[turbofan] Extend optimization of flooring integer division.

src/compiler/operation-typer.cc

Index: src/compiler/operation-typer.cc
diff --git a/src/compiler/operation-typer.cc b/src/compiler/operation-typer.cc
index dfd4c4b60477cad6b154fcbaeb123d472cc85235..fd6dfa444abc15f30e52a5fa7ac675ee55503d97 100644
--- a/src/compiler/operation-typer.cc
+++ b/src/compiler/operation-typer.cc
@@ -625,13 +625,20 @@ Type* OperationTyper::NumberDivide(Type* lhs, Type* rhs) {
   }
 
   if (lhs->Is(Type::NaN()) || rhs->Is(Type::NaN())) return Type::NaN();
+
   // Division is tricky, so all we do is try ruling out -0 and NaN.
-  bool maybe_minuszero = !lhs->Is(cache_.kPositiveIntegerOrNaN) ||
-                         !rhs->Is(cache_.kPositiveIntegerOrNaN);
   bool maybe_nan =
       lhs->Maybe(Type::NaN()) || rhs->Maybe(cache_.kZeroish) ||
       ((lhs->Min() == -V8_INFINITY || lhs->Max() == +V8_INFINITY) &&
        (rhs->Min() == -V8_INFINITY || rhs->Max() == +V8_INFINITY));
+  lhs = Type::Intersect(lhs, Type::OrderedNumber(), zone());
+  rhs = Type::Intersect(rhs, Type::OrderedNumber(), zone());
+
+  // Try to rule out -0.
+  bool maybe_minuszero =
+      lhs->Maybe(Type::MinusZero()) ||
+      (lhs->Maybe(cache_.kZeroish) && rhs->Min() < 0.0) ||
+      (rhs->Min() == -V8_INFINITY || rhs->Max() == +V8_INFINITY);

[Jarin, 2017/03/07 14:00:27]

As discussed offline, this is not correct because of underflow. It should be
fine for lhs integer (i.e., if lhs is not integer the result may be -0).

[Benedikt Meurer, 2017/03/07 14:16:38]

Done.

 
   // Take into account the -0 and NaN information computed earlier.
   Type* type = Type::PlainNumber();