[compiler] No longer expose the OtherString type.

This type is dangerous because it can become smaller over time (as
strings get internalized).

Bug: v8:6521
Change-Id: Iea650789ab52c13a0519f46999edc8a7959ccc71
Reviewed-on: https://chromium-review.googlesource.com/968525
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52040}

src/compiler/typer.cc

@@ -2242,9 +2242,7 @@ Type* Typer::Visitor::TypeNewArgumentsElements(Node* node) {
   return Type::OtherInternal();
 }
 
-Type* Typer::Visitor::TypeNewConsString(Node* node) {
-  return Type::OtherString();
-}
+Type* Typer::Visitor::TypeNewConsString(Node* node) { return Type::String(); }
 
 Type* Typer::Visitor::TypeArrayBufferWasNeutered(Node* node) {
   return Type::Boolean();

src/compiler/types.cc

@@ -163,7 +163,7 @@ Type::bitset BitsetType::Lub(i::Map* map) {
     case SHORT_EXTERNAL_STRING_WITH_ONE_BYTE_DATA_TYPE:
     case STRING_TYPE:
     case ONE_BYTE_STRING_TYPE:
-      return kOtherString;
+      return kString;
     case EXTERNAL_INTERNALIZED_STRING_TYPE:
     case EXTERNAL_ONE_BYTE_INTERNALIZED_STRING_TYPE:
     case EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE:
@@ -361,6 +361,7 @@ size_t BitsetType::BoundariesSize() {
 }
 
 Type::bitset BitsetType::ExpandInternals(Type::bitset bits) {
+  DCHECK_IMPLIES(bits & kOtherString, (bits & kString) == kString);
   DisallowHeapAllocation no_allocation;
   if (!(bits & kPlainNumber)) return bits;  // Shortcut.
   const Boundary* boundaries = Boundaries();
@@ -823,7 +824,7 @@ Type* Type::NewConstant(i::Handle<i::Object> value, Zone* zone) {
   } else if (value->IsHeapNumber()) {
     return NewConstant(value->Number(), zone);
   } else if (value->IsString() && !value->IsInternalizedString()) {
-    return Type::OtherString();
+    return Type::String();
   }
   return HeapConstant(i::Handle<i::HeapObject>::cast(value), zone);
 }

src/compiler/types.h

@@ -103,31 +103,31 @@ namespace compiler {
   V(OtherUnsigned32, 1u << 2)  \
   V(OtherSigned32,   1u << 3)  \
   V(OtherNumber,     1u << 4)  \
+  V(OtherString,     1u << 5)  \
 
 #define PROPER_BITSET_TYPE_LIST(V) \
   V(None,                     0u)        \
-  V(Negative31,               1u << 5)   \
-  V(Null,                     1u << 6)   \
-  V(Undefined,                1u << 7)   \
-  V(Boolean,                  1u << 8)   \
-  V(Unsigned30,               1u << 9)   \
-  V(MinusZero,                1u << 10)  \
-  V(NaN,                      1u << 11)  \
-  V(Symbol,                   1u << 12)  \
-  V(InternalizedString,       1u << 13)  \
-  V(OtherString,              1u << 14)  \
-  V(OtherCallable,            1u << 15)  \
-  V(OtherObject,              1u << 16)  \
-  V(OtherUndetectable,        1u << 17)  \
-  V(CallableProxy,            1u << 18)  \
-  V(OtherProxy,               1u << 19)  \
-  V(Function,                 1u << 20)  \
-  V(BoundFunction,            1u << 21)  \
-  V(Hole,                     1u << 22)  \
-  V(OtherInternal,            1u << 23)  \
-  V(ExternalPointer,          1u << 24)  \
-  V(Array,                    1u << 25)  \
-  V(BigInt,                   1u << 26)  \
+  V(Negative31,               1u << 6)   \
+  V(Null,                     1u << 7)   \
+  V(Undefined,                1u << 8)   \
+  V(Boolean,                  1u << 9)   \
+  V(Unsigned30,               1u << 10)   \
+  V(MinusZero,                1u << 11)  \
+  V(NaN,                      1u << 12)  \
+  V(Symbol,                   1u << 13)  \
+  V(InternalizedString,       1u << 14)  \
+  V(OtherCallable,            1u << 16)  \
+  V(OtherObject,              1u << 17)  \
+  V(OtherUndetectable,        1u << 18)  \
+  V(CallableProxy,            1u << 19)  \
+  V(OtherProxy,               1u << 20)  \
+  V(Function,                 1u << 21)  \
+  V(BoundFunction,            1u << 22)  \
+  V(Hole,                     1u << 23)  \
+  V(OtherInternal,            1u << 24)  \
+  V(ExternalPointer,          1u << 25)  \
+  V(Array,                    1u << 26)  \
+  V(BigInt,                   1u << 27)  \
   \
   V(Signed31,                     kUnsigned30 | kNegative31) \
   V(Signed32,                     kSigned31 | kOtherUnsigned31 | \

src/compiler/verifier.cc

@@ -1214,7 +1214,7 @@ void Verifier::Visitor::Check(Node* node, const AllNodes& all) {
       CheckValueInputIs(node, 0, TypeCache::Get().kStringLengthType);
       CheckValueInputIs(node, 1, Type::String());
       CheckValueInputIs(node, 2, Type::String());
-      CheckTypeIs(node, Type::OtherString());
+      CheckTypeIs(node, Type::String());
       break;
     case IrOpcode::kAllocate:
       CheckValueInputIs(node, 0, Type::PlainNumber());

test/cctest/compiler/test-js-typed-lowering.cc

@@ -186,9 +186,7 @@ class JSTypedLoweringTester : public HandleAndZoneScope {
   }
 };
 
-static Type* kStringTypes[] = {Type::InternalizedString(), Type::OtherString(),
-                               Type::String()};
-
+static Type* kStringTypes[] = {Type::InternalizedString(), Type::String()};
 
 static Type* kInt32Types[] = {Type::UnsignedSmall(), Type::Negative32(),
                               Type::Unsigned31(),    Type::SignedSmall(),

test/cctest/test-types.cc

@@ -624,8 +624,6 @@ struct Tests {
     CheckSub(T.InternalizedString, T.String);
     CheckSub(T.InternalizedString, T.UniqueName);
     CheckSub(T.InternalizedString, T.Name);
-    CheckSub(T.OtherString, T.String);
-    CheckSub(T.OtherString, T.Name);
     CheckSub(T.Symbol, T.UniqueName);
     CheckSub(T.Symbol, T.Name);
     CheckUnordered(T.String, T.UniqueName);
@@ -751,7 +749,6 @@ struct Tests {
     CheckOverlap(T.InternalizedString, T.String);
     CheckOverlap(T.InternalizedString, T.UniqueName);
     CheckOverlap(T.InternalizedString, T.Name);
-    CheckOverlap(T.OtherString, T.String);
     CheckOverlap(T.Symbol, T.UniqueName);
     CheckOverlap(T.Symbol, T.Name);
     CheckOverlap(T.String, T.UniqueName);