[PATCH] D100802: [PassManager] add late LICM to LTO pipeline to undo InstCombine sinking

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D100802#2702510 <https://reviews.llvm.org/D100802#2702510>, @nikic wrote:

> The change you made for the NewPM doesn't just disabled MSSA -- it enables AST instead, which is even worse :)

Oops!

> What you'd actually want for this case is an additional option that disables the memory optimizations in LICM entirely and uses neither MSSA nor AST. That should make this change much cheaper, as MSSA/AST should be the primary costs here.

Ok - let me step back and ask: any ideas about what is an acceptable compile-time cost here?
It seems like we might be better off unifying the behavior between LTO and non-LTO (see table in previous comment) - potentially more compile-time savings?


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https://reviews.llvm.org/D100802