On Apr 23, 2007, at 12:31 PM, Chris Lattner wrote:
> On Mon, 23 Apr 2007, Christopher Lamb wrote:
>> How can one let the back end know how to insert and extract
>> elements of
>> a vector through sub-register copies? I'm at a loss how to do
this...
>
> You probably want to custom lower the insertelement/extractelement
> operations for the cases you support. Take a look at
> X86TargetLowering::LowerEXTRACT_VECTOR_ELT for some examples of how
> to do
> this.
The issue I'm having is that there is no extract/insert instruction
in the ISA, it's simply based on using subregister operands in
subsequent/preliminary instructions. At the pointer of custom
lowering register allocation has not yet been done, so I don't have a
way to communicate the dependency.
--
Christopher Lamb
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