TableGen: Generalize record types to fix typeIsConvertibleTo et al.

Summary:
Allow RecordRecTy to represent the type "subclass of N superclasses",
where N may be zero. Furthermore, generate RecordRecTy instances only
with actual classes in the list.

Keeping track of multiple superclasses is required to resolve the type
of a list correctly in some cases. The old code relied on the incorrect
behavior of typeIsConvertibleTo, and an earlier version of this change
relied on a modified ordering of superclasses (it was committed in
r325884 and then reverted because unfortunately some of clang-tblgen's
backends depend on the ordering).

Previously, the DefInit for each Record would have a RecordRecTy of
that Record as its type. Now, all defs with the same superclasses will
share the same type.

This allows us to be more consistent about type checks involving records:

- typeIsConvertibleTo actually requires the LHS to be a subtype of the
  RHS

- resolveTypes will return the least supertype of given record types in
  all cases

- different record types in the two branches of an !if are handled
  correctly

Add a test that used to be accepted without flagging the obvious type
error.

Change-Id: Ib366db1a4e6a079f1a0851e469b402cddae76714

Reviewers: arsenm, craig.topper, tra, MartinO

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D43680

llvm-svn: 326783

include/llvm/TableGen/Record.h

@@ -223,26 +223,47 @@ public:
   std::string getAsString() const override;
 };
 
-/// '[classname]' - Represent an instance of a class, such as:
-/// (R32 X = EAX).
-class RecordRecTy : public RecTy {
+/// '[classname]' - Type of record values that have zero or more superclasses.
+///
+/// The list of superclasses is non-redundant, i.e. only contains classes that
+/// are not the superclass of some other listed class.
+class RecordRecTy final : public RecTy, public FoldingSetNode,
+                          public TrailingObjects<RecordRecTy, Record *> {
   friend class Record;
 
-  Record *Rec;
+  unsigned NumClasses;
 
-  explicit RecordRecTy(Record *R) : RecTy(RecordRecTyKind), Rec(R) {}
+  explicit RecordRecTy(unsigned Num)
+      : RecTy(RecordRecTyKind), NumClasses(Num) {}
 
 public:
+  RecordRecTy(const RecordRecTy &) = delete;
+  RecordRecTy &operator=(const RecordRecTy &) = delete;
+
+  // Do not use sized deallocation due to trailing objects.
+  void operator delete(void *p) { ::operator delete(p); }
+
   static bool classof(const RecTy *RT) {
     return RT->getRecTyKind() == RecordRecTyKind;
   }
 
-  static RecordRecTy *get(Record *R);
+  /// Get the record type with the given non-redundant list of superclasses.
+  static RecordRecTy *get(ArrayRef<Record *> Classes);
 
-  Record *getRecord() const { return Rec; }
+  void Profile(FoldingSetNodeID &ID) const;
+
+  ArrayRef<Record *> getClasses() const {
+    return makeArrayRef(getTrailingObjects<Record *>(), NumClasses);
+  }
+
+  using const_record_iterator = Record * const *;
+
+  const_record_iterator classes_begin() const { return getClasses().begin(); }
+  const_record_iterator classes_end() const { return getClasses().end(); }
 
   std::string getAsString() const override;
 
+  bool isSubClassOf(Record *Class) const;
   bool typeIsConvertibleTo(const RecTy *RHS) const override;
 };
 
@@ -984,7 +1005,7 @@ class DefInit : public TypedInit {
 
   Record *Def;
 
-  DefInit(Record *D, RecordRecTy *T) : TypedInit(IK_DefInit, T), Def(D) {}
+  explicit DefInit(Record *D);
 
 public:
   DefInit(const DefInit &) = delete;
@@ -1189,6 +1210,9 @@ class Record {
   SmallVector<SMLoc, 4> Locs;
   SmallVector<Init *, 0> TemplateArgs;
   SmallVector<RecordVal, 0> Values;
+
+  // All superclasses in the inheritance forest in reverse preorder (yes, it
+  // must be a forest; diamond-shaped inheritance is not allowed).
   SmallVector<std::pair<Record *, SMRange>, 0> SuperClasses;
 
   // Tracks Record instances. Not owned by Record.
@@ -1269,6 +1293,9 @@ public:
     return SuperClasses;
   }
 
