[TableGen] Add support for the 'assert' statement in multiclasses

Author: Paul C. Anagnostopoulos

llvm/docs/TableGen/ProgRef.rst

@@ -1282,7 +1282,9 @@ placement.
   the subclasses and records that inherit from the class. The assertions are
   then checked when the records are completely built.
 
-* In a multiclass definition, ... [this placement is not yet available]
+* In a multiclass definition, the assertions are saved with the other
+  components of the multiclass and then checked each time the multiclass
+  is instantiated with ``defm``.
 
 Using assertions in TableGen files can simplify record checking in TableGen
 backends. Here is an example of an ``assert`` in two class definitions.

llvm/include/llvm/TableGen/Record.h

@@ -1469,6 +1469,10 @@ inline raw_ostream &operator<<(raw_ostream &OS, const RecordVal &RV) {
 }
 
 class Record {
+public:
+  using AssertionTuple = std::tuple<SMLoc, Init *, Init *>;
+
+private:
   static unsigned LastID;
 
   Init *Name;
@@ -1478,7 +1482,7 @@ class Record {
   SmallVector<Init *, 0> TemplateArgs;
   SmallVector<RecordVal, 0> Values;
   // Vector of [source location, condition Init, message Init].
-  SmallVector<std::tuple<SMLoc, Init *, Init *>, 0> Assertions;
+  SmallVector<AssertionTuple, 0> Assertions;
 
   // All superclasses in the inheritance forest in post-order (yes, it
   // must be a forest; diamond-shaped inheritance is not allowed).
@@ -1553,7 +1557,7 @@ class Record {
 
   ArrayRef<RecordVal> getValues() const { return Values; }
 
-  ArrayRef<std::tuple<SMLoc, Init *, Init *>> getAssertions() const {
+  ArrayRef<AssertionTuple> getAssertions() const {
     return Assertions;
   }
 
@@ -1620,7 +1624,7 @@ class Record {
     Assertions.append(Rec->Assertions);
   }
 
-  void checkAssertions();
+  void checkRecordAssertions();
 
   bool isSubClassOf(const Record *R) const {
     for (const auto &SCPair : SuperClasses)

llvm/lib/TableGen/Record.cpp

@@ -1832,7 +1832,7 @@ DefInit *VarDefInit::instantiate() {
     Records.addDef(std::move(NewRecOwner));
 
     // Check the assertions.
-    NewRec->checkAssertions();
+    NewRec->checkRecordAssertions();
 
     Def = DefInit::get(NewRec);
   }
@@ -2615,7 +2615,7 @@ DagInit *Record::getValueAsDag(StringRef FieldName) const {
 // and message, then call CheckAssert().
 // Note: The condition and message are probably already resolved,
 //       but resolving again allows calls before records are resolved.
-void Record::checkAssertions() {
+void Record::checkRecordAssertions() {
   RecordResolver R(*this);
   R.setFinal(true);
 

llvm/lib/TableGen/TGParser.cpp

@@ -339,27 +339,38 @@ bool TGParser::AddSubMultiClass(MultiClass *CurMC,
   return resolve(SMC->Entries, TemplateArgs, false, &CurMC->Entries);
 }
 
-/// Add a record or foreach loop to the current context (global record keeper,
-/// current inner-most foreach loop, or multiclass).
+/// Add a record, foreach loop, or assertion to the current context.
 bool TGParser::addEntry(RecordsEntry E) {
-  assert(!E.Rec || !E.Loop);
+  assert((!!E.Rec + !!E.Loop + !!E.Assertion) == 1 &&
+         "RecordsEntry has invalid number of items");
 
+  // If we are parsing a loop, add it to the loop's entries.
   if (!Loops.empty()) {
     Loops.back()->Entries.push_back(std::move(E));
     return false;
   }
 
+  // If it is a loop, then resolve and perform the loop.
   if (E.Loop) {
     SubstStack Stack;
     return resolve(*E.Loop, Stack, CurMultiClass == nullptr,
                    CurMultiClass ? &CurMultiClass->Entries : nullptr);
   }
 
+  // If we are parsing a multiclass, add it to the multiclass's entries.
   if (CurMultiClass) {
     CurMultiClass->Entries.push_back(std::move(E));
     return false;
   }
 
+  // If it is an assertion, then it's a top-level one, so check it.
+  if (E.Assertion) {
+    CheckAssert(std::get<0>(*E.Assertion), std::get<1>(*E.Assertion), 
+                std::get<2>(*E.Assertion));
+    return false;
+  }
+
+  // It must be a record, so finish it off.
   return addDefOne(std::move(E.Rec));
 }
 
