FCM<cc> (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

This instruction is used by the pseudo-instructions FCMLE (vectors), and FCMLT (vectors).

It has encodings from 5 classes: Equal , Greater than , Greater than or equal , Not equal and Unordered

Equal

313029282726252423222120191817161514131211109876543210
01100101size0Zm011PgZn0Pd
cmphcmpl

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

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; if size == '00' then UNDEFINED; 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 SVECmp op = Cmp_EQ;

Greater than

313029282726252423222120191817161514131211109876543210
01100101size0Zm010PgZn1Pd
cmphcmpl

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

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; if size == '00' then UNDEFINED; 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 SVECmp op = Cmp_GT;

Greater than or equal

313029282726252423222120191817161514131211109876543210
01100101size0Zm010PgZn0Pd
cmphcmpl

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

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; if size == '00' then UNDEFINED; 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 SVECmp op = Cmp_GE;

Not equal

313029282726252423222120191817161514131211109876543210
01100101size0Zm011PgZn1Pd
cmphcmpl

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

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; if size == '00' then UNDEFINED; 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 SVECmp op = Cmp_NE;

Unordered

313029282726252423222120191817161514131211109876543210
01100101size0Zm110PgZn0Pd

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

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; if size == '00' then UNDEFINED; 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 SVECmp op = Cmp_UN;

Assembler Symbols

<Pd>

Is the name of the destination scalable predicate register, encoded in the "Pd" field.

<T>

Is the size specifier, encoded in size:

size <T>
00 RESERVED
01 H
10 S
11 D
<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.

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 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;

Operational information

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.


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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