src/x64/lithium-gap-resolver-x64.cc - platform/external/chromium_org/v8 - Git at Google

 // Copyright 2011 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"

 #if V8_TARGET_ARCH_X64

 #include "x64/lithium-gap-resolver-x64.h"
 #include "x64/lithium-codegen-x64.h"

 namespace v8 {
 namespace internal {

 LGapResolver::LGapResolver(LCodeGen* owner)
     : cgen_(owner), moves_(32, owner->zone()) {}


 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()) {
       PerformMove(i);
     }
   }

   // 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, 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 use operand swaps to resolve cycles,
   // which means that a call to PerformMove could change any source operand
   // in the move graph.

   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.  Recursion may allow
   // multiple moves to be pending.
   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()) {
       // Though PerformMove can change any source operand in the move graph,
       // this call cannot create a blocking move via a swap (this loop does
       // not miss any).  Assume there is a non-blocking move with source A
       // and this move is blocked on source B and there is a swap of A and
       // B.  Then A and B must be involved in the same cycle (or they would
       // not be swapped).  Since this move's destination is B and there is
       // only a single incoming edge to an operand, this move must also be
       // involved in the same cycle.  In that case, the blocking move will
       // be created but will be "pending" when we return from PerformMove.
       PerformMove(i);
     }
   }

   // We are about to resolve this move and don't need it marked as
   // pending, so restore its destination.
   moves_[index].set_destination(destination);

   // This move's source may have changed due to swaps to resolve cycles and
   // so it may now be the last move in the cycle.  If so remove it.
   if (moves_[index].source()->Equals(destination)) {
     moves_[index].Eliminate();
     return;
   }

   // The move may be blocked on a (at most one) pending move, in which case
   // we have a cycle.  Search for such a blocking move and perform a swap to
   // resolve it.
   for (int i = 0; i < moves_.length(); ++i) {
     LMoveOperands other_move = moves_[i];
     if (other_move.Blocks(destination)) {
       ASSERT(other_move.IsPending());
       EmitSwap(index);
       return;
     }
   }

   // This move is not 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::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 src = cgen_->ToRegister(source);
     if (destination->IsRegister()) {
       Register dst = cgen_->ToRegister(destination);
       __ movq(dst, src);
     } else {
       ASSERT(destination->IsStackSlot());
       Operand dst = cgen_->ToOperand(destination);
       __ movq(dst, src);
     }

   } else if (source->IsStackSlot()) {
     Operand src = cgen_->ToOperand(source);
     if (destination->IsRegister()) {
       Register dst = cgen_->ToRegister(destination);
       __ movq(dst, src);
     } else {
       ASSERT(destination->IsStackSlot());
       Operand dst = cgen_->ToOperand(destination);
       __ movq(kScratchRegister, src);
       __ movq(dst, kScratchRegister);
     }

   } else if (source->IsConstantOperand()) {
     LConstantOperand* constant_source = LConstantOperand::cast(source);
     if (destination->IsRegister()) {
       Register dst = cgen_->ToRegister(destination);
       if (cgen_->IsSmiConstant(constant_source)) {
         __ Move(dst, cgen_->ToSmi(constant_source));
       } else if (cgen_->IsInteger32Constant(constant_source)) {
         __ movl(dst, Immediate(cgen_->ToInteger32(constant_source)));
       } else {
         __ LoadObject(dst, cgen_->ToHandle(constant_source));
       }
     } else if (destination->IsDoubleRegister()) {
       double v = cgen_->ToDouble(constant_source);
       uint64_t int_val = BitCast<uint64_t, double>(v);
       XMMRegister dst = cgen_->ToDoubleRegister(destination);
       if (int_val == 0) {
         __ xorps(dst, dst);
       } else {
         __ movq(kScratchRegister, int_val, RelocInfo::NONE64);
         __ movq(dst, kScratchRegister);
       }
     } else {
       ASSERT(destination->IsStackSlot());
       Operand dst = cgen_->ToOperand(destination);
       if (cgen_->IsSmiConstant(constant_source)) {
         __ Move(dst, cgen_->ToSmi(constant_source));
       } else if (cgen_->IsInteger32Constant(constant_source)) {
         // Zero top 32 bits of a 64 bit spill slot that holds a 32 bit untagged
         // value.
         __ movq(dst, Immediate(cgen_->ToInteger32(constant_source)));
       } else {
         __ LoadObject(kScratchRegister, cgen_->ToHandle(constant_source));
         __ movq(dst, kScratchRegister);
       }
     }

