[PATCH] D84737: [AArch64][SVE] Preserve full vector regs over EH edge.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> What MachineInstr would it need to be attached to?

We'd need some instruction that's guaranteed to be at the beginning of the block.  Probably EH_LABEL should fall into that category.  Granted, I guess the register allocators aren't aware of this restriction at the moment.

> The clobber mask is applied when calculating the live intervals which is used as input to the register allocator, so I would think that register allocators themselves don't need to be aware of this as well. I.e. Once this information is reflected in the live ranges, there isn't anything that the register allocator should do to change that.

We have at least one register allocator that doesn't use LiveIntervals.  Fast regalloc doesn't keep any values live across blocks, though


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