[llvm] [CodeGen][AMDGPU] Replace isBasicBlockPrologue with a MachineInstr::BBProlog flag (PR #225433)

[Matt Arsenault via llvm-commits]

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@@ -1074,6 +1083,8 @@ class MachineBasicBlock
            "iterator points outside of basic block");
     assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
            "Cannot insert instruction with bundle flags");
+    if (isBBPrologInsertPoint(I.getInstrIterator()))
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arsenm wrote:

Yes, and yes 

https://github.com/llvm/llvm-project/pull/225433