[llvm] [MachineOutliner] Properly handle Debug MachineInstrs (PR #219326)

[David Tellenbach via llvm-commits]

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@@ -1290,11 +1294,22 @@ void MachineOutliner::populateMapper(InstructionMapper &Mapper, Module &M) {
       LLVM_DEBUG(dbgs() << "  MAPPING MBB: '" << MBB.getName() << "'\n");
       // If there isn't anything in MBB, then there's no point in outlining from
       // it.
-      // If there are fewer than 2 instructions in the MBB, then it can't ever
-      // contain something worth outlining.
+      // If there are fewer than 2 non-debug instructions in the MBB, then it
+      // can't ever contain something worth outlining. Count raw instructions,
+      // including bundle interiors, to preserve MBB.size() behavior. Pseudo
+      // probes also retain their historical treatment as ordinary
+      // instructions.
       // FIXME: This should be based off of the maximum size in B of an outlined
       // call versus the size in B of the MBB.
-      if (MBB.size() < MinMBBSize) {
+      unsigned NumNonDebugInstrs = 0;
+      for (const MachineInstr &MI : MBB.instrs()) {
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dtellenbach wrote:

You can just use `instructionsWithoutDebug(MBB.instr_begin(), MBB.instr_end(), /* SkipPseudoprobe */ false)`.

https://github.com/llvm/llvm-project/pull/219326