[llvm-dev] RFC: Resolving TBAA issues

[Daniel Berlin via llvm-dev]

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> Finally, the merging of TBAA is definitely going to be more conservative
> than the merging of field offset info: If we merge a load of an int and a
> float, we will, IIRC, go to the nearest common ancestor in TBAA.   The
> field offset info may actually still be identical between the two, but we
> will lose it by creating/or going to the common ancestor.
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Imagine
int - offset 4
float - offset 4
int - offset 12

merge(first int field, float) ==
mergeintfloat -no offset info

You can no longer disambiguate this against second int field, even though
it can't possibly overlap, not for type reasons, but for offset reasons.


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