[llvm] [CodeGen] Check entire block if no threshold was given for neighbors (PR #83526)

[Matt Arsenault via llvm-commits]

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@@ -1598,15 +1598,42 @@ MachineBasicBlock::getProbabilityIterator(MachineBasicBlock::succ_iterator I) {
   return Probs.begin() + index;
 }
 
+MachineBasicBlock::LivenessQueryResult
+MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
+                                           MCRegister Reg,
+                                           const_iterator Before) const {
+  LivePhysRegs UsedRegs(*TRI);
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arsenm wrote:

LiveRegUnits should always be preferred to LivePhysRegs. No new uses of LivePhysRegs should be introduced 

https://github.com/llvm/llvm-project/pull/83526