[PATCH] D153197: [AVR] Expand shifts during AVRISelLowering

[Patryk Wychowaniec via Phabricator via cfe-commits]

Patryk27 added inline comments.


================
Comment at: llvm/lib/Target/AVR/AVRISelLowering.cpp:2207
+  MF->push_back(LoopBB);
+  MachineBasicBlock *ExitBB = EntryBB->splitAt(MI, false);
+
----------------
Alright, this is wrong, after all - I've just tested it on a more elaborate code in rustc and `EntryBB->removeSuccessor(ExitBB);` triggers an LLVM panic (presumably because EntryBB == ExitBB).

I kinda don't understand why doing something like this:

```
MachineBasicBlock *ExitBB = EntryBB->splitAt(MI, false);

if (EntryBB == ExitBB) {
  assert(EntryBB->canFallThrough() && "Expected a fallthrough block!");
  ExitBB = EntryBB->getFallThrough();
}
```

... is not sufficient, though 👀


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D153197/new/

https://reviews.llvm.org/D153197