[llvm] [AMDGPU][True16][CodeGen]Support V2S copy with True16 flow (PR #118037)

[Matt Arsenault via llvm-commits]

================
@@ -1075,10 +1075,25 @@ void SIFixSGPRCopies::lowerVGPR2SGPRCopies(MachineFunction &MF) {
         TRI->getRegClassForOperandReg(*MRI, MI->getOperand(1));
     size_t SrcSize = TRI->getRegSizeInBits(*SrcRC);
     if (SrcSize == 16) {
----------------
arsenm wrote:

It depends what it is. Either way that indicates we should have an end to end IR test for whatever this issue was as well 

https://github.com/llvm/llvm-project/pull/118037