DIVSS—Divide Scalar Single-Precision Floating-Point Values

Opcode/Instruction Op /En 64/32 bit Mode Support CPUID Feature Flag Description
F3 0F 5E /r DIVSS xmm1, xmm2/m32 A V/V SSE Divide low single-precision floating-point value in xmm1 by low single-precision floating-point value in xmm2/m32.
VEX.LIG.F3.0F.WIG 5E /r VDIVSS xmm1, xmm2, xmm3/m32 B V/V AVX Divide low single-precision floating-point value in xmm2 by low single-precision floating-point value in xmm3/m32.
EVEX.LLIG.F3.0F.W0 5E /r VDIVSS xmm1 {k1}{z}, xmm2, xmm3/m32{er} C V/V AVX512F Divide low single-precision floating-point value in xmm2 by low single-precision floating-point value in xmm3/m32.

Instruction Operand Encoding

Op/En Tuple Type Operand 1 Operand 2 Operand 3 Operand 4
A NA ModRM:reg (r, w) ModRM:r/m (r) NA NA
B NA ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA
C Tuple1 Scalar ModRM:reg (w) EVEX.vvvv (r) ModRM:r/m (r) NA

Description

Divides the low single-precision floating-point value in the first source operand by the low single-precision floating-point value in the second source operand, and stores the single-precision floating-point result in the destination operand. The second source operand can be an XMM register or a 32-bit memory location.

128-bit Legacy SSE version: The first source operand and the destination operand are the same. Bits (MAXVL-1:32) of the corresponding YMM destination register remain unchanged.

VEX.128 encoded version: The first source operand is an xmm register encoded by VEX.vvvv. The three high-order doublewords of the destination operand are copied from the first source operand. Bits (MAXVL-1:128) of the desti-nation register are zeroed.

EVEX.128 encoded version: The first source operand is an xmm register encoded by EVEX.vvvv. The doubleword elements of the destination operand at bits 127:32 are copied from the first source operand. Bits (MAXVL-1:128) of the destination register are zeroed.

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

Software should ensure VDIVSS is encoded with VEX.L=0. Encoding VDIVSS with VEX.L=1 may encounter unpre-dictable behavior across different processor generations.

Operation

VDIVSS (EVEX encoded version)

IF (EVEX.b = 1) AND SRC2 *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[31:0] := SRC1[31:0] / SRC2[31:0]
    ELSE
         IF *merging-masking*
                                                    ; merging-masking
              THEN *DEST[31:0] remains unchanged*
              ELSE
                                                    ; zeroing-masking
                    THEN DEST[31:0] := 0
         FI;
FI;
DEST[127:32] := SRC1[127:32]
DEST[MAXVL-1:128] := 0

VDIVSS (VEX.128 encoded version)

DEST[31:0] := SRC1[31:0] / SRC2[31:0]
DEST[127:32] := SRC1[127:32]
DEST[MAXVL-1:128] := 0

DIVSS (128-bit Legacy SSE version)

DEST[31:0] := DEST[31:0] / SRC[31:0]
DEST[MAXVL-1:32] (Unmodified)

Intel C/C++ Compiler Intrinsic Equivalent

VDIVSS __m128 _mm_mask_div_ss(__m128 s, __mmask8 k, __m128 a, __m128 b);

VDIVSS __m128 _mm_maskz_div_ss( __mmask8 k, __m128 a, __m128 b);

VDIVSS __m128 _mm_div_round_ss( __m128 a, __m128 b, int);

VDIVSS __m128 _mm_mask_div_round_ss(__m128 s, __mmask8 k, __m128 a, __m128 b, int);

VDIVSS __m128 _mm_maskz_div_round_ss( __mmask8 k, __m128 a, __m128 b, int);

DIVSS __m128 _mm_div_ss(__m128 a, __m128 b);

SIMD Floating-Point Exceptions

Overflow, Underflow, Invalid, Divide-by-Zero, 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”.