[PATCH] D122582: StackMap: Fix assertion on undef operands for anyregc

[Denis Antrushin via Phabricator via llvm-commits]

dantrushin added a comment.



In D122582#3414852 <https://reviews.llvm.org/D122582#3414852>, @arsenm wrote:

> In D122582#3414700 <https://reviews.llvm.org/D122582#3414700>, @dantrushin wrote:
>
>> 0xFEFEFEFE is a special sentinel value which means dead pointer. Now you just passing garbage to GC. (Theoretically this might be OK, practically I don't think so)
>
> It seems to me like you are blessing undef registers with special semantics, which is not what undef is for. If the value was undefined, it's undefined. The undef marker just informs the register liveness tracking of this. It doesn't make sense to have a lowering pass try to fix up the undefined value to something to avoid a crash. Transforming this is basically creating a mini-sanitizer/hardening.

OK, what about non-callee saved register appearing in stackmap, which is not supported?


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