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

Git repository change summary for qt/clang/llvm
Pushed by mirror-service into branch 'upstream/users/jeanPerier/merge_memory_passes_4'.
Changed from 66cc9218471ed3d0113e395b2892e45d7b2b827f to 26e3b7c257dae5582cc7732d1521b44510a7cf1f
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 29bc0749034c4f2bda0752360ecacd4e89d7439c by GitHub (on behalf of Ebuka Ezike) on 29/07/2026 at 11:30..
[lldb] Fix crash on creating string error (#212503)

It crashes because the `default` error string may not be a format string
compared to the `fallback` error string
https://invent.kde.org/qt/clang/llvm/-/commit/29bc0749034c4f2bda0752360ecacd4e89d7439c

Git commit 5989d40ab1d0db8333b5976d957a49525d36cf35 by GitHub (on behalf of jeanPerier) on 29/07/2026 at 11:31..
[flang] Wire allocation-placement into the optimizer pipeline (default off) - memory passes unification [3/5] (#210745)

Add a hidden -enable-allocation-placement flag that, when set, replaces
the stack-arrays and memory-allocation-opt passes in the default FIR
optimizer pipeline with the unified allocation-placement pass. The flag
is off by default, so the legacy passes remain the default path and
behavior is unchanged.

When enabled, the pass runs with its default byte-size thresholds; the
-fstack-arrays strategy is forwarded through the new stackArrays option.

Assisted-by: AI
https://invent.kde.org/qt/clang/llvm/-/commit/5989d40ab1d0db8333b5976d957a49525d36cf35

Git commit 26e3b7c257dae5582cc7732d1521b44510a7cf1f by jeanPerier (on behalf of Jean Perier) on 29/07/2026 at 11:31..
[flang] Enable allocation-placement pass by default

Make the unified allocation-placement pass the default in the FIR optimizer
pipeline in place of the legacy stack-arrays and memory-allocation-opt passes,
by defaulting -enable-allocation-placement to true. Passing
-enable-allocation-placement=false restores the legacy passes for comparison.

Add a -disable-allocation-placement switch that skips the pass entirely (wired
through addAllocationPlacement like the other optimizer passes), so codegen
tests can opt out of placement policy independently of the legacy fallback.

Update the pipeline-dump tests to expect AllocationPlacement, and disable the
pass in the alloca/allocmem codegen tests (alloc.fir, coordinateof.fir) so they
keep testing lowering rather than placement policy. Document the unified pass,
its policy, thresholds, and options in fstack-arrays.md.
https://invent.kde.org/qt/clang/llvm/-/commit/26e3b7c257dae5582cc7732d1521b44510a7cf1f