+  /// Append the direct super classes of this record to Classes.
+  void getDirectSuperClasses(SmallVectorImpl<Record *> &Classes) const;
+
   bool isTemplateArg(Init *Name) const {
     for (Init *TA : TemplateArgs)
       if (TA == Name) return true;
@@ -1465,8 +1492,10 @@ struct MultiClass {
 };
 
 class RecordKeeper {
+  friend class RecordRecTy;
   using RecordMap = std::map<std::string, std::unique_ptr<Record>>;
   RecordMap Classes, Defs;
+  FoldingSet<RecordRecTy> RecordTypePool;
 
 public:
   const RecordMap &getClasses() const { return Classes; }

lib/TableGen/Record.cpp

@@ -125,54 +125,138 @@ std::string DagRecTy::getAsString() const {
   return "dag";
 }
 
-RecordRecTy *RecordRecTy::get(Record *R) {
-  return dyn_cast<RecordRecTy>(R->getDefInit()->getType());
+static void ProfileRecordRecTy(FoldingSetNodeID &ID,
+                               ArrayRef<Record *> Classes) {
+  ID.AddInteger(Classes.size());
+  for (Record *R : Classes)
+    ID.AddPointer(R);
+}
+
+RecordRecTy *RecordRecTy::get(ArrayRef<Record *> UnsortedClasses) {
+  if (UnsortedClasses.empty()) {
+    static RecordRecTy AnyRecord(0);
+    return &AnyRecord;
+  }
+
+  FoldingSet<RecordRecTy> &ThePool =
+      UnsortedClasses[0]->getRecords().RecordTypePool;
+
+  SmallVector<Record *, 4> Classes(UnsortedClasses.begin(),
+                                   UnsortedClasses.end());
+  std::sort(Classes.begin(), Classes.end(),
+            [](Record *LHS, Record *RHS) {
+              return LHS->getNameInitAsString() < RHS->getNameInitAsString();
+            });
+
+  FoldingSetNodeID ID;
+  ProfileRecordRecTy(ID, Classes);
+
+  void *IP = nullptr;
+  if (RecordRecTy *Ty = ThePool.FindNodeOrInsertPos(ID, IP))
+    return Ty;
+
+#ifndef NDEBUG
+  // Check for redundancy.
+  for (unsigned i = 0; i < Classes.size(); ++i) {
+    for (unsigned j = 0; j < Classes.size(); ++j) {
+      assert(i == j || !Classes[i]->isSubClassOf(Classes[j]));
+    }
+    assert(&Classes[0]->getRecords() == &Classes[i]->getRecords());
+  }
+#endif
+
+  void *Mem = Allocator.Allocate(totalSizeToAlloc<Record *>(Classes.size()),
+                                 alignof(RecordRecTy));
+  RecordRecTy *Ty = new(Mem) RecordRecTy(Classes.size());
+  std::uninitialized_copy(Classes.begin(), Classes.end(),
+                          Ty->getTrailingObjects<Record *>());
+  ThePool.InsertNode(Ty, IP);
+  return Ty;
+}
+
+void RecordRecTy::Profile(FoldingSetNodeID &ID) const {
+  ProfileRecordRecTy(ID, getClasses());
 }
 
 std::string RecordRecTy::getAsString() const {
-  return Rec->getName();
+  if (NumClasses == 1)
+    return getClasses()[0]->getName();
+
+  std::string Str = "{";
+  bool First = true;
+  for (Record *R : getClasses()) {
+    if (!First)
+      Str += ", ";
+    First = false;
+    Str += R->getName();
+  }
+  Str += "}";
+  return Str;
+}
+
+bool RecordRecTy::isSubClassOf(Record *Class) const {
+  return llvm::any_of(getClasses(), [Class](Record *MySuperClass) {
+                                      return MySuperClass == Class ||
+                                             MySuperClass->isSubClassOf(Class);
+                                    });
 }
 
 bool RecordRecTy::typeIsConvertibleTo(const RecTy *RHS) const {
+  if (this == RHS)
+    return true;
+
   const RecordRecTy *RTy = dyn_cast<RecordRecTy>(RHS);
   if (!RTy)
     return false;
 
-  if (RTy->getRecord() == Rec || Rec->isSubClassOf(RTy->getRecord()))
-    return true;
+  return llvm::all_of(RTy->getClasses(), [this](Record *TargetClass) {
+                                           return isSubClassOf(TargetClass);
+                                         });
+}
 
-  for (const auto &SCPair : RTy->getRecord()->getSuperClasses())
-    if (Rec->isSubClassOf(SCPair.first))
-      return true;
+static RecordRecTy *resolveRecordTypes(RecordRecTy *T1, RecordRecTy *T2) {
+  SmallVector<Record *, 4> CommonSuperClasses;
+  SmallVector<Record *, 4> Stack;
 
