[turbofan] Readjust has_slot_use after splintering

has_slot_use is computed early, and we need it to determine if we need
to generate SpillRanges. After splintering, however, the information may
be incorrect - e.g. just the splinter may have slot uses, and not the
original.

BUG=

Review-Url: https://codereview.chromium.org/2312523002
Cr-Commit-Position: refs/heads/master@{#39147}

src/compiler/live-range-separator.cc

@@ -58,6 +58,15 @@ void CreateSplinter(TopLevelLiveRange *range, RegisterAllocationData *data,
   }
 }
 
+void SetSlotUse(TopLevelLiveRange *range) {
+  range->set_has_slot_use(false);
+  for (const UsePosition *pos = range->first_pos();
+       !range->has_slot_use() && pos != nullptr; pos = pos->next()) {
+    if (pos->type() == UsePositionType::kRequiresSlot) {
+      range->set_has_slot_use(true);
+    }
+  }
+}
 
 void SplinterLiveRange(TopLevelLiveRange *range, RegisterAllocationData *data) {
   const InstructionSequence *code = data->code();
@@ -99,7 +108,14 @@ void SplinterLiveRange(TopLevelLiveRange *range, RegisterAllocationData *data) {
   if (first_cut.IsValid()) {
     CreateSplinter(range, data, first_cut, last_cut);
   }
+
+  // Redo has_slot_use
+  if (range->has_slot_use() && range->splinter() != nullptr) {
+    SetSlotUse(range);
+    SetSlotUse(range->splinter());
+  }
 }
+
 }  // namespace
 
 

src/compiler/register-allocator.cc

@@ -1041,6 +1041,8 @@ void TopLevelLiveRange::Merge(TopLevelLiveRange* other, Zone* zone) {
 
   TopLevel()->UpdateParentForAllChildren(TopLevel());
   TopLevel()->UpdateSpillRangePostMerge(other);
+  TopLevel()->set_has_slot_use(TopLevel()->has_slot_use() ||
+                               other->has_slot_use());
 
 #if DEBUG
   Verify();