FMAXNM (vectors)

Floating-point maximum number (predicated)

Determine the maximum number value of active floating-point elements of the second source vector and corresponding floating-point elements of the first source vector and destructively place the results in the corresponding elements of the first source vector.

Regardless of the value of FPCR.AH, the behavior is as follows:

  • Negative zero compares less than positive zero.
  • If one element is numeric and the other is a quiet NaN, the result is the numeric value.
  • When FPCR.DN is 0, if either element is a signaling NaN or if both elements are NaNs, the result is a quiet NaN.
  • When FPCR.DN is 1, if either element is a signaling NaN or if both elements are NaNs, the result is Default NaN.

    • Inactive elements in the destination vector register remain unmodified.

    Encoding: SVE

    Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

    313029282726252423222120191817161514131211109876543210
    01100101!= 00000100100
    sizeopcPgZmZdn

    FMAXNM <Zdn>.<T>, <Pg>/M, <Zdn>.<T>, <Zm>.<T>

    Decoding algorithm

    if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);

constant integer g = UInt(Pg);
constant integer dn = UInt(Zdn);
constant integer m = UInt(Zm);

    Operation

    CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
constant bits(PL) mask = P[g, PL];
constant bits(VL) operand1 = Z[dn, VL];
constant bits(VL) operand2 = if AnyActiveElement(mask, esize) then Z[m, VL] else Zeros(VL);
bits(VL) result;

for e = 0 to elements-1
    constant bits(esize) element1 = Elem[operand1, e, esize];
    if ActivePredicateElement(mask, e, esize) then
        constant bits(esize) element2 = Elem[operand2, e, esize];
        Elem[result, e, esize] = FPMaxNum(element1, element2, FPCR);
    else
        Elem[result, e, esize] = element1;

Z[dn, VL] = result;

    Explanations

    <Zdn>: Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.
    <T>: <Pg>: Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.
    <Zm>: Is the name of the second source scalable vector register, encoded in the "Zm" field.

    Operational Notes

    This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is CONSTRAINED UNPREDICTABLE: