Codegen for the raw/struct buffer access intrinsics would update the
offset in the MMO to reflect the combined offset, if it was known to be
constant. If the combined offset was not known to be constant, or if
there was an index, it would set the offset in the MMO to 0. This is
unsafe because it makes it look like the access does not alias with
another access with a fixed non-zero offset.
Fix these cases by setting the pointer in the MMO to null, to reflect
the fact that we do not have any known IR value pointer + constant
offset for the access.
Differential Revision: https://reviews.llvm.org/D106284
Summary:
The machine instruction scheduler was illegally moving a buffer store
past a buffer load with the same descriptor and offset. Fixed by marking
buffer ops as mayAlias and isAliased. This may be overly conservative,
and we may need to revisit.
Subscribers: arsenm, kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, t-tye, llvm-commits
Differential Revision: https://reviews.llvm.org/D43332
Change-Id: Iff3173d9e0653e830474546276ab9d30318b8ef7
llvm-svn: 325567
Jay Foad