[PATCH] D125485: [ArgPromotion] Unify byval promotion with non-byval

[Pavel Samolysov via Phabricator via llvm-commits]

psamolysov added a comment.

Unfortunately, `PromoteMemToReg` optimizes almost nothing. If there is a `GEP` from an `alloca`, and this `GEP` is used by `store`, for example, the `isAllocaPromotable` function returns `false` because the `if (!onlyUsedByLifetimeMarkersOrDroppableInsts(GEPI))` (which allows intrinsics as `GEP` users only) check fails. I always use `store` instructions to write the new argument values into the `alloca`, so this check will always fail for structures and will pass for primitives only. I've tried to run the `mem2reg` pass using the `opt` utility and get the same result, my IR after the `ArgumentPromotion` pass looks as not optimized. The SROA pass works fine, but I'm not sure is this a good idea to run SROA directly from another pass (the `PromoteMemToReg` function creates an instance of the `PromoteMem2Reg` class and calls its `run` member function but this class is not a pass).


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