FCM (vectors)

Floating-point compare vectors

Compare active floating-point elements in the first source vector with corresponding elements in the second source vector, 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 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						0	1	1									0
								size			Zm					op		cmph	Pg			Zn					cmpl	Pd

FCMEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>

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 m = UInt(Zm);
constant integer d = UInt(Pd);
constant CmpOp cmp_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						0	1	0									1
								size			Zm					op		cmph	Pg			Zn					cmpl	Pd

FCMGT <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>

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 m = UInt(Zm);
constant integer d = UInt(Pd);
constant CmpOp cmp_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						0	1	0									0
								size			Zm					op		cmph	Pg			Zn					cmpl	Pd

FCMGE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>

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 m = UInt(Zm);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_GE;

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						0	1	1									1
								size			Zm					op		cmph	Pg			Zn					cmpl	Pd

FCMNE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>

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 m = UInt(Zm);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_NE;

Encoding: Unordered

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	1	0									0
								size			Zm					op		o2	Pg			Zn					o3	Pd

FCMUO <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>

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 m = UInt(Zm);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_UN;

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 = if AnyActiveElement(mask, esize) then Z[n, VL] else Zeros(VL);
constant bits(VL) operand2 = if AnyActiveElement(mask, esize) then Z[m, 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) element1 = Elem[operand1, e, esize];
        constant bits(esize) element2 = Elem[operand2, e, esize];
        boolean res;
        case cmp_op of
            when Cmp_EQ res = FPCompareEQ(element1, element2, FPCR);
            when Cmp_GE res = FPCompareGE(element1, element2, FPCR);
            when Cmp_GT res = FPCompareGT(element1, element2, FPCR);
            when Cmp_UN res = FPCompareUN(element1, element2, FPCR);
            when Cmp_NE res = FPCompareNE(element1, element2, FPCR);
            when Cmp_LT res = FPCompareGT(element2, element1, FPCR);
            when Cmp_LE res = FPCompareGE(element2, element1, 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 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.

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.