xxsetaccz

VSX Set Accumulator to Zero

xxsetaccz AT

Clears a 512-bit Accumulator register (composed of 4 VSRs) to zero.

Encoding

Binary Layout

31

0:5

/

6:10

/

11:15

AT

16:20

185

21:30

/

31

 

Format X-form

Opcode 0x7C030162

Extension MMA

Operands

• AT
  Accumulator (0-7)

Example

xxsetaccz acc0

Registers Altered

MSR

Related

More in MMA

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

Clears the 512-bit accumulator register AT (which consists of four 128-bit VSRs) to all zeros. This instruction is part of the MMA (Matrix Multiply Assist) extension and provides a fast way to initialize an accumulator before a sequence of matrix operations. No condition registers or status fields are affected.

Operation

ACC[AT] ← 0x0000...0000 (512 bits of zeros)

Programming Note

This instruction zeroes out all elements of the specified VSX accumulator. Ensure that VSX is enabled in the MSR register before using this instruction; otherwise, a VSX_Unavailable exception will be raised. This operation is useful for initializing accumulators or resetting them between operations.