How is VNCLIP.WI different from VNSRL/VNSRA?
VNCLIP rounds according to vxrm and saturates; VNSRL/VNSRA are narrowing right shifts without saturation clipping.
VNCLIP.WI
RISC-V VNCLIP.WI Instruction Details
Instruction ManualI-typesigned 2*SEW-to-SEW narrowing clip with vxrm rounding and saturation.
Instruction Syntax
vnclip.wi vd, vs2, uimm, vm
Operand Breakdown
Destination rd: general-purpose register receiving the result.
Source rs1: register holding the first operand.
Immediate imm: 12-bit signed value, sign-extended before operation with rs1.
VVector Fixed-PointNarrowing/Clip
Instruction Behavior
VNCLIP.WI right-shifts 2*SEW source elements by the selected amount, rounds according to vxrm, narrows to SEW, and saturates to the signed destination range; saturation sets vxsat.
Quick Understanding & Search Notes
VNCLIP.WI is an RVV fixed-point narrowing clip instruction for converting wide intermediate results back to SEW-width signed data.
Source elements are 2*SEW wide and destination elements are SEW wide.
Rounding is controlled by vxrm; this is not an ordinary logical right shift.
Out-of-range results saturate to the destination range and set the vxsat saturation flag.
Common Usage Scenarios
Fixed-Point Conversion
Understand this scenario with real code like «vnclip.wi v8, v12, 3, v0.t».
Precision Reduction
Understand this scenario with real code like «vnclip.wi v8, v12, 3, v0.t».
Pre-Use Checklist
Syntax Check
- Confirm the current instruction format is I-type.
- Confirm the operand order matches the example.
Semantic Check
- Ensure the destination register usage is compatible with the calling convention.
- Confirm this is not the lower-level form of a pseudo-instruction expansion.
Pitfalls / Common Confusions
Rounding by vxrm (rnu/rne/rdn/rod), not frm
Source 2*SEW, dest SEW; EMUL changes
Sets vxsat on saturation