[turbofan] Split pure nodes in the scheduler if beneficial.

src/compiler/common-operator.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/common-operator.h"
 
 #include "src/assembler.h"
 #include "src/base/lazy-instance.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/opcodes.h"
@@ skipping 469 matching lines @@
 
     void PrintParameter(std::ostream& os) const OVERRIDE {
       os << "[" << *parameter() << "]";
     }
   };
   return new (zone()) CallOperator(descriptor, "Call");
 }
 
 
 const Operator* CommonOperatorBuilder::Projection(size_t index) {
-  return new (zone()) Operator1<size_t>(       // --
-      IrOpcode::kProjection, Operator::kPure,  // opcode
-      "Projection",                            // name
-      1, 0, 0, 1, 0, 0,                        // counts
-      index);                                  // parameter
+  return new (zone()) Operator1<size_t>(         // --
+      IrOpcode::kProjection,                     // opcode
+      Operator::kFoldable | Operator::kNoThrow,  // flags
+      "Projection",                              // name
+      1, 0, 0, 1, 0, 0,                          // counts
+      index);                                    // parameter
 }
 
 
 const Operator* CommonOperatorBuilder::ResizeMergeOrPhi(const Operator* op,
                                                         int size) {
   if (op->opcode() == IrOpcode::kPhi) {
     return Phi(OpParameter<MachineType>(op), size);
   } else if (op->opcode() == IrOpcode::kEffectPhi) {
     return EffectPhi(size);
   } else if (op->opcode() == IrOpcode::kMerge) {
     return Merge(size);
   } else if (op->opcode() == IrOpcode::kLoop) {
     return Loop(size);
   } else {
     UNREACHABLE();
     return nullptr;
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8