[turbofan] Transform x * -1.0 to -0.0 - x.

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/base/division-by-constant.h"
 #include "src/codegen.h"
 #include "src/compiler/diamond.h"
@@ skipping 423 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::kFloat64Mul: {
       Float64BinopMatcher m(node);
+      if (m.right().Is(-1)) {  // x * -1.0 => -0.0 - x
+        node->set_op(machine()->Float64Sub());
+        node->ReplaceInput(0, Float64Constant(-0.0));
+        node->ReplaceInput(1, m.left().node());
+        return Changed(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());
       }
       if (m.IsFoldable()) {  // K * K => K
         return ReplaceFloat64(m.left().Value() * m.right().Value());
       }
       break;
     }
     case IrOpcode::kFloat64Div: {
@@ skipping 313 matching lines @@
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8