SQDMLAL, SQDMLAL2 (by element)

Signed saturating doubling multiply-add long (by element)

This instruction multiplies each vector element in the lower or upper half of the first source SIMD&FP register by the specified vector element of the second source SIMD&FP register, doubles the results, and accumulates the final results with the vector elements of the destination SIMD&FP register. The destination vector elements are twice as long as the elements that are multiplied.

If overflow occurs with any of the results, those results are saturated. If saturation occurs, the cumulative saturation bit FPSR.QC is set.

The SQDMLAL instruction extracts vector elements from the lower half of the first source register. The SQDMLAL2 instruction extracts vector elements from the upper half of the first source register.

Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.

It has encodings from 2 classes: Scalar and Vector

Scalar
(FEAT_AdvSIMD)

313029282726252423222120191817161514131211109876543210
01011111sizeLMRm0011H0RnRd
Uo2

Encoding

SQDMLAL <Va><d>, <Vb><n>, V<m>.<Ts>[<index>]

Decode for this encoding

if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; let idxdsize : integer{} = 64 << UInt(H); var index : integer; var Rmhi : bit; case size of when '01' => index = UInt(H::L::M); Rmhi = '0'; when '10' => index = UInt(H::L); Rmhi = M; otherwise => EndOfDecode(Decode_UNDEF); end; let d : integer = UInt(Rd); let n : integer = UInt(Rn); let m : integer = UInt(Rmhi::Rm); let esize : integer{} = 8 << UInt(size); let datasize : integer{} = esize; let elements : integer = 1; let part : integer = 0;

Vector
(FEAT_AdvSIMD)

313029282726252423222120191817161514131211109876543210
0Q001111sizeLMRm0011H0RnRd
Uo2

Encoding

SQDMLAL{2} <Vd>.<Ta>, <Vn>.<Tb>, V<m>.<Ts>[<index>]

Decode for this encoding

if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; let idxdsize : integer{} = 64 << UInt(H); var index : integer; var Rmhi : bit; case size of when '01' => index = UInt(H::L::M); Rmhi = '0'; when '10' => index = UInt(H::L); Rmhi = M; otherwise => EndOfDecode(Decode_UNDEF); end; let d : integer = UInt(Rd); let n : integer = UInt(Rn); let m : integer = UInt(Rmhi::Rm); let esize : integer{} = 8 << UInt(size); let datasize : integer{} = 64; let part : integer = UInt(Q); let elements : integer = datasize DIV esize;

Assembler Symbols

<Va>

Is the destination width specifier, encoded in size:

size <Va>
00 RESERVED
01 S
10 D
11 RESERVED
<d>

Is the number of the SIMD&FP destination register, encoded in the "Rd" field.

<Vb>

Is the source width specifier, encoded in size:

size <Vb>
00 RESERVED
01 H
10 S
11 RESERVED
<n>

Is the number of the first SIMD&FP source register, encoded in the "Rn" field.

<m>

Is the number of the second SIMD&FP source register, encoded in (size :: M :: Rm):

size <m>
00 RESERVED
01 UInt('0' :: Rm)
10 UInt(M :: Rm)
11 RESERVED
Restricted to 0-15 when element size <Ts> is H.
<Ts>

Is an element size specifier, encoded in size:

size <Ts>
00 RESERVED
01 H
10 S
11 RESERVED
<index>

Is the element index, encoded in (size :: H :: L :: M):

size <index>
00 RESERVED
01 UInt(H :: L :: M)
10 UInt(H :: L)
11 RESERVED
2

Is the second and upper half specifier. If present it causes the operation to be performed on the upper 64 bits of the registers holding the narrower elements, and is encoded in Q:

Q 2
0 [absent]
1 [present]
<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<Ta>

Is an arrangement specifier, encoded in size:

size <Ta>
00 RESERVED
01 4S
10 2D
11 RESERVED
<Vn>

Is the name of the first SIMD&FP source register, encoded in the "Rn" field.

<Tb>

Is an arrangement specifier, encoded in (size :: Q):

size Q <Tb>
00 x RESERVED
01 0 4H
01 1 8H
10 0 2S
10 1 4S
11 x RESERVED

Operation

AArch64_CheckFPAdvSIMDEnabled(); let operand1 : bits(datasize) = Vpart{}(n, part); let operand2 : bits(idxdsize) = V{}(m); let operand3 : bits(2*datasize) = V{}(d); var result : bits(2*datasize); var element1 : integer; var element2 : integer; var product : bits(2*esize); var accum : integer; var sat1 : boolean; var sat2 : boolean; element2 = SInt(operand2[index*:esize]); for e = 0 to elements-1 do element1 = SInt(operand1[e*:esize]); (product, sat1) = SignedSatQ{2*esize}(2 * element1 * element2); accum = SInt(operand3[e*:(2*esize)]) + SInt(product); (result[e*:(2*esize)], sat2) = SignedSatQ{2*esize}(accum); if sat1 || sat2 then FPSR().QC = '1'; end; end; V{2*datasize}(d) = result;


2026-03_rel 2026-03-26 20:48:11

Copyright © 2010-2026 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.