[PATCH] D134557: [BranchRelaxation] Fall through only if block has no unconditional branches

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: llvm/lib/CodeGen/BranchRelaxation.cpp:508-510
+    } else if (FailToAnalyze && (!PrevBB->back().isBarrier() ||
+                                 TII->isPredicated(PrevBB->back()))) {
+      InsertUncondBranch(PrevBB, DestBB);
----------------
efriedma wrote:
> gandhi21299 wrote:
> > arsenm wrote:
> > > Is this case covered in the test?
> > I tried out various branching opcodes out there on AMDGPU, none of them satisfied the condition.
> I'd prefer to just check `else if (FailToAnalyze && PrevBB->isSuccessor(DestBB))`, rather than try to figure out the specific properties of the terminator of PrevBB.
I'm not a fan of putting untested code in to satisfy theoretical conditions. If there's a case we don't know how to handle, I would just put a report_fatal_error in for when a target that does needs this runs into it


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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D134557/new/

https://reviews.llvm.org/D134557