llvm dev - Aug 2013 - [LLVMdev] LLVM Disassembler question

Hi,

By way of example, I have the following instruction:
44 8b 80 c8 03 00 00                            movl    968(%rax), %r8d

1) How is this represented in MCInst?
2) Is there information in MCInst that would tell me which bytes of the
instruction are responsible for the 968?

The reason I am asking is that I want to work with the bytes
disassembled/decoded to an instruction at MCInst level. I then wish to
apply customized relocation records at the MCInst level.
My customized relocation records will consist of an byte offset followed by
an expression of what to replace the following X number of bytes with. Much
like a normal relocation record.
I need a way to map relocation byte offsets to the correct operand in
MCInst.
The main difference is generally relocation records are applied before
disassembly, and I wish to do it after disassembly.

Kind Regards

James
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The MCInst in this case would contain a value from the instruction enum and
6 operands. One being the dest and another 5 to represent the maximal
address components used by X86 (base, index, scale, displacement, and
segment). The only code that knows how to map those operands is in
lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp. It does this by looking
up TSFlag bits using the enum value and applying rules based on different
bits in the TSFlags.


On Mon, Aug 26, 2013 at 9:18 AM, James Courtier-Dutton <
james.dutton at gmail.com> wrote:
> Hi,
>
> By way of example, I have the following instruction:
> 44 8b 80 c8 03 00 00                            movl    968(%rax), %r8d
>
> 1) How is this represented in MCInst?
> 2) Is there information in MCInst that would tell me which bytes of the
> instruction are responsible for the 968?
>
> The reason I am asking is that I want to work with the bytes
> disassembled/decoded to an instruction at MCInst level. I then wish to
> apply customized relocation records at the MCInst level.
> My customized relocation records will consist of an byte offset followed
> by an expression of what to replace the following X number of bytes with.
> Much like a normal relocation record.
> I need a way to map relocation byte offsets to the correct operand in
> MCInst.
> The main difference is generally relocation records are applied before
> disassembly, and I wish to do it after disassembly.
>
> Kind Regards
>
> James
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>

-- 
~Craig
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