Roman Lebedev a5b56313dd [llvm-exegesis] AliasingConfigurations: pay attention to forbidden registers ...

When trying to measure latency of certain opcodes, e.g.
`./bin/llvm-exegesis --opcode-name=BT32ri8 --mode=latency --repetition-mode=loop  --benchmarks-file=- --max-configs-per-opcode=65536`,
we'd pick such an aliasing instruction, and such an aliasing registers,
that would alias with forbidden registers.

And in particular with loop counter in `loop` repetition mode,
which made the measurements never finish.
This does not address all such cases, only the most obvious one.

The added test case fails without the patch.

Fixes https://github.com/llvm/llvm-project/issues/59441

2022-12-21 02:01:14 +03:00

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