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VNMLS

Vector Negate Multiply Subtract multiplies together two floating-point register values, adds the negation of the floating-point value in the destination register to the product, and writes the result back to the destination register.

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

Decode for all variants of this encoding

if FPSCR().Len != '000' || FPSCR().Stride != '00' then Undefined(); end; if size == '00' || (size == '01' && !IsFeatureImplemented(FEAT_FP16)) then Undefined(); end; if size == '01' && cond != '1110' then UnpredictableProcedure(); end; let vtype : VFPNegMul = if op == '1' then VFPNegMul_VNMLA else VFPNegMul_VNMLS; let esize : integer{} = 8 << UInt(size); let d : integer = if size == '11' then UInt(D::Vd) else UInt(Vd::D); let n : integer = if size == '11' then UInt(N::Vn) else UInt(Vn::N); 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.

T1

Decode for all variants of this encoding

if FPSCR().Len != '000' || FPSCR().Stride != '00' then Undefined(); end; if size == '00' || (size == '01' && !IsFeatureImplemented(FEAT_FP16)) then Undefined(); end; if size == '01' && InITBlock() then UnpredictableProcedure(); end; let vtype : VFPNegMul = if op == '1' then VFPNegMul_VNMLA else VFPNegMul_VNMLS; let esize : integer{} = 8 << UInt(size); let d : integer = if size == '11' then UInt(D::Vd) else UInt(Vd::D); let n : integer = if size == '11' then UInt(N::Vn) else UInt(Vn::N); 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.