[LLVMdev] Dynamic number of registers

Sean Silva
Sun, 19 Aug 2012 17:09:53 -0000

> It does, but you can dynamically reserve registers.

So, if I'm understanding this correctly, the approach would then be to
use a large upper bound on the number of registers (the instruction
encoding limits it to 256, so that is safe), and then say "don't use
registers [N,256)" in order to effectively codegen for registers
[0,N)?

Also, could you provide me some pointers to the APIs that allow
dynamically reserving registers?

Thanks,

--Sean Silva

On Sun, Aug 19, 2012 at 9:58 AM, Jakob Stoklund Olesen <stoklund at
2pi.dk> wrote:
>
> On Aug 18, 2012, at 8:51 PM, Sean Silva <silvas at purdue.edu> wrote:
>
>> Hi, I'm pondering using LLVM's backend pipeline to generate
code for a
>> virtual machine (the DTrace DIF emulator) where the number of
>> registers must in general be queried dynamically*. Is this a
>> functionality that LLVM's backend pipeline currently supports? Does
>> LLVM's current backend pipeline assume a statically known register
>> set?
>
> It does, but you can dynamically reserve registers.
>
> /jakob
>