Arm® A32/T32 Instruction Set Architecture: Armv8, for Armv8-A architecture profile Documentation

VMOVX

Vector Move extraction. This instruction copies the upper 16 bits of the 32-bit source SIMD&FP register into the lower 16 bits of the 32-bit destination SIMD&FP register, while clearing the remaining bits to zero.

Depending on settings in the CPACR, NSACR, HCPTR, and FPEXC 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 T32 ( T1 ) .

A1
(Armv8.2)

if !HaveFP16Ext() then UNDEFINED;
if FPSCR.Len != '000' || FPSCR.Stride != '00' then UNDEFINED;
d = UInt(Vd:D); m = UInt(Vm:M);

T1
(Armv8.2)

if InITBlock() then UNPREDICTABLE;
if !HaveFP16Ext() then UNDEFINED;
if FPSCR.Len != '000' || FPSCR.Stride != '00' then UNDEFINED;
d = UInt(Vd:D); m = UInt(Vm:M);

CONSTRAINED UNPREDICTABLE behavior

If InITBlock(), then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as if it passes the Condition code check.
• The instruction executes as NOP. This means it behaves as if it fails the Condition code check.

Assembler Symbols

if ConditionPassed() then
    EncodingSpecificOperations();  CheckVFPEnabled(TRUE);
    S[d] = Zeros(16) : S[m]<31:16>;