CMP (immediate)

Compare vector to immediate

Compare active integer elements in the source vector with an immediate, 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. Sets the First (N), None (Z), !Last (C) condition flags based on the predicate result, and 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 LE signed less than or equal LO unsigned lower than LS unsigned lower than or same LT signed less than NE not equal

Encoding: Equal

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

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0	0	1	0	0	1	0	1			0						1	0	0									0
								size			imm5					op		o2	Pg			Zn					ne	Pd

CMPEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_EQ;
constant integer imm = SInt(imm5);
constant boolean unsigned = FALSE;

Encoding: Greater than

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

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0	0	1	0	0	1	0	1			0						0	0	0									1
								size			imm5					op		lt	Pg			Zn					ne	Pd

CMPGT <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_GT;
constant integer imm = SInt(imm5);
constant boolean unsigned = FALSE;

Encoding: Greater than or equal

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

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0	0	1	0	0	1	0	1			0						0	0	0									0
								size			imm5					op		lt	Pg			Zn					ne	Pd

CMPGE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_GE;
constant integer imm = SInt(imm5);
constant boolean unsigned = FALSE;

Encoding: Higher

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

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0	0	1	0	0	1	0	0			1								0									1
								size			imm7							lt	Pg			Zn					ne	Pd

CMPHI <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_GT;
constant integer imm = UInt(imm7);
constant boolean unsigned = TRUE;

Encoding: Higher or same

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	0	1	0	0	1	0	0			1								0									0
								size			imm7							lt	Pg			Zn					ne	Pd

CMPHS <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_GE;
constant integer imm = UInt(imm7);
constant boolean unsigned = TRUE;

Encoding: Less than

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

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0	0	1	0	0	1	0	1			0						0	0	1									0
								size			imm5					op		lt	Pg			Zn					ne	Pd

CMPLT <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_LT;
constant integer imm = SInt(imm5);
constant boolean unsigned = FALSE;

Encoding: Less than or equal

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

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0	0	1	0	0	1	0	1			0						0	0	1									1
								size			imm5					op		lt	Pg			Zn					ne	Pd

CMPLE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_LE;
constant integer imm = SInt(imm5);
constant boolean unsigned = FALSE;

Encoding: Lower

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

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0	0	1	0	0	1	0	0			1								1									0
								size			imm7							lt	Pg			Zn					ne	Pd

CMPLO <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_LT;
constant integer imm = UInt(imm7);
constant boolean unsigned = TRUE;

Encoding: Lower or same

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

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0	0	1	0	0	1	0	0			1								1									1
								size			imm7							lt	Pg			Zn					ne	Pd

CMPLS <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_LE;
constant integer imm = UInt(imm7);
constant boolean unsigned = TRUE;

Encoding: Not equal

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

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0	0	1	0	0	1	0	1			0						1	0	0									1
								size			imm5					op		o2	Pg			Zn					ne	Pd

CMPNE <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>

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 n = UInt(Zn);
constant integer d = UInt(Pd);
constant CmpOp cmp_op = Cmp_NE;
constant integer imm = SInt(imm5);
constant boolean unsigned = FALSE;

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);
bits(PL) result;
constant integer psize = esize DIV 8;

for e = 0 to elements-1
    constant integer element1 = Int(Elem[operand1, e, esize], unsigned);
    if ActivePredicateElement(mask, e, esize) then
        boolean cond;
        case cmp_op of
            when Cmp_EQ cond = element1 == imm;
            when Cmp_NE cond = element1 != imm;
            when Cmp_GE cond = element1 >= imm;
            when Cmp_LT cond = element1 <  imm;
            when Cmp_GT cond = element1 >  imm;
            when Cmp_LE cond = element1 <= imm;
        constant bit pbit = if cond then '1' else '0';
        Elem[result, e, psize] = ZeroExtend(pbit, psize);
    else
        Elem[result, e, psize] = ZeroExtend('0', psize);

PSTATE. = PredTest(mask, result, esize);
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.
<imm>: For the "Equal", "Greater than or equal", "Greater than", "Less than or equal", "Less than", and "Not equal" variants: is the signed immediate operand, in the range -16 to 15, encoded in the "imm5" field.
<imm>: For the "Higher or same", "Higher", "Lower or same", and "Lower" variants: is the unsigned immediate operand, in the range 0 to 127, encoded in the "imm7" field.

Operational Notes

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
  • The values of the data supplied in any of its operand registers when its governing predicate register contains the same value for each execution.
  • The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
  • The values of the data supplied in any of its operand registers when its governing predicate register contains the same value for each execution.
  • The values of the NZCV flags.

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.