# MOVSS — Move or Merge Scalar Single Precision Floating-Point Value

Opcode/Instruction | Op / En | 64/32 bit Mode Support | CPUID Feature Flag | Description
--- | --- | --- | --- | ---
F3 0F 10 /r MOVSS xmm1, xmm2 | A | V/V | SSE | Merge scalar single precision floating-point value from xmm2 to xmm1 register.
F3 0F 10 /r MOVSS xmm1, m32 | A | V/V | SSE | Load scalar single precision floating-point value from m32 to xmm1 register.
VEX.LIG.F3.0F.WIG 10 /r VMOVSS xmm1, xmm2, xmm3 | B | V/V | AVX | Merge scalar single precision floating-point value from xmm2 and xmm3 to xmm1 register
VEX.LIG.F3.0F.WIG 10 /r VMOVSS xmm1, m32 | D | V/V | AVX | Load scalar single precision floating-point value from m32 to xmm1 register.
F3 0F 11 /r MOVSS xmm2/m32, xmm1 | C | V/V | SSE | Move scalar single precision floating-point value from xmm1 register to xmm2/m32.
VEX.LIG.F3.0F.WIG 11 /r VMOVSS xmm1, xmm2, xmm3 | E | V/V | AVX | Move scalar single precision floating-point value from xmm2 and xmm3 to xmm1 register.
VEX.LIG.F3.0F.WIG 11 /r VMOVSS m32, xmm1 | C | V/V | AVX | Move scalar single precision floating-point value from xmm1 register to m32.
EVEX.LLIG.F3.0F.W0 10 /r VMOVSS xmm1 {k1}{z}, xmm2, xmm3 | B | V/V | AVX512F | Move scalar single precision floating-point value from xmm2 and xmm3 to xmm1 register under writemask k1.
EVEX.LLIG.F3.0F.W0 10 /r VMOVSS xmm1 {k1}{z}, m32 | F | V/V | AVX512F | Move scalar single precision floating-point values from m32 to xmm1 under writemask k1.
EVEX.LLIG.F3.0F.W0 11 /r VMOVSS xmm1 {k1}{z}, xmm2, xmm3 | E | V/V | AVX512F | Move scalar single precision floating-point value from xmm2 and xmm3 to xmm1 register under writemask k1.
EVEX.LLIG.F3.0F.W0 11 /r VMOVSS m32 {k1}, xmm1 | G | V/V | AVX512F | Move scalar single precision floating-point values from xmm1 to m32 under writemask k1.

## Instruction Operand Encoding ¶

Op/En | Tuple Type | Operand 1 | Operand 2 | Operand 3 | Operand 4
--- | --- | --- | --- | --- | ---
A | N/A | ModRM:reg (r, w) | ModRM:r/m (r) | N/A | N/A
B | N/A | ModRM:reg (w) | VEX.vvvv (r) | ModRM:r/m (r) | N/A
C | N/A | ModRM:r/m (w) | ModRM:reg (r) | N/A | N/A
D | N/A | ModRM:reg (w) | ModRM:r/m (r) | N/A | N/A
E | N/A | ModRM:r/m (w) | EVEX.vvvv (r) | ModRM:reg (r) | N/A
F | Tuple1 Scalar | ModRM:reg (r, w) | ModRM:r/m (r) | N/A | N/A
G | Tuple1 Scalar | ModRM:r/m (w) | ModRM:reg (r) | N/A | N/A

## Description ¶

Moves a scalar single precision floating-point value from the source operand (second operand) to the destination operand (first operand). The source and destination operands can be XMM registers or 32-bit memory locations. This instruction can be used to move a single precision floating-point value to and from the low doubleword of an XMM register and a 32-bit memory location, or to move a single precision floating-point value between the low doublewords of two XMM registers. The instruction cannot be used to transfer data between memory locations.

Legacy version: When the source and destination operands are XMM registers, bits (MAXVL-1:32) of the corresponding destination register are unmodified. When the source operand is a memory location and destination

operand is an XMM registers, Bits (127:32) of the destination operand is cleared to all 0s, bits MAXVL:128 of the destination operand remains unchanged.

