[llvm] A SCHED_BARRIER in a bundle should not prevent other SCHED_BARRIERs to be considered (PR #152627)

[Yoonseo Choi via llvm-commits]

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@@ -2508,7 +2508,9 @@ bool SchedGroup::canAddSU(SUnit &SU) const {
     ++E;
 
   // Return true if all of the bundled MIs can be added to this group.
-  return std::all_of(B, E, [this](MachineInstr &MI) { return canAddMI(MI); });
+  return std::all_of(B, E, [this](MachineInstr &MI) {
+    return (MI.isMetaInstruction()) || canAddMI(MI);
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yoonseoch wrote:

I see, will do so. 
Initially I did not remove isMetaInstruction inside of canAddMI as I thought that could lead to edges between two sched_barriers, which I thought was unintentional. 

https://github.com/llvm/llvm-project/pull/152627