Merge experimental/a64 to bleeding_edge.

src/a64/lithium-gap-resolver-a64.cc

-// Copyright 2012 the V8 project authors. All rights reserved.
+// Copyright 2013 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"
 
-#include "arm/lithium-gap-resolver-arm.h"
-#include "arm/lithium-codegen-arm.h"
+#include "a64/lithium-gap-resolver-a64.h"
+#include "a64/lithium-codegen-a64.h"
 
 namespace v8 {
 namespace internal {
 
-static const Register kSavedValueRegister = { 9 };
+// 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 kSavedValue root
 
 LGapResolver::LGapResolver(LCodeGen* owner)
     : cgen_(owner), moves_(32, owner->zone()), root_index_(0), in_cycle_(false),
-      saved_destination_(NULL) { }
+      saved_destination_(NULL), need_to_restore_root_(false) { }
 
 
+#define __ ACCESS_MASM(cgen_->masm())
+
 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
+
+    // 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.
+      root_index_ = i;  // Any cycle is found when we reach this move again.
       PerformMove(i);
-      if (in_cycle_) {
-        RestoreValue();
-      }
+      if (in_cycle_) RestoreValue();
     }
   }
 
   // Perform the moves with constant sources.
   for (int i = 0; i < moves_.length(); ++i) {
-    if (!moves_[i].IsEliminated()) {
-      ASSERT(moves_[i].source()->IsConstantOperand());
+    LMoveOperands move = moves_[i];
+
+    if (!move.IsEliminated()) {
+      ASSERT(move.source()->IsConstantOperand());
       EmitMove(i);
     }
   }
 
+  if (need_to_restore_root_) {
+    ASSERT(kSavedValue.Is(root));
+    __ InitializeRootRegister();
+  }
+
   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
+  // 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];
 
-  // 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.
-  ASSERT(!moves_[index].IsPending());
-  ASSERT(!moves_[index].IsRedundant());
+  ASSERT(!current_move.IsPending());
+  ASSERT(!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
+  // destination is saved in a stack allocated local. Multiple moves can
   // be pending because this function is recursive.
-  ASSERT(moves_[index].source() != NULL);  // Or else it will look eliminated.
-  LOperand* destination = moves_[index].destination();
-  moves_[index].set_destination(NULL);
+  ASSERT(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
+  // 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);
+  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)) {
     ASSERT(other_move.IsPending());
     BreakCycle(index);
     return;
   }
 
   // This move is no longer 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::BreakCycle(int index) {
-  // We save in a register the value that should end up in the source of
-  // moves_[root_index].  After performing all moves in the tree rooted
-  // in that move, we save the value to that source.
   ASSERT(moves_[index].destination()->Equals(moves_[root_index_].source()));
   ASSERT(!in_cycle_);
+
+  // We use a register which is not allocatable by crankshaft to break the cycle
+  // to be sure it doesn't interfere with the moves we are resolving.
+  ASSERT(!kSavedValue.IsAllocatable());
+  need_to_restore_root_ = true;
+
+  // 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()) {
-    __ mov(kSavedValueRegister, cgen_->ToRegister(source));
+    __ Mov(kSavedValue, cgen_->ToRegister(source));
   } else if (source->IsStackSlot()) {
-    __ ldr(kSavedValueRegister, cgen_->ToMemOperand(source));
+    __ Ldr(kSavedValue, cgen_->ToMemOperand(source));
   } else if (source->IsDoubleRegister()) {
-    __ vmov(kScratchDoubleReg, cgen_->ToDoubleRegister(source));
+    // TODO(all): We should use a double register to store the value to avoid
+    // the penalty of the mov across register banks. We are going to reserve
+    // d31 to hold 0.0 value. We could clobber this register while breaking the
+    // cycle and restore it after like we do with the root register.
+    // LGapResolver::RestoreValue() will need to be updated as well when we'll
+    // do that.
+    __ Fmov(kSavedValue, cgen_->ToDoubleRegister(source));
   } else if (source->IsDoubleStackSlot()) {
-    __ vldr(kScratchDoubleReg, cgen_->ToMemOperand(source));
+    __ Ldr(kSavedValue, cgen_->ToMemOperand(source));
   } else {
     UNREACHABLE();
   }
-  // This move will be done by restoring the saved value to the destination.
+
+  // 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() {
   ASSERT(in_cycle_);
   ASSERT(saved_destination_ != NULL);
 
-  // Spilled value is in kSavedValueRegister or kSavedDoubleValueRegister.
   if (saved_destination_->IsRegister()) {
-    __ mov(cgen_->ToRegister(saved_destination_), kSavedValueRegister);
+    __ Mov(cgen_->ToRegister(saved_destination_), kSavedValue);
   } else if (saved_destination_->IsStackSlot()) {
-    __ str(kSavedValueRegister, cgen_->ToMemOperand(saved_destination_));
+    __ Str(kSavedValue, cgen_->ToMemOperand(saved_destination_));
   } else if (saved_destination_->IsDoubleRegister()) {
-    __ vmov(cgen_->ToDoubleRegister(saved_destination_), kScratchDoubleReg);
+    __ Fmov(cgen_->ToDoubleRegister(saved_destination_), kSavedValue);
   } else if (saved_destination_->IsDoubleStackSlot()) {
-    __ vstr(kScratchDoubleReg, cgen_->ToMemOperand(saved_destination_));
+    __ Str(kSavedValue, 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);
+      __ Mov(cgen_->ToRegister(destination), source_register);
     } else {
       ASSERT(destination->IsStackSlot());
-      __ str(source_register, cgen_->ToMemOperand(destination));
+      __ 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);
+      __ Ldr(cgen_->ToRegister(destination), source_operand);
     } else {
       ASSERT(destination->IsStackSlot());
-      MemOperand destination_operand = cgen_->ToMemOperand(destination);
-      if (in_cycle_) {
-        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 {
-        __ ldr(kSavedValueRegister, source_operand);
-        __ str(kSavedValueRegister, destination_operand);
-      }
+      EmitStackSlotMove(index);
     }
 
