TableGen: Allow NAME in template arguments in defm in multiclass

Summary:
NAME has already worked for def in a multiclass, since the (protoype)
record including its NAME variable is created before parsing the
superclasses. Since defm's do not have an associated single record,
support for NAME has to be implemented differently here.

Original test cases provided by Artem Belevich (tra)

Change-Id: I933b74f328c0ff202e7dc23a35b78f3505760cc9

Reviewers: arsenm, craig.topper, tra, MartinO

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D43656

llvm-svn: 326700

llvm/lib/TableGen/TGParser.cpp

@@ -740,6 +740,9 @@ Init *TGParser::ParseIDValue(Record *CurRec, StringInit *Name, SMLoc NameLoc,
   }
 
   if (CurMultiClass) {
+    if (Name->getValue() == "NAME")
+      return VarInit::get(Name, StringRecTy::get());
+
     Init *MCName = QualifyName(CurMultiClass->Rec, CurMultiClass, Name, "::");
 
     if (CurMultiClass->Rec.isTemplateArg(MCName)) {

llvm/test/TableGen/MultiClass-defm-fail.td

@@ -0,0 +1,32 @@
+// RUN: not llvm-tblgen %s 2>&1 | FileCheck %s
+// XFAIL: vg_leak
+
+// This test verifies that tablegen does fail if it can't resolve an unresolved
+// !cast() during processing top-level defm.
+
+class A {}
+class B<A a> {
+  A ba = a;
+}
+
+multiclass M0<string s> {
+  // This should work fine.
+  def _m00 : B<!cast<A>(s)>;
+  // CHECK: error: Undefined reference:'d1_r1_no_such_record'
+  def _m01: B<!cast<A>(s#"_no_such_record")>;
+}
+
+multiclass M1<string s> {
+  def _r1 : A;
+  // It would be nice if we could refer to _r1's name without having to pass it
+  // explicitly via 's'.
+  // XCHECK-DAG: note: instantiated from multiclass
+  defm _m1: M0<s # "_r1">;
+}
+
+// CHECK: defm d1: M1
+// CHECK: note: instantiated from multiclass
+// CHECK: defm _m1: M0
+// CHECK: note: instantiated from multiclass
+// CHECK: def _m01: B
+defm d1: M1<"d1">;

llvm/test/TableGen/MultiClass-defm.td

@@ -0,0 +1,50 @@
+// RUN: llvm-tblgen %s | FileCheck %s
+// XFAIL: vg_leak
+
+class A {}
+class B<A a> {
+  A ba = a;
+}
+
+multiclass M0<string s> {
+  def _m0 : B<!cast<A>(s)>;
+
+  // Uncomment to test that !cast will eventually fail if the record it refers
+  // to does not exist by the time we instantiate this record from the top
+  // level.
+  //def _m1 : B<!cast<A>(s#"X")>;
+}
+
+multiclass M1<string s> {
+  def _r1 : A;
+  // It would be nice if we could refer to _r1's name without having to pass it
+  // explicitly via 's'.
+  defm _m1: M0<s # "_r1">;
+}
+
+multiclass M2 {
+  def _x : A {
+    string n = NAME;
+  }
+
+  def _y : B<!cast<A>(NAME # "_x")>;
+
+  // This used to throw an error during multiclass parsing as NAME was not
+  // recognized when parsing the template arguments.
+  defm NAME: M1<NAME>;
+}
+defm d0: M2;
+// CHECK-LABEL: def d0_m1_m0
+// CHECK: A ba = d0_r1;
+//
+// CHECK-LABEL: def d0_x {
+// CHECK: string n = "d0";
+//
+// CHECK-LABEL: def d0_y {
+// CHECK: A ba = d0_x;
+
+// This always works, because d1_r1 is instantiated before d1_m1 which would
+// attempt to !cast to it.
+defm d1: M1<"d1">;
+// CHECK-LABEL: def d1_m1_m0
+// CHECK: A ba = d1_r1;