ADDSS—Add Scalar Single-Precision Floating-Point Values

Opcode/Instruction Op /En 64/32 bit Mode Support CPUID Feature Flag Description
F3 0F 58 /r ADDSS xmm1, xmm2/m32 A V/V SSE Add the low single-precision floating-point value from xmm2/mem to xmm1 and store the result in xmm1.
VEX.LIG.F3.0F.WIG 58 /r VADDSS xmm1,xmm2, xmm3/m32 B V/V AVX Add the low single-precision floating-point value from xmm3/mem to xmm2 and store the result in xmm1.
EVEX.LLIG.F3.0F.W0 58 /r VADDSS xmm1{k1}{z}, xmm2, xmm3/m32{er} C V/V AVX512F Add the low single-precision floating-point value from xmm3/m32 to xmm2 and store the result in xmm1with writemask k1.

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

Adds the low single-precision floating-point values from the second source operand and the first source operand, and stores the double-precision floating-point result in the destination operand.

The second source operand can be an XMM register or a 64-bit memory location. The first source and destination operands are XMM registers.

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

EVEX and VEX.128 encoded version: The first source operand is encoded by EVEX.vvvv/VEX.vvvv. Bits (127:32) of the XMM register destination are copied from corresponding bits in 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 VADDSS is encoded with VEX.L=0. Encoding VADDSS with VEX.L=1 may encounter unpre-dictable behavior across different processor generations.

Operation

VADDSS (EVEX encoded versions)

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

VADDSS DEST, SRC1, SRC2 (VEX.128 encoded version)

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

ADDSS DEST, SRC (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

VADDSS __m128 _mm_mask_add_ss (__m128 s, __mmask8 k, __m128 a, __m128 b);

VADDSS __m128 _mm_maskz_add_ss (__mmask8 k, __m128 a, __m128 b);

VADDSS __m128 _mm_add_round_ss (__m128 a, __m128 b, int);

VADDSS __m128 _mm_mask_add_round_ss (__m128 s, __mmask8 k, __m128 a, __m128 b, int);

VADDSS __m128 _mm_maskz_add_round_ss (__mmask8 k, __m128 a, __m128 b, int);

ADDSS __m128 _mm_add_ss (__m128 a, __m128 b);

SIMD Floating-Point Exceptions

Overflow, Underflow, Invalid, Precision, Denormal

Other Exceptions

VEX-encoded instruction, see Table 2-20, “Type 3 Class Exception Conditions”.
EVEX-encoded instruction, see Table 2-47, “Type E3 Class Exception Conditions”.