[PATCH] D77849: [calcspillweights] mark LiveIntervals from INLINEASM_BR defs as not spillable

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> If a block has its address taken, whether it's used in a callbr or some other instruction, is it ever safe to remove the block if the blockaddress instruction referencing it still exists?

The way that indirectbr works is that blockaddress passes out an opaque value, and that address is supposed to be passed to the corresponding indirectbr.  It doesn't really matter where the blockaddress is computed; what matters is that there's an indirectbr that branches to the block mentioned in the blockaddress constant.

We don't promise that a blockaddress is usable for any other purpose.  If there is no indirectbr to pass the blockaddress to, there isn't anything constraining the opaque value, so it can be transformed to an arbitrary integer.


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  https://reviews.llvm.org/D77849/new/

https://reviews.llvm.org/D77849