[llvm] [MISched] Dump region header under -misched-print-dags (PR #215090)

[Tomer Shafir via llvm-commits]

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@@ -860,13 +860,20 @@ void MachineSchedulerBase::scheduleRegions(ScheduleDAGInstrs &Scheduler,
         Scheduler.exitRegion();
         continue;
       }
-      LLVM_DEBUG(dbgs() << "********** MI Scheduling **********\n");
-      LLVM_DEBUG(dbgs() << MF->getName() << ":" << printMBBReference(*MBB)
-                        << " " << MBB->getName() << "\n  From: " << *I
-                        << "    To: ";
-                 if (RegionEnd != MBB->end()) dbgs() << *RegionEnd;
-                 else dbgs() << "End\n";
-                 dbgs() << " RegionInstrs: " << NumRegionInstrs << '\n');
+      auto DumpRegionHeader = [&] {
+        dbgs() << "********** MI Scheduling **********\n";
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tomershafir wrote:

sorry missed that comment, I did not want to over complicate the control flow for this simple printing. Its also not really pass start debug here, and the idiom itself is not a very common among passes. Im thinking to change it to `Current Schedule Region` for both cases in a followup patch

https://github.com/llvm/llvm-project/pull/215090