[turbofan] Insert sigma nodes for loop variable backedge.

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 203 matching lines @@
   }
   UNREACHABLE();
   return os;
 }
 
 RegionObservability RegionObservabilityOf(Operator const* op) {
   DCHECK_EQ(IrOpcode::kBeginRegion, op->opcode());
   return OpParameter<RegionObservability>(op);
 }
 
+Type* SigmaTypeOf(Operator const* op) {
+  DCHECK_EQ(IrOpcode::kSigma, op->opcode());
+  return OpParameter<Type*>(op);
+}
+
 std::ostream& operator<<(std::ostream& os,
                          const ZoneVector<MachineType>* types) {
   // Print all the MachineTypes, separated by commas.
   bool first = true;
   for (MachineType elem : *types) {
     if (!first) {
       os << ", ";
     }
     first = false;
     os << elem;
@@ skipping 612 matching lines @@
   CACHED_PHI_LIST(CACHED_PHI)
 #undef CACHED_PHI
   // Uncached.
   return new (zone()) Operator1<MachineRepresentation>(  // --
       IrOpcode::kPhi, Operator::kPure,                   // opcode
       "Phi",                                             // name
       value_input_count, 0, 1, 1, 0, 0,                  // counts
       rep);                                              // parameter
 }
 
+const Operator* CommonOperatorBuilder::Sigma(Type* type) {
+  return new (zone()) Operator1<Type*>(   // --
+      IrOpcode::kSigma, Operator::kPure,  // opcode
+      "Sigma",                            // name
+      1, 0, 1, 1, 0, 0,                   // counts
+      type);                              // parameter
+}
 
 const Operator* CommonOperatorBuilder::EffectPhi(int effect_input_count) {
   DCHECK(effect_input_count > 0);  // Disallow empty effect phis.
   switch (effect_input_count) {
 #define CACHED_EFFECT_PHI(input_count) \
   case input_count:                    \
     return &cache_.kEffectPhi##input_count##Operator;
     CACHED_EFFECT_PHI_LIST(CACHED_EFFECT_PHI)
 #undef CACHED_EFFECT_PHI
     default:
@@ skipping 164 matching lines @@
 CommonOperatorBuilder::CreateFrameStateFunctionInfo(
     FrameStateType type, int parameter_count, int local_count,
     Handle<SharedFunctionInfo> shared_info) {
   return new (zone()->New(sizeof(FrameStateFunctionInfo)))
       FrameStateFunctionInfo(type, parameter_count, local_count, shared_info);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8