Move Hydrogen and Lithium to src/crankshaft/

src/arm/lithium-gap-resolver-arm.cc

-// Copyright 2012 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/arm/lithium-codegen-arm.h"
-#include "src/arm/lithium-gap-resolver-arm.h"
-
-namespace v8 {
-namespace internal {
-
-// We use the root register to spill a value while breaking a cycle in parallel
-// moves. We don't need access to roots while resolving the move list and using
-// the root register has two advantages:
-//  - It is not in crankshaft allocatable registers list, so it can't interfere
-//    with any of the moves we are resolving.
-//  - We don't need to push it on the stack, as we can reload it with its value
-//    once we have resolved a cycle.
-#define kSavedValueRegister kRootRegister
-
-
-LGapResolver::LGapResolver(LCodeGen* owner)
-    : cgen_(owner), moves_(32, owner->zone()), root_index_(0), in_cycle_(false),
-      saved_destination_(NULL), need_to_restore_root_(false) { }
-
-
-#define __ ACCESS_MASM(cgen_->masm())
-
-
-void LGapResolver::Resolve(LParallelMove* parallel_move) {
-  DCHECK(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()) {
-      DCHECK(moves_[i].source()->IsConstantOperand());
-      EmitMove(i);
-    }
-  }
-
-  if (need_to_restore_root_) {
-    DCHECK(kSavedValueRegister.is(kRootRegister));
-    __ InitializeRootRegister();
-    need_to_restore_root_ = false;
-  }
-
-  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, 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.
-
-  // 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.
-  DCHECK(!moves_[index].IsPending());
-  DCHECK(!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.
-  DCHECK(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)) {
-    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) {
-  // 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.
-  DCHECK(moves_[index].destination()->Equals(moves_[root_index_].source()));
-  DCHECK(!in_cycle_);
-  in_cycle_ = true;
-  LOperand* source = moves_[index].source();
-  saved_destination_ = moves_[index].destination();
-  if (source->IsRegister()) {
-    need_to_restore_root_ = true;
-    __ mov(kSavedValueRegister, cgen_->ToRegister(source));
-  } else if (source->IsStackSlot()) {
-    need_to_restore_root_ = true;
-    __ 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() {
-  DCHECK(in_cycle_);
-  DCHECK(saved_destination_ != NULL);
-
-  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 {
-      DCHECK(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 {
-      DCHECK(destination->IsStackSlot());
-      MemOperand destination_operand = cgen_->ToMemOperand(destination);
-      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 if (source->IsConstantOperand()) {
-    LConstantOperand* constant_source = LConstantOperand::cast(source);
-    if (destination->IsRegister()) {
-      Register dst = cgen_->ToRegister(destination);
-      Representation r = cgen_->IsSmi(constant_source)
-          ? Representation::Smi() : Representation::Integer32();
-      if (cgen_->IsInteger32(constant_source)) {
-        __ mov(dst, Operand(cgen_->ToRepresentation(constant_source, r)));
-      } else {
-        __ Move(dst, cgen_->ToHandle(constant_source));
-      }
-    } else if (destination->IsDoubleRegister()) {
-      DwVfpRegister result = cgen_->ToDoubleRegister(destination);
-      double v = cgen_->ToDouble(constant_source);
-      __ Vmov(result, v, ip);
-    } else {
-      DCHECK(destination->IsStackSlot());
-      DCHECK(!in_cycle_);  // Constant moves happen after all cycles are gone.
-      need_to_restore_root_ = true;
-      Representation r = cgen_->IsSmi(constant_source)
-          ? Representation::Smi() : Representation::Integer32();
-      if (cgen_->IsInteger32(constant_source)) {
-        __ mov(kSavedValueRegister,
-               Operand(cgen_->ToRepresentation(constant_source, r)));
-      } else {
-        __ Move(kSavedValueRegister, cgen_->ToHandle(constant_source));
-      }
-      __ str(kSavedValueRegister, cgen_->ToMemOperand(destination));
-    }
-
-  } else if (source->IsDoubleRegister()) {
-    DwVfpRegister source_register = cgen_->ToDoubleRegister(source);
-    if (destination->IsDoubleRegister()) {
-      __ vmov(cgen_->ToDoubleRegister(destination), source_register);
-    } else {
-      DCHECK(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 {
-      DCHECK(destination->IsDoubleStackSlot());
-      MemOperand destination_operand = cgen_->ToMemOperand(destination);
-      if (in_cycle_) {
-        // kScratchDoubleReg was used to break the cycle.
-        __ vpush(kScratchDoubleReg);
-        __ vldr(kScratchDoubleReg, source_operand);
-        __ vstr(kScratchDoubleReg, destination_operand);
-        __ vpop(kScratchDoubleReg);
-      } else {
-        __ vldr(kScratchDoubleReg, source_operand);
-        __ vstr(kScratchDoubleReg, destination_operand);
-      }
-    }
-  } else {
-    UNREACHABLE();
-  }
-
-  moves_[index].Eliminate();
-}
-
-
-#undef __
-
-}  // namespace internal
-}  // namespace v8