[llvm] [AMDGPU][gfx1250] Check for GloballyAddressableScratch in mayAccessScratchThroughFlat (PR #160669)

[Jay Foad via llvm-commits]

jayfoad wrote:

To explain a bit more: in normal wave termination, the hw waits for outstanding stores to complete, and then releases the wave's VGPRs and scratch. If you send MSG_DEALLOC_VGPRS before the end of the shader, then VGPRs *and scratch* will be released before the hw waits for outstanding stores to complete. If there were any outstanding stores to this wave's scratch then that will cause a problem.

https://github.com/llvm/llvm-project/pull/160669