Is VSLIDE1DOWN.VX a memory move?
No. It moves data among vector-register elements and does not access memory.
VSLIDE1DOWN.VX
RISC-V VSLIDE1DOWN.VX Instruction Details
Instruction ManualR-typeSlide vector elements toward lower indexes and insert a scalar.
Instruction Syntax
vslide1down.vx vd, vs2, rs1, vm
Operand Breakdown
Destination rd: register receiving the operation result.
Source rs1: register holding the first operand.
Source rs2: register holding the second operand.
VVector PermutationSlide
Related Search Terms
Instruction Behavior
VSLIDE1DOWN.VX moves vs2 elements by offset 1 toward lower indexes into vd. The boundary element is filled from scalar x[rs1].
Quick Understanding & Search Notes
VSLIDE1DOWN.VX moves element positions within a vector register, useful for windows, shift-register patterns, and boundary insertion.
VSLIDE1DOWN writes vs2[i+1] to vd[i] and inserts the scalar into vd[vl-1].
The instruction may be masked; mask element i controls whether destination element i is written.
If vstart>=vl or vl=0, no destination update is performed.
Common Usage Scenarios
Data Shift
Understand this scenario with real code like «vslide1down.vx v8, v12, x5, v0.t».
Convolution
Understand this scenario with real code like «vslide1down.vx v8, v12, x5, v0.t».
Shift Register
Understand this scenario with real code like «vslide1down.vx v8, v12, x5, v0.t».
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
If vstart>=vl or vl=0, the destination is not updated.
The scalar x[rs1] is inserted at vd[vl-1], not vd[0].
When XLEN and SEW differ, the inserted scalar is sign-extended or low-bit truncated by the official rule.