[qt/clang/llvm]: Summary of bulk changes made

Git repository change summary for qt/clang/llvm
Pushed by mirror-service into branch 'upstream/release/23.x'.
Changed from 45a9d73790257968607978479cbc1d1956047522 to fdf8b84c79164e6f8bcbabcf7f6f79cbe4e20b1f
Acknowledgement was received that this change introduces only existing code that has been pushed to another public open source repository.

This change contains the following new commits:

Git commit 81fba7a0d0c31033db8eff71b7ad91a1660661e5 by Douglas Yung (on behalf of George Burgess IV) on 06/08/2026 at 00:45..
[mlir] fix builders by moving var into assert (#209494)

non-asserts builders are failing since `vecTy` is unused aside from this
one assertion: https://lab.llvm.org/buildbot/#/builders/228/builds/4754

Since side-effects here are uninteresting, move the entire expr into the
assert, per CodingStandards.md

Fix-forward for #199700

(cherry picked from commit e217dcb8de5dd83b307fe8b95b43de11a7d894ab)
https://invent.kde.org/qt/clang/llvm/-/commit/81fba7a0d0c31033db8eff71b7ad91a1660661e5

Git commit 7db2e3307ce6a8bcc0f20caa16e1fd031013281f by Douglas Yung (on behalf of Zeyi Xu) on 06/08/2026 at 00:46..
[Clang] Define `__SIG_ATOMIC_TYPE__` macro (#213934)

Define `__SIG_ATOMIC_TYPE__` for compatibility with GCC.

This fixes `riscv32-netbsd` and `riscv64-netbsd` system headers that
define `sig_atomic_t` using this macro.

Reference:
https://gcc.gnu.org/onlinedocs/gcc-16.1.0/cpp/Common-Predefined-Macros.html

Follow up of #199678, Closes #213895

(cherry picked from commit c08ed4c1ab086aad6f22cfc499e74d92953045ae)
https://invent.kde.org/qt/clang/llvm/-/commit/7db2e3307ce6a8bcc0f20caa16e1fd031013281f

Git commit fd71684ea064bfbf79ffed9b437d978eb15414bf by Douglas Yung (on behalf of Tom Stellard) on 06/08/2026 at 00:47..
workflows/zizmor: Update to latest version (#213922)

This is required to handle the new import syntax for same-repository
actions:

https://github.blog/changelog/2026-07-30-reference-same-repository-actions-with-self-repository-syntax/
(cherry picked from commit da2a4685fe5c23f90c8357c2d6732396adbe74be)
https://invent.kde.org/qt/clang/llvm/-/commit/fd71684ea064bfbf79ffed9b437d978eb15414bf

Git commit 121d539a6e83609c943f054dcc5b2c5ed48c5281 by Douglas Yung (on behalf of Sébastien Marchand) on 06/08/2026 at 00:48..
[AArch64][Windows] Fix swift async context slot placement (#212922)

Swift async functions can miscompile on Windows ARM64 at `-O2`, when
there's enough register pressure that a local gets scavenged into the
callee-save area: the local ends up sharing an address with the saved
caller x29, so the epilogue restores a value the function has already
overwritten. swiftlang/swift#90920 has a reduced repro.

`assignCalleeSavedSpillSlots` creates the swift async context object
before the callee-save loop instead of inside it next to the FP slot.
MachineFrameInfo ends up with it above the frame record while the
prologue stores it below at FP-8, and the 8 byte disagreement leaves a
hole in the middle of the callee-save area. PEI's scavenger hands that
hole to the local. Only reproduces at -O2 and up since scavenging is
gated on the opt level.

```
	sub	sp, sp, #112
	str	x19, [sp, #16]                  // 8-byte Spill
	str	x21, [sp, #24]                  // 8-byte Spill
	stp	x23, x24, [sp, #32]             // 16-byte Folded Spill
	stp	x25, x26, [sp, #48]             // 16-byte Folded Spill
	stp	x27, x28, [sp, #64]             // 16-byte Folded Spill
	stp	x29, x30, [sp, #88]             // 16-byte Folded Spill
	str	xzr, [sp, #80]
	add	x29, sp, #88
	...
	str	x7, [x29]                       // 8-byte Spill
	...
	ldr	x1, [x29]                       // 8-byte Reload
	ldp	x29, x30, [sp, #88]             // 16-byte Folded Reload
```

This creates the object inside the loop so the two agree. The other
option was leaving the creation site alone and teaching MachineFrameInfo
about the expanded 24 byte FP/LR slot, but that puts the layout in two
places. Not sure which is preferred here, I don't know this code well.

This also asserts the saved FP object resolves to FP+0, since nothing
checks that today. Reverting the fix makes it fire on the same funclet.
`store-swift-async-context-clobber-live-reg.ll` already miscompiles with
`-regalloc=fast`, so this isn't Swift specific.

(cherry picked from commit c358e8d90b3b26db86046f19de29bc848f255ac8)
https://invent.kde.org/qt/clang/llvm/-/commit/121d539a6e83609c943f054dcc5b2c5ed48c5281

Git commit fdf8b84c79164e6f8bcbabcf7f6f79cbe4e20b1f by Douglas Yung (on behalf of Tom Stellard) on 06/08/2026 at 00:48..
workflows/upload-release-artifact: Make this action self-contained (#213828)

The action now checks out its own files so calling workflows don't need
to do this.  This helps prevent mistakes where the calling workflow
does not checkout the right files causing this action to fail.

(cherry picked from commit 4e725a2c756f32c4fe7512d9b30c6bf831e4d4a5)
https://invent.kde.org/qt/clang/llvm/-/commit/fdf8b84c79164e6f8bcbabcf7f6f79cbe4e20b1f