Currently, when making the ioctl system call, we're not preserving rcx
and r11. The system call will clobber these registers, meaning that the
values of the registers in the snippet will be different than expected.
This patch fixes that be preserving the registers around the system
call, similar to how the other registers involved in the making the
system call get preserved.

Fixes #72741.

If there were some scheduler effects where something like the parent
process got interrupted while the child process continued to run, there
would be nothing blocking it from exiting before the parent process
issued a PTRACE_ATTACH call. This would cause transient failures as this
occurred pretty rarely. This patch removes the possibility of a
transient failure by ensuring that the parent process attaches to the
child process before sending the counter file descriptor through the
socket, ensuring that the child process has at most progressed to being
blocked in the read call for the counter file descriptor.

This pass isn't used anywhere upstream and thus has no test coverage.
Because of these reasons, remove it.

Diff Revision: https://reviews.llvm.org/D123235

This legacy pass isn't used anywhere upstream and thus has no test
coverage, so remove it.

This pass isn't used upstream anywhere and doesn't have have a
create...() function, thus isn't tested anywhere. Because of this,
remove it.

UnifyFunctionExitNodesLegacyPass isn't used anywhere in upstream and
thus isn't tested at all. For these reasons, remove it.

For chain functions, PAL uses a `backend_stack_size` metadata item,
which at the moment has the same meaning as `stack_frame_size_in_bytes`.
We emit both for now in order to simplify coordination with PAL.

The new item must be emitted in the `shader_functions` section, just as
the metadata for other module entry functions. For simplicity, we mark
chain functions as module entry functions and emit the same metadata for
all of them.

This reverts commit 0d109035.

Changes make Python bindings unbuildable without additional cmake
modifications (or modified `$PATH`).

```
/llvm-project/mlir/lib/Bindings/Python/IRCore.cpp:33:10: fatal error: 'funcobject.h' file not found
```

This header is provided by cpython, and we are not looking for that in
cmake.

Moreover, the nature of this change is not very clear to me. Seems to
replace one include with two dozens, presumably because the code is only
using transitively included headers, but the value for readability is
dubious. LLVM is also not strictly following IWYU.

This pass isn't used anywhere and thus isn't tested anywhere. Because of
these reasons, remove it.

This pass isn't used anywhere and thus has no test coverage. Remove it
for these reasons.

For whatever reason, there was no entry in
`llvm/include/llvm/LinkAllPasses.h` to remove.

This pass isn't used anywhere and thus has no test coverage. For these
reasons, remove it.

This legacy pass isn't used anywhere and there is no test coverage, so
at this point it should be removed.

This patch extends TransferReadDropUnitDimsPattern to support dropping
unit dims from partially-static memrefs, for example:

%v = vector.transfer_read %base[%c0, %c0], %pad {in_bounds = [true, true]} :
  memref<?x1xi8, strided<[?, ?], offset: ?>>, vector<[16]x1xi8>

Is rewritten as:

%dim0 = memref.dim %base, %c0 : memref<?x1xi8, strided<[?, ?], offset: ?>>
%subview = memref.subview %base[0, 0] [%dim0, 1] [1, 1] :
  memref<?x1xi8, strided<[?, ?], offset: ?>> to memref<?xi8, #map1>
%v = vector.transfer_read %subview[%c0], %pad {in_bounds = [true]}
  : memref<?xi8, #map1>, vector<[16]xi8>

Scalable vectors are now also supported, the scalable dims were being
dropped when creating the rank-reduced vector type. The xfer op can also
have a mask of type 'vector.create_mask', which gets rewritten as long
as the mask of the unit dim is a constant of 1.

The change implements lowering of `get_fpenv`, `set_fpenv` and
`reset_fpenv`.

Differential Revision: https://reviews.llvm.org/D81843

PowerPC AIX backend does not support float128 at all. Diagnose even when
specifying -mfloat128 to avoid backend crash.

---------

Co-authored-by: Kai Luo <gluokai@gmail.com>

This reverts commit e2fb816c.
It breaks TestLinuxCore.py on lldb-*-windows. See buildbot below:
https://lab.llvm.org/buildbot/#/builders/219/builds/7014

It's always guaranteed to be valid since we compute it ourselves from MI.
This should simplify an upcoming change in #72352

The property we're explicitly looking for is whether or not MI only cares about
VL zeroness and not VL itself, so we can just use DemandedFields for this. This
should simplify an upcoming change in #72352

If there are two 'or' instructions concat variables in opposite order
and the first 'or' dominates the second one, the second 'or' can be
optimized to fshl to rotate shift first 'or'. This can eliminate an shl
and expose more optimization opportunity for bswap/bitreverse.

InitUndef pass need replace the implicit def with Undef pseudo, but
current remove method will make noreg2implicit borken.

This patch postpone the removal until all basicblock be processed.

The code that calculates the flexible array member size is big enough to
warrant its own method.

Some subtargets of PPC don't support `isel` instruction, early-ifcvt
should not insert this instruction.

Also fixed some existing test cases.

Fixed #57305.
Fixed #58251.

Fixed #72751.

Fixed #72785.

This reverts commit 4323da92.

This broke building libffi for ARM on Windows (and probably Darwin),
where one extern function intentionally falls through to another
one, while sharing one CFI region.

As long as one isn't using .subsections_via_symbols on MachO,
this probably shouldn't be a hard error.

Secondly, the tested pattern only produces an error on MachO and
COFF targets, but not for ELF, making the error case even more
inconsistent.

Reverting this commit for now, to figure out the best way forward.

This matches what PowerPC and X86 do.

This reverts commit aa6be2f7.

Some tests for the obsoleted NaCl misuse the -e for linking.