[PATCH] D156345: RegisterCoalescer: Add implicit-def of super register when coalescing SUBREG_TO_REG

[Quentin Colombet via Phabricator via llvm-commits]

qcolombet added a comment.

> The same problem likely exists everywhere trying to do anything with SUBREG_TO_REG. I don't understand how this managed to be broken for so long.

Wow, looking at the lowering of SUBREG_TO_REG, I agree with this assessment!
SUBREG_TO_REG is supposed to be an assert point and yet to we produce code that may break this assertion.

Like you said in a different PR, we likely want to use a tied-operand here. (Though we may have some infrastructure gap here to fix.)

Looking at the patch now.


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  https://reviews.llvm.org/D156345/new/

https://reviews.llvm.org/D156345