llvm dev - Apr 2017 - MIR instruction size

Hello,
Is there any common way to determine a size of MIR instruction? I've tried
both: MachineInstr::getDesc().getSize() and
TargetInstrInfo::getInstSizeInBytes(I),
and unfortunately, both interfaces can't determine instruction sizes for
x86_64, though they could do it for arm architecture.
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No,
X86 instructions are variable size. Depending on which registers are allocated
or what sized immediate an instruction variant takes you may need additional
rex/rex.w prefixes immediate bytes etc.
There is no API today that would answer that question, and even if there were it
would be a dangerous API as later passes could change the size just by swapping
some registers.

- Matthias
> On Apr 20, 2017, at 11:28 AM, Ilya Skapenko via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hello,
> Is there any common way to determine a size of MIR instruction? I've
tried both: MachineInstr::getDesc().getSize() and
TargetInstrInfo::getInstSizeInBytes(I), and unfortunately, both interfaces
can't determine instruction sizes for x86_64, though they could do it for
arm architecture.
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