Port new version of ParallelMove's LGapResolver to X64.

src/x64/lithium-gap-resolver-x64.cc

+// 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 "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));
+      }
+    }

[Kevin Millikin (Chromium), 2011/01/24 14:57:12]

I guess there should be a blank line after this one to match the other cases.

+  } 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()) {
+    // Register-register.
+    Register src = cgen_->ToRegister(source);
+    Register dst = cgen_->ToRegister(destination);
+    __ xchg(dst, src);
+
+  } else if ((source->IsRegister() && destination->IsStackSlot()) ||
+             (source->IsStackSlot() && destination->IsRegister())) {
+    // Register-memory.  Use a free register as a temp if possible.  Do not

[Kevin Millikin (Chromium), 2011/01/24 14:57:12]

Update the comment so it doesn't mention the spill on demand trick of IA32. 
Just say you'll use on kScratchRegister.

[William Hesse, 2011/01/26 10:05:57]

Done.

+    // spill on demand because the simple spill implementation cannot avoid
+    // spilling src at this point.
+    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()) {

[Kevin Millikin (Chromium), 2011/01/24 14:57:12]

This case could be

} else if ((source->IsStackSlot() && destination->IsStackSlot()) ||
           (source->IsDoubleStackSlot() && destination->IsDoubleStackSlot())) {

[William Hesse, 2011/01/26 10:05:57]

Done.

+    // Memory-memory.
+    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()) {
+    // XMM register-register or register-memory.  We rely on having xmm0
+    // available as a fixed scratch register.
+    ASSERT(source->IsDoubleRegister() || source->IsDoubleStackSlot());
+    ASSERT(destination->IsDoubleRegister() ||
+           destination->IsDoubleStackSlot());
+    XMMRegister reg = cgen_->ToDoubleRegister(source->IsDoubleRegister()
+                                                  ? source
+                                                  : destination);
+    LOperand* other = source->IsDoubleRegister() ? destination : source;
+    if (other->IsDoubleRegister()) {

[Kevin Millikin (Chromium), 2011/01/24 14:57:12]

I think this case (double register/double register) would be clearer if you had
before this:

} else if (source->IsDoubleRegister() && destination->IsDoubleRegister()) {
  ... 
} else if ...  // double register/memory cases.

[William Hesse, 2011/01/26 10:05:57]

Done.

+      XMMRegister other_reg = cgen_->ToDoubleRegister(other);
+      __ movsd(xmm0, other_reg);
+      __ movsd(other_reg, reg);
+      __ movsd(reg, xmm0);
+    } else {
+      ASSERT(other->IsDoubleStackSlot());
+      Operand other_operand = cgen_->ToOperand(other);
+      __ movsd(xmm0, other_operand);
+      __ movsd(other_operand, reg);
+      __ movsd(reg, xmm0);
+    }
+  } else if (source->IsDoubleStackSlot() && destination->IsDoubleStackSlot()) {
+    // Double-width memory-to-memory.  Spill on demand to use a general

[Kevin Millikin (Chromium), 2011/01/24 14:57:12]

If you don't move this to share the other memory/memory case, update the comment
here because you don't spill on demand.

[William Hesse, 2011/01/26 10:05:57]

Done.

+    // purpose temporary register and also rely on having xmm0 available as
+    // a fixed scratch register.
+    Operand src = cgen_->ToOperand(source);
+    Operand dst = cgen_->ToOperand(destination);
+    __ movsd(xmm0, dst);
+    __ movq(kScratchRegister, src);
+    __ movsd(src, xmm0);
+    __ movq(dst, kScratchRegister);
+  } 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