[turbofan] Improve typing rules for NumberFloor and NumberDivide.

src/compiler/operation-typer.cc

 // Copyright 2016 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/operation-typer.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/type-cache.h"
 #include "src/compiler/types.h"
 #include "src/factory.h"
@@ skipping 348 matching lines @@
 }
 
 Type* OperationTyper::NumberExpm1(Type* type) {
   DCHECK(type->Is(Type::Number()));
   return Type::Union(Type::PlainNumber(), Type::NaN(), zone());
 }
 
 Type* OperationTyper::NumberFloor(Type* type) {
   DCHECK(type->Is(Type::Number()));
   if (type->Is(cache_.kIntegerOrMinusZeroOrNaN)) return type;
-  // TODO(bmeurer): We could infer a more precise type here.
-  return cache_.kIntegerOrMinusZeroOrNaN;
+  type = Type::Intersect(type, Type::MinusZeroOrNaN(), zone());
+  type = Type::Union(type, cache_.kInteger, zone());
+  return type;
 }
 
 Type* OperationTyper::NumberFround(Type* type) {
   DCHECK(type->Is(Type::Number()));
   return Type::Number();
 }
 
 Type* OperationTyper::NumberLog(Type* type) {
   DCHECK(type->Is(Type::Number()));
   return Type::Number();
@@ skipping 236 matching lines @@
 
 Type* OperationTyper::NumberDivide(Type* lhs, Type* rhs) {
   DCHECK(lhs->Is(Type::Number()));
   DCHECK(rhs->Is(Type::Number()));
 
   if (!lhs->IsInhabited() || !rhs->IsInhabited()) {
     return Type::None();
   }
 
   if (lhs->Is(Type::NaN()) || rhs->Is(Type::NaN())) return Type::NaN();
-  // Division is tricky, so all we do is try ruling out 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));
-  return maybe_nan ? Type::Number() : Type::OrderedNumber();
+
+  // Take into account the -0 and NaN information computed earlier.
+  Type* type = Type::PlainNumber();
+  if (maybe_minuszero) type = Type::Union(type, Type::MinusZero(), zone());
+  if (maybe_nan) type = Type::Union(type, Type::NaN(), zone());
+  return type;
 }
 
 Type* OperationTyper::NumberModulus(Type* lhs, Type* rhs) {
   DCHECK(lhs->Is(Type::Number()));
   DCHECK(rhs->Is(Type::Number()));
 
   // Modulus can yield NaN if either {lhs} or {rhs} are NaN, or
   // {lhs} is not finite, or the {rhs} is a zero value.
   bool maybe_nan = lhs->Maybe(Type::NaN()) || rhs->Maybe(cache_.kZeroish) ||
                    lhs->Min() == -V8_INFINITY || lhs->Max() == +V8_INFINITY;
@@ skipping 341 matching lines @@
   return singleton_true();
 }
 
 Type* OperationTyper::TypeTypeGuard(const Operator* sigma_op, Type* input) {
   return Type::Intersect(input, TypeGuardTypeOf(sigma_op), zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8