[llvm] [llvm][CodeGen] Fix the empty interval issue in Window Scheduler(#128714) (PR #129204)

[Hua Tian via llvm-commits]

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@@ -923,6 +942,25 @@ void ModuloScheduleExpander::addBranches(MachineBasicBlock &PreheaderBB,
   }
 }
 
+/// Some new registers are generated during the kernel expansion. We recalculate
+/// the live intervals of these registers after the expansion.
+void ModuloScheduleExpander::recalcEmptyIntervals() {
+  // The interval can be computed if the register's non-debug users have
+  // slot indexes.
+  auto CanRecalculateInterval = [this](unsigned Reg) -> bool {
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huaatian wrote:

Updated

https://github.com/llvm/llvm-project/pull/129204