Fix Hack array specializations in JIT type system

Summary:
The set of allowed bits for ArraySpec didn't include Hack arrays, which meant
the type-system would never make use of them (which is odd because I could
swear I've seen Hack array specializations before in IR dumps). Change the
allowed bits from Arr to ArrLike, and fix a few bugs this uncovered.

Reviewed By: mxw

Differential Revision: D13107383

fbshipit-source-id: 1d6baf94f85630bf920877c3fe3679dc9c9b9f48

hphp/runtime/vm/jit/type-inl.h

@@ -341,9 +341,11 @@ inline Type Type::dropConstVal() const {
   if (!m_hasConstVal) return *this;
   assertx(!isUnion());
 
-  if (*this <= TStaticArr) {
-    return Type::StaticArray(arrVal()->kind());
-  }
+  if (*this <= TStaticArr)    return Type::StaticArray(arrVal()->kind());
+  if (*this <= TStaticVec)    return TStaticVec;
+  if (*this <= TStaticDict)   return TStaticDict;
+  if (*this <= TStaticKeyset) return TStaticKeyset;
+
   return Type(m_bits, ptrKind(), memKind());
 }
 
@@ -521,9 +523,8 @@ inline ArraySpec Type::arrSpec() const {
   // all of them.
   if (supports(SpecKind::Class)) return ArraySpec::Top;
 
-  if (m_hasConstVal) {
-    return ArraySpec(arrVal()->kind());
-  }
+  if (m_hasConstVal) return ArraySpec(m_arrVal->kind());
+
   assertx(m_arrSpec != ArraySpec::Bottom);
   return m_arrSpec;
 }

hphp/runtime/vm/jit/type.cpp

@@ -621,11 +621,11 @@ bool Type::operator<=(Type rhs) const {
     return true;
   }
 
-  if (lhs.hasConstVal(TArr)) {
+  if (lhs.hasConstVal(TArrLike)) {
     // Arrays can be specialized in different ways.  Here, we check if the
     // constant array fits the kind()/type() of the specialization of `rhs', if
     // any.
-    auto const lhs_arr = lhs.arrVal();
+    auto const lhs_arr = lhs.m_arrVal;
     auto const rhs_as = rhs.arrSpec();
     return arrayFitsSpec(lhs_arr, rhs_as);
   }

hphp/runtime/vm/jit/type.h

@@ -479,7 +479,7 @@ struct Type {
     kAnyDict      = kDict | kBoxedDict,
     kAnyKeyset    = kKeyset | kBoxedKeyset,
     kAnyArrLike   = kAnyArr | kAnyVec | kAnyDict | kAnyKeyset,
-    kArrSpecBits  = kAnyArr,
+    kArrSpecBits  = kAnyArrLike,
     kAnyObj       = kObj | kBoxedObj,
     kClsSpecBits  = kAnyObj | kCls,
   };