[turbofan] add some simplifications in the machine operator reducer

src/compiler/machine-operator-reducer.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/machine-operator-reducer.h"
 
 #include "src/base/bits.h"
 #include "src/compiler/generic-node-inl.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/js-graph.h"
@@ skipping 320 matching lines @@
       if (m.left().Is(0)) return ReplaceBool(true);            // 0 <= x => true
       if (m.right().Is(kMaxUInt32)) return ReplaceBool(true);  // x <= M => true
       if (m.IsFoldable()) {                                    // K <= K => K
         return ReplaceBool(m.left().Value() <= m.right().Value());
       }
       if (m.LeftEqualsRight()) return ReplaceBool(true);  // x <= x => true
       break;
     }
     case IrOpcode::kFloat64Add: {
       Float64BinopMatcher m(node);
+      if (m.right().IsNaN()) {  // x + NaN => NaN
+        return Replace(m.right().node());
+      }
       if (m.IsFoldable()) {  // K + K => K
         return ReplaceFloat64(m.left().Value() + m.right().Value());
       }
       break;
     }
     case IrOpcode::kFloat64Sub: {
       Float64BinopMatcher m(node);
+      if (m.right().Is(0) && (Double(m.right().Value()).Sign() > 0)) {
+        return Replace(m.left().node());  // x - 0 => x
+      }
+      if (m.right().IsNaN()) {  // x - NaN => NaN
+        return Replace(m.right().node());
+      }
+      if (m.left().IsNaN()) {  // NaN - x => NaN
+        return Replace(m.left().node());
+      }
       if (m.IsFoldable()) {  // K - K => K
         return ReplaceFloat64(m.left().Value() - m.right().Value());
       }
       break;
     }
     case IrOpcode::kFloat64Mul: {
       Float64BinopMatcher m(node);
       if (m.right().Is(1)) return Replace(m.left().node());  // x * 1.0 => x
       if (m.right().IsNaN()) {                               // x * NaN => NaN
         return Replace(m.right().node());
@@ skipping 12 matching lines @@
       if (m.left().IsNaN()) {  // NaN / x => NaN
         return Replace(m.left().node());
       }
       if (m.IsFoldable()) {  // K / K => K
         return ReplaceFloat64(m.left().Value() / m.right().Value());
       }
       break;
     }
     case IrOpcode::kFloat64Mod: {
       Float64BinopMatcher m(node);
+      if (m.right().Is(0)) {  // x % 0 => NaN
+        return ReplaceFloat64(base::OS::nan_value());
+      }
       if (m.right().IsNaN()) {  // x % NaN => NaN
         return Replace(m.right().node());
       }
       if (m.left().IsNaN()) {  // NaN % x => NaN
         return Replace(m.left().node());
       }
       if (m.IsFoldable()) {  // K % K => K
         return ReplaceFloat64(modulo(m.left().Value(), m.right().Value()));
       }
       break;
@@ skipping 105 matching lines @@
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8