[Flang] enable fir.is_present and fir.absent with function types

[kiranchandramohan]

Summary

Fortran dummy procedures and procedure pointer can be OPTIONAL, and
there is no technical reason to prevent fir.is_present and
fir.absent from accepting function types, so allow it and add test.

Note: This is part of upstreaming from the fir-dev branch of
https://github.com/flang-compiler/f18-llvm-project. This patch is
basically upstreaming the following PR.
https://github.com/flang-compiler/f18-llvm-project/pull/1568

Co-authored-by: Jean Perier <[e-mail]>

[clementval]

LGTM

flang/include/flang/Optimizer/Dialect/FIRTypes.td

 
 def RefOrLLVMPtr : TypeConstraint<Or<[fir_ReferenceType.predicate,
     fir_LLVMPointerType.predicate]>, "fir.ref or fir.llvm_ptr">;
 
 def AnyBoxLike : TypeConstraint<Or<[fir_BoxType.predicate,
     fir_BoxCharType.predicate, fir_BoxProcType.predicate]>, "any box">;
 
 def AnyRefOrBoxLike : TypeConstraint<Or<[AnyReferenceLike.predicate,
-    AnyBoxLike.predicate]>,
+    AnyBoxLike.predicate, FunctionType.predicate]>,
     "any reference or box like">;
 def AnyRefOrBox : TypeConstraint<Or<[fir_ReferenceType.predicate,
     fir_HeapType.predicate, fir_PointerType.predicate, fir_BoxType.predicate]>,
     "any reference or box">;
 
 def AnyShapeLike : TypeConstraint<Or<[fir_ShapeType.predicate,
     fir_ShapeShiftType.predicate]>, "any legal shape type">;
 def AnyShapeType : Type<AnyShapeLike.predicate, "any legal shape type">;

flang/test/Fir/optional.fir

 
 // CHECK-LABEL: @bar3
 func.func @bar3() -> i1 {
   %0 = fir.absent !fir.boxchar<1>
   // CHECK: call i1 @foo3(ptr null, i64 undef)
   %1 = fir.call @foo3(%0) : (!fir.boxchar<1>) -> i1
   return %1 : i1
 }
+
+// CHECK-LABEL: @foo4(
+// CHECK-SAME: ptr %[[arg:.*]])
+func.func @foo4(%arg0: !fir.boxproc<(i32)->(i64)>) -> i1 {
+  // CHECK: %[[ptr:.*]] = ptrtoint ptr %[[arg]] to i64
+  // CHECK: icmp ne i64 %[[ptr]], 0
+  %0 = fir.is_present %arg0 : (!fir.boxproc<(i32)->(i64)>) -> i1
+  return %0 : i1
+}
+
+// CHECK-LABEL: @bar4
+func.func @bar4() -> i1 {
+  %0 = fir.absent !fir.boxproc<(i32)->(i64)>
+  // CHECK: call i1 @foo4(ptr null)
+  %1 = fir.call @foo4(%0) : (!fir.boxproc<(i32)->(i64)>) -> i1
+  return %1 : i1
+}
+
+// CHECK-LABEL: @foo5(
+// CHECK-SAME: ptr %[[arg:.*]])
+func.func @foo5(%arg0: (i32)->(i64)) -> i1 {
+  // CHECK: %[[ptr:.*]] = ptrtoint ptr %[[arg]] to i64
+  // CHECK: icmp ne i64 %[[ptr]], 0
+  %0 = fir.is_present %arg0 : ((i32)->(i64)) -> i1
+  return %0 : i1
+}
+
+// CHECK-LABEL: @bar5
+func.func @bar5() -> i1 {
+  %0 = fir.absent (i32)->(i64)
+  // CHECK: call i1 @foo5(ptr null)
+  %1 = fir.call @foo5(%0) : ((i32)->(i64)) -> i1
+  return %1 : i1
+}