[Turbofan] Merge SpillRanges by byte_width rather than kind.

src/compiler/register-allocator.cc

Index: src/compiler/register-allocator.cc
diff --git a/src/compiler/register-allocator.cc b/src/compiler/register-allocator.cc
index 119e11f031c372f8a49732dc8940975b33d180c4..146ab4a72716bc94a46e8b05f196a1ffa1f10386 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -1222,12 +1222,11 @@ std::ostream& operator<<(std::ostream& os,
   return os;
 }
 
-
 SpillRange::SpillRange(TopLevelLiveRange* parent, Zone* zone)
     : live_ranges_(zone),
       assigned_slot_(kUnassignedSlot),
-      byte_width_(GetByteWidth(parent->representation())),
-      kind_(parent->kind()) {
+      representation_(parent->representation()),
+      byte_width_(GetByteWidth(parent->representation())) {
   // Spill ranges are created for top level, non-splintered ranges. This is so
   // that, when merging decisions are made, we consider the full extent of the
   // virtual register, and avoid clobbering it.
@@ -1254,12 +1253,6 @@ SpillRange::SpillRange(TopLevelLiveRange* parent, Zone* zone)
   parent->SetSpillRange(this);
 }
 
-
-int SpillRange::ByteWidth() const {
-  return GetByteWidth(live_ranges_[0]->representation());
-}
-
-
 bool SpillRange::IsIntersectingWith(SpillRange* other) const {
   if (this->use_interval_ == nullptr || other->use_interval_ == nullptr ||
       this->End() <= other->use_interval_->start() ||
@@ -1272,8 +1265,8 @@ bool SpillRange::IsIntersectingWith(SpillRange* other) const {
 
 bool SpillRange::TryMerge(SpillRange* other) {
   if (HasSlot() || other->HasSlot()) return false;
-  // TODO(dcarney): byte widths should be compared here not kinds.
-  if (live_ranges_[0]->kind() != other->live_ranges_[0]->kind() ||
+  if (live_ranges_[0]->representation() !=
+          other->live_ranges_[0]->representation() ||

[bbudge, 2016/06/18 23:33:22]

It occurs to me that this will now prevent non-FP spill ranges from being
merged. Could that cause a problem? The comment I deleted implies that this
should be possible, at least for non-FP types which are all different sizes.

       IsIntersectingWith(other)) {
     return false;
   }
@@ -3167,7 +3160,7 @@ void OperandAssigner::AssignSpillSlots() {
     if (range == nullptr || range->IsEmpty()) continue;
     // Allocate a new operand referring to the spill slot.
     if (!range->HasSlot()) {
-      int byte_width = range->ByteWidth();
+      int byte_width = range->byte_width();
       int index = data()->frame()->AllocateSpillSlot(byte_width);
       range->set_assigned_slot(index);
     }