[llvm-dev] adding 2 new functions to the AliasAnalysis interface
Friedman, Eli via llvm-dev
llvm-dev at lists.llvm.org
Wed Jun 20 12:02:01 PDT 2018
On 6/20/2018 2:31 AM, Atheel Massalha via llvm-dev wrote:
> Im adding 2 new functions to the AliasAnalysis interface:
> 1) ModRefSameBufferCheck:
> this function will receive 2 memoryLocation as parameters, and returns
> true if the parameters are modifying or refering the same buffer or
> same memory block, false otherwise.
I'm not completely sure what "same buffer" means; is it just that given
MemoryLocations with addresses A and B, an offset N exists such that
gep(A,N) is mustalias with B? What happens if alias can't prove whether
the two locations point to the "same buffer"?
Is that actually the property you care about? DependenceAnalysis would
probably be more appropriate if you're trying to analyze cross-iteration
dependencies in loops.
Could you implement this by just calling alias() with the sizes set to
> 2) getAddressesDistance:
> the function will recieve 2 memoryLocation, if they are mod/ref-ing
> the same buffer/memory block, the function will return the distance
> between those locations at the memory. None otherwise
If I'm following correctly, given two values A and B, if a small
constant offset N is known such that A+N==B, N is returned; if the
distance is unknown or not a constant, None is returned. Not sure why
the API takes memoryLocations, instead of just two Value*. Not sure
this really belongs in AliasAnalysis.
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Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
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