[turbofan] Splinter into one range.

src/compiler/live-range-separator.cc

Index: src/compiler/live-range-separator.cc
diff --git a/src/compiler/live-range-separator.cc b/src/compiler/live-range-separator.cc
index f29e4b4a202efb26c320c5892b464ba62fa38ea4..ea9152b818566e4cb25f3ac34404105484a33c99 100644
--- a/src/compiler/live-range-separator.cc
+++ b/src/compiler/live-range-separator.cc
@@ -78,12 +78,14 @@ void CreateSplinter(TopLevelLiveRange *range, RegisterAllocationData *data,
     if (range->MayRequireSpillRange()) {
       data->CreateSpillRangeForLiveRange(range);
     }
-    TopLevelLiveRange *result = data->NextLiveRange(range->machine_type());
-    DCHECK_NULL(data->live_ranges()[result->vreg()]);
-    data->live_ranges()[result->vreg()] = result;
-
+    if (range->splinter() == nullptr) {
+      TopLevelLiveRange *splinter = data->NextLiveRange(range->machine_type());
+      DCHECK_NULL(data->live_ranges()[splinter->vreg()]);
+      data->live_ranges()[splinter->vreg()] = splinter;
+      range->SetSplinter(splinter);
+    }
     Zone *zone = data->allocation_zone();
-    range->Splinter(start, end, result, zone);
+    range->Splinter(start, end, zone);
   }
 }