[Turbofan] Add the concept of aliasing to RegisterConfiguration.

src/compiler/register-allocator.h

Index: src/compiler/register-allocator.h
diff --git a/src/compiler/register-allocator.h b/src/compiler/register-allocator.h
index 933d1d2472974dc4804582618d050baab6805849..f987736aa21fefc85bcece80e0672acd82c80a8c 100644
--- a/src/compiler/register-allocator.h
+++ b/src/compiler/register-allocator.h
@@ -678,8 +678,7 @@ class SpillRange final : public ZoneObject {
   SpillRange(TopLevelLiveRange* range, Zone* zone);
 
   UseInterval* interval() const { return use_interval_; }
-  // Currently, only 4 or 8 byte slots are supported.
-  int ByteWidth() const;

[bbudge, 2016/06/21 23:09:35]

This is redundant, as a byte_width() getter is defined below.

[Mircea Trofin, 2016/06/22 06:07:34]

Acknowledged.

+
   bool IsEmpty() const { return live_ranges_.empty(); }
   bool TryMerge(SpillRange* other);
   bool HasSlot() const { return assigned_slot_ != kUnassignedSlot; }
@@ -768,6 +767,12 @@ class RegisterAllocationData final : public ZoneObject {
   ZoneVector<TopLevelLiveRange*>& fixed_live_ranges() {
     return fixed_live_ranges_;
   }
+  ZoneVector<TopLevelLiveRange*>& fixed_float_live_ranges() {
+    return fixed_float_live_ranges_;
+  }
+  const ZoneVector<TopLevelLiveRange*>& fixed_float_live_ranges() const {
+    return fixed_float_live_ranges_;
+  }
   ZoneVector<TopLevelLiveRange*>& fixed_double_live_ranges() {
     return fixed_double_live_ranges_;
   }
@@ -779,7 +784,7 @@ class RegisterAllocationData final : public ZoneObject {
   ZoneVector<SpillRange*>& spill_ranges() { return spill_ranges_; }
   DelayedReferences& delayed_references() { return delayed_references_; }
   InstructionSequence* code() const { return code_; }
-  // This zone is for datastructures only needed during register allocation
+  // This zone is for data structures only needed during register allocation
   // phases.
   Zone* allocation_zone() const { return allocation_zone_; }
   // This zone is for InstructionOperands and moves that live beyond register
@@ -810,7 +815,7 @@ class RegisterAllocationData final : public ZoneObject {
   bool ExistsUseWithoutDefinition();
   bool RangesDefinedInDeferredStayInDeferred();
 
-  void MarkAllocated(RegisterKind kind, int index);
+  void MarkAllocated(MachineRepresentation rep, int index);
 
   PhiMapValue* InitializePhiMap(const InstructionBlock* block,
                                 PhiInstruction* phi);
@@ -835,6 +840,7 @@ class RegisterAllocationData final : public ZoneObject {
   ZoneVector<BitVector*> live_out_sets_;
   ZoneVector<TopLevelLiveRange*> live_ranges_;
   ZoneVector<TopLevelLiveRange*> fixed_live_ranges_;
+  ZoneVector<TopLevelLiveRange*> fixed_float_live_ranges_;
   ZoneVector<TopLevelLiveRange*> fixed_double_live_ranges_;
   ZoneVector<SpillRange*> spill_ranges_;
   DelayedReferences delayed_references_;
@@ -911,9 +917,9 @@ class LiveRangeBuilder final : public ZoneObject {
   void ProcessLoopHeader(const InstructionBlock* block, BitVector* live);
 
   static int FixedLiveRangeID(int index) { return -index - 1; }
-  int FixedDoubleLiveRangeID(int index);
+  int FixedFPLiveRangeID(int index, MachineRepresentation rep);
   TopLevelLiveRange* FixedLiveRangeFor(int index);
-  TopLevelLiveRange* FixedDoubleLiveRangeFor(int index);
+  TopLevelLiveRange* FixedFPLiveRangeFor(int index, MachineRepresentation rep);
 
   void MapPhiHint(InstructionOperand* operand, UsePosition* use_pos);
   void ResolvePhiHint(InstructionOperand* operand, UsePosition* use_pos);
@@ -947,7 +953,7 @@ class LiveRangeBuilder final : public ZoneObject {
 
 class RegisterAllocator : public ZoneObject {
  public:
-  explicit RegisterAllocator(RegisterAllocationData* data, RegisterKind kind);
+  RegisterAllocator(RegisterAllocationData* data, RegisterKind kind);
 
  protected:
   RegisterAllocationData* data() const { return data_; }
@@ -955,9 +961,10 @@ class RegisterAllocator : public ZoneObject {
   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];
+  const int* allocatable_register_codes() const {
+    return allocatable_register_codes_;
   }
+  bool no_combining() const { return no_combining_; }

[Mircea Trofin, 2016/06/22 06:07:34]

could you add a comment as to what this represents? Should it be no_aliasing
rather?

[bbudge, 2016/06/22 20:16:04]

Done.

[Mircea Trofin, 2016/06/22 21:37:37]

Where?

[bbudge, 2016/06/22 21:51:13]

See the next revision. As for your question, I considered no_aliasing() but
decided that since all platforms have aliasing (OVERLAP for Intel, COMBINE for
ARM), that this was preferable. Note that no_combine() is always true when
allocating general regs.

 
   // TODO(mtrofin): explain why splitting in gap START is always OK.
   LifetimePosition GetSplitPositionForInstruction(const LiveRange* range,
@@ -1009,6 +1016,9 @@ class RegisterAllocator : public ZoneObject {
   int num_allocatable_registers_;
   const int* allocatable_register_codes_;
 
+ private:
+  bool no_combining_;
+
   DISALLOW_COPY_AND_ASSIGN(RegisterAllocator);
 };