Handle negative input in inlined Math.round on Intel CPUs.

src/assembler.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 73 matching lines @@
 
 namespace v8 {
 namespace internal {
 
 // -----------------------------------------------------------------------------
 // Common double constants.
 
 struct DoubleConstant BASE_EMBEDDED {
   double min_int;
   double one_half;
+  double minus_one_half;
   double minus_zero;
   double zero;
   double uint8_max_value;
   double negative_infinity;
   double canonical_non_hole_nan;
   double the_hole_nan;
 };
 
 static DoubleConstant double_constants;
 
@@ skipping 742 matching lines @@
 }
 #endif  // VERIFY_HEAP
 
 
 // -----------------------------------------------------------------------------
 // Implementation of ExternalReference
 
 void ExternalReference::SetUp() {
   double_constants.min_int = kMinInt;
   double_constants.one_half = 0.5;
+  double_constants.minus_one_half = -0.5;
   double_constants.minus_zero = -0.0;
   double_constants.uint8_max_value = 255;
   double_constants.zero = 0.0;
   double_constants.canonical_non_hole_nan = OS::nan_value();
   double_constants.the_hole_nan = BitCast<double>(kHoleNanInt64);
   double_constants.negative_infinity = -V8_INFINITY;
 
   math_exp_data_mutex = OS::CreateMutex();
 }
 
@@ skipping 336 matching lines @@
 ExternalReference ExternalReference::address_of_min_int() {
   return ExternalReference(reinterpret_cast<void*>(&double_constants.min_int));
 }
 
 
 ExternalReference ExternalReference::address_of_one_half() {
   return ExternalReference(reinterpret_cast<void*>(&double_constants.one_half));
 }
 
 
+ExternalReference ExternalReference::address_of_minus_one_half() {
+  return ExternalReference(reinterpret_cast<void*>(
+      &double_constants.minus_one_half));

[Jakob Kummerow, 2013/02/27 14:40:07]

nit: for consistency with the code below, please break the line right after
"ExternalReference(".

+}
+
+
 ExternalReference ExternalReference::address_of_minus_zero() {
   return ExternalReference(
       reinterpret_cast<void*>(&double_constants.minus_zero));
 }
 
 
 ExternalReference ExternalReference::address_of_zero() {
   return ExternalReference(reinterpret_cast<void*>(&double_constants.zero));
 }
 
@@ skipping 378 matching lines @@
     assembler_->RecordRelocInfo(RelocInfo::POSITION, state_.current_position);
     state_.written_position = state_.current_position;
     written = true;
   }
 
   // Return whether something was written.
   return written;
 }
 
 } }  // namespace v8::internal