[llvm-dev] GVN removing loads that are affected by call

[Ryan Taylor via llvm-dev]

So given an intrinsic that has a pointer as in/out and IntrWriteMem
property.

call intrinsic(address a, ....);
loop over address a
  load from address a + offset
call intrinsic (address a, ...);
loop over address a
  load from address a + offset

GVN is removing the second loads, despite the second call overwriting the
memory starting at address a. AA has the intrinsics marked as unknown
instructions but has all of these as mayAlias in a set. I'm not seeing this
issue with -fno-unroll-loops.

Thanks.
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