   } else if (source->IsDoubleRegister()) {
     XMMRegister src = cgen_->ToDoubleRegister(source);
     if (destination->IsDoubleRegister()) {
       __ movaps(cgen_->ToDoubleRegister(destination), src);
     } else {
       ASSERT(destination->IsDoubleStackSlot());
       __ movsd(cgen_->ToOperand(destination), src);
     }
   } else if (source->IsDoubleStackSlot()) {
     Operand src = cgen_->ToOperand(source);
     if (destination->IsDoubleRegister()) {
       __ movsd(cgen_->ToDoubleRegister(destination), src);
     } else {
       ASSERT(destination->IsDoubleStackSlot());
       __ movsd(xmm0, src);
       __ movsd(cgen_->ToOperand(destination), xmm0);
     }
   } else {
     UNREACHABLE();
   }

   moves_[index].Eliminate();
 }


 void LGapResolver::EmitSwap(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() && destination->IsRegister()) {
     // Swap two general-purpose registers.
     Register src = cgen_->ToRegister(source);
     Register dst = cgen_->ToRegister(destination);
     __ xchg(dst, src);

   } else if ((source->IsRegister() && destination->IsStackSlot()) ||
              (source->IsStackSlot() && destination->IsRegister())) {
     // Swap a general-purpose register and a stack slot.
     Register reg =
         cgen_->ToRegister(source->IsRegister() ? source : destination);
     Operand mem =
         cgen_->ToOperand(source->IsRegister() ? destination : source);
     __ movq(kScratchRegister, mem);
     __ movq(mem, reg);
     __ movq(reg, kScratchRegister);

   } else if ((source->IsStackSlot() && destination->IsStackSlot()) ||
       (source->IsDoubleStackSlot() && destination->IsDoubleStackSlot())) {
     // Swap two stack slots or two double stack slots.
     Operand src = cgen_->ToOperand(source);
     Operand dst = cgen_->ToOperand(destination);
     __ movsd(xmm0, src);
     __ movq(kScratchRegister, dst);
     __ movsd(dst, xmm0);
     __ movq(src, kScratchRegister);

   } else if (source->IsDoubleRegister() && destination->IsDoubleRegister()) {
     // Swap two double registers.
     XMMRegister source_reg = cgen_->ToDoubleRegister(source);
     XMMRegister destination_reg = cgen_->ToDoubleRegister(destination);
     __ movaps(xmm0, source_reg);
     __ movaps(source_reg, destination_reg);
     __ movaps(destination_reg, xmm0);

   } else if (source->IsDoubleRegister() || destination->IsDoubleRegister()) {
     // Swap a double register and a double stack slot.
     ASSERT((source->IsDoubleRegister() && destination->IsDoubleStackSlot()) ||
            (source->IsDoubleStackSlot() && destination->IsDoubleRegister()));
     XMMRegister reg = cgen_->ToDoubleRegister(source->IsDoubleRegister()
                                                   ? source
                                                   : destination);
     LOperand* other = source->IsDoubleRegister() ? destination : source;
     ASSERT(other->IsDoubleStackSlot());
     Operand other_operand = cgen_->ToOperand(other);
     __ movsd(xmm0, other_operand);
     __ movsd(other_operand, reg);
     __ movsd(reg, xmm0);

   } else {
     // No other combinations are possible.
     UNREACHABLE();
   }

   // The swap of source and destination has executed a move from source to
   // destination.
   moves_[index].Eliminate();

   // Any unperformed (including pending) move with a source of either
   // this move's source or destination needs to have their source
   // changed to reflect the state of affairs after the swap.
   for (int i = 0; i < moves_.length(); ++i) {
     LMoveOperands other_move = moves_[i];
     if (other_move.Blocks(source)) {
       moves_[i].set_source(destination);
     } else if (other_move.Blocks(destination)) {
       moves_[i].set_source(source);
     }
   }
 }

 #undef __

 } }  // namespace v8::internal

 #endif  // V8_TARGET_ARCH_X64
	// Copyright 2011 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"

	#if V8_TARGET_ARCH_X64

	#include "x64/lithium-gap-resolver-x64.h"
	#include "x64/lithium-codegen-x64.h"

	namespace v8 {
	namespace internal {

	LGapResolver::LGapResolver(LCodeGen* owner)
	: cgen_(owner), moves_(32, owner->zone()) {}


	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()) {
	PerformMove(i);
	}
	}

	// 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, 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 use operand swaps to resolve cycles,
	// which means that a call to PerformMove could change any source operand
	// in the move graph.