-  return false;
+  Stack.insert(Stack.end(), T1->classes_begin(), T1->classes_end());
+
+  while (!Stack.empty()) {
+    Record *R = Stack.back();
+    Stack.pop_back();
+
+    if (T2->isSubClassOf(R)) {
+      CommonSuperClasses.push_back(R);
+    } else {
+      R->getDirectSuperClasses(Stack);
+    }
+  }
+
+  return RecordRecTy::get(CommonSuperClasses);
 }
 
 RecTy *llvm::resolveTypes(RecTy *T1, RecTy *T2) {
+  if (T1 == T2)
+    return T1;
+
+  if (RecordRecTy *RecTy1 = dyn_cast<RecordRecTy>(T1)) {
+    if (RecordRecTy *RecTy2 = dyn_cast<RecordRecTy>(T2))
+      return resolveRecordTypes(RecTy1, RecTy2);
+  }
+
   if (T1->typeIsConvertibleTo(T2))
     return T2;
   if (T2->typeIsConvertibleTo(T1))
     return T1;
 
-  // If one is a Record type, check superclasses
-  if (RecordRecTy *RecTy1 = dyn_cast<RecordRecTy>(T1)) {
-    // See if T2 inherits from a type T1 also inherits from
-    for (const auto &SuperPair1 : RecTy1->getRecord()->getSuperClasses()) {
-      RecordRecTy *SuperRecTy1 = RecordRecTy::get(SuperPair1.first);
-      RecTy *NewType1 = resolveTypes(SuperRecTy1, T2);
-      if (NewType1)
-        return NewType1;
-    }
-  }
-  if (RecordRecTy *RecTy2 = dyn_cast<RecordRecTy>(T2)) {
-    // See if T1 inherits from a type T2 also inherits from
-    for (const auto &SuperPair2 : RecTy2->getRecord()->getSuperClasses()) {
-      RecordRecTy *SuperRecTy2 = RecordRecTy::get(SuperPair2.first);
-      RecTy *NewType2 = resolveTypes(T1, SuperRecTy2);
-      if (NewType2)
-        return NewType2;
+  if (ListRecTy *ListTy1 = dyn_cast<ListRecTy>(T1)) {
+    if (ListRecTy *ListTy2 = dyn_cast<ListRecTy>(T2)) {
+      RecTy* NewType = resolveTypes(ListTy1->getElementType(),
+                                    ListTy2->getElementType());
+      if (NewType)
+        return NewType->getListTy();
     }
   }
+
   return nullptr;
 }
 
@@ -1082,9 +1166,12 @@ std::string TernOpInit::getAsString() const {
 }
 
 RecTy *TypedInit::getFieldType(StringInit *FieldName) const {
-  if (RecordRecTy *RecordType = dyn_cast<RecordRecTy>(getType()))
-    if (RecordVal *Field = RecordType->getRecord()->getValue(FieldName))
-      return Field->getType();
+  if (RecordRecTy *RecordType = dyn_cast<RecordRecTy>(getType())) {
+    for (Record *Rec : RecordType->getClasses()) {
+      if (RecordVal *Field = Rec->getValue(FieldName))
+        return Field->getType();
+    }
+  }
   return nullptr;
 }
 
@@ -1159,11 +1246,8 @@ TypedInit::convertInitializerTo(RecTy *Ty) const {
   }
 
   if (auto *SRRT = dyn_cast<RecordRecTy>(Ty)) {
-    // Ensure that this is compatible with Rec.
-    if (RecordRecTy *DRRT = dyn_cast<RecordRecTy>(getType()))
-      if (DRRT->getRecord()->isSubClassOf(SRRT->getRecord()) ||
-          DRRT->getRecord() == SRRT->getRecord())
-        return const_cast<TypedInit *>(this);
+    if (getType()->typeIsConvertibleTo(SRRT))
+      return const_cast<TypedInit *>(this);
     return nullptr;
   }
 
@@ -1302,13 +1386,22 @@ Init *VarListElementInit::getBit(unsigned Bit) const {
   return VarBitInit::get(const_cast<VarListElementInit*>(this), Bit);
 }
 
+static RecordRecTy *makeDefInitType(Record *Rec) {
+  SmallVector<Record *, 4> SuperClasses;
+  Rec->getDirectSuperClasses(SuperClasses);
+  return RecordRecTy::get(SuperClasses);
+}
+
+DefInit::DefInit(Record *D)
+    : TypedInit(IK_DefInit, makeDefInitType(D)), Def(D) {}
+
 DefInit *DefInit::get(Record *R) {
   return R->getDefInit();
 }
 
