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VCMP

Vector Compare compares two floating-point registers, or one floating-point register and zero. It writes the result to the FPSCR flags. These are normally transferred to the PSTATE.{N, Z, C, V} Condition flags by a subsequent VMRS instruction.

This instruction raises an Invalid Operation floating-point exception if either or both of the operands is a signaling NaN.

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

Decode for all variants of this encoding

if size == '00' || (size == '01' && !IsFeatureImplemented(FEAT_FP16)) then Undefined(); end; if size == '01' && cond != '1110' then UnpredictableProcedure(); end; let quiet_nan_exc : boolean = (E == '1'); let with_zero : boolean = FALSE; let esize : integer{} = 8 << UInt(size); let d : integer = if size == '11' then UInt(D::Vd) else UInt(Vd::D); let m : integer = if size == '11' then UInt(M::Vm) else UInt(Vm::M);

CONSTRAINED UNPREDICTABLE behavior

If size == '01' && cond != '1110', 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.

A2

Decode for all variants of this encoding

if size == '00' || (size == '01' && !IsFeatureImplemented(FEAT_FP16)) then Undefined(); end; if size == '01' && cond != '1110' then UnpredictableProcedure(); end; let quiet_nan_exc : boolean = (E == '1'); let with_zero : boolean = TRUE; let esize : integer{} = 8 << UInt(size); let d : integer = if size == '11' then UInt(D::Vd) else UInt(Vd::D); let m : integer = ARBITRARY : integer;

CONSTRAINED UNPREDICTABLE behavior

If size == '01' && cond != '1110', 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.

T1

Decode for all variants of this encoding

if size == '00' then Undefined(); end; if size == '01' && !IsFeatureImplemented(FEAT_FP16) then Undefined(); end; if size == '01' && InITBlock() then UnpredictableProcedure(); end; let quiet_nan_exc : boolean = (E == '1'); let with_zero : boolean = FALSE; let esize : integer{} = 8 << UInt(size); let d : integer = if size == '11' then UInt(D::Vd) else UInt(Vd::D); let m : integer = if size == '11' then UInt(M::Vm) else UInt(Vm::M);

CONSTRAINED UNPREDICTABLE behavior

If size == '01' && 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.

T2

Decode for all variants of this encoding

if size == '00' then Undefined(); end; if size == '01' && !IsFeatureImplemented(FEAT_FP16) then Undefined(); end; if size == '01' && InITBlock() then UnpredictableProcedure(); end; let quiet_nan_exc : boolean = (E == '1'); let with_zero : boolean = TRUE; let esize : integer{} = 8 << UInt(size); let d : integer = if size == '11' then UInt(D::Vd) else UInt(Vd::D); let m : integer = ARBITRARY : integer;

CONSTRAINED UNPREDICTABLE behavior

If size == '01' && 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