Is VFMV.S.F a broadcast?
No. It writes only vd[0]; the broadcast form is VFMV.V.F.
VFMV.S.F
RISC-V VFMV.S.F Instruction Details
Instruction ManualR-typeCopy scalar f register rs1 to vd element 0; remaining elements follow tail policy.
Instruction Syntax
vfmv.s.f vd, rs1
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.S.F copies floating-point scalar f[rs1] to element 0 of vd; remaining elements are handled according to tail policy. It is a scalar-to-vector-element move, not FMA.
Quick Understanding & Search Notes
VFMV.S.F places one FP scalar into element 0 of a vector register.
Unlike VFMV.V.F, it does not copy the scalar to all active elements.
Common Usage Scenarios
Reduction Init
Understand this scenario with real code like «vsetvli t0, a0, e32, m1, ta, ma vfmv.s.f v1, ft0 # v1[0] = ft0, other elements follow tail policy».
Scalar to Element 0
Understand this scenario with real code like «vsetvli t0, a0, e32, m1, ta, ma vfmv.s.f v1, ft0 # v1[0] = ft0, other elements follow tail policy».
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 explicitly written; use VFMV.V.F for broadcast.
Other elements follow tail policy; do not rely on unspecified preserved values.