[LLVMdev] Bind a LLVM variable to a CPU register

[Xin Tong]

On Thu, Jul 19, 2012 at 2:28 PM, John Criswell <criswell at illinois.edu> wrote:
> On 7/19/12 1:23 PM, Jim Grosbach wrote:
>>
>> Not really, no.
>
>
> If you really, really, wanted to do it, you could:
>
> 1) Hack the code generator to not use that register.  It might be as simple
> as modifying the TableGen file to not know that the register exists.
> 2) Use inline asm to put the constant into that register and fetch it from
> that register.
>
> The real question is: what larger goal are you trying to accomplish?
> Holding a constant value in a register might not be the best way to do what
> you're doing.
>
I am using LLVM as the code generator for my system emulator. I need
one register holding the address of the CPUState struct.  most of the
emulation code is generated by LLVM. a small amount of code is not (
typically binary patched) . I must make sure that i know in which
register is the CPUState held when i am patching some code.

Xin

> -- John T.
>
>
>>
>> On Jul 19, 2012, at 11:14 AM, Xin Tong <xerox.time.tech at gmail.com> wrote:
>>
>>> I have a constant parameter in a LLVM function. Is there a way to
>>> reserve a CPU register such that it also holds the value of the
>>> parameter in LLVM x86 codegen ?
>>>
>>> Thanks
>>>
>>> Xin
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