Shift left long (by element size)
This instruction reads each vector element in the lower or upper half of the source SIMD&FP register, left shifts each result by the element size, writes the final result to a vector, and writes the vector to the destination SIMD&FP register. The destination vector elements are twice as long as the source vector elements.
The SHLL instruction extracts vector elements from the lower half of the source register. The SHLL2 instruction extracts vector elements from the upper half of the 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.
| 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 | Q | 1 | 0 | 1 | 1 | 1 | 0 | size | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | Rn | Rd | |||||||||
| U | opcode | ||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); if size == '11' then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let datasize : integer{} = 64; let part : integer = UInt(Q); let elements : integer = datasize DIV esize; let shift : integer = esize;
| <Vd> |
Is the name of the SIMD&FP destination register, encoded in the "Rd" field. |
| <Ta> |
Is an arrangement specifier,
encoded in
|
| <Vn> |
Is the name of the SIMD&FP source register, encoded in the "Rn" field. |
| <Tb> |
Is an arrangement specifier,
encoded in
|
| <shift> |
Is the left shift amount, which must be equal to the source element width in bits,
encoded in
|
AArch64_CheckFPAdvSIMDEnabled(); let operand : bits(datasize) = Vpart{}(n, part); var result : bits(2*datasize); var element : integer; for e = 0 to elements-1 do element = SInt(operand[e*:esize]) << shift; result[e*:(2*esize)] = element[2*esize-1:0]; end; V{2*datasize}(d) = result;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
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.