Polymorphic entity lowering status is good. The main remaining TODO is
to allow lowering of vector subscripted polymorphic entity, but this
does not deserve blocking all application using polymorphism.
Remove experimental option and enable lowering of polymorphic entity by
default.
Patch 2/3 of the transition step 1 described in
https://discourse.llvm.org/t/rfc-enabling-the-hlfir-lowering-by-default/72778/7.
All the modified tests are still here since coverage for the direct
lowering to FIR was still needed while it was default. Some already have
an HLFIR version, some have not and will need to be ported in step 2
described in the RFC.
Note that another 147 lit tests use -emit-fir/-emit-llvm outputs but do
not need a flag since the HLFIR/no HLFIR output is the same for what is
being tested.
With HLFIR the lbounds for the ALLOCATABLE result are taken from the
mutable box created for the result, so the non-default lbounds might be
propagated further causing incorrect result, e.g.:
```
program p
real, allocatable :: p5(:)
allocate(p5, source=real_init())
print *, lbound(p5, 1) ! must print 1, but prints 7
contains
function real_init()
real, allocatable :: real_init(:)
allocate(real_init(7:8))
end function real_init
end program p
```
With FIR lowering the box passed for `source` has explicit lower bound 1
at the call site, but the runtime box initialized by `real_init` call
still has lower bound 7. I am not sure if the runtime box initialized by
`real_init` will ever be accessed in a debugger via Fortran variable
names, but I think that having the right runtime bounds that can be
accessible via examining registers/stack might be good in general. So I
decided to update the runtime bounds at the point of return.
This change fixes the test above for HLFIR.
Reviewed By: jeanPerier
Differential Revision: https://reviews.llvm.org/D156187
