[PATCH] D69954: [OpenMP][Opt] Delete read-only parallel regions

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert marked an inline comment as done.
jdoerfert added inline comments.


================
Comment at: llvm/lib/Transforms/IPO/OpenMPOpt.cpp:127
+        return false;
+
+      LLVM_DEBUG(dbgs() << Tag << "Delete read-only parallel region in "
----------------
JonChesterfield wrote:
> I'm not totally confident that onlyReadsMemory is sufficient here (concerned about I/O, functions that do not return).
> 
> LICM hoists based on this so it's safe for I/O. Likewise malloc/free are fine.
> 
> Please could you point me to the reason this is safe for functions that don't return?
> Please could you point me to the reason this is safe for functions that don't return?

It is not. I'll add the proper checks, we have the attribute (`willreturn`) so it is not a problem to look for it.

I/O is not read only. Malloc/free are neither. 


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https://reviews.llvm.org/D69954