Fix for issue 2132.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index c66a7a137d5cbe67b9c76166d84997f77c4ec8ef..f495eeef0f838faf8209efed205b19554ad2e1f3 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -522,8 +522,23 @@ void HValue::RemoveLastAddedRange() {
 
 
 void HValue::ComputeInitialRange(Zone* zone) {
+  ASSERT(CheckFlag(kHasPreinitializedRange) || !HasRange());
+  Range* new_range = InferRange(zone);
+  if (CheckFlag(kHasPreinitializedRange)) {
+    range_->Intersect(new_range);
+    ClearFlag(kHasPreinitializedRange);
+  } else {
+    range_ = new_range;
+  }
+  ASSERT(HasRange());
+}
+
+
+void HValue::PreinitializeRange(Zone* zone) {
   ASSERT(!HasRange());
-  range_ = InferRange(zone);
+  range_ = new(zone) Range();
+  range_->set_can_be_minus_zero(true);
+  SetFlag(kHasPreinitializedRange);
   ASSERT(HasRange());
 }
 
@@ -861,11 +876,15 @@ HValue* HBitwise::Canonicalize() {
   if (left()->IsConstant() &&
       HConstant::cast(left())->HasInteger32Value() &&
       HConstant::cast(left())->Integer32Value() == nop_constant) {
+    right()->PreinitializeRange(block()->zone());
+    right()->range()->set_can_be_minus_zero(false);

[Vyacheslav Egorov (Chromium), 2012/05/18 17:39:05]

I don't think this is correct. Consider code like:

function mul(a, b) {
  var x = a * b;
  x | 0;
  return x;
}

your code will remove minus zero from the range of x but this is incorrect.

     return right();
   }
   if (right()->IsConstant() &&
       HConstant::cast(right())->HasInteger32Value() &&
       HConstant::cast(right())->Integer32Value() == nop_constant) {
+    left()->PreinitializeRange(block()->zone());
+    left()->range()->set_can_be_minus_zero(false);
     return left();
   }
   return this;