[LLVMdev] Some bugs in x86 disasm (llvm-mc)

[Jun Koi]

On Thu, Nov 28, 2013 at 1:03 AM, Kay Tiong Khoo <kkhoo at perfwizard.com>wrote:

> Hi Jun,
>
> I'm not sure how to fix this yet, but this looks incorrectly defined in
> lib/Target/X86/X86InstrInfo.td:
>
> def MOV32o32a : Ii32 <0xA1, RawFrm, (outs), (ins offset32:$src),
>                       "mov{l}\t{$src, %eax|eax, $src}", [], IIC_MOV_MEM>,
>                      Requires<[In32BitMode]>;
>
> This instruction can be REX-prefixed for a 64-bit move, and that also
> doesn't appear to be defined anywhere.
>
> I would file a bugzilla in the x86 component and cc Craig Topper, the x86
> disasm/codegen expert.
>
>
>
> On Wed, Nov 27, 2013 at 8:56 AM, Jun Koi <junkoi2004 at gmail.com> wrote:
>
>> Hi,
>>
>> With objdump, i have this (Intel syntax)
>>
>>          64 a1 00 00 00 00        mov    eax,fs:0x0
>>
>>
>> However, if I pass above string to llvm-mc, I would have:
>>
>> $ echo "0x64 0xa1 0x00 0x00 0x00 0x00"|./Release+Asserts/bin/llvm-mc
>> -disassemble -arch=x86 --output-asm-variant=1
>>     .text
>>     mov    eax, dword ptr [0]
>>
>>
>> You can see a big difference. This is on the latest code. Any idea how to
>> fix this bug?
>>
>>
Any plan to fix this bug?

Thanks.
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