[llvm] [RegisterCoalescer] Skip the pattern that can't resolve (PR #71024)

[Matt Arsenault via llvm-commits]

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@@ -3599,6 +3634,10 @@ bool RegisterCoalescer::joinVirtRegs(CoalescerPair &CP) {
   if (!LHSVals.resolveConflicts(RHSVals) || !RHSVals.resolveConflicts(LHSVals))
     return false;
 
+  // Some CR_Replace can't be solved by pruneValues. Early exit here.
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arsenm wrote:

Instead of fixing this up after the fact, you should avoid reporting CR_Replace in the first place

https://github.com/llvm/llvm-project/pull/71024