[TableGen] Make sure !if is evaluated throughout class inheritance.

Without the patch !if() is only evaluated if it's used directly.
If it's passed through more than one level of class inheritance,
we end up with a reference to an anonymous record with unresolved
references to the original arguments !if may have used.

The root cause of the problem is that TernOpInit::isComplete()
was always returning false and that prevented use of the folded
value of !if() as an initializer for the record at the next level
of inheritance.

Differential Revision: https://reviews.llvm.org/D42695

llvm-svn: 323807

2 files changed, 20 insertions, 1 deletions

diff --git a/llvm/include/llvm/TableGen/Record.h b/llvm/include/llvm/TableGen/Record.h
index 9736e015008..50477402a89 100644
--- a/llvm/include/llvm/TableGen/Record.h
+++ b/llvm/include/llvm/TableGen/Record.h
@@ -905,7 +905,9 @@ public:
   // possible to fold.
   Init *Fold(Record *CurRec, MultiClass *CurMultiClass) const override;
 
-  bool isComplete() const override { return false; }
+  bool isComplete() const override {
+    return LHS->isComplete() && MHS->isComplete() && RHS->isComplete();
+  }
 
   Init *resolveReferences(Record &R, const RecordVal *RV) const override;
 
diff --git a/llvm/test/TableGen/if.td b/llvm/test/TableGen/if.td
index 05a2d992856..019e4dd1585 100644
--- a/llvm/test/TableGen/if.td
+++ b/llvm/test/TableGen/if.td
@@ -56,6 +56,23 @@ def D128: S<128>;
 // CHECK: def D8
 // CHECK-NEXT: bits<2> val = { 0, 0 };
 
+// Make sure !if gets propagated across multiple layers of inheritance.
+class getInt<int c> {
+  int ret = !if(c, 0, 1);
+}
+class I1<int c> {
+  int i = getInt<c>.ret;
+}
+class I2<int c> : I1<c>;
+
+// CHECK: def DI1 {     // I1
+// CHECK-NEXT: int i = 0;
+def DI1: I1<1>;
+
+// CHECK: def DI2 {     // I1 I2
+// CHECK-NEXT: int i = 0;
+def DI2: I2<1>;
+
 // CHECK:      def One
 // CHECK-NEXT: list<int> first = [1, 2, 3];
 // CHECK-NEXT: list<int> rest = [1, 2, 3];