| Opcode/Instruction | Op/En | 64/32-bit Mode | CPUID Feature Flag | Description |
|---|---|---|---|---|
|
F2 0F F0 /r LDDQU xmm1, mem |
RM | V/V | SSE3 | Load unaligned data from mem and return double quadword in xmm1. |
|
VEX.128.F2.0F.WIG F0 /r VLDDQU xmm1, m128 |
RM | V/V | AVX | Load unaligned packed integer values from mem to xmm1. |
|
VEX.256.F2.0F.WIG F0 /r VLDDQU ymm1, m256 |
RM | V/V | AVX | Load unaligned packed integer values from mem to ymm1. |
| Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
|---|---|---|---|---|
| RM | ModRM:reg (w) | ModRM:r/m (r) | N/A | N/A |
The instruction is functionally similar to (V)MOVDQU ymm/xmm, m256/m128 for loading from memory. That is: 32/16 bytes of data starting at an address specified by the source memory operand (second operand) are fetched from memory and placed in a destination register (first operand). The source operand need not be aligned on a 32/16-byte boundary. Up to 64/32 bytes may be loaded from memory; this is implementation dependent.
This instruction may improve performance relative to (V)MOVDQU if the source operand crosses a cache line boundary. In situations that require the data loaded by (V)LDDQU be modified and stored to the same location, use (V)MOVDQU or (V)MOVDQA instead of (V)LDDQU. To move a double quadword to or from memory locations that are known to be aligned on 16-byte boundaries, use the (V)MOVDQA instruction.
In 64-bit mode, use of the REX.R prefix permits this instruction to access additional registers (XMM8-XMM15).
Note: In VEX-encoded versions, VEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.
LDDQU (128-bit Legacy SSE Version)
DEST[127:0] := SRC[127:0] DEST[MAXVL-1:128] (Unmodified)
VLDDQU (VEX.128 Encoded Version)
DEST[127:0] := SRC[127:0] DEST[MAXVL-1:128] := 0
VLDDQU (VEX.256 Encoded Version)
DEST[255:0] := SRC[255:0]
LDDQU __m128i _mm_lddqu_si128 (__m128i * p);
VLDDQU __m256i _mm256_lddqu_si256 (__m256i * p);
None.
See Table 2-21, “Type 4 Class Exception Conditions.”
Note treatment of #AC varies.