TableGen: fix assert in !cast when used out of definition in a multiclass

[vpykhtin]

Summary

The attached testcase asserts on !cast without the patch. The reason is that there is no CurRec when !cast used inside foreach. Let's postpone CurRec check until isFinal.

[nhaehnle]

Nice catch. LGTM.

lib/TableGen/Record.cpp

if (isa<StringRecTy>(getType())) {
 
       if (DefInit *LHSd = dyn_cast<DefInit>(LHS))
         return StringInit::get(LHSd->getAsString());
 
       if (IntInit *LHSi = dyn_cast<IntInit>(LHS))
         return StringInit::get(LHSi->getAsString());
     } else if (isa<RecordRecTy>(getType())) {
       if (StringInit *Name = dyn_cast<StringInit>(LHS)) {
+        if (!CurRec && !IsFinal)
+          break;
         assert(CurRec && "NULL pointer");
         Record *D;
 
         // Self-references are allowed, but their resolution is delayed until
         // the final resolve to ensure that we get the correct type for them.
         if (Name == CurRec->getNameInit()) {
           if (!IsFinal)
             break;

test/TableGen/cast-multiclass.td

+// RUN: llvm-tblgen %s | FileCheck %s
+
+class AClass<bit C> {
+  bit Cond = C;
+}
+
+def A0: AClass<0>;
+def A1: AClass<1>;
+
+class BoolToList<bit Value> {
+  list<int> ret = !if(Value, [1]<int>, []<int>);
+}
+
+multiclass P<string AStr> {
+  foreach i = BoolToList<!cast<AClass>(AStr).Cond>.ret in
+    def SubDef;
+}
+
+// CHECK-NOT: def XSubDef
+defm X : P<"A0">;
+
+// CHECK: def YSubDef
+defm Y : P<"A1">;
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