[clang][Interp] Support __builtin_eh_return_data_regno

Author: tbaederr

clang/lib/AST/Interp/InterpBuiltin.cpp

@@ -645,6 +645,19 @@ static bool interp__builtin_move(InterpState &S, CodePtr OpPC,
   return Func->getDecl()->isConstexpr();
 }
 
+static bool interp__builtin_eh_return_data_regno(InterpState &S, CodePtr OpPC,
+                                                 const InterpFrame *Frame,
+                                                 const Function *Func,
+                                                 const CallExpr *Call) {
+  PrimType ArgT = *S.getContext().classify(Call->getArg(0)->getType());
+  APSInt Arg = peekToAPSInt(S.Stk, ArgT);
+
+  int Result =
+      S.getCtx().getTargetInfo().getEHDataRegisterNumber(Arg.getZExtValue());
+  pushInt(S, Result);
+  return true;
+}
+
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
                       const CallExpr *Call) {
   InterpFrame *Frame = S.Current;
@@ -869,6 +882,11 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
       return false;
     break;
 
+  case Builtin::BI__builtin_eh_return_data_regno:
+    if (!interp__builtin_eh_return_data_regno(S, OpPC, Frame, F, Call))
+      return false;
+    break;
+
   default:
     return false;
   }

clang/test/AST/Interp/builtin-functions.cpp

@@ -363,3 +363,16 @@ namespace ffs {
   char ffs6[__builtin_ffsl(0x10L) == 5 ? 1 : -1];
   char ffs7[__builtin_ffsll(0x100LL) == 9 ? 1 : -1];
 }
+
+namespace EhReturnDataRegno {
+  void test11(int X) {
+    switch (X) {
+      case __builtin_eh_return_data_regno(0):  // constant foldable.
+      break;
+    }
+
+    __builtin_eh_return_data_regno(X);  // expected-error {{argument to '__builtin_eh_return_data_regno' must be a constant integer}} \
+                                        // ref-error {{argument to '__builtin_eh_return_data_regno' must be a constant integer}}
+
+  }
+}