[WIP] Faster smi tagging.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 0fa2b95ebd3460350def99acdd14b2341d7b1b00..745a43536afeeb6997adb43d468fa559c92cef82 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -739,6 +739,11 @@ Type* Typer::Visitor::JSBitwiseAndTyper(Type* lhs, Type* rhs, Typer* t) {
   double rmin = rhs->Min();
   double lmax = lhs->Max();
   double rmax = rhs->Max();
+  if (std::min(lmax, rmax) < kMaxInt) {
+    Handle<Object> min = f->NewNumber(0);
+    Handle<Object> max = f->NewNumber(std::min(lmax, rmax));
+    return Type::Range(min, max, t->zone());
+  }
   // And-ing any two values results in a value no larger than their maximum.
   // Even no larger than their minimum if both values are non-negative.
   Handle<Object> max = f->NewNumber(
@@ -780,6 +785,7 @@ Type* Typer::Visitor::JSShiftLeftTyper(Type* lhs, Type* rhs, Typer* t) {
 
 Type* Typer::Visitor::JSShiftRightTyper(Type* lhs, Type* rhs, Typer* t) {
   lhs = NumberToInt32(ToNumber(lhs, t), t);
+  rhs = NumberToInt32(ToNumber(rhs, t), t);
   Factory* f = t->isolate()->factory();
   if (lhs->Min() >= 0) {
     // Right-shifting a non-negative value cannot make it negative, nor larger.
@@ -793,6 +799,12 @@ Type* Typer::Visitor::JSShiftRightTyper(Type* lhs, Type* rhs, Typer* t) {
     Handle<Object> max = f->NewNumber(-1);
     return Type::Range(min, max, t->zone());
   }
+  if (rhs->Min() > 0) {
+    // Right-shifting by a positve value yields a small integer value.
+    Handle<Object> min = f->NewNumber(kMinInt >> static_cast<int>(rhs->Min()));
+    Handle<Object> max = f->NewNumber(kMaxInt >> static_cast<int>(rhs->Min()));
+    return Type::Range(min, max, t->zone());
+  }
   return Type::Signed32();
 }