FCM (zero)

Floating-point compare vector with zero

Compare active floating-point elements in the source vector with zero, and place the boolean results of the specified comparison in the corresponding elements of the destination predicate. Inactive elements in the destination predicate register are set to zero. Does not set the condition flags.

<cc> Comparison EQ equal GE greater than or equal GT greater than LE less than or equal LT less than NE not equal UO unordered

Encoding: Equal

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1			0	1	0	0	1	0	0	0	1									0
								size						eq	lt				Pg			Zn					ne	Pd

FCMEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #0.0

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer g = UInt(Pg);
constant integer n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp op = Cmp_EQ;

Encoding: Greater than

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1			0	1	0	0	0	0	0	0	1									1
								size						eq	lt				Pg			Zn					ne	Pd

FCMGT <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #0.0

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer g = UInt(Pg);
constant integer n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp op = Cmp_GT;

Encoding: Greater than or equal

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1			0	1	0	0	0	0	0	0	1									0
								size						eq	lt				Pg			Zn					ne	Pd

FCMGE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #0.0

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer g = UInt(Pg);
constant integer n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp op = Cmp_GE;

Encoding: Less than

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1			0	1	0	0	0	1	0	0	1									0
								size						eq	lt				Pg			Zn					ne	Pd

FCMLT <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #0.0

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer g = UInt(Pg);
constant integer n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp op = Cmp_LT;

Encoding: Less than or equal

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1			0	1	0	0	0	1	0	0	1									1
								size						eq	lt				Pg			Zn					ne	Pd

FCMLE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #0.0

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer g = UInt(Pg);
constant integer n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp op = Cmp_LE;

Encoding: Not equal

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1			0	1	0	0	1	1	0	0	1									0
								size						eq	lt				Pg			Zn					ne	Pd

FCMNE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #0.0

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer g = UInt(Pg);
constant integer n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp op = Cmp_NE;

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) operand = if AnyActiveElement(mask, esize) then Z[n, VL] else Zeros(VL);
bits(PL) result;
constant integer psize = esize DIV 8;

for e = 0 to elements-1
    if ActivePredicateElement(mask, e, esize) then
        constant bits(esize) element = Elem[operand, e, esize];
        boolean res;
        case op of
            when Cmp_EQ res = FPCompareEQ(element, 0, FPCR);
            when Cmp_GE res = FPCompareGE(element, 0, FPCR);
            when Cmp_GT res = FPCompareGT(element, 0, FPCR);
            when Cmp_NE res = FPCompareNE(element, 0, FPCR);
            when Cmp_LT res = FPCompareGT(0, element, FPCR);
            when Cmp_LE res = FPCompareGE(0, element, FPCR);
        constant bit pbit = if res then '1' else '0';
        Elem[result, e, psize] = ZeroExtend(pbit, psize);
    else
        Elem[result, e, psize] = ZeroExtend('0', psize);

P[d, PL] = result;

Explanations

<Pd>: Is the name of the destination scalable predicate register, encoded in the "Pd" field.
<T>: <Pg>: Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.
<Zn>: Is the name of the source scalable vector register, encoded in the "Zn" field.

Operational Notes

If FEAT_SME is implemented and the PE is in Streaming SVE mode, then any subsequent instruction which is dependent on the predicate register written by this instruction might be significantly delayed.