[llvm-dev] Mapping InlineAsm parameters to ConstraintInfoVector elements

[Alexander Potapenko via llvm-dev]

Hi all,

I'm trying to figure out which parameters of a given InlineAsm instruction
are its inputs, and which are the outputs (rationale: make sure MSan
doesn't check the output parameters of an asm() statement).

As far as I understand, this information is only available through the
ConstraintInfoVector for the InlineAsm. However there's no exact match
between the constraints and the InlineAsm params. In addition to clobber
constraints, which should be safe to ignore, there can be multiple
occurrences  of a single parameter having different constraints. Also, for
InlineAsm instructions returning non-void values there's one additional
constraint, but it's unclear whether it always goes first.

My current implementation is quite ad-hoc, so I'm wondering if there's any
code that already does what I'm trying to achieve.

Thanks in advance,
Alexander

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Alexander Potapenko
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