When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes https://github.com/llvm/llvm-project/issues/70068
Fixes https://github.com/llvm/llvm-project/issues/69167

Fixes https://github.com/llvm/llvm-project/issues/69369.
Fixes https://github.com/clangd/clangd/issues/1700.

(cherry picked from commit e63ab13c)

Our coefficients are 64-bits, so adding/multiplying them can wrap in
64-bits even if there would be no wrapping the full bit width.

The alternative would be to check for overflows during all adds/muls in
decomposition. I assume that we don't particularly care about handling
wide integers here, so I've opted to bail out.

Fixes https://github.com/llvm/llvm-project/issues/68751.

(cherry picked from commit 1d43096e)

(cherry picked from commit 2b74db6c)

(cherry picked from commit a157a82b)

Fixes #68682.

(cherry picked from commit 2ad9a658)

Specifically, the test std/input.output/string.streams/stringstream/stringstream.members/gcount.pass.cpp
allocates a std::string with INT_MAX-1 elements, and then writes this to
a std::stringstream. On Linux, running this test consumes around 5.0 GB
of memory; on Windows, it ends up using up to 6.8 GB of memory.

This limits whether such tests can run on e.g. GitHub Actions runners,
where the free runners are limited to 8 GB of memory.

This is somewhat similar to, but still notably different, from the
existing test parameter long_tests.

(cherry picked from commit 122064a6)

(cherry picked from commit afdad4fd)

(cherry picked from commit 1db8abf2)

This was broken by b71edfaa.

(cherry picked from commit 6a7f0b9d)

On ELF platforms, when there is no global variable and the unique module ID is
non-empty, COMDAT asan.module_ctor is created with no
`__asan_register_elf_globals` calls. If this COMDAT is the prevailing copy
selected by the linker, the linkage unit will have no
`__asan_register_elf_globals` call: the redzone will not be poisoned and ODR
violation checker will not work (#67677).

This behavior is benign for -fno-sanitize-address-globals-dead-stripping because
asan.module_ctor functions that call `__asan_register_globals`
(`InstrumentGlobalsWithMetadataArray`) do not use COMDAT.

To fix #67677:

* Use COMDAT for -fsanitize-address-globals-dead-stripping on ELF platforms.
* Call `__asan_register_elf_globals` even if there is no global variable.
* If the unique module ID is empty, don't call SetComdatForGlobalMetadata:
  placing `@.str` in a COMDAT would incorrectly discard internal COMDAT `@.str`
  in other compile units.

Alternatively, when there is no global variable, asan.module_ctor is not COMDAT
and does not call `__asan_register_elf_globals`. However, the asan.module_ctor
function cannot be eliminated by the linker.

Tested the following script. Only ELF -fsanitize-address-globals-dead-stripping has changed behaviors.
```
echo > a.cc  # no global variable, empty uniqueModuleId
echo 'void f() {}' > b.cc  # with global variable, with uniqueModuleId
echo 'int g;' > c.cc  # with global variable
for t in x86_64-linux-gnu arm64-apple-macosx x86_64-windows-msvc; do
  for gc in -f{,no-}sanitize-address-globals-dead-stripping; do
    for f in a.cc b.cc c.cc; do
      echo /tmp/Rel/bin/clang -S --target=$t -fsanitize=address $gc $f -o -
      /tmp/Rel/bin/clang -S --target=$t -fsanitize=address $gc $f -o - | sed -n '/asan.module_ctor/,/ret/p'
    done
  done
done
```

---

Identical to commit 16eed8c9.
6420d330 is an incorrect revert for genuine
purely internal issues.

(cherry picked from commit 8902f12e)

When applying format changes to staged files, git-clang-format
erroneously checks out all files in the index and thus may overwrite
unstaged changes.

Fixes #65643.

(cherry picked from commit 743659be)

It started to fail in a flaky manner a few days ago on GreenDragon buildbots
(i.e. x86_64-darwin). I didn't track down the root cause but LSan isn't
actually supported on darwin anyway, so UNSUPPORTED seems appropriate.

Prior art: 3ff080b5.

(cherry picked from commit 0a3519d5)

This custom combine currently converts `and(anyext(x),c)` into
`anyext(and(x,c))`. This is not correct, because the original expression
guaranteed that the high bits are zero, while the new one sets them to
undef.

Emit `zext(and(x,c))` instead.

Fixes https://github.com/llvm/llvm-project/issues/68783.

(cherry picked from commit 127ed9ae)

(cherry picked from commit 0ead1fae)

Don't remove the outermost parentheses surrounding a return statement
expression when inside a function/lambda that has the decltype(auto)
return type.

