Return a reciprocal estimate for the input operand, or an empty value if unsupported.
Declared in <llvm/CodeGen/TargetLowering.h>
virtual
SDValue
getRecipEstimate(
SDValue Operand,
SelectionDAG& DAG,
int Enabled,
int& RefinementSteps) const;Return a reciprocal estimate value for the input operand.
Enabled is a ReciprocalEstimate enum with value either 'Unspecified' or 'Enabled' as set by a potential default override attribute. If RefinementSteps is 'Unspecified', the number of Newton-Raphson refinement iterations required to generate a sufficient (though not necessarily IEEE-754 compliant) estimate is returned in that parameter. A target may choose to implement its own refinement within this function. If that's true, then return '0' as the number of RefinementSteps to avoid any further refinement of the estimate. An empty SDValue return means no estimate sequence can be created.
A reciprocal estimate for the input operand, or an empty value if unsupported.
| Name | Description |
|---|---|
| Operand | Input operand to the estimate. |
| DAG | SelectionDAG providing context. |
| Enabled | Whether reciprocal estimates are enabled. |
| RefinementSteps | NR refinement step count. |