xvi4ger8pp

VSX Vector Integer 4-bit GER (Rank-8 Update) Plus/Plus

xvi4ger8pp AT, XA, XB

Unsigned 4-bit integer matrix multiply accumulate.

Details

Performs an unsigned 4-bit integer matrix multiplication with rank-8 accumulation, accumulating the result with plus-signed saturation. This MMA instruction multiplies 4-bit elements from two VSX registers and adds the partial products to an MMA accumulator, treating both input and output as unsigned values. The plus/plus variant saturates on overflow using unsigned saturation semantics.

Pseudocode Operation

AT ← ACC[AT] + (XA × XB)

Programming Note

This instruction is commonly used for matrix multiplication and accumulation operations on VSX registers with saturation handling. Ensure that the input matrices are correctly aligned and masked as per requirements. The instruction operates at a privilege level that allows access to FPSCR and XER, and it may raise exceptions if there are issues with operand alignment or access rights. Performance can be optimized by ensuring that the masks (XMSK and YMSK) are efficiently set to minimize unnecessary computations.

Example

xvi4ger8pp acc0, vs2, vs3

Encoding

Binary Layout
60
0
AT
6
XA
11
XB
16
35
21
 
Format XX3-form
Opcode 0xF0000023
Extension MMA
Registers Altered FPSCR, XER

Operands

  • AT
    Accumulator
  • XA
    Src A
  • XB
    Src B