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

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

If I'm understanding correctly, the issue is that the INLINEASM_BR is producing a virtual register, we try to spill that register, and the spill is inserted in the same block as the INLINEASM_BR?

I can see two possible approaches here, at a high level:

1. Forbid directly spilling registers produced by an INLINEASM_BR; instead, force a live interval split, and then we can spill the split interval.
2. Allow spilling registers produced by an INLINEASM_BR, but teach the spill insertion code to insert the spill into the fallthrough succecssor, as opposed to the INLINEASM_BR block itself.

This patch is sort of along the lines of (1), but I'm not sure this is enough to make the interval split reliably (in which case, the allocator could potentially run out of registers).  I haven't spent enough time with the spill weight code to say for sure.


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https://reviews.llvm.org/D77849