This adds a per-global code model attribute, which can override the
target's code model to access global variables.

Suggested-by: Arthur Eubanks <aeubanks@google.com>
Link: https://discourse.llvm.org/t/how-to-best-implement-code-model-overriding-for-certain-values/71816
Link: https://discourse.llvm.org/t/rfc-add-per-global-code-model-attribute/74944

When two `complex.bitcast` ops are folded and the resulting bitcast is a
non-complex -> non-complex bitcast, an `arith.bitcast` should be
generated. Otherwise, the generated `complex.bitcast` op is invalid.

Also remove a pattern that convertes non-complex -> non-complex
`complex.bitcast` ops to `arith.bitcast`. Such `complex.bitcast` ops are
invalid and should not appear in the input.

Note: This bug can only be triggered by running with `-debug` (which
will should intermediate IR that does not verify) or with
`MLIR_ENABLE_EXPENSIVE_PATTERN_API_CHECKS` (#74270).

psABI v2.20 added R_LARCH_CALL36 and removed R_LARCH_DELETE / R_LARCH_CFA.

R_LARCH_CALL36 was designed for function call on medium code model where
the 2 instructions (pcaddu18i + jirl) must be adjacent.

We accessed the `Devices` container most of the time while holding the
RTLsMtx, but not always. Sometimes we used the mutex for the size query,
but then accessed Devices again unguarded. From now we properly
encapsulate the container in a ProtectedObj which ensures exclusive
accesses. We also hide the "isReady" part in the `getDevice` accessor
and use an `llvm::Expected` to allow to return errors.

When all the large const offsets masked with the same value from bit-12 to bit-23.
Fold
  add     x8, x0, #2031, lsl #12
  add     x8, x8, #960
  ldr     x9, [x8, x8]
  ldr     x8, [x8, #2056]

into
  add     x8, x0, #2031, lsl #12
  ldr     x9, [x8, #960]
  ldr     x8, [x8, #3016]

lldb/source/Host/netbsd/HostInfoNetBSD.cpp:48:8: warning: unused variable 'osrev_str' [-Wunused-variable]
  char osrev_str[12];
       ^
1 warning generated.

The printf float to string conversion functions had some implicit
integer conversion warnings on gcc. This patch adds explicit casts to
these places.

Re-implement ObjCPropertyAttributeOrder using std::set for sorting and
removing duplicates. (We can't use llvm::SmallSet because it's
unordered.)

This works around an AIX assembler and linker bug. If the
-fno-integrated-as and -frecord-command-line options are used but
there's no actual code in the source file, the assembler creates an
object file with only an .info section. The AIX linker rejects such an
object file.

```
/usr/bin/ld: CMakeFiles/obj.MLIRMeshDialect.dir/MeshOps.cpp.o: in function
 `mlir::mesh::BroadcastOp::print(mlir::OpAsmPrinter&) [clone .localalias]':
MeshOps.cpp:(.text._ZN4mlir4mesh11BroadcastOp5printERNS_12OpAsmPrinterE+0x2 d3): undefined reference to `mlir::printDynamicIndexList(mlir::OpAsmPrinter&, mlir::Operation*, mlir::OperandRange, llvm::ArrayRef<long>, mlir::TypeRange, llvm::ArrayRef<bool>, mlir::AsmParser::Delimiter)'
```

This reverts commit fef18543.

The Arithmetic, Load, and Store sequencers can accept instructions in
parallel. The PipeV blocked that from happening since it became busy if
any of the sequencers were busy. This change allows the sequencers to
accept instructions in parallel.

The VCQ accepts instructions from the the A Pipe and holds them until
the vector unit is ready to dequeue them. The unit dequeues up to one
instruction per cycle, in order, as soon as the sequencer for that type
of instruction is avaliable. This resource is meant to be used for 1
cycle by all vector instructions, to model that only one vector
instruction may be dequed at a time. The actual dequeueing into the
sequencer is modeled by the VA, VL, and VS sequencer resources below.
Each of them will only accept a single instruction at a time and remain
busy for the number of cycles associated with that instruction.

This should say "Assume that VL output is <= 65536".

According to https://lab.llvm.org/buildbot/#/builders/163/builds/48002,
the generic build on HashTable fails with two major issues with
`werror`:
1. warnings on `error: suggest braces around initialization of
subobject`.
2. `__support/HashTable` tests are built regardless of its entrypoints`

This PR attempts to fix such issues.

Enables Type Units with DWARF5 accelerator tables for split dwarf. It is
still
under discussion what is the best way to implement support for
de-duplication in
DWP. This will be in follow up PR.

CodeGen options do not affect the AST, so they usually can be ignored.
The only exception to the rule is when a PCM is created with
`-gmodules`.
In that case the Clang module format is switched to object file
container and contains also serialized debug information that can be
affected by debug options. There the following approach was choosen:

1.) Split out all the debug options into a separate `DebugOptions.def`
    file. The file is included by `CodeGenOptions.def`, so the change is
    transparent to all existing users of `CodeGenOptions.def`.
2.) Reset all CodeGen options, but excluding affecting debug options.
3.) Conditionally reset debug options that can affect the PCM.

