[turbofan] Quit storing strings in types.

BUG=

Review-Url: https://codereview.chromium.org/2402313003
Cr-Commit-Position: refs/heads/master@{#40245}

src/compiler/typer.cc

@@ -1527,28 +1527,10 @@ Type* Typer::Visitor::TypeStringLessThanOrEqual(Node* node) {
 }
 
 Type* Typer::Visitor::StringFromCharCodeTyper(Type* type, Typer* t) {
-  type = NumberToUint32(ToNumber(type, t), t);
-  Factory* f = t->isolate()->factory();
-  double min = type->Min();
-  double max = type->Max();
-  if (min == max) {
-    uint32_t code = static_cast<uint32_t>(min) & String::kMaxUtf16CodeUnitU;
-    Handle<String> string = f->LookupSingleCharacterStringFromCode(code);
-    return Type::HeapConstant(string, t->zone());
-  }
   return Type::String();
 }
 
 Type* Typer::Visitor::StringFromCodePointTyper(Type* type, Typer* t) {
-  type = NumberToUint32(ToNumber(type, t), t);
-  Factory* f = t->isolate()->factory();
-  double min = type->Min();
-  double max = type->Max();
-  if (min == max) {
-    uint32_t code = static_cast<uint32_t>(min) & String::kMaxUtf16CodeUnitU;
-    Handle<String> string = f->LookupSingleCharacterStringFromCode(code);
-    return Type::HeapConstant(string, t->zone());
-  }
   return Type::String();
 }
 

src/compiler/types.cc

@@ -407,6 +407,7 @@ HeapConstantType::HeapConstantType(BitsetType::bitset bitset,
                                    i::Handle<i::HeapObject> object)
     : TypeBase(kHeapConstant), bitset_(bitset), object_(object) {
   DCHECK(!object->IsHeapNumber());
+  DCHECK(!object->IsString());
 }
 
 // -----------------------------------------------------------------------------
@@ -782,6 +783,17 @@ Type* Type::NewConstant(i::Handle<i::Object> value, Zone* zone) {
     return Range(v, v, zone);
   } else if (value->IsHeapNumber()) {
     return NewConstant(value->Number(), zone);
+  } else if (value->IsString()) {
+    bitset b = BitsetType::Lub(*value);
+    DCHECK(b == BitsetType::kInternalizedString ||
+           b == BitsetType::kOtherString);
+    if (b == BitsetType::kInternalizedString) {
+      return Type::InternalizedString();
+    } else if (b == BitsetType::kOtherString) {
+      return Type::OtherString();
+    } else {
+      UNREACHABLE();
+    }
   }
   return HeapConstant(i::Handle<i::HeapObject>::cast(value), zone);
 }

test/unittests/compiler/graph-unittest.cc

@@ -58,7 +58,7 @@ Node* GraphTest::NumberConstant(volatile double value) {
 
 Node* GraphTest::HeapConstant(const Handle<HeapObject>& value) {
   Node* node = graph()->NewNode(common()->HeapConstant(value));
-  Type* type = Type::HeapConstant(value, zone());
+  Type* type = Type::NewConstant(value, zone());
   NodeProperties::SetType(node, type);
   return node;
 }