llvm-project

a7763646 - [ScalarizeMaskedMemIntrin] Preserve metadata during scalarization (#218753)

[ScalarizeMaskedMemIntrin] Preserve metadata during scalarization (#218753) I based `copyMetadataForScalarizedLoad` on the `copyMetadataForLoad` helper in Local.cpp. These both preserve: - `!tbaa` - `!fpmath` - `!invariant.load` - `!alias.scope` - `!noalias` - `!nontemporal` - `!mem.cache_hint` - `!llvm.mem.parallel_loop_access` - `!llvm.access.group` - `!noalias.addrspace` - `!range` - range metadata applies elementwise, so the range guarantee works for each scalarized load/store. `copyMetadataForLoad` additionally preserves: - `!nonnull`, `!align`, `!dereferenceable`, `!dereferenceable_or_null`, `!noundef`, `!nofpclass`, and `!invariant.group`, which are not valid on intrinsics - `!prof`, which I don't think we can propagate. `copyMetadataForLoad` is documented to only be used when we change a load instruction's type. This profiling doesn't look valid to propagate for more complex transformations. - `!tbaa.struct`, which I don't think we can propagate because this is specifying an offset into a struct we access and our transformations are too complex. - `!dbg`, which I don't think we need to propagate because we call `Builder.SetCurrentDebugLocation(CI->getDebugLoc());` `copyMetadataForScalarizedLoad` additionally preserves: - `!annotation`, I don't know why `copyMetadataForLoad` doesn't preserve this. I think this is meant to be preserved through transformations, maybe a bug. - `!nosanitize` - `!mmra` `copyMemCacheHint` was necessary because for the histogram add intrinsic unfortunately the pointer we store to is operand 0, when it should really be operand 1 for consistency. We only preserve `!DIAssignID` when we do a 1-1 transformation. I think otherwise you'd need to do some smarter splitting of `dbg_assign` records like SROA does in `migrateDebugInfo`, but I'm not so familiar with debug so I don't want to implement this. Disclaimer: I'm not familiar with all of these metadatas so I might've gotten something wrong. Assisted by AI.