[llvm] [AMDGPU][WIP] Optimize SGPR spills (PR #93668)

[Christudasan Devadasan via llvm-commits]

================
@@ -0,0 +1,353 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
----------------
cdevadas wrote:

Should precommit the test. But I'm not sure this test currently does anything significant to the slot optimization.
Add another run line to show the output after stack-slot-coloring as well to see the effect of this pass.
Should add a short description at each test what it meant for?
I don't see the slot-indices being shared for the SGPR spills.

https://github.com/llvm/llvm-project/pull/93668