VSHLL

Vector Shift Left Long takes each element in a doubleword vector, left shifts them by an immediate value, and places the results in a quadword vector.

The operand elements can be:

The result elements are twice the length of the operand elements.

Depending on settings in the CPACR, NSACR, and HCPTR registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.

It has encodings from the following instruction sets: A32 ( A1 and A2 ) and T32 ( T1 and T2 ) .

A1

313029282726252423222120191817161514131211109876543210
1111001U1Dimm6Vd101000M1Vm

Encoding for the A1 variant

Applies when (imm6 != 000xxx)

VSHLL{<c>}{<q>}.<type><size> <Qd>, <Dm>, #<imm>

Decode for this encoding

if imm6 == '000xxx' then SEE "Related encodings"; if imm6 IN {'001000', '010000', '100000'} then SEE "VMOVL"; if Vd<0> == '1' then UNDEFINED; constant integer esize = 8 << HighestSetBit(imm6<5:3>); constant integer elements = 64 DIV esize; constant integer shift_amount = UInt(imm6) - esize; constant unsigned = (U == '1'); constant d = UInt(D:Vd); constant m = UInt(M:Vm);

A2

313029282726252423222120191817161514131211109876543210
111100111D11size10Vd001100M0Vm

Encoding for the A2 variant

VSHLL{<c>}{<q>}.<type><size> <Qd>, <Dm>, #<imm>

Decode for this encoding

if size == '11' || Vd<0> == '1' then UNDEFINED; constant integer esize = 8 << UInt(size); constant elements = 64 DIV esize; constant shift_amount = esize; constant unsigned = FALSE; // Or TRUE without change of functionality constant d = UInt(D:Vd); constant m = UInt(M:Vm);

T1

15141312111098765432101514131211109876543210
111U11111Dimm6Vd101000M1Vm

Encoding for the T1 variant

Applies when (imm6 != 000xxx)

VSHLL{<c>}{<q>}.<type><size> <Qd>, <Dm>, #<imm>

Decode for this encoding

if imm6 == '000xxx' then SEE "Related encodings"; if imm6 IN {'001000', '010000', '100000'} then SEE "VMOVL"; if Vd<0> == '1' then UNDEFINED; constant integer esize = 8 << HighestSetBit(imm6<5:3>); constant integer elements = 64 DIV esize; constant integer shift_amount = UInt(imm6) - esize; constant unsigned = (U == '1'); constant d = UInt(D:Vd); constant m = UInt(M:Vm);

T2

15141312111098765432101514131211109876543210
111111111D11size10Vd001100M0Vm

Encoding for the T2 variant

VSHLL{<c>}{<q>}.<type><size> <Qd>, <Dm>, #<imm>

Decode for this encoding

if size == '11' || Vd<0> == '1' then UNDEFINED; constant integer esize = 8 << UInt(size); constant elements = 64 DIV esize; constant shift_amount = esize; constant unsigned = FALSE; // Or TRUE without change of functionality constant d = UInt(D:Vd); constant m = UInt(M:Vm);

Related encodings: See Advanced SIMD one register and modified immediate for the T32 instruction set, or Advanced SIMD one register and modified immediate for the A32 instruction set.

Assembler Symbols

<c>

For encoding A1 and A2: see Standard assembler syntax fields. This encoding must be unconditional.

For encoding T1 and T2: see Standard assembler syntax fields.

<q>

See Standard assembler syntax fields.

<type>

The data type for the elements of the operand. It must be one of:

S
Signed. In encoding T1/A1, encoded as U = 0.
U
Unsigned. In encoding T1/A1, encoded as U = 1.
I
Untyped integer, Available only in encoding T2/A2.
<size>

The data size for the elements of the operand. The following table shows the permitted values and their encodings:

<size> Encoding T1/A1 Encoding T2/A2
8 Encoded as imm6<5:3> = 0b001 Encoded as size = 0b00
16 Encoded as imm6<5:4> = 0b01 Encoded as size = 0b01
32 Encoded as imm6<5> = 1 Encoded as size = 0b10
<Qd>

Is the 128-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field as <Qd>*2.

<Dm>

Is the 64-bit name of the SIMD&FP source register, encoded in the "M:Vm" field.

<imm>

The immediate value. <imm> must lie in the range 1 to <size>, and:

  • If <size> == <imm>, the encoding is T2/A2.
  • Otherwise, the encoding is T1/A1, and:
    • If <size> == 8, <imm> is encoded in imm6<2:0>.
    • If <size> == 16, <imm> is encoded in imm6<3:0>.
    • If <size> == 32, <imm> is encoded in imm6<4:0>.

Operation

if ConditionPassed() then EncodingSpecificOperations(); CheckAdvSIMDEnabled(); for e = 0 to elements-1 constant result = Int(Elem[Din[m],e,esize], unsigned) << shift_amount; Elem[Q[d>>1],e,2*esize] = result<2*esize-1:0>;

Operational information

If CPSR.DIT is 1 and this instruction passes its condition execution check:


Internal version only: isa v01_32, pseudocode v2024-12_rel ; Build timestamp: 2024-12-16T10:54

Copyright © 2010-2024 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.