llvm dev - Aug 2012 - [LLVMdev] x86 REP-prefixed instructions seem to be dropped by instruction decoder?

I think there's a bug somewhere in TableGen for the X86 disassembler
emitter. The following test:

$ echo "0xF3 0xA5" | ./bin/llvm-mc -disassemble
.section        __TEXT,__text,regular,pure_instructions
        movsd

(from llvm trunk)

0xF3 is the REP prefix, so the printed instruction should be 'rep
movsd', however all that is printed is 'movsd'. It seems that there
is
an instruction enum for REP_MOVSD, but it isn't emitted in the
generated .inc file? Is this a bug/oversight, or is there something I
don't understand about the instruction decoding infrastructure and the
MCInst class?

On 13 August 2012 12:02, Andrew Ruef <awruef at umd.edu>
wrote:
> I think there's a bug somewhere in TableGen for the X86 disassembler
> emitter. The following test:
>
> $ echo "0xF3 0xA5" | ./bin/llvm-mc -disassemble
> .section        __TEXT,__text,regular,pure_instructions
>         movsd
>
> (from llvm trunk)
>
> 0xF3 is the REP prefix, so the printed instruction should be 'rep
> movsd', however all that is printed is 'movsd'. It seems that
there is
> an instruction enum for REP_MOVSD, but it isn't emitted in the
> generated .inc file? Is this a bug/oversight, or is there something I
> don't understand about the instruction decoding infrastructure and the
> MCInst class?
It looks like a bug. Would you mind reporting it in llvm.org/bugs? Thanks.

Cheers,
Rafael

It's an already filed bug.

http://llvm.org/bugs/show_bug.cgi?id=7709

On Tue, Aug 14, 2012 at 2:34 PM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:
> On 13 August 2012 12:02, Andrew Ruef <awruef at umd.edu> wrote:
> > I think there's a bug somewhere in TableGen for the X86
disassembler
> > emitter. The following test:
> >
> > $ echo "0xF3 0xA5" | ./bin/llvm-mc -disassemble
> > .section        __TEXT,__text,regular,pure_instructions
> >         movsd
> >
> > (from llvm trunk)
> >
> > 0xF3 is the REP prefix, so the printed instruction should be 'rep
> > movsd', however all that is printed is 'movsd'. It seems
that there is
> > an instruction enum for REP_MOVSD, but it isn't emitted in the
> > generated .inc file? Is this a bug/oversight, or is there something I
> > don't understand about the instruction decoding infrastructure and
the
> > MCInst class?
>
> It looks like a bug. Would you mind reporting it in llvm.org/bugs? Thanks.
>
> Cheers,
> Rafael
> _______________________________________________
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>


-- 
~Craig
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