 Init *DefInit::convertInitializerTo(RecTy *Ty) const {
   if (auto *RRT = dyn_cast<RecordRecTy>(Ty))
-    if (getDef()->isSubClassOf(RRT->getRecord()))
+    if (getType()->typeIsConvertibleTo(RRT))
       return const_cast<DefInit *>(this);
   return nullptr;
 }
@@ -1497,7 +1590,7 @@ void Record::checkName() {
 
 DefInit *Record::getDefInit() {
   if (!TheInit)
-    TheInit = new(Allocator) DefInit(this, new(Allocator) RecordRecTy(this));
+    TheInit = new(Allocator) DefInit(this);
   return TheInit;
 }
 
@@ -1517,6 +1610,17 @@ void Record::setName(Init *NewName) {
   // this.  See TGParser::ParseDef and TGParser::ParseDefm.
 }
 
+void Record::getDirectSuperClasses(SmallVectorImpl<Record *> &Classes) const {
+  ArrayRef<std::pair<Record *, SMRange>> SCs = getSuperClasses();
+  while (!SCs.empty()) {
+    // Superclasses are in reverse preorder, so 'back' is a direct superclass,
+    // and its transitive superclasses are directly preceding it.
+    Record *SC = SCs.back().first;
+    SCs = SCs.drop_back(1 + SC->getSuperClasses().size());
+    Classes.push_back(SC);
+  }
+}
+
 void Record::resolveReferences(Resolver &R, const RecordVal *SkipVal) {
   for (RecordVal &Value : Values) {
     if (SkipVal == &Value) // Skip resolve the same field as the given one

lib/TableGen/TGParser.cpp

@@ -1178,12 +1178,10 @@ Init *TGParser::ParseOperation(Record *CurRec, RecTy *ItemType) {
         return nullptr;
       }
 
-      if (MHSTy->typeIsConvertibleTo(RHSTy)) {
-        Type = RHSTy;
-      } else if (RHSTy->typeIsConvertibleTo(MHSTy)) {
-        Type = MHSTy;
-      } else {
-        TokError("inconsistent types for !if");
+      Type = resolveTypes(MHSTy, RHSTy);
+      if (!Type) {
+        TokError(Twine("inconsistent types '") + MHSTy->getAsString() +
+                 "' and '" + RHSTy->getAsString() + "' for !if");
         return nullptr;
       }
       break;
@@ -1364,7 +1362,7 @@ Init *TGParser::ParseSimpleValue(Record *CurRec, RecTy *ItemType,
                                                        MCNameRV->getType()),
                                           NewRec->getNameInit(),
                                           StringRecTy::get()),
-                           Class->getDefInit()->getType());
+                           NewRec->getDefInit()->getType());
     }
 
     // The result of the expression is a reference to the new record.

test/TableGen/if-type.td

@@ -0,0 +1,11 @@
+// RUN: not llvm-tblgen %s 2>&1 | FileCheck %s
+// XFAIL: vg_leak
+
+class A<int dummy> {}
+class B<int dummy> : A<dummy> {}
+class C<int dummy> : A<dummy> {}
+
+// CHECK: Value 'x' of type 'C' is incompatible with initializer '{{.*}}' of type 'A'
+class X<int cc, B b, C c> {
+  C x = !if(cc, b, c);
+}

test/TableGen/if.td

@@ -73,6 +73,30 @@ def DI1: I1<1>;
 // CHECK-NEXT: int i = 0;
 def DI2: I2<1>;
 
+// Check that !if with operands of different subtypes can initialize a
+// supertype variable.
+//
+// CHECK: def EXd1 {
+// CHECK:   E x = E1d;
+// CHECK: }
+//
+// CHECK: def EXd2 {
+// CHECK:   E x = E2d;
+// CHECK: }
+class E<int dummy> {}
+class E1<int dummy> : E<dummy> {}
+class E2<int dummy> : E<dummy> {}
+
+class EX<int cc, E1 b, E2 c> {
+  E x = !if(cc, b, c);
+}
+
+def E1d : E1<0>;
+def E2d : E2<0>;
+
+def EXd1 : EX<1, E1d, E2d>;
+def EXd2 : EX<0, E1d, E2d>;
+
 // CHECK:      def One
 // CHECK-NEXT: list<int> first = [1, 2, 3];
 // CHECK-NEXT: list<int> rest = [1, 2, 3];