	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. Recursion may allow
	// multiple moves to be pending.
	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()) {
	// Though PerformMove can change any source operand in the move graph,
	// this call cannot create a blocking move via a swap (this loop does
	// not miss any). Assume there is a non-blocking move with source A
	// and this move is blocked on source B and there is a swap of A and
	// B. Then A and B must be involved in the same cycle (or they would
	// not be swapped). Since this move's destination is B and there is
	// only a single incoming edge to an operand, this move must also be
	// involved in the same cycle. In that case, the blocking move will
	// be created but will be "pending" when we return from PerformMove.
	PerformMove(i);
	}
	}

	// We are about to resolve this move and don't need it marked as
	// pending, so restore its destination.
	moves_[index].set_destination(destination);

	// This move's source may have changed due to swaps to resolve cycles and
	// so it may now be the last move in the cycle. If so remove it.
	if (moves_[index].source()->Equals(destination)) {
	moves_[index].Eliminate();
	return;
	}

	// The move may be blocked on a (at most one) pending move, in which case
	// we have a cycle. Search for such a blocking move and perform a swap to
	// resolve it.
	for (int i = 0; i < moves_.length(); ++i) {
	LMoveOperands other_move = moves_[i];
	if (other_move.Blocks(destination)) {
	ASSERT(other_move.IsPending());
	EmitSwap(index);
	return;
	}
	}

	// This move is not 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::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 src = cgen_->ToRegister(source);
	if (destination->IsRegister()) {
	Register dst = cgen_->ToRegister(destination);
	__ movq(dst, src);
	} else {
	ASSERT(destination->IsStackSlot());
	Operand dst = cgen_->ToOperand(destination);
	__ movq(dst, src);
	}

	} else if (source->IsStackSlot()) {
	Operand src = cgen_->ToOperand(source);
	if (destination->IsRegister()) {
	Register dst = cgen_->ToRegister(destination);
	__ movq(dst, src);
	} else {
	ASSERT(destination->IsStackSlot());
	Operand dst = cgen_->ToOperand(destination);
	__ movq(kScratchRegister, src);
	__ movq(dst, kScratchRegister);
	}

	} else if (source->IsConstantOperand()) {
	LConstantOperand* constant_source = LConstantOperand::cast(source);
	if (destination->IsRegister()) {
	Register dst = cgen_->ToRegister(destination);
	if (cgen_->IsSmiConstant(constant_source)) {
	__ Move(dst, cgen_->ToSmi(constant_source));
	} else if (cgen_->IsInteger32Constant(constant_source)) {
	__ movl(dst, Immediate(cgen_->ToInteger32(constant_source)));
	} else {
	__ LoadObject(dst, cgen_->ToHandle(constant_source));
	}
	} else if (destination->IsDoubleRegister()) {
	double v = cgen_->ToDouble(constant_source);
	uint64_t int_val = BitCast<uint64_t, double>(v);
	XMMRegister dst = cgen_->ToDoubleRegister(destination);
	if (int_val == 0) {
	__ xorps(dst, dst);
	} else {
	__ movq(kScratchRegister, int_val, RelocInfo::NONE64);
	__ movq(dst, kScratchRegister);
	}
	} else {
	ASSERT(destination->IsStackSlot());
	Operand dst = cgen_->ToOperand(destination);
	if (cgen_->IsSmiConstant(constant_source)) {
	__ Move(dst, cgen_->ToSmi(constant_source));
	} else if (cgen_->IsInteger32Constant(constant_source)) {
	// Zero top 32 bits of a 64 bit spill slot that holds a 32 bit untagged
	// value.
	__ movq(dst, Immediate(cgen_->ToInteger32(constant_source)));
	} else {
	__ LoadObject(kScratchRegister, cgen_->ToHandle(constant_source));
	__ movq(dst, kScratchRegister);
	}
	}

