[llvm] [Windows SEH] fix failed assert and crash (PR #107031)

[Matt Arsenault via llvm-commits]

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@@ -1476,6 +1476,11 @@ void SelectionDAGISel::reportIPToStateForBlocks(MachineFunction *MF) {
     if (BB->getFirstMayFaultInst()) {
       // Report IP range only for blocks with Faulty inst
       auto MBBb = MBB.getFirstNonPHI();
+
+      // Avoids attempting to dereference a sentintel which fails an assert
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arsenm wrote:

Don't need this comment 

https://github.com/llvm/llvm-project/pull/107031