Make Candidate's front() and back() functions return references to
MachineInstr and introduce begin() and end() returning iterators, the
same way it is usually done in other container-like classes.

This makes possible to iterate over the instructions contained in
Candidate the same way one can iterate over MachineBasicBlock (note that
begin() and end() return bundled iterators, just like MachineBasicBlock
does, but no instr_begin() and instr_end() are defined yet).

Mistake with #78628 that got caught after being merged

So we have all the complex casts together.

These are largely copy-pasted from the corresponding function
descriptions. Added \see cross-references. Also changed <c> tags to \c.

Revert 10f3296d - [openmp] Fix warnings when building on Windows with latest MSVC or Clang ToT (#77853)

It broke the AMDGPU buildbot: https://lab.llvm.org/buildbot/#/builders/193/builds/45378

Replace cp with a cat. This allows to create a writable file when the
original one is read-only.

There were quite a few compilation warnings when building openmp on Windows with
the latest Visual Studios 2022 version 17.8.4. Some other warnings were visible
with the latest Clang at tip. This commit fixes all of them.

These were missed and hopefully avoids assertions when
dc3faf0e is recommitted.

This patch restores PR#78498

- reland #79113
- Fix aarch64 RISC-V build

3ab8d2aa relanded in 31125785, so reland this too.

Might want to set this to True (and add a few source files to
builtins) at some point, but for now heal the bots.

Extra tests for
  https://github.com/llvm/llvm-project/pull/78637
  https://github.com/llvm/llvm-project/pull/78632

This is /almost/ NFC - the only annoyance is that for some reason we were using "<C1,C2,..>" for ConstantVector types unlike all other cases - these now use the same "[C1,C2,..]" format as the other constant printers.

Following on from the previous patch 6aeb7a71,
this patch adds the necessary code to process the DPV equivalents of
llvm.dbg.assign intrinsics. Most of the content of this patch is simply
duplicating existing functionality, using generic code for simple
functions and PointerUnions where storage is required. The most complex
changes are in the places that iterate over instructions, as iterating
over DPValues between instructions is different to iterating over
instructions that may or may not be debug intrinsics; this is most
complex in `AssignmentTrackingLowering::process`, where I've added some
comments to explain the state of the program at each key point depending
on whether we are operating on intrinsics or DPValues.

Fixes #78856

This reverts commit a301fb11.

The changes caused failures like:
https://lab.llvm.org/buildbot/#/builders/91/builds/22189

The constructor args are passed by reference since d6790a0a

Fixes MSVC static analysis warning

These stem from 4821c90c.

When cross compiling, CMAKE_SYSTEM_PROCESSOR is empty, if the
target processor hasn't been set when setting up the cross
compilation. Ideally, when setting up cross compilation with
CMake, the user is supposed to set CMAKE_SYSTEM_PROCESSOR, but
so far, compilation has worked just fine even without it.

Quote the string where CMAKE_SYSTEM_PROCESSOR is expanded, to
avoid argument errors when it expands to an empty string.

In acd8791c, a call to FlushFileBuffers
was added to work around a rare kernel bug. In
3b9b4d21, the scope of that workaround
was limited, for performance reasons, as the flushes are quite
expensive.

On VirtualBox shared folders, closing a memory mapping that has been
written to, also needs to be explicitly flushed, if renaming the output
file before it is closed. Contrary to the kernel bug, this always
happens on such mounts. In these cases, the output ends up as a file of
the right size, but the contents are all zeros.

The sequence to trigger the issue on the VirtualBox Shared Folders is
this, summarized:

    file = CreateFile()
    mapping = CreateFileMapping(file)
    mem = MapViewOfFile()
    CloseHandle(mapping)
    write(mem)
    UnmapViewOfFile(mem)
    SetFileInformationByHandle(file, FileRenameInfo)
    CloseHandle(file)

With this sequence, the output file always ends up with all zeros. See
https://github.com/mstorsjo/llvm-mingw/issues/393 for a full
reproduction example.

To avoid this issue, call FlushFileBuffers() when the file may reside on
a VitualBox shared folder. As the flushes are expensive, only do them
when the output isn't on a local file system.

The issue with VirtualBox shared folders could also be fixed by calling
FlushViewOfFile before UnmapViewOfFile, and doing that could be slightly
less expensive than FlushFileBuffers.

Empirically, the difference between the two is very small though, and as
it's not easy to verify whether switching FlushFileBuffers to
FlushViewOfFile helps with the rare kernel bug, keep using
FlushFileBuffers for both cases, for code simplicity.

This fixes downstream bug
https://github.com/mstorsjo/llvm-mingw/issues/393.

Depends on #79038 which makes cov5 as the default code
object version.

Also update LIT tests and docs.
For more details, see
https://llvm.org/docs/AMDGPUUsage.html#code-object-v5-metadata

Corresponding llvm-objdump AMDGPU lit tests are updated
in a follow-up PR.

End-to-end test for https://github.com/llvm/llvm-project/issues/71517,
testing IndVars/LoopVectorize interaction

This patch builds on top of #76971 and implements support for:
* __arm_new("zt0")
* __arm_in("zt0")
* __arm_out("zt0")
* __arm_inout("zt0")
* __arm_preserves("zt0")

Allows shuffle to fold constant vectors that have already been lowered to constant pool - shuffle combining can then constant fold this.

Noticed while triaging #79100

Add naive implementation of memcpy, memset, memmove, memchr for SME
targets.
Co-authored-by: David Sherwood <david.sherwood@arm.com>

llvm.dbg.assign intrinsics have 2 {value, expression} pairs; fix hwasan to update
the second expression.

Fixes #76545

We're calling it four times in the same function.

By using `match(W, m_ImmConstant())`, we do not need to worry about
one-time use anymore.

As part of a recent patch landing, some tests that are not yet ready
to support RemoveDIs were turned on; this patch disables those tests
in RemoveDIs mode.

Fixes buildbot failure:
https://lab.llvm.org/buildbot/#/builders/275/builds/3640

Reverts llvm/llvm-project#79113
It broke aarch64 build bot machines.

Likely related to platform-specific expansion of gtest macros:
```
llvm/unittests/ExecutionEngine/Orc/CoreAPIsTest.cpp:1276:12: warning: suggest explicit
braces to avoid ambiguous 'else' [-Wdangling-else]
```

This patch reduces the surface of `FPBits`.

I failed to delete the old definition as a part of
https://github.com/llvm/llvm-project/pull/73838.

A follow-up from <https://github.com/llvm/llvm-project/pull/79025>.

Remove unnecessary assert for a sorted StandardNames after
implementation of getLibFunc is changed from binary search to a DenseMap
Lookup in commit 7d950f04.

The original getLibFunc binary search implementation is in commit
c740e3f0

.

Co-authored-by: Tony Tao <tonytao@ca.ibm.com>