[RFC][flang] Add support for assumed-shape dummy arrays repacking. (#127147)

This is a document describing why and how to add support for repacking
of assumed-shape dummy arrrays to provide more efficient data cache.
It proposes adding new FIR operations and outlines the compiler flow
handling these operations.
I would like to hear feedback on all of it, but especially on:
  * The possibility of detecting safeness of the repacking
    in the context of OpenACC/OpenMP. If it is not possible
    to do the runtime checks to determine safety, then
    there is not need to add the `TempCopyIsSafe` attributes
    to the instruction.
  * Whether it is possible to preserve the debug information
    in cases where `fir.pack_array` is sunk after `[hl]fir.declare`,
    so that before the `fir.pack_array` a debugger will refer
    to the values in the original array, and after `fir.pack_array`
    it will refer to the copy.

GitOrigin-RevId: aa3875411746de0a24a8de0d40def711cd70153d
2 files changed
tree: 0d89d69a65f43627672a74f49c07ee397a5ace52
  1. cmake/
  2. docs/
  3. examples/
  4. include/
  5. lib/
  6. module/
  7. runtime/
  8. test/
  9. tools/
  10. unittests/
  11. .clang-format
  12. .clang-tidy
  13. .drone.star
  14. .gitignore
  15. CMakeLists.txt
  16. LICENSE.TXT
  17. Maintainers.md
  18. README.md
README.md

Flang

Flang is a ground-up implementation of a Fortran front end written in modern C++. It started off as the f18 project (https://github.com/flang-compiler/f18) with an aim to replace the previous flang project (https://github.com/flang-compiler/flang) and address its various deficiencies. F18 was subsequently accepted into the LLVM project and rechristened as Flang.

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