VEX and EVEX encoded register-register syntax: Moves a scalar single precision floating-point value from the second source operand (the third operand) to the low doubleword element of the destination operand (the first operand). Bits 127:32 of the destination operand are copied from the first source operand (the second operand). Bits (MAXVL-1:128) of the corresponding destination register are zeroed.

VEX and EVEX encoded memory load syntax: When the source operand is a memory location and destination operand is an XMM registers, bits MAXVL:32 of the destination operand is cleared to all 0s.

EVEX encoded versions: The low doubleword of the destination is updated according to the writemask.

Note: For memory store form instruction “VMOVSS m32, xmm1”, VEX.vvvv is reserved and must be 1111b otherwise instruction will #UD. For memory store form instruction “VMOVSS mv {k1}, xmm1”, EVEX.vvvv is reserved and must be 1111b otherwise instruction will #UD.

Software should ensure VMOVSS is encoded with VEX.L=0. Encoding VMOVSS with VEX.L=1 may encounter unpredictable behavior across different processor generations.

## Operation ¶

### VMOVSS (EVEX.LLIG.F3.0F.W0 11 /r When the Source Operand is Memory and the Destination is an XMM Register) ¶

    IF k1[0] or *no writemask*
        THEN DEST[31:0] := SRC[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[MAXVL-1:32] := 0

### VMOVSS (EVEX.LLIG.F3.0F.W0 10 /r When the Source Operand is an XMM Register and the Destination is Memory) ¶

    IF k1[0] or *no writemask*
        THEN DEST[31:0] := SRC[31:0]
        ELSE *DEST[31:0] remains unchanged* ; merging-masking
    FI;

### VMOVSS (EVEX.LLIG.F3.0F.W0 10/11 /r Where the Source and Destination are XMM Registers) ¶

    IF k1[0] or *no writemask*
        THEN DEST[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

### MOVSS (Legacy SSE Version When the Source and Destination Operands are Both XMM Registers) ¶

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

### VMOVSS (VEX.128.F3.0F 11 /r Where the Destination is an XMM Register) ¶

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

### VMOVSS (VEX.128.F3.0F 10 /r Where the Source and Destination are XMM Registers) ¶

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

### VMOVSS (VEX.128.F3.0F 10 /r When the Source Operand is Memory and the Destination is an XMM Register) ¶

    DEST[31:0] := SRC[31:0]
    DEST[MAXVL-1:32] := 0

### MOVSS/VMOVSS (When the Source Operand is an XMM Register and the Destination is Memory) ¶

    DEST[31:0] := SRC[31:0]

### MOVSS (Legacy SSE Version when the Source Operand is Memory and the Destination is an XMM Register) ¶

    DEST[31:0] := SRC[31:0]
    DEST[127:32] := 0
    DEST[MAXVL-1:128] (Unmodified)

## Intel C/C++ Compiler Intrinsic Equivalent ¶

    VMOVSS __m128 _mm_mask_load_ss(__m128 s, __mmask8 k, float * p);

    VMOVSS __m128 _mm_maskz_load_ss( __mmask8 k, float * p);

    VMOVSS __m128 _mm_mask_move_ss(__m128 sh, __mmask8 k, __m128 sl, __m128 a);

    VMOVSS __m128 _mm_maskz_move_ss( __mmask8 k, __m128 s, __m128 a);

    VMOVSS void _mm_mask_store_ss(float * p, __mmask8 k, __m128 a);

    MOVSS __m128 _mm_load_ss(float * p)

    MOVSS void_mm_store_ss(float * p, __m128 a)

    MOVSS __m128 _mm_move_ss(__m128 a, __m128 b)

## SIMD Floating-Point Exceptions ¶

None.

## Other Exceptions ¶

Non-EVEX-encoded instruction, see Table 2-22, “Type 5 Class Exception Conditions,” additionally:

#UD | If VEX.vvvv != 1111B.

EVEX-encoded instruction, see Table 2-58, “Type E10 Class Exception Conditions.”