[llvm] [NFC] Various Cleanup in StackColoring, StackSlotColoring, LiveStacks (PR #143931)

[Eli Friedman via llvm-commits]

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@@ -1221,8 +1262,8 @@ bool StackColoring::run(MachineFunction &Func) {
   unsigned NumSlots = MFI->getObjectIndexEnd();
 
   // If there are no stack slots then there are no markers to remove.
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efriedma-quic wrote:

Maybe fix this comment?

https://github.com/llvm/llvm-project/pull/143931