Compare vectors
This instruction compares active integer elements in the first source vector with the corresponding elements in the second source vector, and places 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. This instruction sets the First (N), None (Z), and !Last (C) condition flags based on the predicate result, and sets the V flag to zero.
| <cc> | Comparison |
|---|---|
| EQ | equal |
| GE | signed greater than or equal |
| GT | signed greater than |
| HI | unsigned higher than |
| HS | unsigned higher than or same |
| NE | not equal |
This instruction is used by the pseudo-instructions CMPLE (vectors), CMPLO (vectors), CMPLS (vectors), and CMPLT (vectors).
It has encodings from 6 classes: Equal , Greater than , Greater than or equal , Higher , Higher or same and Not equal
| 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 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | size | 0 | Zm | 1 | 0 | 1 | Pg | Zn | 0 | Pd | ||||||||||||||
| op | o2 | ne | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let d : integer = UInt(Pd); let cmp_op : CmpOp = Cmp_EQ; let unsigned : boolean = FALSE;
| 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 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | size | 0 | Zm | 1 | 0 | 0 | Pg | Zn | 1 | Pd | ||||||||||||||
| op | o2 | ne | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let d : integer = UInt(Pd); let cmp_op : CmpOp = Cmp_GT; let unsigned : boolean = FALSE;
| 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 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | size | 0 | Zm | 1 | 0 | 0 | Pg | Zn | 0 | Pd | ||||||||||||||
| op | o2 | ne | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let d : integer = UInt(Pd); let cmp_op : CmpOp = Cmp_GE; let unsigned : boolean = FALSE;
| 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 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | size | 0 | Zm | 0 | 0 | 0 | Pg | Zn | 1 | Pd | ||||||||||||||
| op | o2 | ne | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let d : integer = UInt(Pd); let cmp_op : CmpOp = Cmp_GT; let unsigned : boolean = TRUE;
| 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 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | size | 0 | Zm | 0 | 0 | 0 | Pg | Zn | 0 | Pd | ||||||||||||||
| op | o2 | ne | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let d : integer = UInt(Pd); let cmp_op : CmpOp = Cmp_GE; let unsigned : boolean = TRUE;
| 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 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | size | 0 | Zm | 1 | 0 | 1 | Pg | Zn | 1 | Pd | ||||||||||||||
| op | o2 | ne | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let d : integer = UInt(Pd); let cmp_op : CmpOp = Cmp_NE; let unsigned : boolean = FALSE;
| <Pd> |
Is the name of the destination scalable predicate register, encoded in the "Pd" field. |
| <T> |
Is the size specifier,
encoded in
|
| <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. |
CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; let mask : bits(PL) = P{}(g); let operand1 : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(n) else Zeros{VL}; let operand2 : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(m) else Zeros{VL}; var result : bits(PL); let psize : integer{} = esize DIV 8; for e = 0 to elements-1 do let op1elt : bits(esize) = operand1[e*:esize]; let element1 : integer = if unsigned then UInt(op1elt) else SInt(op1elt); if ActivePredicateElement{PL}(mask, e, esize) then var cond : boolean; let op2elt : bits(esize) = operand2[e*:esize]; let element2 : integer = if unsigned then UInt(op2elt) else SInt(op2elt); case cmp_op of when Cmp_EQ => cond = element1 == element2; when Cmp_NE => cond = element1 != element2; when Cmp_GE => cond = element1 >= element2; when Cmp_LT => cond = element1 < element2; when Cmp_GT => cond = element1 > element2; when Cmp_LE => cond = element1 <= element2; end; let pbit : bit = if cond then '1' else '0'; result[e*:psize] = ZeroExtend{psize}(pbit); else result[e*:psize] = ZeroExtend{psize}('0'); end; end; PSTATE.[N,Z,C,V] = PredTest{PL}(mask, result, esize); P{PL}(d) = result;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
If FEAT_SME is implemented and the PE is in Streaming SVE mode, then any subsequent instruction which is dependent on the predicate register or NZCV condition flags written by this instruction might be significantly delayed.
2026-03_rel 2026-03-26 20:48:11
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