@@ -414,6 +425,24 @@ bool TGParser::resolve(const std::vector<RecordsEntry> &Source,
   for (auto &E : Source) {
     if (E.Loop) {
       Error = resolve(*E.Loop, Substs, Final, Dest);
+
+    } else if (E.Assertion) {
+      MapResolver R;
+      for (const auto &S : Substs)
+        R.set(S.first, S.second);
+      Init *Condition = std::get<1>(*E.Assertion)->resolveReferences(R);
+      Init *Message = std::get<2>(*E.Assertion)->resolveReferences(R);
+
+      if (Dest) {
+        std::unique_ptr<Record::AssertionTuple> tuple =
+            std::make_unique<Record::AssertionTuple>(std::get<0>(*E.Assertion),
+                                                     std::move(Condition),
+                                                     std::move(Message));
+        Dest->push_back(std::move(tuple));
+      } else {
+        CheckAssert(std::get<0>(*E.Assertion), Condition, Message);
+      }
+
     } else {
       auto Rec = std::make_unique<Record>(*E.Rec);
       if (Loc)
@@ -459,7 +488,7 @@ bool TGParser::addDefOne(std::unique_ptr<Record> Rec) {
   }
 
   // Check the assertions.
-  Rec->checkAssertions();
+  Rec->checkRecordAssertions();
 
   // If ObjectBody has template arguments, it's an error.
   assert(Rec->getTemplateArgs().empty() && "How'd this get template args?");
@@ -2842,10 +2871,15 @@ bool TGParser::ApplyLetStack(Record *CurRec) {
   return false;
 }
 
+/// Apply the current let bindings to the RecordsEntry.
 bool TGParser::ApplyLetStack(RecordsEntry &Entry) {
   if (Entry.Rec)
     return ApplyLetStack(Entry.Rec.get());
 
+  // Let bindings are not applied to assertions.
+  if (Entry.Assertion)
+    return false;
+
   for (auto &E : Entry.Loop->Entries) {
     if (ApplyLetStack(E))
       return true;
@@ -2889,8 +2923,8 @@ bool TGParser::ParseObjectBody(Record *CurRec) {
   return ParseBody(CurRec);
 }
 
-/// ParseDef - Parse and return a top level or multiclass def, return the record
-/// corresponding to it.  This returns null on error.
+/// ParseDef - Parse and return a top level or multiclass record definition.
+/// Return false if okay, true if error.
 ///
 ///   DefInst ::= DEF ObjectName ObjectBody
 ///
@@ -3184,12 +3218,12 @@ bool TGParser::ParseAssert(MultiClass *CurMultiClass, Record *CurRec) {
   if (!consume(tgtok::semi))
     return TokError("expected ';'");
 
-  if (CurMultiClass) {
-    assert(false && "assert in multiclass not yet supported");
-  } else if (CurRec) {
+  if (CurRec) {
     CurRec->addAssertion(ConditionLoc, Condition, Message);
-  } else { // at top level
-    CheckAssert(ConditionLoc, Condition, Message);
+  } else {
+    std::unique_ptr<Record::AssertionTuple> tuple =
+         std::make_unique<Record::AssertionTuple>(ConditionLoc, Condition, Message);
+    addEntry(std::move(tuple));
   }
 
   return false;
@@ -3328,10 +3362,13 @@ bool TGParser::ParseTopLevelLet(MultiClass *CurMultiClass) {
 ///  MultiClassInst ::= MULTICLASS ID TemplateArgList?
 ///                     ':' BaseMultiClassList '{' MultiClassObject+ '}'
 ///  MultiClassObject ::= DefInst
-///  MultiClassObject ::= MultiClassInst
 ///  MultiClassObject ::= DefMInst
+///  MultiClassObject ::= Defvar
+///  MultiClassObject ::= Foreach
+///  MultiClassObject ::= If
 ///  MultiClassObject ::= LETCommand '{' ObjectList '}'
 ///  MultiClassObject ::= LETCommand Object
+///  MultiClassObject ::= Assert
 ///
 bool TGParser::ParseMultiClass() {
   assert(Lex.getCode() == tgtok::MultiClass && "Unexpected token");
@@ -3396,15 +3433,14 @@ bool TGParser::ParseMultiClass() {
       default:
         return TokError("expected 'assert', 'def', 'defm', 'defvar', "
                         "'foreach', 'if', or 'let' in multiclass body");
-      case tgtok::Assert:
-        return TokError("an assert statement in a multiclass is not yet supported");
 