This fixes rdar://113135909.

This is a rework of #74176, which erroneously changed the default
clang-format filename (`clang-format`, `clang-format.exe`, etc.) to an
absolute pathname. Instead, we should do that only if the name is a
pathname, e.g. `./clang-format`,
`llvm-project/build/bin/clang-format.exe`, etc. See also
https://github.com/llvm/llvm-project/pull/74176#issuecomment-1837921351.

free(nullptr) is guaranteed by ISO and POSIX to be a no-op, we should not pay for the overhead of maybeInit() in this case.

Additionally, Bionic calls free(nullptr) before the allocator settings are finalized.
Scudo should not run allocator initialization at that time. Doing so
causes various bad things to happen, like mapping primary regions with
the wrong PROT_MTE setting.

This redoes the fix from 3ab6209a
differently, without the unwanted effect of preserving unnecessary
`__imp_` prefixed symbols.

If the referencing object is a regular object, the `__imp_` symbol will
have `isUsedInRegularObj` set on it from that already. If the
referencing object is an LTO object, we set `isUsedInRegularObj` for any
symbol starting with `__imp_`.

If the object file defining the `__imp_` symbol is a regular object, the
`isUsedInRegularObj` flag has no effect. If it is an LTO object, it
causes the symbol to be preserved.

The `llvm::sys::fs::getMainExecutable(nullptr, nullptr)` is not able to
obtain the correct executable path on AIX without Argv0 due to the lack
of a current process on AIX's `proc` filesystem. This causes a build
failure on AIX as intrinsic module directory is missing.

---------

Co-authored-by: Mark Danial <mak.danial@ibm.com>

Fixes:
libc/src/__support/float_to_string.h:551:48: error: conversion from
‘long
unsigned int’ to ‘int32_t’ {aka ‘int’} may change value
[-Werror=conversion]
551 | const int32_t shift_amount = SHIFT_CONST + (-exponent - IDX_SIZE *
idx);
| ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Observed in gcc fullbuilds.

IDX_SIZE is a size_t (aka 'long unsigned int'), but has the value 128,
so the
expression is undergoing implicit promotion.

Link: https://lab.llvm.org/buildbot/#/builders/250/builds/14891

Opaque ptr cleanup effort

The header file has been deprecated since:

  commit f09cf34d
  Author: Archibald Elliott <archibald.elliott@arm.com>
  Date:   Tue Dec 20 10:24:02 2022 +0000

The test cases of mincore require getting correct page size from OS. As
`sysconf` is not functioning correctly, these patches are implemented in
a somewhat confusing way. We revert such patches and will reintroduce
mincore after we correct sysconf.

This reverts 54878b80, 985c0d19 and 418a3a45.

In preparation for the moment when we'll clang-format the whole code
base, this patch adds a script that can be used to rebase patches across
clang-format changes mechanically, without requiring manual
intervention.

See https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all.

This is in preparation for clang-formatting the whole code base. These
annotations are required either to avoid clang-format bugs or because
the manually formatted code is significantly more readable than the
clang-formatted alternative. All in all, it seems like very few
annotations are required, which means that clang-format is doing a very
good job in most cases.

Tests for support for the disjoint flag added in #72583.

As [scottmcm
described](https://discourse.llvm.org/t/conv-c-and-conv-preservemost-mix-badly-on-windows-x64/73054),
the `preserve_most` calling convention, as currently implemented, is a
bad fit for Windows on x64. The intent of `preserve_most` is "to make
the code in the caller as unintrusive as possible", but `preserve_most`
causes the caller to spill and restore ten SIMD registers. It would be
preferable to make `preserve_most` treat the XMM registers however the C
calling convention does on the target operating system.

This is a breaking change, but the documentation indicates that
`preserve_most` is still experimental, so I believe that ABI
compatibility is not yet a requirement.

I've plumbed the LLVM DebugInfoD client into LLDB, and added automatic
downloading of DWP files to the SymbolFileDWARF.cpp plugin. If you have
DEBUGINFOD_URLS set to a space delimited set of web servers, LLDB will
try to use them as a last resort when searching for DWP files. If you do
*not* have that environment variable set, nothing should be changed.
There's also a setting, per @clayborg 's suggestion, that will override
the environment variable, or can be used instead of the environment
variable. The setting is why I also needed to add an API to the
llvm-debuginfod library

### Test Plan:

Suggestions are welcome here. I should probably have some positive and
negative tests, but I wanted to get the diff up for people who have a
clue what they're doing to rip it to pieces before spending too much
time validating the initial implementation.

---------

Co-authored-by: Kevin Frei <freik@meta.com>
Co-authored-by: Alex Langford <nirvashtzero@gmail.com>