Does it copy the whole vector?
No. It reads only element 0 of vs2 and writes floating-point scalar rd.
VFMV.F.S
RISC-V VFMV.F.S Instruction Details
Instruction ManualR-typeCopy element 0 (float) of vs2 to scalar f register rd.
Instruction Syntax
vfmv.f.s rd, vs2
Operand Breakdown
Destination rd: register receiving the operation result.
Source rs1: register holding the first operand.
Source rs2: register holding the second operand.
VZvfhVector OperationsRegister Move
Related Search Terms
Instruction Behavior
VFMV.F.S copies element 0 of vector source vs2 to floating-point scalar register rd. It is a scalar move, not element-wise FP arithmetic and not FMA.
Quick Understanding & Search Notes
VFMV.F.S moves vector element 0 to a floating-point scalar register.
Do not treat it as element-wise vector arithmetic controlled by the normal execution mask.
Common Usage Scenarios
Reduction Result
Understand this scenario with real code like «vsetvli t0, a0, e32, m1, ta, ma vfmv.f.s ft0, v1 # ft0 = v1[0]».
Scalar-Vector Interface
Understand this scenario with real code like «vsetvli t0, a0, e32, m1, ta, ma vfmv.f.s ft0, v1 # ft0 = v1[0]».
Pre-Use Checklist
Syntax Check
- Confirm the current instruction format is R-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
Only element 0 is copied, not the whole vector.
The destination is a floating-point scalar register; the integer version is VMV.X.S.