RFR: 8255553: [PPC64] Introduce and use setbc and setnbc P10 instructions [v6]

[Martin Doerr]

On Thu, 5 Nov 2020 14:04:27 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Wow, thanks for catching it. But, let me make my naive question: why is it necessary?
>
> E.g. instruct testI_reg_imm sets cr0 as result and branchConFar uses it. The kill cr0 effect disallows scheduling your nodes between them.

Btw. advantage of the expand rules is that the single instructions in a basic block can get scheduled in an interleaved fashion to hide instruction latencies. But this has become less relevant with modern out-of-order CPUs. We had done that for Power 6, but we're no longer optimizing for it.

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PR: https://git.openjdk.java.net/jdk/pull/907