VFMSUB132SD/VFMSUB213SD/VFMSUB231SD—Fused Multiply-Subtract of Scalar Double-Precision 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 inter-mediate 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 inter-mediate 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).

IF (EVEX.b = 1) and SRC3 *is a register*
    THEN
    SET_RM(EVEX.RC);
    ELSE
    SET_RM(MXCSR.RM);
FI;
IF k1[0] or *no writemask*
    THEN
    DEST[63:0] (cid:197) 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] (cid:197) 0
    FI;
FI;
DEST[127:64] (cid:197) DEST[127:64]
DEST[MAX_VL-1:128] (cid:197) 0

IF (EVEX.b = 1) and SRC3 *is a register*
    THEN
    SET_RM(EVEX.RC);
    ELSE
    SET_RM(MXCSR.RM);
FI;
IF k1[0] or *no writemask*
    THEN
    DEST[63:0] (cid:197) 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] (cid:197) 0
    FI;
FI;
DEST[127:64] (cid:197) DEST[127:64]
DEST[MAX_VL-1:128] (cid:197) 0

IF (EVEX.b = 1) and SRC3 *is a register*
    THEN
    SET_RM(EVEX.RC);
    ELSE
    SET_RM(MXCSR.RM);
FI;
IF k1[0] or *no writemask*
    THEN
    DEST[63:0] (cid:197) 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] (cid:197) 0
    FI;
FI;
DEST[127:64] (cid:197) DEST[127:64]
DEST[MAX_VL-1:128] (cid:197) 0

DEST[63:0] (cid:197)RoundFPControl_MXCSR(DEST[63:0]*SRC3[63:0] - SRC2[63:0])
DEST[127:64] (cid:197)DEST[127:64]
DEST[MAX_VL-1:128] (cid:197)0

DEST[63:0] (cid:197)RoundFPControl_MXCSR(SRC2[63:0]*DEST[63:0] - SRC3[63:0])
DEST[127:64] (cid:197)DEST[127:64]
DEST[MAX_VL-1:128] (cid:197)0

DEST[63:0] (cid:197)RoundFPControl_MXCSR(SRC2[63:0]*SRC3[63:0] - DEST[63:0])
DEST[127:64] (cid:197)DEST[127:64]
DEST[MAX_VL-1:128] (cid:197)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