[Flang] Mark 128 float MODULO intrinsic calls as "TODO"

[PeteSteinfeld]

Summary

The code generated for this version of the intrinsic is broken. I'm
marking it as a "TODO" for now so that people don't get unannounce bad
results.

[vdonaldson]

I suggest changing the format of the message to something like

intrinsic: MODULO (kind 16)

to more closely match other intrinsic call TODO messages.

[PeteSteinfeld]

Responding to Val's comments.

Here's a sample of a message that the current code produces:

error: loc("./vx2b.f90":12:5): /local/home/psteinfeld/up/llvm-project/flang/lib/Lower/IntrinsicCall.cpp:3481: not yet implemented: intrinsic: MODULO for floating point of KIND=16

flang/lib/Lower/IntrinsicCall.cpp

if (resultType.isa<mlir::IntegerType>()) {
     auto mustAddP = builder.create<mlir::arith::AndIOp>(loc, remainderIsNotZero,
                                                         argSignDifferent);
     auto remPlusP =
         builder.create<mlir::arith::AddIOp>(loc, remainder, args[1]);
     return builder.create<mlir::arith::SelectOp>(loc, mustAddP, remPlusP,
                                                  remainder);
   }
   // Real case
+  if (resultType == mlir::FloatType::getF128(builder.getContext()))
+
+    TODO(loc, "intrinsic: MODULO for floating point of KIND=16");
   auto remainder = builder.create<mlir::arith::RemFOp>(loc, args[0], args[1]);
   mlir::Value zero = builder.createRealZeroConstant(loc, remainder.getType());
   auto remainderIsNotZero = builder.create<mlir::arith::CmpFOp>(
       loc, mlir::arith::CmpFPredicate::UNE, remainder, zero);
   auto aLessThanZero = builder.create<mlir::arith::CmpFOp>(
       loc, mlir::arith::CmpFPredicate::OLT, args[0], zero);
   auto pLessThanZero = builder.create<mlir::arith::CmpFOp>(
       loc, mlir::arith::CmpFPredicate::OLT, args[1], zero);