[turbofan] Introduce simplified operator NumberAbs.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 556efa553192a3b4771b028cab96f5b70f730f56..2bc0bb333f3f8e6749a59fead251ce4bf00a08a3 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -243,6 +243,7 @@ class Typer::Visitor : public Reducer {
   static Type* ToNumber(Type*, Typer*);
   static Type* ToObject(Type*, Typer*);
   static Type* ToString(Type*, Typer*);
+  static Type* NumberAbs(Type*, Typer*);
   static Type* NumberCeil(Type*, Typer*);
   static Type* NumberFloor(Type*, Typer*);
   static Type* NumberRound(Type*, Typer*);
@@ -479,6 +480,34 @@ Type* Typer::Visitor::ToString(Type* type, Typer* t) {
 }
 
 // static
+Type* Typer::Visitor::NumberAbs(Type* type, Typer* t) {
+  DCHECK(type->Is(Type::Number()));
+  Factory* const f = t->isolate()->factory();
+  bool const maybe_nan = type->Maybe(Type::NaN());
+  bool const maybe_minuszero = type->Maybe(Type::MinusZero());
+  type = Type::Intersect(type, Type::PlainNumber(), t->zone());
+  double const max = type->Max();
+  double const min = type->Min();
+  if (min < 0) {
+    if (type->Is(t->cache_.kInteger)) {
+      type =
+          Type::Range(0.0, std::max(std::fabs(min), std::fabs(max)), t->zone());
+    } else if (min == max) {
+      type = Type::Constant(f->NewNumber(std::fabs(min)), t->zone());
+    } else {
+      type = Type::PlainNumber();
+    }
+  }
+  if (maybe_minuszero) {
+    type = Type::Union(type, t->cache_.kSingletonZero, t->zone());
+  }
+  if (maybe_nan) {
+    type = Type::Union(type, Type::NaN(), t->zone());
+  }
+  return type;
+}
+
+// static
 Type* Typer::Visitor::NumberCeil(Type* type, Typer* t) {
   DCHECK(type->Is(Type::Number()));
   if (type->Is(t->cache_.kIntegerOrMinusZeroOrNaN)) return type;
@@ -1597,6 +1626,10 @@ Type* Typer::Visitor::TypePlainPrimitiveToFloat64(Node* node) {
 
 Type* Typer::Visitor::TypeNumberImul(Node* node) { return Type::Signed32(); }
 
+Type* Typer::Visitor::TypeNumberAbs(Node* node) {
+  return TypeUnaryOp(node, NumberAbs);
+}
+
 Type* Typer::Visitor::TypeNumberClz32(Node* node) {
   return typer_->cache_.kZeroToThirtyTwo;
 }