// Copyright 2013 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/v8.h" #include "src/arm64/delayed-masm-arm64-inl.h" #include "src/arm64/lithium-codegen-arm64.h" #include "src/arm64/lithium-gap-resolver-arm64.h" namespace v8 { namespace internal { #define __ ACCESS_MASM((&masm_)) void DelayedGapMasm::EndDelayedUse() { DelayedMasm::EndDelayedUse(); if (scratch_register_used()) { DCHECK(ScratchRegister().Is(root)); DCHECK(!pending()); InitializeRootRegister(); reset_scratch_register_used(); } } LGapResolver::LGapResolver(LCodeGen* owner) : cgen_(owner), masm_(owner, owner->masm()), moves_(32, owner->zone()), root_index_(0), in_cycle_(false), saved_destination_(NULL) { } void LGapResolver::Resolve(LParallelMove* parallel_move) { DCHECK(moves_.is_empty()); DCHECK(!masm_.pending()); // 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 we reach this move again. PerformMove(i); if (in_cycle_) RestoreValue(); } } // Perform the moves with constant sources. for (int i = 0; i < moves_.length(); ++i) { LMoveOperands move = moves_[i]; if (!move.IsEliminated()) { DCHECK(move.source()->IsConstantOperand()); EmitMove(i); } } __ EndDelayedUse(); 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* moves = parallel_move->move_operands(); for (int i = 0; i < moves->length(); ++i) { LMoveOperands move = moves->at(i); if (!move.IsRedundant()) moves_.Add(move, cgen_->zone()); } 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. LMoveOperands& current_move = moves_[index]; DCHECK(!current_move.IsPending()); DCHECK(!current_move.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. DCHECK(current_move.source() != NULL); // Otherwise it will look eliminated. LOperand* destination = current_move.destination(); current_move.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. current_move.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)) { DCHECK(other_move.IsPending()); BreakCycle(index); return; } // This move is no longer blocked. EmitMove(index); } void LGapResolver::Verify() { #ifdef ENABLE_SLOW_DCHECKS // 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_DCHECK(!destination->Equals(moves_[j].destination())); } } #endif } void LGapResolver::BreakCycle(int index) { DCHECK(moves_[index].destination()->Equals(moves_[root_index_].source())); DCHECK(!in_cycle_); // We save in a register the source of that move and we remember its // destination. Then we mark this move as resolved so the cycle is // broken and we can perform the other moves. in_cycle_ = true; LOperand* source = moves_[index].source(); saved_destination_ = moves_[index].destination(); if (source->IsRegister()) { AcquireSavedValueRegister(); __ Mov(SavedValueRegister(), cgen_->ToRegister(source)); } else if (source->IsStackSlot()) { AcquireSavedValueRegister(); __ Load(SavedValueRegister(), cgen_->ToMemOperand(source)); } else if (source->IsDoubleRegister()) { __ Fmov(SavedFPValueRegister(), cgen_->ToDoubleRegister(source)); } else if (source->IsDoubleStackSlot()) { __ Load(SavedFPValueRegister(), cgen_->ToMemOperand(source)); } else { UNREACHABLE(); } // Mark this move as resolved. // This move will be actually performed by moving the saved value to this // move's destination in LGapResolver::RestoreValue(). moves_[index].Eliminate(); } void LGapResolver::RestoreValue() { DCHECK(in_cycle_); DCHECK(saved_destination_ != NULL); if (saved_destination_->IsRegister()) { __ Mov(cgen_->ToRegister(saved_destination_), SavedValueRegister()); ReleaseSavedValueRegister(); } else if (saved_destination_->IsStackSlot()) { __ Store(SavedValueRegister(), cgen_->ToMemOperand(saved_destination_)); ReleaseSavedValueRegister(); } else if (saved_destination_->IsDoubleRegister()) { __ Fmov(cgen_->ToDoubleRegister(saved_destination_), SavedFPValueRegister()); } else if (saved_destination_->IsDoubleStackSlot()) { __ Store(SavedFPValueRegister(), 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 { DCHECK(destination->IsStackSlot()); __ Store(source_register, cgen_->ToMemOperand(destination)); } } else if (source->IsStackSlot()) { MemOperand source_operand = cgen_->ToMemOperand(source); if (destination->IsRegister()) { __ Load(cgen_->ToRegister(destination), source_operand); } else { DCHECK(destination->IsStackSlot()); EmitStackSlotMove(index); } } else if (source->IsConstantOperand()) { LConstantOperand* constant_source = LConstantOperand::cast(source); if (destination->IsRegister()) { Register dst = cgen_->ToRegister(destination); if (cgen_->IsSmi(constant_source)) { __ Mov(dst, cgen_->ToSmi(constant_source)); } else if (cgen_->IsInteger32Constant(constant_source)) { __ Mov(dst, cgen_->ToInteger32(constant_source)); } else { __ LoadObject(dst, cgen_->ToHandle(constant_source)); } } else if (destination->IsDoubleRegister()) { DoubleRegister result = cgen_->ToDoubleRegister(destination); __ Fmov(result, cgen_->ToDouble(constant_source)); } else { DCHECK(destination->IsStackSlot()); DCHECK(!in_cycle_); // Constant moves happen after all cycles are gone. if (cgen_->IsSmi(constant_source)) { Smi* smi = cgen_->ToSmi(constant_source); __ StoreConstant(reinterpret_cast(smi), cgen_->ToMemOperand(destination)); } else if (cgen_->IsInteger32Constant(constant_source)) { __ StoreConstant(cgen_->ToInteger32(constant_source), cgen_->ToMemOperand(destination)); } else { Handle handle = cgen_->ToHandle(constant_source); AllowDeferredHandleDereference smi_object_check; if (handle->IsSmi()) { Object* obj = *handle; DCHECK(!obj->IsHeapObject()); __ StoreConstant(reinterpret_cast(obj), cgen_->ToMemOperand(destination)); } else { AcquireSavedValueRegister(); __ LoadObject(SavedValueRegister(), handle); __ Store(SavedValueRegister(), cgen_->ToMemOperand(destination)); ReleaseSavedValueRegister(); } } } } else if (source->IsDoubleRegister()) { DoubleRegister src = cgen_->ToDoubleRegister(source); if (destination->IsDoubleRegister()) { __ Fmov(cgen_->ToDoubleRegister(destination), src); } else { DCHECK(destination->IsDoubleStackSlot()); __ Store(src, cgen_->ToMemOperand(destination)); } } else if (source->IsDoubleStackSlot()) { MemOperand src = cgen_->ToMemOperand(source); if (destination->IsDoubleRegister()) { __ Load(cgen_->ToDoubleRegister(destination), src); } else { DCHECK(destination->IsDoubleStackSlot()); EmitStackSlotMove(index); } } else { UNREACHABLE(); } // The move has been emitted, we can eliminate it. moves_[index].Eliminate(); } } } // namespace v8::internal