A direct call to a function casted to a different type is still not
really an address taken event. We allow the user to opt out of these
now.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D159149
GlobalValues are often interesting, especially if they have local
linkage. We now track all uses of those and refine potential callees
with it. Effectively, if an internal function cannot reach an indirect
call site, it cannot be a potential callee, even if it has its address
taken.
The Attributor user can now set the closed world flag
(`AttributorConfig.IsClosedWorldModule` or
`-attributor-assume-closed-world`) in order to specialize call edges
based only on available callees. That means, we assume all functions are
known and hence all potential callees must be declared/defined in the
module. We will use this for GPUs and LTO cases, but for now the user
has to set it via a flag.
If a potential callee has more arguments than the call site, the values
passed will be `poison`. If the potential callee would exhibit UB for
such `undef` argument, e.g., they are marked `noundef`, we can rule the
potential callee out.
The user can now limit the number of indirect calls specialized for a
given call site with `-attributor-max-specializations-per-call-base=N`
or the AttributorConfig callback. We further attach the `!callee`
metadata if all remaining callees are known.
AAIndirectCallInfo will collect information and specialize indirect call
sites. It is similar to our IndirectCallPromotion but runs as part of
the Attributor (so with assumed callee information). It also expands
more calls and let's the rest of the pipeline figure out what is UB, for
now. We use existing call promotion logic to improve the result,
otherwise we rely on the (implicit) function pointer cast.
This effectively "fixes" #60327 as it will undo the type punning early
enough for the inliner to work with the (now specialized, thus direct)
call.
Fixes: https://github.com/llvm/llvm-project/issues/60327
AANonNull is now the first AA that is always queried via the new APIs
and not created manually. Others will follow shortly to avoid trivial
AAs whenever possible.
This commit introduced some helper logic that will make it simpler to
port the next one. It also untangles AADereferenceable and AANonNull
such that the former does not keep a handle on the latter. Finally,
we stop deducing `nonnull` for `undef`, which was incorrect.
When we do simplification via AAPotentialValues or AAValueConstantRange
we need to simplify the operands of an instruction we deconstruct first.
This does not only improve the result, see for example range.ll, but is
required as we allow outside AAs to provide simplification rules via
callbacks. If we do ignore the simplification rules and base other
simplifications on the IR instead we can create an inconsistent state.
This looks like not a practical pattern in our codebase (it could fail
in some sandbox environement).
Instead we print it via standard output, and it is controled by the
-attributor-print-call-graph, this follows a similiar pattern of attributor-print-dep.
This attribute computes the optimistic live call edges using the attributor
liveness information. This attribute will be used for deriving a
inter-procedural function reachability attribute.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D104059