	} else if (source->IsDoubleRegister()) {
	XMMRegister src = cgen_->ToDoubleRegister(source);
	if (destination->IsDoubleRegister()) {
	__ movaps(cgen_->ToDoubleRegister(destination), src);
	} else {
	ASSERT(destination->IsDoubleStackSlot());
	__ movsd(cgen_->ToOperand(destination), src);
	}
	} else if (source->IsDoubleStackSlot()) {
	Operand src = cgen_->ToOperand(source);
	if (destination->IsDoubleRegister()) {
	__ movsd(cgen_->ToDoubleRegister(destination), src);
	} else {
	ASSERT(destination->IsDoubleStackSlot());
	__ movsd(xmm0, src);
	__ movsd(cgen_->ToOperand(destination), xmm0);
	}
	} else {
	UNREACHABLE();
	}

	moves_[index].Eliminate();
	}


	void LGapResolver::EmitSwap(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() && destination->IsRegister()) {
	// Swap two general-purpose registers.
	Register src = cgen_->ToRegister(source);
	Register dst = cgen_->ToRegister(destination);
	__ xchg(dst, src);

	} else if ((source->IsRegister() && destination->IsStackSlot()) \|\|
	(source->IsStackSlot() && destination->IsRegister())) {
	// Swap a general-purpose register and a stack slot.
	Register reg =
	cgen_->ToRegister(source->IsRegister() ? source : destination);
	Operand mem =
	cgen_->ToOperand(source->IsRegister() ? destination : source);
	__ movq(kScratchRegister, mem);
	__ movq(mem, reg);
	__ movq(reg, kScratchRegister);

	} else if ((source->IsStackSlot() && destination->IsStackSlot()) \|\|
	(source->IsDoubleStackSlot() && destination->IsDoubleStackSlot())) {
	// Swap two stack slots or two double stack slots.
	Operand src = cgen_->ToOperand(source);
	Operand dst = cgen_->ToOperand(destination);
	__ movsd(xmm0, src);
	__ movq(kScratchRegister, dst);
	__ movsd(dst, xmm0);
	__ movq(src, kScratchRegister);

	} else if (source->IsDoubleRegister() && destination->IsDoubleRegister()) {
	// Swap two double registers.
	XMMRegister source_reg = cgen_->ToDoubleRegister(source);
	XMMRegister destination_reg = cgen_->ToDoubleRegister(destination);
	__ movaps(xmm0, source_reg);
	__ movaps(source_reg, destination_reg);
	__ movaps(destination_reg, xmm0);

	} else if (source->IsDoubleRegister() \|\| destination->IsDoubleRegister()) {
	// Swap a double register and a double stack slot.
	ASSERT((source->IsDoubleRegister() && destination->IsDoubleStackSlot()) \|\|
	(source->IsDoubleStackSlot() && destination->IsDoubleRegister()));
	XMMRegister reg = cgen_->ToDoubleRegister(source->IsDoubleRegister()
	? source
	: destination);
	LOperand* other = source->IsDoubleRegister() ? destination : source;
	ASSERT(other->IsDoubleStackSlot());
	Operand other_operand = cgen_->ToOperand(other);
	__ movsd(xmm0, other_operand);
	__ movsd(other_operand, reg);
	__ movsd(reg, xmm0);

	} else {
	// No other combinations are possible.
	UNREACHABLE();
	}

	// The swap of source and destination has executed a move from source to
	// destination.
	moves_[index].Eliminate();

	// Any unperformed (including pending) move with a source of either
	// this move's source or destination needs to have their source
	// changed to reflect the state of affairs after the swap.
	for (int i = 0; i < moves_.length(); ++i) {
	LMoveOperands other_move = moves_[i];
	if (other_move.Blocks(source)) {
	moves_[i].set_source(destination);
	} else if (other_move.Blocks(destination)) {
	moves_[i].set_source(source);
	}
	}
	}

	#undef __

	} } // namespace v8::internal

	#endif // V8_TARGET_ARCH_X64