aarch64: add instructions

[nkaretnikov]

This change is 

[nkaretnikov]

See #1366 (comment).

[ehennenfent]

Reviewed 16 of 18 files at r1, 1 of 1 files at r2.
Reviewable status: 17 of 18 files reviewed, 1 unresolved discussion (waiting on @nkaretnikov)

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manticore/native/cpu/aarch64.py, line 436 at r2 (raw file):

    def _adds_subs_immediate(cpu, res_op, reg_op, imm_op, mnem):
        assert res_op.type is cs.arm64.ARM64_OP_REG

The asserts here (and in following functions) should probably be removed. I'm open to arguing about it if anyone on the team feels differently, but as a general rule, use of asserts should be limited in production code. Logically, they check conditions that are never supposed to be false, so even the modest performance penalty typically isn't worth it in expressions that are evaluated often. We do make use of asserts elsewhere in Manticore, but (with the exception of expression.py, which we probably need to refactor) they're mostly used during initialization and teardown. Having 2-4 asserts per instruction is going to be have a much more significant impact on aarch64 performance.

For parameter sanity checks like the ones in this file, type hints are usually a better way to go because they're ignored by the default Python interpreter and only incur a performance penalty when the developer wants to enforce them.

[ehennenfent]

Reviewed 1 of 18 files at r1, 3 of 3 files at r3.
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[ehennenfent]

We're going to retract the request to remove the asserts for now. Since this is a big new branch, we'll accept the performance hit of having some extra sanity checks. Once this has been out in the real world for a while, we'll convert them to type hints ourselves.

[nkaretnikov]

Okay, sure. I've caught a few issues this way, but this doesn't seem to justify performance implications. Also, the current style is really verbose, which might be a disadvantage for those reading the code.

Have you considered running with -O in production? This will disable all asserts, so asserts in critical places would need to be converted to exceptions first.

As for the hints, could you show me how to do it if you know offhand? I can't figure this out: one would need to match a constant against the type attribute.

[ehennenfent]

Reviewed 1 of 1 files at r4.
Reviewable status: complete! all files reviewed, all discussions resolved