand source_operand = cgen_->ToMemOperand(source); |
| if (destination->IsDoubleRegister()) { |
| __ vldr(cgen_->ToDoubleRegister(destination), source_operand); |
| } else { |
| ASSERT(destination->IsDoubleStackSlot()); |
| MemOperand destination_operand = cgen_->ToMemOperand(destination); |
| if (in_cycle_) { |
| // kSavedDoubleValueRegister was used to break the cycle, |
| // but kSavedValueRegister is free. |
| MemOperand source_high_operand = |
| cgen_->ToHighMemOperand(source); |
| MemOperand destination_high_operand = |
| cgen_->ToHighMemOperand(destination); |
| __ ldr(kSavedValueRegister, source_operand); |
| __ str(kSavedValueRegister, destination_operand); |
| __ ldr(kSavedValueRegister, source_high_operand); |
| __ str(kSavedValueRegister, destination_high_operand); |
| } else { |
| __ vldr(kScratchDoubleReg, source_operand); |
| __ vstr(kScratchDoubleReg, destination_operand); |
| } |
| } |
| } else { |
| UNREACHABLE(); |
| } |
| |
| moves_[index].Eliminate(); |
| } |
| |
| |
| #undef __ |
| |
| } } // namespace v8::internal |