[llvm] [Hexagon] Optimize post-increment load and stores in loops. (PR #82011)

[Steven Johnson via llvm-commits]

steven-johnson wrote:

This has broken HVX Codegen in Halide; our tests now fail with

```
vsub(v*:*.h,v*:*.h)  Failed Opcode is : 2656 (V6_vL32b_pred_ai)
No offset range is defined for this opcode. Please define it in the above switch statement!
UNREACHABLE executed at /home/halidenightly/build_bot/worker/llvm-19-x86-64-linux/llvm-project/llvm/lib/Target/Hexagon/HexagonInstrInfo.cpp:2981!
```
(see e.g. https://buildbot.halide-lang.org/master/#/builders/118/builds/86/steps/12/logs/correctness_simd_op_check_hvx)

Please either roll back this change ASAP or offer a fix-forward as this is blocking Halide from passing our tests.



https://github.com/llvm/llvm-project/pull/82011