[TableGen] Fix bug in !interleave operator

[Paul-C-Anagnostopoulos]

Summary

I forgot to account for the possibility that some elements of the list being interleaved might not be resolved and so final evaluation has to be delayed. Each element must be checked to see if it can be dyn_cast to a StringInit or IntInit.

[Paul-C-Anagnostopoulos]

llvm/lib/TableGen/Record.cpp

897

I will remove these obsolete lines of code.

[Paul-C-Anagnostopoulos]

interleaveIntList() needs to use convertInitializerTo(), not getCastTo. Both can fail, so dyn_cast_or_null is required.

[Paul-C-Anagnostopoulos]

Let's actually update the patch this time.

llvm/lib/TableGen/Record.cpp

return StringInit::get(Concat,
                          StringInit::determineFormat(I0->getFormat(),
                                                      I1->getFormat()));
 }
 
 static StringInit *interleaveStringList(const ListInit *List,
                                         const StringInit *Delim) {
   if (List->size() == 0)
     return StringInit::get("");
-  SmallString<80> Result(cast<StringInit>(List->getElement(0))->getValue());
+  StringInit *Element = dyn_cast<StringInit>(List->getElement(0));
+  if (!Element)
+    return nullptr;
+  SmallString<80> Result(Element->getValue());
   StringInit::StringFormat Fmt = StringInit::SF_String;
 
   for (unsigned I = 1, E = List->size(); I < E; ++I) {
     Result.append(Delim->getValue());
-    auto *StrInit = cast<StringInit>(List->getElement(I));
-    Result.append(StrInit->getValue());
-    Fmt = StringInit::determineFormat(Fmt, StrInit->getFormat());
+    StringInit *Element = dyn_cast<StringInit>(List->getElement(I));
+    if (!Element)
+      return nullptr;
+    Result.append(Element->getValue());
+    Fmt = StringInit::determineFormat(Fmt, Element->getFormat());
   }
   return StringInit::get(Result, Fmt);
 }
 
 static StringInit *interleaveIntList(const ListInit *List,
                                      const StringInit *Delim) {
   if (List->size() == 0)
     return StringInit::get("");
-  SmallString<80> Result(
-      cast<IntInit>(List->getElement(0)->getCastTo(IntRecTy::get()))
-          ->getAsString());
+  IntInit *Element =
+      dyn_cast<IntInit>(List->getElement(0)->getCastTo(IntRecTy::get()));
+  if (!Element)
+    return nullptr;
+  SmallString<80> Result(Element->getAsString());
 
   for (unsigned I = 1, E = List->size(); I < E; ++I) {
     Result.append(Delim->getValue());
-    Result.append(cast<IntInit>(List->getElement(I)->getCastTo(IntRecTy::get()))
-                      ->getAsString());
+    IntInit *Element =
+        dyn_cast<IntInit>(List->getElement(I)->getCastTo(IntRecTy::get()));
+    if (!Element)
+      return nullptr;
+    Result.append(Element->getAsString());
   }
   return StringInit::get(Result);
 }
 
 Init *BinOpInit::getStrConcat(Init *I0, Init *I1) {
   // Shortcut for the common case of concatenating two strings.
   if (const StringInit *I0s = dyn_cast<StringInit>(I0))
     if (const StringInit *I1s = dyn_cast<StringInit>(I1))
       return ConcatStringInits(I0s, I1s);
   return BinOpInit::get(BinOpInit::STRCONCAT, I0, I1, StringRecTy::get());
 }
 
 static ListInit *ConcatListInits(const ListInit *LHS,
case STRCONCAT: {
     if (LHSs && RHSs)
       return ConcatStringInits(LHSs, RHSs);
     break;
   }
   case INTERLEAVE: {
     ListInit *List = dyn_cast<ListInit>(LHS);
     StringInit *Delim = dyn_cast<StringInit>(RHS);
     if (List && Delim) {
+      StringInit *Result;
       if (isa<StringRecTy>(List->getElementType()))
-        return interleaveStringList(List, Delim);
+        Result = interleaveStringList(List, Delim);
       else
-        return interleaveIntList(List, Delim);
+        Result = interleaveIntList(List, Delim);
+      if (Result)
+        return Result;
     }
     break;
   }
   case EQ:
   case NE:
   case LE:
   case LT:
   case GE:

llvm/test/TableGen/interleave.td

 // CHECK: def Rec6
 // CHECK:   code OperatorList = [{+, -, *, /, ?:, ;}];
 
 def Rec6 {
   list<string> Operators = ["+", "-", "*", "/", "?:"];
   code OperatorList = !interleave(!listconcat(Operators, [[{;}]]), ", ");
 }
 
+// CHECK: def Rec7
+// CHECK:   str = "foo/bar/zoo";
+
+def Rec7 {
+  string foo = "foo";
+  string zoo = "oops, not zoo";
+  string str = !interleave([foo, "bar", zoo], "/");
+  let zoo = "zoo";
+}
 
 #ifdef ERROR1
 def op;
 
 // ERROR1: expected list of string, int, bits, or bit; got value of type
 
 def Rec6 {
   string Bad = !interleave([(op), (op "hello")], " = ");
 }
 #endif