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registers `al`, `cl`, `dl`, and `bl` could have two different
representations - with `rex.w` and without. these two forms of `RegSpec`
would not compare equal, nor has the same, so for code relying on
`RegSpec` to faithfully represent a 1-1 mapping to x86 registers, these
synonyms would introduce bugs in register analysis.
for example, in `yaxpeax-core`, this would result in instructions
writing to `rex.w al` not being visible as definitions for a future
read of `!rex.w al`.
fix this in `x86_64` code, add new test cases about the confusion,
adjust register names to make this situation more clearly a bug, and
introduce two new fuzz targets that would have helped spot this error.
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* the first four 1-byte registers, `al`, `cl`, `dl`, `bl`, can be
constructed in two ways that produce "identical" `RegSpec` that are..
not.
e.g. `RegSpec::al() != Regspec::rb(0)` even though
`RegSpec::al().name() == RegSpec::rb(0).name()`.
this corrects the `rb` constructor at least, but instructions like
`4830c0` and `30c0` still produce incompatible versions of `al`.
* also fix register numbering used explicit qword-sized RegSpec
constructors, r12 and r13 used to produce r8 and r9
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these instructions ignored rex bits even for xmm reigsters, which is
incorrect (so says xed)
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in the process, fixed a decoding bug dealing with a0/a1/a2/a3 movs
(respected rex.b when rex.b should have been ignored)
this seems to maybe improve runtime ever so slightly, but this is really
meant as a cleanup commit more than anything.
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this request/suggestion comes from
[github](https://github.com/iximeow/yaxpeax-x86/issues/29)! thank you!
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the correct bank is applied far after register numbers are read. a
correct annotation would need to know to defer emission until setting
register banks, but also would need to work backwards for the number of
bits between the current byte and modrm. not impossible, but substantial
refactoring.
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this includes a `Makefile` that exercises the various crate configs.
most annoyingly, several doc comments needed to grow
`#[cfg(feature="fmt")]` blocks so docs continue to build with that
feature enabled or disabled.
carved out a way to run exhaustive tests; they should be written as
`#[ignore]`, and then the makefile will run even ignored tests on the
expectation that this will run the exhaustive (but slower) suite.
exhaustive tests are not yet written. they'll probably involve spanning
4 byte sequences from 0 to 2^32-1.
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not only did the instruction have wrong data, but if displayed, the
formatter would panic.
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in the process, fix 64-bit rex-byte limit, 32/16-bit mode mask reg limit
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so multiplying to expand EVEX compressed offsets can overflow, and that
needs to be okay.
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these instructions had memory sizes reported for the operand, if it was
a memory operand, but for versions with non-memory operands the decoded
`Instruction` would imply that non memory access would happen at all.
now, decoded instructions in these cases will report a more useful
memory size.
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while x86 branches of immediates are all relative to PC, other
architectures may have absolute branches to immediate addresses, leaving
this syntax ambiguous and potentially confusing. yaxpeax prefers to
write relative offsets `$+...` as a rule, so uphold that here.
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also remove redundant assignments of operand_count and some OperandSpec,
bulk-assign all registers and operands on entry to `read_instr`. this
all, taken together, shaves off about 7 cycles per decode.
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