MOVLPD (Move Low Packed Double-Precision Floating-Point Value)

Opcodes

Opcode/Instruction Op/En 64/32-bit Mode CPUID Feature Flag Description
66 0F 12 /r MOVLPD xmm, m64 RM V/V SSE2 Move double-precision floating-point value from m64 to low quadword of xmm register.
66 0F 13 /r MOVLPD m64, xmm MR V/V SSE2 Move double-precision floating-point nvalue from low quadword of xmm register to m64.
VEX.NDS.128.66.0F.WIG 12 /r VMOVLPD xmm2, xmm1, m64 RVM V/V AVX Merge double-precision floating-point value from m64 and the high quadword of xmm1.
VEX.128.66.0F.WIG 13/r VMOVLPD m64, xmm1 MR V/V AVX Move double-precision floating-point values from low quadword of xmm1 to m64.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (r, w) ModRM:r/m (r) NA NA
MR ModRM:r/m (w) ModRM:reg (r) NA NA
RVM ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA

Description

This instruction cannot be used for register to register or memory to memory moves.

128-bit Legacy SSE load:

Moves a double-precision floating-point value from the source 64-bit memory operand and stores it in the low 64-bits of the destination XMM register. The upper 64bits of the XMM register are preserved. The upper 128-bits of the corresponding YMM destination register are preserved.

In 64-bit mode, use of the REX.R prefix permits this instruction to access additional registers (XMM8-XMM15).

VEX.128 encoded load:

Loads a double-precision floating-point value from the source 64-bit memory operand (third operand), merges it with the upper 64-bits of the first source XMM register (second operand), and stores it in the low 128-bits of the destination XMM register (first operand). The upper 128-bits of the destination YMM register are zeroed.

128-bit store:

Stores a double-precision floating-point value from the low 64-bits of the XMM register source (second operand) to the 64-bit memory location (first operand).

Note: VMOVLPD (store) (VEX.128.66.0F 13 /r) is legal and has the same behavior as the existing 66 0F 13 store. For VMOVLPD (store) (VEX.128.66.0F 13 /r) instruction version, VEX.vvvv is reserved and must be 1111b other-wise instruction will #UD.

If VMOVLPD is encoded with VEX.L= 1, an attempt to execute the instruction encoded with VEX.L= 1 will cause an #UD exception.

Operation

MOVLPD (128-bit Legacy SSE load)

DEST[63:0] ← SRC[63:0]
DEST[VLMAX-1:64] (Unmodified)

VMOVLPD (VEX.128 encoded load)

DEST[63:0] ← SRC2[63:0]
DEST[127:64] ← SRC1[127:64]
DEST[VLMAX-1:128] ← 0

VMOVLPD (store)

DEST[63:0] ← SRC[63:0]

Intel C/C++ Compiler Intrinsic Equivalent

MOVLPD:

__m128d _mm_loadl_pd ( __m128d a, double *p)

MOVLPD:

void _mm_storel_pd (double *p, __m128d a)

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type 5; additionally

#UD If VEX.L= 1. If VEX.vvvv ≠ 1111B.