For swift async code, we need to use a debug intrinsic that behaves like
an llvm.dbg.declare but can take any location type rather than just a
pointer or integer.

To solve this, a new debug instrinsic called llvm.dbg.declare_value has
been created, which behaves exactly like an llvm.dbg.declare but can
take non pointer and integer location types.

More information here:
https://discourse.llvm.org/t/rfc-introduce-new-llvm-dbg-coroframe-entry-intrinsic/88269

This is the first patch as part of a stack of patches, with the one
succeeding it being: https://github.com/llvm/llvm-project/pull/168134

Also add a corresponding intrinsic property that can be used to mark
intrinsics that do not introduce poison, for example simple arithmetic
intrinsics that propagate poison just like a simple arithmetic
instruction.

As a smoke test this patch adds the new property to
llvm.amdgcn.fmul.legacy.

DW_TAG_base_type DIEs are permitted to have both byte_size and bit_size
attributes "If the value of an object of the given type does not fully
occupy the storage described by a byte size attribute"

* Add DataSizeInBits to DIBasicType (`DIBasicType(... dataSize: n ...)` in IR).
* Change Clang to add DataSizeInBits to _BitInt type metadata.
* Change LLVM to add DW_AT_bit_size to base_type DIEs that have non-zero
  DataSizeInBits.

TODO: Do we need to emit DW_AT_data_bit_offset for big endian targets?
See discussion on the PR.

Fixes [#61952](https://github.com/llvm/llvm-project/issues/61952)

---------

Co-authored-by: David Stenberg <david.stenberg@ericsson.com>

In preparation for a follow on change that will require checking every
time a new summary is added to the SummaryList for a GUID, make the
SummaryList private and require all accesses to go through one of two
new interfaces. Most changes are to access the list via the read only
getSummaryList() method, and the few that add new summaries (e.g. while
building the combined summary) use the new addSummary() method.

Depends on:
* https://github.com/llvm/llvm-project/pull/162445

In preparation to emit DWARFv6's `DW_AT_language_version`.

This patch moves the `preserve-bc-uselistorder` and
`preserve-ll-uselistorder` options out of individual tools(opt, llvm-as,
llvm-dis, llvm-link, llvm-extract) and make them global defaults for
AsmWriter and BitcodeWriter.

These options are useful when we use `-print-*` options to dump LLVM IR.

Depends on:
* https://github.com/llvm/llvm-project/pull/162255
* https://github.com/llvm/llvm-project/pull/162434

Part of a patch series to support the DWARFv6
`DW_AT_language_name`/`DW_AT_language_version` attributes.

This patch sets up `DICompileUnit` to support the DWARFv6
`DW_AT_language_name` and `DW_AT_language_version` attributes (which are
set to replace `DW_AT_language`). This patch changes the
`DICompileUnit::SourceLanguage` field type to a `DISourceLanguageName`
that encapsulates the notion of "versioned vs. unversioned name". A
"versioned" name is one that has an associated version stored separately
in `DISourceLanguageName::Version`.

This patch just changes all the clients of the `getSourceLanguage` API
to the expect a `DISourceLanguageName`. Currently they all just `assert`
(via `DISourceLanguageName::getUnversionedName`) that we're dealing with
"unversioned names" (i.e., the pre-DWARFv6 language codes). In follow-up
patches (e.g., draft is at
https://github.com/llvm/llvm-project/pull/162261), when we start
emitting versioned language codes, the `getUnversionedName` calls can
then be adjusted to `getName`.

**Implementation considerations**

* We could have added a new member to `DICompileUnit` alongside the
existing `SourceLanguage` field. I don't think this would have made the
transition any simpler (clients would still need to be aware of
"versioned" vs. "unversioned" language names). I felt that encapsulating
this inside a `DISourceLanguageName` was easier to reason about for
maintainers.
* Currently DISourceLanguageName is a `12` byte structure. We could
probably pack all the info inside a `uint64_t` (16-bits for the name,
32-bits for the version, 1-bit for answering the `hasVersionedName`).
Just to keep the prototype simple I used a `std::optional`. But since
the guts of the structure are hidden, we can always change the layout to
a more compact representation instead.

**How to review**

* The new `DISourceLanguageName` structure is defined in
`DebugInfoMetadata.h`. All the other changes fall out from changing the
`DICompileUnit::SourceLanguage` from `unsigned` to
`DISourceLanguageName`.

In preparation of adding the "AllocToken" pass, add the pre-requisite
`sanitize_alloc_token` function attribute and `alloc_token` metadata.

---

This change is part of the following series:
  1. https://github.com/llvm/llvm-project/pull/160131
  2. https://github.com/llvm/llvm-project/pull/156838
  3. https://github.com/llvm/llvm-project/pull/162098
  4. https://github.com/llvm/llvm-project/pull/162099
  5. https://github.com/llvm/llvm-project/pull/156839
  6. https://github.com/llvm/llvm-project/pull/156840
  7. https://github.com/llvm/llvm-project/pull/156841
  8. https://github.com/llvm/llvm-project/pull/156842

Teach the IR parser and writer to support metadata on ifuncs, and update
documentation.

In PR #153049, we have a use case of attaching the `!associated`
metadata to an ifunc.
Since an ifunc is similar to a function declaration, it seems natural to
allow metadata on ifuncs.
Currently, the metadata API allows adding Metadata to
llvm::GlobalObject, so the in-memory IR allows for metadata on ifuncs,
but the IR reader/writer is not aware of that.

---------

Co-authored-by: Wael Yehia <wyehia@ca.ibm.com>