TableGen: Fix type deduction for !foreach

Summary:
In the case of !foreach(id, input-list, transform) where the type of
input-list is list<A> and the type of transform is B, we now correctly
deduce list<B> as the type of the !foreach.

Change-Id: Ia19dd65eecc5991dd648280ba6a15f6a20fd61de

Reviewers: arsenm, craig.topper, tra, MartinO

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D43555

llvm-svn: 325797

llvm/lib/TableGen/TGParser.cpp

@@ -1075,6 +1075,14 @@ Init *TGParser::ParseOperation(Record *CurRec, RecTy *ItemType) {
         return nullptr;
       }
       Type = MHSt->getType();
+      if (isa<ListRecTy>(Type)) {
+        TypedInit *RHSt = dyn_cast<TypedInit>(RHS);
+        if (!RHSt) {
+          TokError("could not get type of !foreach list elements");
+          return nullptr;
+        }
+        Type = RHSt->getType()->getListTy();
+      }
       break;
     }
     case tgtok::XSubst: {

llvm/test/TableGen/foreach.td

@@ -7,12 +7,18 @@
 // CHECK: "NAME"
 
 // CHECK: Defs
+
+// CHECK: def DX {
+// CHECK:   list<string> x = ["0", "1", "2"];
+// CHECK: }
+
 // CHECK: Jr
 // CHECK: Sr
 
 // Variables for foreach
 class decls {
   string name;
+  int num;
 }
 
 def Decls : decls;
@@ -37,3 +43,9 @@ def Seniors : B<People.values>;
 def Juniors : C<People.values>;
 def Smiths : D<["NAME", "Jane Smith"]>;
 def Unprocessed : D<People.values>;
+
+class X<list<int> a> {
+    list<string> x = !foreach(Decls.num, a, !cast<string>(Decls.num));
+}
+
+def DX : X<[0, 1, 2]>;