[PATCH] D63885: [LOOPINFO] Introduce the loop guard API.

[Michael Kruse via Phabricator via llvm-commits]

Meinersbur added inline comments.


================
Comment at: llvm/lib/Analysis/LoopInfo.cpp:415
+
+      if (!isGuaranteedToTransferExecutionToSuccessor(Succ))
+        return true;
----------------
Whitney wrote:
> Meinersbur wrote:
> > If you want to disallow throwing instructions, how did  you conclude that `isGuaranteedToTransferExecutionToSuccessor` is what you want and not `->mayThrow`?
> > 
> > There might be dynamically endless loops as well that isGuaranteedToTransferExecutionToSuccessor does not check (that is, only if the endless loop was inside a call).
> I chose `isGuaranteedToTransferExecutionToSuccessor` instead of `->mayThrow` is because it consider more cases, for example it checks if memory operation trap. `isGuaranteedToTransferExecutionToSuccessor` is a superset of `->mayThrow`. 
> 
> What is dynamically endless loops? 
> What is dynamically endless loops?
```
header:
  %cmp = icmp ule i32 0, %a ; anything that always returns true but LLVM cannot figure out
  br i1 %cmp, label %header, label %exit

exit:
```


Repository:
  rL LLVM

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  https://reviews.llvm.org/D63885/new/

https://reviews.llvm.org/D63885