   } 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)));
+      if (cgen_->IsSmi(constant_source)) {
+        __ Mov(dst, Operand(cgen_->ToSmi(constant_source)));
+      } else if (cgen_->IsInteger32Constant(constant_source)) {
+        __ Mov(dst, cgen_->ToInteger32(constant_source));
       } else {
-        __ Move(dst, cgen_->ToHandle(constant_source));
+        __ LoadObject(dst, cgen_->ToHandle(constant_source));
       }
     } else if (destination->IsDoubleRegister()) {
-      DwVfpRegister result = cgen_->ToDoubleRegister(destination);
-      double v = cgen_->ToDouble(constant_source);
-      __ Vmov(result, v, ip);
+      DoubleRegister result = cgen_->ToDoubleRegister(destination);
+      __ Fmov(result, cgen_->ToDouble(constant_source));
     } else {
       ASSERT(destination->IsStackSlot());
       ASSERT(!in_cycle_);  // Constant moves happen after all cycles are gone.
-      Representation r = cgen_->IsSmi(constant_source)
-          ? Representation::Smi() : Representation::Integer32();
-      if (cgen_->IsInteger32(constant_source)) {
-        __ mov(kSavedValueRegister,
-               Operand(cgen_->ToRepresentation(constant_source, r)));
+      need_to_restore_root_ = true;
+      if (cgen_->IsSmi(constant_source)) {
+        __ Mov(kSavedValue, Operand(cgen_->ToSmi(constant_source)));
+      } else if (cgen_->IsInteger32Constant(constant_source)) {
+        __ Mov(kSavedValue, cgen_->ToInteger32(constant_source));
       } else {
-        __ Move(kSavedValueRegister,
-                      cgen_->ToHandle(constant_source));
+        __ LoadObject(kSavedValue, cgen_->ToHandle(constant_source));
       }
-      __ str(kSavedValueRegister, cgen_->ToMemOperand(destination));
+      __ Str(kSavedValue, cgen_->ToMemOperand(destination));
     }
 
   } else if (source->IsDoubleRegister()) {
-    DwVfpRegister source_register = cgen_->ToDoubleRegister(source);
+    DoubleRegister src = cgen_->ToDoubleRegister(source);
     if (destination->IsDoubleRegister()) {
-      __ vmov(cgen_->ToDoubleRegister(destination), source_register);
+      __ Fmov(cgen_->ToDoubleRegister(destination), src);
     } else {
       ASSERT(destination->IsDoubleStackSlot());
-      __ vstr(source_register, cgen_->ToMemOperand(destination));
+      __ Str(src, cgen_->ToMemOperand(destination));
     }
 
   } else if (source->IsDoubleStackSlot()) {
-    MemOperand source_operand = cgen_->ToMemOperand(source);
+    MemOperand src = cgen_->ToMemOperand(source);
     if (destination->IsDoubleRegister()) {
-      __ vldr(cgen_->ToDoubleRegister(destination), source_operand);
+      __ Ldr(cgen_->ToDoubleRegister(destination), src);
     } else {
       ASSERT(destination->IsDoubleStackSlot());
-      MemOperand destination_operand = cgen_->ToMemOperand(destination);
-      if (in_cycle_) {
-        // kSavedDoubleValueRegister was used to break the cycle,
-        // but kSavedValueRegister is free.
-        MemOperand source_high_operand =
-            cgen_->ToHighMemOperand(source);
-        MemOperand destination_high_operand =
-            cgen_->ToHighMemOperand(destination);
-        __ ldr(kSavedValueRegister, source_operand);
-        __ str(kSavedValueRegister, destination_operand);
-        __ ldr(kSavedValueRegister, source_high_operand);
-        __ str(kSavedValueRegister, destination_high_operand);
-      } else {
-        __ vldr(kScratchDoubleReg, source_operand);
-        __ vstr(kScratchDoubleReg, destination_operand);
-      }
+      EmitStackSlotMove(index);
     }
+
   } else {
     UNREACHABLE();
   }
 
+  // The move has been emitted, we can eliminate it.
   moves_[index].Eliminate();
 }
 
 
-#undef __
+void LGapResolver::EmitStackSlotMove(int index) {
+  // We need a temp register to perform a stack slot to stack slot move, and
+  // the register must not be involved in breaking cycles.
+
+  // Use the Crankshaft double scratch register as the temporary.
+  DoubleRegister temp = crankshaft_fp_scratch;
+
+  LOperand* src = moves_[index].source();
+  LOperand* dst = moves_[index].destination();
+
+  ASSERT(src->IsStackSlot());
+  ASSERT(dst->IsStackSlot());
+  __ Ldr(temp, cgen_->ToMemOperand(src));
+  __ Str(temp, cgen_->ToMemOperand(dst));
+}
 
 } }  // namespace v8::internal