[LLVMdev] Lowering Call Return

Khaled Mohammed khaled.mohammed at gmail.com
Wed Sep 5 15:02:58 PDT 2012

How about vector parameters?

define internal fastcc <4 x float> @add(<4 x float> %a.val, <4 x float>
%b.val) nounwind {
  %tmp4 = fadd <4 x float> %a.val, %b.val
  ret <4 x float> %tmp4

a and b are flattened by SelectionDAGISel::LowerArguments(const BasicBlock
*LLVMBB) before letting the target handle it.

  SDValue NewRoot = TLI.LowerFormalArguments(DAG.getRoot(),
                                             F.isVarArg(), Ins,
                                             dl, DAG, InVals);

The "Ins" have all the parameters flattened to primitive types. I would
like the vector parameters to be lowered using vector registers.

On Tue, Sep 4, 2012 at 11:35 AM, Krzysztof Parzyszek <
kparzysz at codeaurora.org> wrote:

> On 9/4/2012 11:16 AM, Khaled Mohammed wrote:
>> Is there an option to do sret demotion via a register? if yes, do we
>> have a Target to see an example implementation?
> Hi Khaled,
> Check out X86TargetLowering::**LowerReturn, and the call to
> getSRetReturnReg.
> The SRetReturnReg looks like a hack (each target that uses it, declares
> this variable individually), but that seems to be the current way of
> handling it.
> -K
> --
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