[llvm] [AMDGCN][SIWholeQuadMode] Handle case when SI_KILL_I1_TERMINATOR -1,0 is not the only terminator (PR #122922)

[Juan Manuel Martinez Caamaño via llvm-commits]

================
@@ -96,6 +96,9 @@ enum {
   StateStrict = StateStrictWWM | StateStrictWQM,
 };
 
+using InstRange =
----------------
jmmartinez wrote:

I've rolled back some of those changes (I found it easier to follow what was going on when splitBlock was closer to the place where the split instruction was selected. But it adds too much noise to the PR.

I've also split the PR into more commits.

https://github.com/llvm/llvm-project/pull/122922