VFNMSUB132SS/VFNMSUB213SS/VFNMSUB231SS (Fused Negative Multiply-Subtract of Scalar Single-Precision Floating-Point Values)

Opcodes

Opcode/Instruction Op/En 64/32 -bit Mode CPUID Feature Flag Description
VEX.DDS.LIG.128.66.0F38.W0 9F /r VFNMSUB132SS xmm0, xmm1, xmm2/m32 A V/V FMA Multiply scalar single-precision floating-point value from xmm0 and xmm2/mem, negate the multiplication result and subtract xmm1 and put result in xmm0.
VEX.DDS.LIG.128.66.0F38.W0 AF /r VFNMSUB213SS xmm0, xmm1, xmm2/m32 A V/V FMA Multiply scalar single-precision floating-point value from xmm0 and xmm1, negate the multiplication result and subtract xmm2/mem and put result in xmm0.
VEX.DDS.LIG.128.66.0F38.W0 BF /r VFNMSUB231SS xmm0, xmm1, xmm2/m32 A V/V FMA Multiply scalar single-precision floating-point value from xmm1 and xmm2/mem, negate the multiplication result and subtract xmm0 and put result in xmm0.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
A ModRM:reg (r, w) VEX.vvvv (r) ModRM:r/m (r) NA

Description

VFNMSUB132SS: Multiplies the low packed single-precision floating-point value from the first source operand to the low packed single-precision floating-point value in the third source operand. From negated infinite precision intermediate result, the low single-precision floating-point value in the second source operand, performs rounding and stores the resulting packed single-precision floating-point value to the destination operand (first source operand).

VFNMSUB213SS: Multiplies the low packed single-precision floating-point value from the second source operand to the low packed single-precision floating-point value in the first source operand. From negated infinite precision intermediate result, the low single-precision floating-point value in the third source operand, performs rounding and stores the resulting packed single-precision floating-point value to the destination operand (first source operand).

VFNMSUB231SS: Multiplies the low packed single-precision floating-point value from the second source to the low packed single-precision floating-point value in the third source operand. From negated infinite precision interme-diate result, the low single-precision floating-point value in the first source operand, performs rounding and stores the resulting packed single-precision floating-point value to the destination operand (first source operand).

VEX.128 encoded version: The destination operand (also first source operand) is a XMM register and encoded in reg_field. The second source operand is a XMM register and encoded in VEX.vvvv. The third source operand is a XMM register or a 32-bit memory location and encoded in rm_field. The upper bits ([VLMAX-1:128]) of the YMM destination register are zeroed.

Compiler tools may optionally support a complementary mnemonic for each instruction mnemonic listed in the opcode/instruction column of the summary table. The behavior of the complementary mnemonic in situations involving NANs are governed by the definition of the instruction mnemonic defined in the opcode/instruction column. See also Section 14.5.1, “FMA Instruction Operand Order and Arithmetic Behavior” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1.

Operation

In the operations below, "+", "-", and "*" symbols represent addition, subtraction, and multiplication operations with infinite precision inputs and outputs (no rounding).

VFNMSUB132SS DEST, SRC2, SRC3

DEST[31:0] ← RoundFPControl_MXCSR(- (DEST[31:0]*SRC3[31:0]) - SRC2[31:0])
DEST[127:32] ← DEST[127:32]
DEST[VLMAX-1:128] ← 0 VFNMSUB213SS DEST, SRC2, SRC3
DEST[31:0] ← RoundFPControl_MXCSR(- (SRC2[31:0]*DEST[31:0]) - SRC3[31:0])
DEST[127:32] ← DEST[127:32]
DEST[VLMAX-1:128] ← 0

VFNMSUB231SS DEST, SRC2, SRC3

DEST[31:0] ← RoundFPControl_MXCSR(- (SRC2[31:0]*SRC3[63:0]) - DEST[31:0])
DEST[127:32] ← DEST[127:32]
DEST[VLMAX-1:128] ← 0

Intel C/C++ Compiler Intrinsic Equivalent

VFNMSUB132SS: __m128 _mm_fnmsub_ss (__m128 a, __m128 b, __m128 c);

VFNMSUB213SS: __m128 _mm_fnmsub_ss (__m128 a, __m128 b, __m128 c);

VFNMSUB231SS: __m128 _mm_fnmsub_ss (__m128 a, __m128 b, __m128 c);

SIMD Floating-Point Exceptions

Overflow, Underflow, Invalid, Precision, Denormal

Other Exceptions

See Exceptions Type 3