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// 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 defined(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) {}
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);
}
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_->IsInteger32Constant(constant_source)) {
__ movl(dst, Immediate(cgen_->ToInteger32(constant_source)));
} else {
__ Move(dst, cgen_->ToHandle(constant_source));
}
} else {
ASSERT(destination->IsStackSlot());
Operand dst = cgen_->ToOperand(destination);
if (cgen_->IsInteger32Constant(constant_source)) {
// Allow top 32 bits of an untagged Integer32 to be arbitrary.
__ movl(dst, Immediate(cgen_->ToInteger32(constant_source)));
} else {
__ Move(dst, cgen_->ToHandle(constant_source));
}
}
} else if (source->IsDoubleRegister()) {
XMMRegister src = cgen_->ToDoubleRegister(source);
if (destination->IsDoubleRegister()) {
__ movsd(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);
__ movsd(xmm0, source_reg);
__ movsd(source_reg, destination_reg);
__ movsd(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