[llvm-dev] llvm-objdump cannot recognize mul&mulh RISC-V M Instructions

James Y Knight via llvm-dev llvm-dev at lists.llvm.org
Mon Mar 30 07:14:46 PDT 2020


On Fri, Mar 27, 2020 at 7:07 AM Simon Cook via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi,
>
> Unlike GNU objdump, llvm-objdump doesn't assume that for RISC-V all
> standard extensions are available by default, and so need to be
> provided on the command line. I'm not aware of a flag that you can
> pass a RISC-V ISA string to (from your command it seems --arch doesn't
> do this for you), but you can enable the disassembly of instructions
> using the underlying attributes and the --mattr flag, so in your case
> adding `--mattr=+m` to your llvm-objdump command (I think `--mattr=m`
> should work as well).
>

Seems like it'd make sense to change this? Is there any benefit to not
disassemble the standard extensions unless requested?
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