BFMMLA
BFloat16 floating-point matrix multiply-accumulate into 2×2 matrices
If FEAT_EBF16 is not implemented or FPCR.EBF is 0, this instruction:
Performs two unfused sums-of-products within each two pairs of adjacent BFloat16 elements while multiplying the 2×4 matrix of BFloat16 values held in each 128-bit segment of the first source vector by the 4×2 matrix of BFloat16 values in the corresponding segment of the second source vector. The intermediate single-precision products are rounded before they are summed and the intermediate sum is rounded before accumulation into the 2×2 single-precision matrix in the corresponding segment of the destination vector. This is equivalent to accumulating two 2-way unfused dot products per destination element.
Uses the non-IEEE 754 Round-to-Odd rounding mode, which forces bit 0 of an inexact result to 1, and rounds an overflow to an appropriately signed Infinity.
Flushes denormalized inputs and results to zero, as if FPCR.{FZ, FIZ} is {1, 1}.
Disables alternative floating point behaviors, as if FPCR.AH is 0.
If FEAT_EBF16 is implemented and FPCR.EBF is 1, then this instruction:
Performs two fused sums-of-products within each two pairs of adjacent BFloat16 elements while multiplying the 2×4 matrix of BFloat16 values held in each 128-bit segment of the first source vector by the 4×2 matrix of BFloat16 values in the corresponding segment of the second source vector. The intermediate single-precision products are not rounded before they are summed, but the intermediate sum is rounded before accumulation into the 2×2 single-precision matrix in the corresponding segment of the destination vector. This is equivalent to accumulating two 2-way fused dot products per destination element.
Follows all other floating-point behaviors that apply to single-precision arithmetic, as governed by FPCR.RMode, FPCR.FZ, FPCR.AH, and FPCR.FIZ.
Irrespective of FEAT_EBF16 and FPCR.EBF, this instruction:
Does not modify the cumulative FPSR exception bits (IDC, IXC, UFC, OFC, DZC, and IOC).
Disables trapped floating-point exceptions, as if the FPCR trap enable bits (IDE, IXE, UFE, OFE, DZE, and IOE) are all zero.
Generates only the default NaN, as if FPCR.DN is 1.
This instruction is unpredicated and vector length agnostic.
ID_AA64ZFR0_EL1.BF16 indicates whether this instruction is implemented.
This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.
Green
False
True
SM_0_only
0
1
1
0
0
1
0
0
0
1
1
1
1
1
0
0
1
BFMMLA <Zda>.S, <Zn>.H, <Zm>.H
if !IsFeatureImplemented(FEAT_SVE) || !IsFeatureImplemented(FEAT_BF16) then UNDEFINED;
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer da = UInt(Zda);
<Zda>
Is the name of the third source and destination scalable vector register, encoded in the "Zda" field.
<Zn>
Is the name of the first source scalable vector register, encoded in the "Zn" field.
<Zm>
Is the name of the second source scalable vector register, encoded in the "Zm" field.
CheckNonStreamingSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer segments = VL DIV 128;
constant bits(VL) operand1 = Z[n, VL];
constant bits(VL) operand2 = Z[m, VL];
constant bits(VL) operand3 = Z[da, VL];
bits(VL) result;
bits(128) op1, op2;
bits(128) res, addend;
for s = 0 to segments-1
op1 = Elem[operand1, s, 128];
op2 = Elem[operand2, s, 128];
addend = Elem[operand3, s, 128];
res = BFMatMulAdd(addend, op1, op2, FPCR);
Elem[result, s, 128] = res;
Z[da, VL] = result;