[llvm] [GlobalISel] Fold instructions with fully-known bits to a constant. (PR #224254)

[Matt Arsenault via llvm-commits]

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@@ -3363,6 +3363,35 @@ bool CombinerHelper::matchRedundantAnd(MachineInstr &MI,
   return false;
 }
 
+bool CombinerHelper::matchKnownBitsToConstant(MachineInstr &MI,
+                                              APInt &MatchInfo) const {
+  if (!VT)
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arsenm wrote:

We really ought to be able to mark a pattern as requiring ValueTracking 

https://github.com/llvm/llvm-project/pull/224254