x86 Instruction Set Reference

MOVQ

Move Quadword

Opcode Mnemonic Description
0F 6F /r MOVQ mm, mm/m64 Move quadword from mm/m64 to mm.
0F 7F /r MOVQ mm/m64, mm Move quadword from mm to mm/m64.
F3 0F 7E MOVQ xmm1, xmm2/m64 Move quadword from xmm2/mem64 to xmm1.
66 0F D6 MOVQ xmm2/m64, xmm1 Move quadword from xmm1 to xmm2/mem64.
Description

Copies a quadword from the source operand (second operand) to the destination operand (first operand). The source and destination operands can be MMX technology registers, XMM registers, or 64-bit memory locations. This instruction can be used to move a quadword between two MMX technology registers or between an MMX technology register and a 64-bit memory location, or to move data between two XMM registers or between an XMM register and a 64-bit memory location. The instruction cannot be used to transfer data between memory locations.

When the source operand is an XMM register, the low quadword is moved; when the destination operand is an XMM register, the quadword is stored to the low quadword of the register, and the high quadword is cleared to all 0s.
Operation 
//MOVQ instruction when operating on MMX technology registers and memory locations:
if(IsMMX(Source) || IsMMX(Destination)) Destination = Source;
//MOVQ instruction when source and destination operands are XMM registers:
else if(IsXMM(Source) && IsXMM(Destination)) Destination[0..63] = Source[0..63];
//MOVQ instruction when source operand is XMM register and destination operand is memory location:
else if(IsXMM(Source) && IsMemory(Destination)) Destination = Source[0..63];
//MOVQ instruction when source operand is memory location and destination operand is XMM register:
else {
	Destination[0..63] = Source;
	Destination[64..127] = 0;
}
Flags affected

None.

SIMD Floating-Point Exceptions
None.
Protected Mode Exceptions
#GP(0)If the destination operand is in a non-writable segment. If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
#GP(0)If the destination operand is in a non-writable segment. If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
#SS(0)If a memory operand effective address is outside the SS segment limit.
#UDIf EM in CR0 is set. 128-bit operations will generate #UD only if OSFXSR in CR4 is 0. Execution of 128-bit instructions on a non-SSE2 capable processor (one that is MMX technology capable) will result in the instruction operating on the mm registers, not #UD.
#NMIf TS in CR0 is set.
#MF(MMX technology register operations only.) If there is a pending FPU exception.
#PF(fault-code)If a page fault occurs.
Real-Address Mode Exceptions
#GPIf any part of the operand lies outside of the effective address space from 0 to FFFFH.
#GPIf any part of the operand lies outside of the effective address space from 0 to FFFFH.
#UDIf EM in CR0 is set. 128-bit operations will generate #UD only if OSFXSR in CR4 is 0. Execution of 128-bit instructions on a non-SSE2 capable processor (one that is MMX technology capable) will result in the instruction operating on the mm registers, not #UD.
#NMIf TS in CR0 is set.
Virtual-8086 Mode Exceptions
Same exceptions as in Real Address Mode
#PF(fault-code)If a page fault occurs.
#PF(fault-code)If a page fault occurs.
Instruction Latency Throughput Execution Unit
CPUID0F3n/0F2n/069n0F3n/0F2n/069n0F2n
MOVQ mm, mm6/6/-1/1/-FP_MOV
MOVQ xmm, xmm2/2/12/2/1MMX_SHFT