[llvm] [AMDGPU][True16] Legalize S16 for stores & loads in GlobalISel when True16 is enabled (PR #176963)

[Petar Avramovic via llvm-commits]

================
@@ -464,8 +464,8 @@ static bool isLoadStoreSizeLegal(const GCNSubtarget &ST,
     MemSize = std::max(MemSize, Align);
 #endif
 
-  // Only 1-byte and 2-byte to 32-bit extloads are valid.
-  if (MemSize != RegSize && RegSize != 32)
+  // Only allow extloads to up to 32 bits.
+  if (MemSize != RegSize && RegSize > 32)
----------------
petar-avramovic wrote:

some s16 G_LOADs are actually already legal, iirc this came up from adding s16 to isRegisterType for true16

I was checking it again, and seems like there are some overlaps between
legalForTypesWithMemDesc and legalIf with your changes to AMDGPULegalizerInfo.cpp.
Could you try rewriting this a bit and split legalizerinfo changes one by one in another PR if necessary.

https://github.com/llvm/llvm-project/pull/176963