[PATCH] D82550: [SLPVectorizer] handle vectorized lib functions

[Francesco Petrogalli via Phabricator via llvm-commits]

fpetrogalli added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:5208
+          bool SrcMayWrite = BundleMember->Inst->mayWriteToMemory() &&
+                             !isVectorizableLibFunctionCall(BundleMember->Inst);
           unsigned numAliased = 0;
----------------
ABataev wrote:
> fpetrogalli wrote:
> > ABataev wrote:
> > > Still, this is a bad solution. Add proper attributes to the vector variants of the functions, so all memory access interfaces could properly handle such functions.
> > HI @ABataev, if I understood correctly, you are asking to add a new attribute that guaranteed that the function does not have side effects? If that's the case, that is already guaranteed by the `vector-function-abi-variant` attribute.
> Hi. No, what I'm asking is to mark the vectorized function versions with attributes that they don't write to the memory (what this change implies), so all attribute interfaces properly handle such functions as no-write functions.
I just had a chat with @sanwou01 , we agreed that it is better to use the VFABI variant attribute just to describe the mapping, and have other attributes (like `readonly`) attached to the function to guarantee the fact that there is not side effects.

@sanwou01 is coming up with a unit test in which a function is marked with both the `readonly` and `vector-function-abi-variant`. Is there any other attribute he should add to guarantee that the memory accesses are compatible with a concurrent invocation of the function?


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  https://reviews.llvm.org/D82550/new/

https://reviews.llvm.org/D82550