SMLALT (indexed)

Multiply the odd-numbered signed elements within each 128-bit segment of the first source vector by the specified signed element in the corresponding second source vector segment and destructively add to the overlapping double-width elements of the addend vector.

The elements within the second source vector are specified using an immediate index which selects the same element position within each 128-bit vector segment. The index range is from 0 to one less than the number of elements per 128-bit segment, encoded in 2 or 3 bits depending on the size of the element.

32-bit

if !HaveSVE2() && !HaveSME() then UNDEFINED; constant integer esize = 16; integer index = UInt(i3h:i3l); integer n = UInt(Zn); integer m = UInt(Zm); integer da = UInt(Zda); integer sel = 1;

64-bit

if !HaveSVE2() && !HaveSME() then UNDEFINED; constant integer esize = 32; integer index = UInt(i2h:i2l); integer n = UInt(Zn); integer m = UInt(Zm); integer da = UInt(Zda); integer sel = 1;

Assembler Symbols

<Zda>

Is the name of the third source and destination scalable vector register, encoded in the "Zda" field.

<Zn>	Is the name of the first source scalable vector register, encoded in the "Zn" field.

<Zm>	For the 32-bit variant: is the name of the second source scalable vector register Z0-Z7, encoded in the "Zm" field.
	For the 64-bit variant: is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field.

<imm>	For the 32-bit variant: is the element index, in the range 0 to 7, encoded in the "i3h:i3l" fields.
	For the 64-bit variant: is the element index, in the range 0 to 3, encoded in the "i2h:i2l" fields.

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV (2 * esize); constant integer eltspersegment = 128 DIV (2 * esize); bits(VL) operand1 = Z[n, VL]; bits(VL) operand2 = Z[m, VL]; bits(VL) result = Z[da, VL]; for e = 0 to elements-1 integer s = e - (e MOD eltspersegment); integer element1 = SInt(Elem[operand1, 2 * e + sel, esize]); integer element2 = SInt(Elem[operand2, 2 * s + index, esize]); bits(2*esize) product = (element1 * element2)<2*esize-1:0>; Elem[result, e, 2*esize] = Elem[result, e, 2*esize] + product; Z[da, VL] = result;

Operational information

If FEAT_SVE2 is implemented or FEAT_SME is implemented, then if PSTATE.DIT is 1:

The execution time of this instruction is independent of:
- The values of the data supplied in any of its registers.
- 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 registers.
- The values of the NZCV flags.

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX instruction must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is unpredictable:

The MOVPRFX instruction must be unpredicated.
The MOVPRFX instruction must specify the same destination register as this instruction.
The destination register must not refer to architectural register state referenced by any other source operand register of this instruction.

Internal version only: aarchmrs v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46

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	0	0	0	1	0	0	1	0	1	i3h		Zm			1	0	0	0	i3l	1	Zn					Zda
								size<1>	size<0>									S	U		T

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	0	0	0	1	0	0	1	1	1	i2h	Zm				1	0	0	0	i2l	1	Zn					Zda
								size<1>	size<0>									S	U		T