Fixed #67892.

(cherry picked from commit 75441a68)

Prior logic would remove the shuffle iff all of the elements in `x`
where used. This is incorrect.

The issue is `movmsk` only cares about the highbits, so if the width
of the elements in `x` is smaller than the width of the elements
for the `movmsk`, then the shuffle, even if it preserves all the elements,
may change which ones are used by the highbits.

For example:
`movmsk64(bitcast(shuffle32(x, (1,0,3,2))))`

Even though the shuffle mask `(1,0,3,2)` preserves all the elements, it
flips which will be relevant to the `movmsk64` (x[1] and x[3]
before and x[0] and x[2] after).

The fix here, is to ensure that the shuffle mask can be scaled to the
element width of the `movmsk` instruction. This ensure that the
"high" elements stay "high". This is overly conservative as it
misses cases like `(1,1,3,3)` where the "high" elements stay
intact despite not be scalable, but for an relatively edge-case
optimization that should generally be handled during
simplifyDemandedBits, it seems okay.

(cherry picked from commit 1684c65b)

(cherry picked from commit 65a576e2)

On MinGW targets, the .ctors section is always used for constructors.

When using the .ctors section, the constructors need to be emitted in
reverse order to get them execute in the right order. (Constructors with
a specific priority are sorted separately by the linker later.) In LLVM,
in CodeGen/AsmPrinter/AsmPrinter.cpp, there's code that reverses them
before writing them out, executed when using the .ctors section. This
logic is done whenever TM.Options.UseInitArray is set to false. Thus,
make sure to set UseInitArray to false for this target.

This fixes https://github.com/llvm/llvm-project/issues/55938.

(cherry picked from commit a2b8c49c)

When converting to ConstantRange, we should treat undef like a full range.
Fixes #68381.

(cherry picked from commit 81857940)

We could maybe extend this by allowing the lowest subop to have multiple uses and extract the lowest subvector result of the concatenated op, but let's just get the fix in first.

Fixes #67333

```c++
AArch64SVEPcsAttr *AArch64SVEPcsAttr::CreateImplicit(ASTContext &Ctx, SourceRange Range, Spelling S) {
  AttributeCommonInfo I(Range, NoSemaHandlerAttribute, (
    S == GNU_aarch64_sve_pcs ? AttributeCommonInfo::Form{AttributeCommonInfo::AS_GNU, GNU_aarch64_sve_pcs, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/} :
    S == CXX11_clang_aarch64_sve_pcs ? AttributeCommonInfo::Form{AttributeCommonInfo::AS_CXX11, CXX11_clang_aarch64_sve_pcs, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/} :
    S == C23_clang_aarch64_sve_pcs ? AttributeCommonInfo::Form{AttributeCommonInfo::AS_C23, C23_clang_aarch64_sve_pcs, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/} :
    (llvm_unreachable("Unknown attribute spelling!"),  AttributeCommonInfo::Form{AttributeCommonInfo::AS_GNU, 0, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/})));
  return CreateImplicit(Ctx, I);
}
```

```c++
AArch64SVEPcsAttr *AArch64SVEPcsAttr::CreateImplicit(ASTContext &Ctx, SourceRange Range, Spelling S) {
  AttributeCommonInfo I(Range, NoSemaHandlerAttribute, [&]() {
    switch (S) {
    case GNU_aarch64_sve_pcs:
      return AttributeCommonInfo::Form{AttributeCommonInfo::AS_GNU, GNU_aarch64_sve_pcs, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/};
    case CXX11_clang_aarch64_sve_pcs:
      return AttributeCommonInfo::Form{AttributeCommonInfo::AS_CXX11, CXX11_clang_aarch64_sve_pcs, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/};
    case C23_clang_aarch64_sve_pcs:
      return AttributeCommonInfo::Form{AttributeCommonInfo::AS_C23, C23_clang_aarch64_sve_pcs, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/};
    default:
      llvm_unreachable("Unknown attribute spelling!");
      return AttributeCommonInfo::Form{AttributeCommonInfo::AS_GNU, 0, false /*IsAlignas*/, false /*IsRegularKeywordAttribute*/};
    }
  }());
  return CreateImplicit(Ctx, I);
}
```

Fixes https://github.com/llvm/llvm-project/issues/68237
Conflicts:
	clang/docs/ReleaseNotes.rst

This can happen when manually emitting strings into .drectve sections
with `__attribute__((section(".drectve")))`, which is a way to emulate
`#pragma comment(linker, "...")` for mingw compilers, without requiring
building with -fms-extensions.

