v_writelane_b32 GPU Native ISA AMD Vector

Vector Arithmetic

v_writelane_b32

Write the scalar value in the first input into the specified lane of a vector register where the lane select is in the second input.

Encoding

Verified bit-level encoding data is not yet available for this instruction. The instruction-format classification below (VOP2) is well-documented and stable; exact per-target opcode/field bit positions have not yet been imported from a verified source.
Format VOP2

Operands

  • 1: VGPR
    Vector general-purpose register, one value per lane. Written v5 in the assembler example.
  • 2: SGPR
    Scalar general-purpose register, uniform across the wavefront. Written s1 in the assembler example.
  • 3: SGPR
    Scalar general-purpose register, uniform across the wavefront. Written s2 in the assembler example.

Register classes read from the LLVM assembler example on this page. No source this site uses names these operands, so no names are given.

GFX Target Compatibility

TargetSupport
gfx1100✅ Supported

Related

More in Vector Arithmetic

Reference

AMDGPU / GFX ISA

Example

v_writelane_b32 v5, s1, s2

A real instruction accepted by the LLVM assembler, taken verbatim from LLVM's own AMDGPU MC test suite. Not from an AMD document, and not authored here.

Sources