Changes

[clang-format] Fix C# nullable-related errors

This fixes two errors:

Previously, clang-format was splitting up type identifiers from the
nullable ?. This changes this behavior so that the type name sticks with
the operator.

Additionally, nullable operators attached to return types in interface
functions were not parsed correctly. Digging deeper, it looks like
interface bodies were being parsed differently than classes and structs,
causing MustBeDeclaration to be incorrect for interface members. They
now share the same logic.

One other change is reintroducing the CSharpNullable type independent of
JsTypeOptionalQuestion. Despite having a similar semantic purpose, their
actual syntax differs quite a bit.

Reviewed By: MyDeveloperDay, curdeius

Differential Revision: https://reviews.llvm.org/D101860

[clang-format] Rename common types between C#/JS

Reviewed By: curdeius

Differential Revision: https://reviews.llvm.org/D101862

[SVE][LoopVectorize] Add support for scalable vectorization of first-order recurrences

Adds support for scalable vectorization of loops containing first-order recurrences, e.g:
```
for(int i = 0; i < n; i++)
  b[i] =  a[i] + a[i - 1]
```
This patch changes fixFirstOrderRecurrence for scalable vectors to take vscale into
account when inserting into and extracting from the last lane of a vector.
CreateVectorSplice has been added to construct a vector for the recurrence, which
returns a splice intrinsic for scalable types. For fixed-width the behaviour
remains unchanged as CreateVectorSplice will return a shufflevector instead.

The tests included here are the same as test/Transform/LoopVectorize/first-order-recurrence.ll

Reviewed By: david-arm, fhahn

Differential Revision: https://reviews.llvm.org/D101076

[SystemZ] Support builtin_frame_address with packed stack without backchain.

In order to use __builtin_frame_address(0) with packed stack and no
backchain, the address of where the backchain would have been written is
returned (like GCC).

This address may either contain a saved register or be unused.

Review: Ulrich Weigand

Differential Revision: https://reviews.llvm.org/D101897

[AMDGPU] Regenerate shift tests. NFCI.

[AMDGPU] Regenerate fp2int tests. NFCI.

[mlir] Add support for ops with regions in 'gpu-async-region' rewriter.

Reviewed By: herhut

Differential Revision: https://reviews.llvm.org/D101757

[LLD] Improve --strip-all help text

This is a slight improvement to the help text, as I was slightly
surprised when strip-all did more than remove the symbol table.

Currently, we match gold's help text for strip-all and strip-debug.
I think that the GNU documentation for these options is not particularly
clear. However, I have opted to make only a minor change here and keep
the help text similar to gold's as these are mature options that are
well understood.

ld.bfd (https://sourceware.org/binutils/docs/ld/Options.html) has a
similar implication although it defines strip-debug as a subset of
strip-all. However, felt that noting that strip-all implies strip-debug
is better; because, with the ld.bfd approach you have to read both the
--strip-debug and the --strip-all help text to understand the behaviour
of --strip-all (and the --strip-all help text doesn't indicate that he
--strip-debug help text is related).

Differential Revision: https://reviews.llvm.org/D101890

[LV] Account for tripcount when calculation vectorization profitability

The loop vectorizer will currently assume a large trip count when
calculating which of several vectorization factors are more profitable.
That is often not a terrible assumption to make as small trip count
loops will usually have been fully unrolled. There are cases however
where we will try to vectorize them, and especially when folding the
tail by masking can incorrectly choose to vectorize loops that are not
beneficial, due to the folded tail rounding the iteration count up for
the vectorized loop.

The motivating example here has a trip count of 5, so either performs 5
scalar iterations or 2 vector iterations (with VF=4). At a high enough
trip count the vectorization becomes profitable, but the rounding up to
2 vector iterations vs only 5 scalar makes it unprofitable.

This adds an alternative cost calculation when we know the max trip
count and are folding tail by masking, rounding the iteration count up
to the correct number for the vector width. We still do not account for
anything like setup cost or the mixture of vector and scalar loops, but
this is at least an improvement in a few cases that we have had
reported.

Differential Revision: https://reviews.llvm.org/D101726

[ORC] Silence unused variable warnings in Release builds. NFC.

Revert "[ARM] Transforming memcpy to Tail predicated Loop"

Reverting commit since it causes failure (10462).
This reverts commit b856f4a232cbd43476e9b9f75c80aacfc6f5c152.

[AMDGPU] Fix WQM failure with single block inactive demote

Instruction test for inactive kill/demote needs to be based on
actual opcode not whether instruction would be lowered to demote.

Reviewed By: piotr

Differential Revision: https://reviews.llvm.org/D101966

[amdgpu-arch] Fix rpath to run from build dir

[amdgpu-arch] Fix rpath to run from build dir

Prior to this, amdgpu-arch has RUNPATH set to $ORIGIN/../lib which works
for some installs, but not from the build directory where clang executes
the tool from when running tests.

This cmake option adds the location of the rocr runtime to the RUNPATH
(note, it amends RUNPATH here, despite the cmake option referring to RPATH)
to create a binary that runs from build or install location.

Before:
RUNPATH [$ORIGIN/../lib]
After:
RUNPATH [$ORIGIN/../lib:$HOME/llvm-install/lib]

Credit to Greg for knowing this trick and pointing to examples of it in use
for the aomp build scripts.

Reviewed By: pdhaliwal

Differential Revision: https://reviews.llvm.org/D101926

[OpenCL] Remove subgroups pragma in enqueue kernel and pipe builtins.

This patch simplifies the parser and makes the language semantics
consistent. There is no extension pragma requirement in the spec
for the subgroup functions in enqueue kernel or pipes and all other
builtin functions are available without the pragama.

Differential Revision: https://reviews.llvm.org/D100984