       case tgtok::Def:
       case tgtok::Defm:
       case tgtok::Defvar:
       case tgtok::Foreach:
       case tgtok::If:
       case tgtok::Let:
+      case tgtok::Assert:
         if (ParseObject(CurMultiClass))
           return true;
         break;
@@ -3564,7 +3600,7 @@ bool TGParser::ParseObject(MultiClass *MC) {
   default:
     return TokError(
                "Expected assert, class, def, defm, defset, foreach, if, or let");
-  case tgtok::Assert:  return ParseAssert(MC, nullptr);
+  case tgtok::Assert:  return ParseAssert(MC);
   case tgtok::Def:     return ParseDef(MC);
   case tgtok::Defm:    return ParseDefm(MC);
   case tgtok::Defvar:  return ParseDefvar();

llvm/lib/TableGen/TGParser.h

@@ -36,17 +36,21 @@ namespace llvm {
     }
   };
 
-  /// RecordsEntry - Can be either a record or a foreach loop.
+  /// RecordsEntry - Holds exactly one of a Record, ForeachLoop, or
+  /// assertion tuple.
   struct RecordsEntry {
     std::unique_ptr<Record> Rec;
     std::unique_ptr<ForeachLoop> Loop;
+    std::unique_ptr<Record::AssertionTuple> Assertion;
 
     void dump() const;
 
     RecordsEntry() {}
     RecordsEntry(std::unique_ptr<Record> Rec) : Rec(std::move(Rec)) {}
     RecordsEntry(std::unique_ptr<ForeachLoop> Loop)
       : Loop(std::move(Loop)) {}
+    RecordsEntry(std::unique_ptr<Record::AssertionTuple> Assertion)
+      : Assertion(std::move(Assertion)) {}
   };
 
   /// ForeachLoop - Record the iteration state associated with a for loop.
@@ -222,7 +226,7 @@ class TGParser {
   bool ParseForeach(MultiClass *CurMultiClass);
   bool ParseIf(MultiClass *CurMultiClass);
   bool ParseIfBody(MultiClass *CurMultiClass, StringRef Kind);
-  bool ParseAssert(MultiClass *CurMultiClass, Record *CurRec);
+  bool ParseAssert(MultiClass *CurMultiClass, Record *CurRec = nullptr);
   bool ParseTopLevelLet(MultiClass *CurMultiClass);
   void ParseLetList(SmallVectorImpl<LetRecord> &Result);
 

llvm/test/TableGen/assert.td

@@ -39,6 +39,15 @@ class Cube<int n> {
 
 assert !eq(Cube<9>.result, 81), "cube of 9 should be 729";
 
+// CHECK: assertion failed
+// CHECK: note: foreach i cannot be 2
+// CHECK-NOT: note: foreach i cannot be 2
+
+foreach i = 1...3 in {
+  assert !ne(i, 2), "foreach i cannot be 2";
+  def bar_ # i;
+}
+
 // Test the assert statement in a record definition.
 
 // CHECK: assertion failed
@@ -136,3 +145,47 @@ def Rec32 {
 
 // Test the assert statement in a multiclass.
 
+// CHECK: assertion failed
+// CHECK: note: MC1 id string is too long
+// CHECK: assertion failed
+// CHECK: note: MC1 seq is too high
+
+multiclass MC1<string id, int seq> {
+  assert !le(!size(id), 5), "MC1 id string is too long";
+  assert !le(seq, 999999), "MC1 seq is too high";
+
+  def _mc1 {
+    string ID = id;
+    int Seq = seq;
+  }
+}
+
+defm Rec40 : MC1<"ILISP", 999>;
+defm Rec41 : MC1<"ILISPX", 999>;
+defm Rec42 : MC1<"ILISP", 999999999>;
+
+// CHECK: assertion failed
+// CHECK: note: MC2 phrase must be secret: secrex code
+
+multiclass MC2<string phr> {
+  assert !eq(!substr(phr, 0, 6), "secret"), "MC2 phrase must be secret: " # phr;
+
+  def _mc2 {
+    string phrase = phr;
+  }
+}
+
+multiclass MC3<string phr> {
+  defm _mc3 : MC2<phr>;
+}
+
+defm Rec43 : MC3<"secrex code">;
+
+// CHECK: assertion failed
+// CHECK: note: MC2 phrase must be secret: xecret code
+
+multiclass MC4<string phr> : MC2<phr> {
+  def _def;
+}
+
+defm Rec44 : MC4<"xecret code">;