xvf64gernn
VSX Vector 64-bit Floating-Point GER (rank-1 update) Negative multiply, Negative accumulate XX3-form
Performs a VSX Vector 64-bit Floating-Point GER (rank-1 update) with negative multiply and negative accumulate, updating an accumulator register.
Details
The xvf64gernn instruction computes a rank-1 General External Product (GER) update using 64-bit floating-point values from two VSX vector registers. The products of corresponding elements are negated, and the result is subtracted from (negatively accumulated into) the target accumulator register. This instruction is part of the MMA (Matrix-Multiply Assist) facility introduced in PowerISA v3.1.
Programming Note
When Rc=1 (dot form), CR0 is updated with the signed comparison of the result against zero (LT, GT, EQ) and the current SO bit from XER.