[llvm-dev] IR question re: constants

Krzysztof Parzyszek via llvm-dev
2015-09-02T18:24:18Z

On 9/2/2015 1:16 PM, via llvm-dev wrote:
> I'm curious.  Is there a specific technical reason that the high-level
> IR doesn't have an instruction to simply set a register to a constant?
> This limitation means we cannot hoist an "expensive" constant out
of a
> loop until we lower the IR to MachineInstrs.  Or more to the point, it
> forces backends to undo any such hoisting done by frontends.
>
> Or am I not understanding something?

The LLVM IR doesn't have registers.  The computations are values and a
constant represents itself.

-Krzysztof

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