[llvm] [AMDGPU][Scheduler] Scoring system for rematerialization candidates (PR #153092)

[Lucas Ramirez via llvm-commits]

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@@ -2040,6 +2257,13 @@ void GCNScheduleDAGMILive::updateRegionBoundaries(
     RegionBounds.first = NewMI; // Insertion
 }
 
+void GCNScheduleDAGMILive::deleteMI(unsigned RegionIdx, MachineInstr *MI) {
+  updateRegionBoundaries(Regions[RegionIdx], MI, nullptr);
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lucas-rami wrote:

Added `test_rollback_remats_emptydefregion_barrier` (renamed the existing test to `test_rollback_remats_emptydefregion_block`). It seems to be working fine (and I checked the logs to makes sure it is actually rematerializing and then rolling back remats). Let me know if there is still a concern.

https://github.com/llvm/llvm-project/pull/153092