This patch adds `host_assoc` attribute for operations that implement
FortranVariableInterface (e.g. `hlfir.declare`). The attribute is used
by the alias analysis to make better conclusions about memory overlap.
For example, a dummy argument of an inner subroutine and a host's
variable used inside the inner subroutine cannot refer to the same
object (if the dummy argument does not satisify exceptions in F2018
15.5.2.13).
This closes a performance gap between HLFIR optimization pipeline
and FIR ArrayValueCopy for Polyhedron/nf.
Add a rough alias analysis rule for hlfir.designate which just follows
the memref argument. This could be extended in the future to take into
account the indices or derived type fields accessed to spot for provably
non-overlapping cases. In the meantime, we need a flag to ensure we
never say "MustAlias" when following a value through a hlfir.designate
because the designate analysis is only approximate.
Differential Revision: https://reviews.llvm.org/D157718
These make it easier to debug and improve alias analysis. Enable with
--debug-only=fir-alias-analysis.
Differential Revision: https://reviews.llvm.org/D157105
These are experimental changes in Flang AA to provide
at least some means to disambiguate memory accesses in some
simple cases. This AA is still not used by any transformation,
so the LIT tests are the only way to trigger it currently.
I will further look into applying this AA within Flang
to address some of the known performance issues in the benchmarks.
Credits to @Renaud-K for the initial implementation.
Differential Revision: https://reviews.llvm.org/D141410
