SQDMLSLB (indexed)

Signed saturating doubling multiply-subtract long from accumulator (bottom, indexed)

Multiply then double the even-numbered signed elements within each 128-bit segment of the first source vector and the specified signed element in the corresponding second source vector segment. Each intermediate value is saturated to the double-width N-bit value's signed integer range -2(N-1) to (2(N-1) )-1. Then destructively subtract from the overlapping double-width elements of the addend and destination vector. Each destination element is saturated to the double-width N-bit element's signed integer range -2(N-1) to (2(N-1) )-1.

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.

It has encodings from 2 classes: 32-bit and 64-bit

32-bit

313029282726252423222120191817161514131211109876543210
01000100101i3hZm0011i3l0ZnZda
size<1>size<0>ST

SQDMLSLB <Zda>.S, <Zn>.H, <Zm>.H[<imm>]

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 16; constant integer index = UInt(i3h:i3l); constant integer n = UInt(Zn); constant integer m = UInt(Zm); constant integer da = UInt(Zda); constant integer sel = 0;

64-bit

313029282726252423222120191817161514131211109876543210
01000100111i2hZm0011i2l0ZnZda
size<1>size<0>ST

SQDMLSLB <Zda>.D, <Zn>.S, <Zm>.S[<imm>]

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 32; constant integer index = UInt(i2h:i2l); constant integer n = UInt(Zn); constant integer m = UInt(Zm); constant integer da = UInt(Zda); constant integer sel = 0;

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); constant bits(VL) operand1 = Z[n, VL]; constant bits(VL) operand2 = Z[m, VL]; bits(VL) result = Z[da, VL]; for e = 0 to elements-1 constant integer s = e - (e MOD eltspersegment); constant integer element1 = SInt(Elem[operand1, 2 * e + sel, esize]); constant integer element2 = SInt(Elem[operand2, 2 * s + index, esize]); constant integer element3 = SInt(Elem[result, e, 2*esize]); constant integer product = SInt(SignedSat(2 * element1 * element2, 2*esize)); constant integer res = element3 - product; Elem[result, e, 2*esize] = SignedSat(res, 2*esize); Z[da, VL] = result;

Operational information

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


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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