[flang-commits] [compiler-rt] [flang] [openmp] [clang-tools-extra] [mlir] [clang] [lldb] [llvm] [lld] [libunwind] [BranchFolding] Fix missing predecessors of landing-pad (PR #77608)

[Phoebe Wang via flang-commits]

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@@ -1624,6 +1632,15 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
             } else {
               DidChange = true;
               PMBB->ReplaceUsesOfBlockWith(MBB, CurTBB);
+              // Add rest successors of MBB to successors of CurTBB. Those
+              // successors are not directly reachable via MBB, so it should be
+              // landing-pad.
+              for (auto SI = MBB->succ_begin(), SE = MBB->succ_end(); SI != SE;
+                   ++SI)
+                if (*SI != CurTBB && !CurTBB->isSuccessor(*SI)) {
+                  assert((*SI)->isEHPad() && "Bad CFG");
+                  CurTBB->copySuccessor(MBB, SI);
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phoebewang wrote:

I see we assert for `(*SI)->isEHPad()`, but `bb.6` is not a EHPad. Did I misunderstand something here?
BTW, can we use `SI->isEHPad()` directly?

https://github.com/llvm/llvm-project/pull/77608