[llvm] [LoongArch] Add `isSafeToMove` hook to prevent unsafe instruction motion (PR #163725)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -1993,6 +1994,10 @@ bool BranchFolder::HoistCommonCodeInSuccs(MachineBasicBlock *MBB) {
       // Hard to reason about register liveness with predicated instruction.
       break;
 
+    if (!TII->isSafeToMove(*TIB, MBB, MF))
+      // Don't hoist the instruction if it isn't safe to move.
+      break;
+
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OCHyams wrote:

I'm not best placed to review a target hook change - I'm not sure of best practice there. Your change here in BranchFolding.cpp STGM though. 

https://github.com/llvm/llvm-project/pull/163725