[turbofan] Simplified splintering code.

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index 67ea99292e091d7e7794f096e73ee8f993c78d47..55cef8a062da2d0875f51c820cb90937922beb5f 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -844,6 +844,31 @@ struct AllocateDoubleRegistersPhase {
 };
 
 
+struct MarkSpilledOnlyInDeferredPhase {

[Jarin, 2015/11/25 10:33:08]

I think there is no need to introduce a new phase for this. It could be done as
part of MergeSplintersPhase.

[Mircea Trofin, 2015/11/25 16:21:36]

It can be done, but it seemed cleaner to have it separate - merged it in for
now, because I can't find a better defense for separation than "it seems
cleaner".

+  static const char* phase_name() {
+    return "mark ranges spilled in deferred blocks";
+  }
+
+  void Run(PipelineData* pipeline_data, Zone* temp_zone) {
+    RegisterAllocationData* data = pipeline_data->register_allocation_data();
+    for (TopLevelLiveRange* top : data->live_ranges()) {

[Jarin, 2015/11/25 10:33:08]

The pipeline should not know about implementation details, such as the live
range data structure. The code here should be moved to a method of the register
allocator and the method should be called from here.

[Mircea Trofin, 2015/11/25 16:21:36]

done as a side-effect of addressing the above.

+      if (top == nullptr || top->IsEmpty() || top->splinter() == nullptr) {
+        continue;
+      }
+
+      LiveRange* child = top;
+      for (; child != nullptr; child = child->next()) {
+        if (child->spilled() ||
+            child->NextSlotPosition(child->Start()) != nullptr) {
+          break;
+        }
+      }
+      if (child == nullptr) top->MarkSpilledInDeferredBlock();
+    }
+  }
+};
+
+
 struct MergeSplintersPhase {
   static const char* phase_name() { return "merge splintered ranges"; }
   void Run(PipelineData* pipeline_data, Zone* temp_zone) {
@@ -1376,6 +1401,8 @@ void Pipeline::AllocateRegisters(const RegisterConfiguration* config,
   }
   if (verifier != nullptr) {
     CHECK(!data->register_allocation_data()->ExistsUseWithoutDefinition());
+    CHECK(data->register_allocation_data()
+              ->RangesDefinedInDeferredStaysInDeferred());
   }
 
   if (FLAG_turbo_preprocess_ranges) {
@@ -1391,6 +1418,7 @@ void Pipeline::AllocateRegisters(const RegisterConfiguration* config,
   }
 
   if (FLAG_turbo_preprocess_ranges) {
+    Run<MarkSpilledOnlyInDeferredPhase>();
     Run<MergeSplintersPhase>();
   }