[llvm] r293537 - GlobalISel: permit unused vregs without a register-class after ISel.

Quentin Colombet via llvm-commits llvm-commits at lists.llvm.org
Mon Jan 30 11:48:52 PST 2017

> On Jan 30, 2017, at 11:43 AM, Tim Northover <tnorthover at apple.com> wrote:
> On 30 Jan 2017, at 11:32, Quentin Colombet <qcolombet at apple.com> wrote:
>> I would have expected InstructionSelect to get rid of the unused vregs.
> Why?
> It seems like a pretty arbitrary place to do that. The sensible choices seem to be "leave them be, they're harmless" or "every time a transformation might leave a register unused”.

My problem is not with unused register, it is with unused register without register class.
After ISel everything should have a register class otherwise that means that the instruction hasn’t been selected.

> Cheers.
> Tim.

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