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

Git repository change summary for qt/clang/llvm-project
Pushed by mirror-service into branch 'upstream/users/jeanPerier/merge_memory_passes_2'.
Changed from e0e7544fd7d593175f863e198d1e9e20824e74fa to baf2adb8b8ed72b25ddd784d25d47b5b1c36e7bd
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 baf2adb8b8ed72b25ddd784d25d47b5b1c36e7bd by Jean Perier (on behalf of root) on 21/07/2026 at 10:12..
[flang] Add policy-driven allocation-placement pass

Introduce a new function-level pass, allocation-placement, that unifies the
stack/heap placement decisions currently split between the stack-arrays and
memory-allocation-opt passes. For each array allocation it consults a policy
to decide whether it should live on the stack (fir.alloca) or the heap
(fir.allocmem) and rewrites it accordingly, reusing fir::replaceAllocas for
stack-to-heap and the StackArrays analysis/rewrite for heap-to-stack (so
heap-to-stack only happens where it is provably safe).

The default policy (AllocationPlacementPolicy.h) is threshold-driven:
  - small constant-size arrays go on the stack within a per-function stack
    budget, otherwise on the heap;
  - big constant-size arrays: user variables stay on the stack, temporaries
    go on the heap;
  - runtime-sized arrays go on the heap;
  - an aggressive mode places all arrays on the stack (best effort).
User variables are distinguished from compiler temporaries via the presence
of a uniqued name. A hook lets downstream users override the thresholds per
allocation (e.g. for device routines or parallel regions).

The pass is not wired into any pipeline yet; it is reachable through fir-opt
and covered by isolated tests.
https://invent.kde.org/qt/clang/llvm-project/-/commit/baf2adb8b8ed72b25ddd784d25d47b5b1c36e7bd