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

[Anshil Gandhi via Phabricator via llvm-commits]

gandhi21299 added inline comments.


================
Comment at: llvm/lib/CodeGen/BranchRelaxation.cpp:485
     MachineBasicBlock *PrevBB = &*std::prev(DestBB->getIterator());
-    if (auto *FT = PrevBB->getFallThrough()) {
-      assert(FT == DestBB);
-      TII->insertUnconditionalBranch(*PrevBB, FT, DebugLoc());
-      // Recalculate the block size.
-      BlockInfo[PrevBB->getNumber()].Size = computeBlockSize(*PrevBB);
+    if (PrevBB->terminators().empty()) {
+      if (auto *FT = PrevBB->getFallThrough()) {
----------------
arsenm wrote:
> I'd expect for this to be covered by getFallThrough check for false. Did something weird happen with an unanalyzable branch?
We found a case where fixupUnconditionalBranch() appends a s_branch X to a block with terminators s_cbranch X, s_branch Y.


Repository:
  rG LLVM Github Monorepo

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

https://reviews.llvm.org/D134557