[turbofan] Simplified splintering code.

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 6591d71e72b3f66a309452cb4d88ea2d2f2109bb..d7ef5ddbc2a2c1a720cb16b55d9c1c73f6ac2090 100644
--- a/src/compiler/live-range-separator.cc
+++ b/src/compiler/live-range-separator.cc
@@ -58,26 +58,6 @@ void CreateSplinter(TopLevelLiveRange *range, RegisterAllocationData *data,
 }
 
 
-int FirstInstruction(const UseInterval *interval) {
-  LifetimePosition start = interval->start();
-  int ret = start.ToInstructionIndex();
-  if (start.IsInstructionPosition() && start.IsEnd()) {
-    ++ret;
-  }
-  return ret;
-}
-
-
-int LastInstruction(const UseInterval *interval) {
-  LifetimePosition end = interval->end();
-  int ret = end.ToInstructionIndex();
-  if (end.IsGapPosition() || end.IsStart()) {
-    --ret;
-  }
-  return ret;
-}
-
-
 void SplinterLiveRange(TopLevelLiveRange *range, RegisterAllocationData *data) {
   const InstructionSequence *code = data->code();
   UseInterval *interval = range->first_interval();
@@ -88,9 +68,9 @@ void SplinterLiveRange(TopLevelLiveRange *range, RegisterAllocationData *data) {
   while (interval != nullptr) {
     UseInterval *next_interval = interval->next();
     const InstructionBlock *first_block =
-        code->GetInstructionBlock(FirstInstruction(interval));
+        code->GetInstructionBlock(interval->FirstInstructionIndex());
     const InstructionBlock *last_block =
-        code->GetInstructionBlock(LastInstruction(interval));
+        code->GetInstructionBlock(interval->LastInstructionIndex());
     int first_block_nr = first_block->rpo_number().ToInt();
     int last_block_nr = last_block->rpo_number().ToInt();
     for (int block_id = first_block_nr; block_id <= last_block_nr; ++block_id) {
@@ -129,7 +109,10 @@ void LiveRangeSeparator::Splinter() {
     if (range == nullptr || range->IsEmpty() || range->IsSplinter()) {
       continue;
     }
-    SplinterLiveRange(range, data());
+    int first_instr = range->first_interval()->FirstInstructionIndex();
+    if (!data()->code()->GetInstructionBlock(first_instr)->IsDeferred()) {
+      SplinterLiveRange(range, data());
+    }
   }
 }