Normally, this doesn't generate any comdat, but if compiled with
-fsanitize=address, this section does get turned into a comdat section.

This fixes #67261. This issue can be seen as a regression; a change in
the "lli" tool in 17.x triggers this case, if compiled with ASAN
enabled, triggering this unsupported corner case in LLD. With this
change, LLD can handle it.

(cherry picked from commit 503bc5f6)

(cherry picked from commit 95b2c6b3)

This should fix #66912. When emitting SEH unwind info, we need to be
able to calculate the exact length of functions before alignments are
fixed. Until that limitation is overcome, just disable all loop
alignment on Windows targets.

(cherry picked from commit 6ae36c01)

Right now, `-Wformat` for a scoped enum will suggest a cast based on the
format specifier being used. This can lead to incorrect results, e.g.
attempting to format a scoped enum with `%s` would suggest casting to
`char *` instead of fixing the specifier. Change the logic to treat the
scoped enum's underlying type as the intended type to be printed, and
suggest format specifier changes and casts based on that.

(cherry picked from commit 0b07b06e)

This addresses missing cmake files needed to build some sub-projects
like libstdcxx.

Co-authored-by: René Rebe <rene@exactcode.de>

The helper function `__pair_like_explicit_wknd` is only SFINAE-ed with
`tuple_size<remove_cvref_t<_PairLike>>::value == 2`, but its function
body assumes `std::get` being valid.

Fixes #65620

(cherry picked from commit 054f9c55)

Otherwise they may mistakenly get the large section flag.

(cherry picked from commit b915f606)
(fix was slightly different since cherry-pick didn't apply well)

[workflow] Fix abi checker in llvm-tests. Same fix as in 99fb0af8 (#67957)

Fixes #67651

Prior to 591c4b64, the mingw specific
linker options -mthreads, -mconsole, -mwindows and -mdll would be
tolerated also at compile time, but generating a warning about being
unused.

After that commit, they were marked as target specific, which means that
it's an error if they're unused (which would consider them used for the
wrong target). These specific options are only relevant when linking,
but we want to tolerate them at compile time too, like before.

This was fixed for -mthreads in
a79995ca, while the other options didn't
seem to be commonly used during compilation.

After the 17.x release, we've got more reports about this actually being
an issue, in #64464. Therefore, apply the same fix for them; marking
them as tolerated for mingw targets during compilation, even if they're
unused. Also add a testcase for -mthreads which was already handled.

Thus, this fixes #64464.

(cherry picked from commit e39de2b8)

Adapted from the original commit; the test in the original commit
depended on f39c399d. Instead of
using -###, when we're not actually using the printed output of
-###, instead use -fdriver-only.

Before af744f0b, the first entry
among the search paths was the empty string, indicating searching
in (or starting from) the current directory. After
af744f0b, the toolchain/clang
specific lib directories were added at the head of the search path.

This would cause lookups of literal file names or relative paths
to match paths in the toolchain, if there are coincidental files
with similar names there, even if they would be find in the current
directory as well.

Change addClangLibSearchPaths to append to the list like all other
operations on searchPaths - but move the invocation of the
function to the right place in the sequence.

This fixes #67779.

(cherry picked from commit f906fd53)

Also switch the test case to use -NEXT to strictly match all lines.

(cherry picked from commit 7d7d9e46)

In order to reduce noise for a MR.

(cherry picked from commit a5e280bc)

This reverts one part of commit
9f4dfcb7, with a modified comment added
about the code.

Ideally, this would only be reinstated temporarily - but given the
situation in vcpkg, it looks likely that they would keep passing the
duplicate options for quite some time. The conflicting CRT choice
usually are benign but only would cause warnings about one option
overriding the other, if passing e.g. "/MDd /MT".

However when vcpkg currently sets these options in CMAKE_*_FLAGS_DEBUG,
it passes the redundant option /D_DEBUG; thus the compiler finally ends
up with e.g. "/D_DEBUG /MDd /MT", which has the effect of defining
_DEBUG while using a release mode CRT, which allegedly breaks the build.

There's a PR up for removing this redundant /D_DEBUG option in vcpkg in
https://github.com/microsoft/vcpkg/pull/34123. With that in place, this
change wouldn't be strictly needed.

(cherry picked from commit 7bc09a47)

Alias metadata may no longer be valid after replacing the call argument.
Fix this by merging it with the memcpy alias metadata.

This fixes a miscompilation encountered in
https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Failing.20tests.20when.20rustc.20is.20compiled.20with.201.20CGU.

(cherry picked from commit 4e6e4763)