[turbofan] Centralize splitting for memory operands.

src/compiler/register-allocator.h

 // Copyright 2014 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.
 
 #ifndef V8_REGISTER_ALLOCATOR_H_
 #define V8_REGISTER_ALLOCATOR_H_
 
 #include "src/compiler/instruction.h"
 #include "src/ostreams.h"
 #include "src/register-configuration.h"
@@ skipping 544 matching lines @@
 
   TopLevelLiveRange* splintered_from() const { return splintered_from_; }
   bool IsSplinter() const { return splintered_from_ != nullptr; }
   bool MayRequireSpillRange() const {
     DCHECK(!IsSplinter());
     return !HasSpillOperand() && spill_range_ == nullptr;
   }
   void UpdateSpillRangePostMerge(TopLevelLiveRange* merged);
   int vreg() const { return vreg_; }
 
+#if DEBUG
+  int debug_virt_reg() const;
+#endif
+
   int GetNextChildId() {
     return IsSplinter() ? splintered_from()->GetNextChildId()
                         : ++last_child_id_;
   }
 
   bool IsSpilledOnlyInDeferredBlocks() const {
     return spilled_in_deferred_blocks_;
   }
 
   struct SpillAtDefinitionList;
@@ skipping 327 matching lines @@
  protected:
   RegisterAllocationData* data() const { return data_; }
   InstructionSequence* code() const { return data()->code(); }
   RegisterKind mode() const { return mode_; }
   int num_registers() const { return num_registers_; }
   int num_allocatable_registers() const { return num_allocatable_registers_; }
   int allocatable_register_code(int allocatable_index) const {
     return allocatable_register_codes_[allocatable_index];
   }
 
+  // TODO(mtrofin): explain why splitting in gap START is always OK.
+  LifetimePosition GetSplitPositionForInstruction(const LiveRange* range,
+                                                  int instruction_index);
+
   Zone* allocation_zone() const { return data()->allocation_zone(); }
 
+  // Find the optimal split for ranges defined by a memory operand, e.g.
+  // constants or function parameters passed on the stack.
+  void SplitAndSpillRangesDefinedByMemoryOperand();
+
   // Split the given range at the given position.
   // If range starts at or after the given position then the
   // original range is returned.
   // Otherwise returns the live range that starts at pos and contains
   // all uses from the original range that follow pos. Uses at pos will
   // still be owned by the original range after splitting.
   LiveRange* SplitRangeAt(LiveRange* range, LifetimePosition pos);
 
+  bool CanProcessRange(LiveRange* range) const {
+    return range != nullptr && !range->IsEmpty() && range->kind() == mode();
+  }
+
+
   // Split the given range in a position from the interval [start, end].
   LiveRange* SplitBetween(LiveRange* range, LifetimePosition start,
                           LifetimePosition end);
 
   // Find a lifetime position in the interval [start, end] which
   // is optimal for splitting: it is either header of the outermost
   // loop covered by this interval or the latest possible position.
   LifetimePosition FindOptimalSplitPos(LifetimePosition start,
                                        LifetimePosition end);
 
@@ skipping 167 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_