Add a genuine unary minus instruction to Crankshaft....

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc	(revision 6698)
+++ src/hydrogen-instructions.cc	(working copy)
@@ -680,6 +680,12 @@
 }
 
 
+void HNeg::PrintDataTo(StringStream* stream) const {
+  HUnaryOperation::PrintDataTo(stream);
+  if (CheckFlag(kBailoutOnMinusZero)) stream->Add(" -0?");
+}
+
+
 HCheckInstanceType* HCheckInstanceType::NewIsJSObjectOrJSFunction(
     HValue* value)  {
   STATIC_ASSERT((LAST_JS_OBJECT_TYPE + 1) == JS_FUNCTION_TYPE);
@@ -874,6 +880,22 @@
 }
 
 
+Range* HNeg::InferRange() {
+  if (representation().IsInteger32()) {
+    Range* input_range = value()->range();
+    Range* result = input_range->Copy();
+    Range neg_one(-1, -1);
+    if (!result->MulAndCheckOverflow(&neg_one)) {
+      ClearFlag(HValue::kCanOverflow);
+    }
+    result->set_can_be_minus_zero(input_range->CanBeZero());
+    return result;
+  } else {
+    return HValue::InferRange();
+  }
+}
+
+
 void HPhi::PrintTo(StringStream* stream) const {
   stream->Add("[");
   for (int i = 0; i < OperandCount(); ++i) {
@@ -1288,6 +1310,11 @@
 }
 
 
+HType HNeg::CalculateInferredType() const {
+  return HType::TaggedNumber();
+}
+
+
 HType HUnaryMathOperation::CalculateInferredType() const {
   return HType::TaggedNumber();
 }
@@ -1366,6 +1393,15 @@
 }
 
 
+HValue* HNeg::EnsureAndPropagateNotMinusZero(BitVector* visited) {
+  visited->Add(id());
+  if (range() == NULL || range()->CanBeMinusZero()) {
+    SetFlag(kBailoutOnMinusZero);
+  }
+  return NULL;
+}
+
+
 HValue* HSub::EnsureAndPropagateNotMinusZero(BitVector* visited) {
   visited->Add(id());
   // Propagate to the left argument. If the left argument cannot be -0, then