[DebugInfo][SimpleLoopUnswitch] Missing debug location updates (Part 1)

[Apochens]

SimpleLoopUnswitch-L1248

->    auto *MergePN =
          PHINode::Create(I.getType(), /*NumReservedValues*/ 2, ".us-phi");
      MergePN->insertBefore(MergeBB->getFirstInsertionPt());
      I.replaceAllUsesWith(MergePN);
      MergePN->addIncoming(&I, ExitBB);
      MergePN->addIncoming(&ClonedI, ClonedExitBB);

SimpleLoopUnswitch-L1310

    ClonedTerminator->eraseFromParent();
->  BranchInst::Create(ClonedSuccBB, ClonedParentBB);

SimpleLoopUnswitch-L2339

This instruction TI is moved out of the loop (i.e., the hoisted conditional instruction in LoopUnswitch) without dropping its debug location.

    TI.moveBefore(*SplitBB, SplitBB->end());

SimpleLoopUnswitch-L2352

      Value *Cond = skipTrivialSelect(BI->getCondition());
      if (InsertFreeze)
->      Cond = new FreezeInst(Cond, Cond->getName() + ".fr", BI->getIterator());
      BI->setCondition(Cond);

SimpleLoopUnswitch-L2440

    // After MSSAU update, remove the cloned terminator instruction NewTI.
    ParentBB->getTerminator()->eraseFromParent();

    // Create a new unconditional branch to the continuing block (as opposed to
    // the one cloned).
->  BranchInst::Create(RetainedSuccBB, ParentBB);

SimpleLoopUnswitch-L2709

->  PHINode *Phi =
        PHINode::Create(SI->getType(), 2, "unswitched.select", SI->getIterator());
    Phi->addIncoming(SI->getTrueValue(), ThenBB);
    Phi->addIncoming(SI->getFalseValue(), HeadBB);
    SI->replaceAllUsesWith(Phi);
    SI->eraseFromParent();

godbolt: https://godbolt.org/z/dGGs89eKT (Note that the hoisted br instruction with !dbg !8 in %entry is corresponding to L2339 and other instructions without !dbg are corresponding to other Lxxx)

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: Shan Huang (Apochens)

[**SimpleLoopUnswitch-L1248**](https://github.com/llvm/llvm-project/blob/298e292a76289d93f7c1a80c26e354830c6080e4/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp#L1248C1-L1253C52)

->    auto *MergePN =
          PHINode::Create(I.getType(), /*NumReservedValues*/ 2, ".us-phi");
      MergePN->insertBefore(MergeBB->getFirstInsertionPt());
      I.replaceAllUsesWith(MergePN);
      MergePN->addIncoming(&I, ExitBB);
      MergePN->addIncoming(&ClonedI, ClonedExitBB);

SimpleLoopUnswitch-L1310

    ClonedTerminator->eraseFromParent();
->  BranchInst::Create(ClonedSuccBB, ClonedParentBB);

SimpleLoopUnswitch-L2339

This instruction TI is moved out of the loop (i.e., the hoisted conditional instruction in LoopUnswitch) without dropping its debug location.

    TI.moveBefore(*SplitBB, SplitBB->end());

SimpleLoopUnswitch-L2352

      Value *Cond = skipTrivialSelect(BI->getCondition());
      if (InsertFreeze)
->      Cond = new FreezeInst(Cond, Cond->getName() + ".fr", BI->getIterator());
      BI->setCondition(Cond);

SimpleLoopUnswitch-L2440

    // After MSSAU update, remove the cloned terminator instruction NewTI.
    ParentBB->getTerminator()->eraseFromParent();

    // Create a new unconditional branch to the continuing block (as opposed to
    // the one cloned).
->  BranchInst::Create(RetainedSuccBB, ParentBB);

SimpleLoopUnswitch-L2709

->  PHINode *Phi =
        PHINode::Create(SI->getType(), 2, "unswitched.select", SI->getIterator());
    Phi->addIncoming(SI->getTrueValue(), ThenBB);
    Phi->addIncoming(SI->getFalseValue(), HeadBB);
    SI->replaceAllUsesWith(Phi);
    SI->eraseFromParent();

godbolt: https://godbolt.org/z/dGGs89eKT (Note that the hoisted br instruction with !dbg !8 in %entry is corresponding to L2339 and other instructions without !dbg are corresponding to other Lxxx)