VFMSUB132SD/VFMSUB213SD/VFMSUB231SD — Fused Multiply-Subtract of Scalar DoublePrecision Floating-Point Values

Instruction Operand Encoding ¶

Description ¶

Performs a SIMD multiply-subtract computation on the low packed double precision floating-point values using three source operands and writes the multiply-subtract result in the destination operand. The destination operand is also the first source operand. The second operand must be a XMM register. The third source operand can be a XMM register or a 64-bit memory location.

VFMSUB132SD: Multiplies the low packed double precision floating-point value from the first source operand to the low packed double precision floating-point value in the third source operand. From the infinite precision intermediate result, subtracts the low packed double precision floating-point values in the second source operand, performs rounding and stores the resulting packed double precision floating-point value to the destination operand (first source operand).

VFMSUB213SD: Multiplies the low packed double precision floating-point value from the second source operand to the low packed double precision floating-point value in the first source operand. From the infinite precision intermediate result, subtracts the low packed double precision floating-point value in the third source operand, performs rounding and stores the resulting packed double precision floating-point value to the destination operand (first source operand).

VFMSUB231SD: Multiplies the low packed double precision floating-point value from the second source to the low packed double precision floating-point value in the third source operand. From the infinite precision intermediate result, subtracts the low packed double precision floating-point value in the first source operand, performs rounding and stores the resulting packed double precision floating-point value to the destination operand (first source operand).

VEX.128 and EVEX encoded version: The destination operand (also first source operand) is encoded in reg_field. The second source operand is encoded in VEX.vvvv/EVEX.vvvv. The third source operand is encoded in rm_field. Bits 127:64 of the destination are unchanged. Bits MAXVL-1:128 of the destination register are zeroed.

EVEX encoded version: The low quadword element of the destination is updated according to the writemask.

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.

Operation ¶

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

VFMSUB132SD DEST, SRC2, SRC3 (EVEX encoded version) ¶

IF (EVEX.b = 1) and SRC3 *is a register*
    THEN
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(EVEX.RC);
    ELSE
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(MXCSR.RC);
FI;
IF k1[0] or *no writemask*
    THEN DEST[63:0] := RoundFPControl(DEST[63:0]*SRC3[63:0] - SRC2[63:0])
    ELSE
        IF *merging-masking* ; merging-masking
            THEN *DEST[63:0] remains unchanged*
            ELSE ; zeroing-masking
                THEN DEST[63:0] := 0
        FI;
FI;
DEST[127:64] := DEST[127:64]
DEST[MAXVL-1:128] := 0

VFMSUB213SD DEST, SRC2, SRC3 (EVEX encoded version) ¶

IF (EVEX.b = 1) and SRC3 *is a register*
    THEN
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(EVEX.RC);
    ELSE
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(MXCSR.RC);
FI;
IF k1[0] or *no writemask*
    THEN DEST[63:0] := RoundFPControl(SRC2[63:0]*DEST[63:0] - SRC3[63:0])
    ELSE
        IF *merging-masking* ; merging-masking
            THEN *DEST[63:0] remains unchanged*
            ELSE ; zeroing-masking
                THEN DEST[63:0] := 0
        FI;
FI;
DEST[127:64] := DEST[127:64]
DEST[MAXVL-1:128] := 0

VFMSUB231SD DEST, SRC2, SRC3 (EVEX encoded version) ¶

IF (EVEX.b = 1) and SRC3 *is a register*
    THEN
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(EVEX.RC);
    ELSE
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(MXCSR.RC);
FI;
IF k1[0] or *no writemask*
    THEN DEST[63:0] := RoundFPControl(SRC2[63:0]*SRC3[63:0] - DEST[63:0])
    ELSE
        IF *merging-masking* ; merging-masking
            THEN *DEST[63:0] remains unchanged*
            ELSE ; zeroing-masking
                THEN DEST[63:0] := 0
        FI;
FI;
DEST[127:64] := DEST[127:64]
DEST[MAXVL-1:128] := 0

VFMSUB132SD DEST, SRC2, SRC3 (VEX encoded version) ¶

DEST[63:0] := RoundFPControl_MXCSR(DEST[63:0]*SRC3[63:0] - SRC2[63:0])
DEST[127:64] := DEST[127:64]
DEST[MAXVL-1:128] := 0

VFMSUB213SD DEST, SRC2, SRC3 (VEX encoded version) ¶

DEST[63:0] := RoundFPControl_MXCSR(SRC2[63:0]*DEST[63:0] - SRC3[63:0])
DEST[127:64] := DEST[127:64]
DEST[MAXVL-1:128] := 0

VFMSUB231SD DEST, SRC2, SRC3 (VEX encoded version) ¶

DEST[63:0] := RoundFPControl_MXCSR(SRC2[63:0]*SRC3[63:0] - DEST[63:0])
DEST[127:64] := DEST[127:64]
DEST[MAXVL-1:128] := 0

Intel C/C++ Compiler Intrinsic Equivalent ¶

VFMSUBxxxSD __m128d _mm_fmsub_round_sd(__m128d a, __m128d b, __m128d c, int r);

VFMSUBxxxSD __m128d _mm_mask_fmsub_sd(__m128d a, __mmask8 k, __m128d b, __m128d c);

VFMSUBxxxSD __m128d _mm_maskz_fmsub_sd(__mmask8 k, __m128d a, __m128d b, __m128d c);

VFMSUBxxxSD __m128d _mm_mask3_fmsub_sd(__m128d a, __m128d b, __m128d c, __mmask8 k);

VFMSUBxxxSD __m128d _mm_mask_fmsub_round_sd(__m128d a, __mmask8 k, __m128d b, __m128d c, int r);

VFMSUBxxxSD __m128d _mm_maskz_fmsub_round_sd(__mmask8 k, __m128d a, __m128d b, __m128d c, int r);

VFMSUBxxxSD __m128d _mm_mask3_fmsub_round_sd(__m128d a, __m128d b, __m128d c, __mmask8 k, int r);

VFMSUBxxxSD __m128d _mm_fmsub_sd (__m128d a, __m128d b, __m128d c);

SIMD Floating-Point Exceptions ¶

Overflow, Underflow, Invalid, Precision, Denormal

Other Exceptions ¶

VEX-encoded instructions, see Table 2-20, “Type 3 Class Exception Conditions.”

EVEX-encoded instructions, see Table 2-47, “Type E3 Class Exception Conditions.”