[PATCH] D79956: [InstCombine] Teach PromoteCastOfAllocation to not insert a bitcast into the middle of a group of allocas

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

In D79956#2037134 <https://reviews.llvm.org/D79956#2037134>, @craig.topper wrote:

> FWIW, there's another place in InstCombine that does something like this,  simplifyAllocaArraySize in InstCombineLoadStoreAlloca.cpp  So I thought maybe this was desired behavior.


I saw multiple places over the years. I also heard from people they think there is some kind of guarantee or canonical form that the allocas are in the beginning and grouped. I don't think there is, e.g., I checked the other day and SROA scans the entire entry block.

Personally, I'd say we need to fix the passes to deal with this. But I do not have a strong opinion.


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