[llvm-dev] XMMs unused

Craig Topper via llvm-dev llvm-dev at lists.llvm.org
Wed Oct 24 22:14:35 PDT 2018


Can you provide an example?

~Craig


On Wed, Oct 24, 2018 at 9:52 PM Dangeti Tharun kumar via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi,
>
> I see that, in Greedy register allocation not all the XMM registers are
> used(even there is a need) if there is a function call crossing the live
> range.
> There are spills which can be avoided just by using them.
>
> The reason I see is the CCC declares XMMs are not callee saved. This means
> they are caller saved, correct me if I am wrong.
> Is the greedy RA intentionally not using XMMs in order to avoid saving and
> restoring regs at call site?
>
>
> --
> Regards,
> DTharun
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