[llvm] [AMDGPU] Reject sub-dword format buffer loads and stores (PR #209703)

[Matt Arsenault via llvm-commits]

================
@@ -6871,6 +6874,9 @@ bool AMDGPULegalizerInfo::legalizeBufferLoad(MachineInstr &MI,
   const bool IsD16 = IsFormat && (EltTy.getSizeInBits() == 16);
   const bool Unpacked = ST.hasUnpackedD16VMem();
 
+  if (IsFormat && !IsTyped && !IsD16 && MemTy.getSizeInBits() < 32)
+    return false;
----------------
arsenm wrote:

Should emit the same error, erase, and report successfully legalized 

https://github.com/llvm/llvm-project/pull/209703