[llvm] [CodeGen] Stop exporting cl::opts. NFC (PR #228728)

[Fangrui Song via llvm-commits]

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@@ -224,6 +224,11 @@ LiveInterval *LiveIntervals::createInterval(Register reg) {
   return new LiveInterval(reg, Weight);
 }
 
+LiveRange *LiveIntervals::createRegUnitRange() {
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MaskRay wrote:

Yes, we need it.  getRegUnit is inline in LiveIntervals.h and reads -use-segment-set-for-physregs, so the old code needs the extern cl::opt. createRegUnitRange() lets the option be file-local.

https://github.com/llvm/llvm-project/pull/228728