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.
Follow up up of https://github.com/llvm/llvm-project/pull/67693
- Zero initialize uninitialized components of saved derived type entity
with a default initial value.
- Zero initialize uninitialized storage of common blocks with a member
with an initial value.
- Zero initialized uninitialized saved equivalence
This removes all the cases where fir.global are created with an initial
value that results in an undef in LLVM for part of the global, leading
in surprising LLVM optimizations at -O2 for Fortran folks that expects
there saved variables to be zero initialized if there is no explicit or
default initial value.
Follow up of https://reviews.llvm.org/D149979 for lowering.
In Fortran, it is possible to assign a pointer to another pointer
with an undefined association status.
When using the runtime do to none trivial pointer association, if the
descriptor are garbage, the runtime cannot safely detect that it has
a garbage descriptor, and it cannot safely know the descriptor size
leading to undefined behavior.
Another reason to initialize descriptor of pointers is to record any
non deferred length parameter value.
Hence, although this is not required by Fortran, f18 always initialize
pointers to NULL().
This was already done in lowering for whole pointer object, but not for
pointer components.
This patch uses the related semantics patch that updated
derivedTypeSpe::HasDefaultInitialization to ensure pointer components
of local and global object are always initialized.
It adds tests to ensure that allocation of such derived type uses the
runtime to ensure the storage is initialized, and that structure
constructors are setting the descriptor component to NULL() if no
initial target is given.
Differential Revision: https://reviews.llvm.org/D150180
