[PATCH] D75098: Add TCOPY, a terminator form of the COPY instr

[Quentin Colombet via Phabricator via llvm-commits]

qcolombet added a comment.

Thanks Bill for the detailed explanations. A couple more questions.

> CodeGen wants registers to be spilled at the end of a block.

That's fast reg alloc only. What is happening with the other allocators?

> The spill slot is recorded and used later on when accessing the value. If we just add a COPY into the default block it won't have the necessary information available to load the correct value.

Why is that? (Why doesn't it have the necessary information to load the correct value.)

I feel that we are trying to work around a bug/limitation in the fast register allocator where physreg are assumed not to cross basic block boundaries. I wonder if it wouldn't be easier to fix fast reg alloc if that is the problem.

Out-of-curiosity, how do we deal with invoke? I would expect we have the exact same problems.


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https://reviews.llvm.org/D75098