CMOVcc — Conditional Move

Opcode Instruction Op/En 64-Bit Mode Compat/Leg Mode Description
0F 47 /r CMOVA r16, r/m16 RM Valid Valid Move if above (CF=0 and ZF=0).
0F 47 /r CMOVA r32, r/m32 RM Valid Valid Move if above (CF=0 and ZF=0).
REX.W + 0F 47 /r CMOVA r64, r/m64 RM Valid N.E. Move if above (CF=0 and ZF=0).
0F 43 /r CMOVAE r16, r/m16 RM Valid Valid Move if above or equal (CF=0).
0F 43 /r CMOVAE r32, r/m32 RM Valid Valid Move if above or equal (CF=0).
REX.W + 0F 43 /r CMOVAE r64, r/m64 RM Valid N.E. Move if above or equal (CF=0).
0F 42 /r CMOVB r16, r/m16 RM Valid Valid Move if below (CF=1).
0F 42 /r CMOVB r32, r/m32 RM Valid Valid Move if below (CF=1).
REX.W + 0F 42 /r CMOVB r64, r/m64 RM Valid N.E. Move if below (CF=1).
0F 46 /r CMOVBE r16, r/m16 RM Valid Valid Move if below or equal (CF=1 or ZF=1).
0F 46 /r CMOVBE r32, r/m32 RM Valid Valid Move if below or equal (CF=1 or ZF=1).
REX.W + 0F 46 /r CMOVBE r64, r/m64 RM Valid N.E. Move if below or equal (CF=1 or ZF=1).
0F 42 /r CMOVC r16, r/m16 RM Valid Valid Move if carry (CF=1).
0F 42 /r CMOVC r32, r/m32 RM Valid Valid Move if carry (CF=1).
REX.W + 0F 42 /r CMOVC r64, r/m64 RM Valid N.E. Move if carry (CF=1).
0F 44 /r CMOVE r16, r/m16 RM Valid Valid Move if equal (ZF=1).
0F 44 /r CMOVE r32, r/m32 RM Valid Valid Move if equal (ZF=1).
REX.W + 0F 44 /r CMOVE r64, r/m64 RM Valid N.E. Move if equal (ZF=1).
0F 4F /r CMOVG r16, r/m16 RM Valid Valid Move if greater (ZF=0 and SF=OF).
0F 4F /r CMOVG r32, r/m32 RM Valid Valid Move if greater (ZF=0 and SF=OF).
REX.W + 0F 4F /r CMOVG r64, r/m64 RM V/N.E. N/A Move if greater (ZF=0 and SF=OF).
0F 4D /r CMOVGE r16, r/m16 RM Valid Valid Move if greater or equal (SF=OF).
0F 4D /r CMOVGE r32, r/m32 RM Valid Valid Move if greater or equal (SF=OF).
REX.W + 0F 4D /r CMOVGE r64, r/m64 RM Valid N.E. Move if greater or equal (SF=OF).
0F 4C /r CMOVL r16, r/m16 RM Valid Valid Move if less (SF≠ OF).
0F 4C /r CMOVL r32, r/m32 RM Valid Valid Move if less (SF≠ OF).
REX.W + 0F 4C /r CMOVL r64, r/m64 RM Valid N.E. Move if less (SF≠ OF).
0F 4E /r CMOVLE r16, r/m16 RM Valid Valid Move if less or equal (ZF=1 or SF≠ OF).
0F 4E /r CMOVLE r32, r/m32 RM Valid Valid Move if less or equal (ZF=1 or SF≠ OF).
REX.W + 0F 4E /r CMOVLE r64, r/m64 RM Valid N.E. Move if less or equal (ZF=1 or SF≠ OF).
0F 46 /r CMOVNA r16, r/m16 RM Valid Valid Move if not above (CF=1 or ZF=1).
0F 46 /r CMOVNA r32, r/m32 RM Valid Valid Move if not above (CF=1 or ZF=1).
REX.W + 0F 46 /r CMOVNA r64, r/m64 RM Valid N.E. Move if not above (CF=1 or ZF=1).
0F 42 /r CMOVNAE r16, r/m16 RM Valid Valid Move if not above or equal (CF=1).
0F 42 /r CMOVNAE r32, r/m32 RM Valid Valid Move if not above or equal (CF=1).
REX.W + 0F 42 /r CMOVNAE r64, r/m64 RM Valid N.E. Move if not above or equal (CF=1).
0F 43 /r CMOVNB r16, r/m16 RM Valid Valid Move if not below (CF=0).
0F 43 /r CMOVNB r32, r/m32 RM Valid Valid Move if not below (CF=0).
REX.W + 0F 43 /r CMOVNB r64, r/m64 RM Valid N.E. Move if not below (CF=0).
0F 47 /r CMOVNBE r16, r/m16 RM Valid Valid Move if not below or equal (CF=0 and ZF=0).
0F 47 /r CMOVNBE r32, r/m32 RM Valid Valid Move if not below or equal (CF=0 and ZF=0).
REX.W + 0F 47 /r CMOVNBE r64, r/m64 RM Valid N.E. Move if not below or equal (CF=0 and ZF=0).
0F 43 /r CMOVNC r16, r/m16 RM Valid Valid Move if not carry (CF=0).
0F 43 /r CMOVNC r32, r/m32 RM Valid Valid Move if not carry (CF=0).
REX.W + 0F 43 /r CMOVNC r64, r/m64 RM Valid N.E. Move if not carry (CF=0).
0F 45 /r CMOVNE r16, r/m16 RM Valid Valid Move if not equal (ZF=0).
0F 45 /r CMOVNE r32, r/m32 RM Valid Valid Move if not equal (ZF=0).
REX.W + 0F 45 /r CMOVNE r64, r/m64 RM Valid N.E. Move if not equal (ZF=0).
0F 4E /r CMOVNG r16, r/m16 RM Valid Valid Move if not greater (ZF=1 or SF≠ OF).
0F 4E /r CMOVNG r32, r/m32 RM Valid Valid Move if not greater (ZF=1 or SF≠ OF).
REX.W + 0F 4E /r CMOVNG r64, r/m64 RM Valid N.E. Move if not greater (ZF=1 or SF≠ OF).
0F 4C /r CMOVNGE r16, r/m16 RM Valid Valid Move if not greater or equal (SF≠ OF).
0F 4C /r CMOVNGE r32, r/m32 RM Valid Valid Move if not greater or equal (SF≠ OF).
REX.W + 0F 4C /r CMOVNGE r64, r/m64 RM Valid N.E. Move if not greater or equal (SF≠ OF).
0F 4D /r CMOVNL r16, r/m16 RM Valid Valid Move if not less (SF=OF).
0F 4D /r CMOVNL r32, r/m32 RM Valid Valid Move if not less (SF=OF).
REX.W + 0F 4D /r CMOVNL r64, r/m64 RM Valid N.E. Move if not less (SF=OF).
0F 4F /r CMOVNLE r16, r/m16 RM Valid Valid Move if not less or equal (ZF=0 and SF=OF).
0F 4F /r CMOVNLE r32, r/m32 RM Valid Valid Move if not less or equal (ZF=0 and SF=OF).
REX.W + 0F 4F /r CMOVNLE r64, r/m64 RM Valid N.E. Move if not less or equal (ZF=0 and SF=OF).
0F 41 /r CMOVNO r16, r/m16 RM Valid Valid Move if not overflow (OF=0).
0F 41 /r CMOVNO r32, r/m32 RM Valid Valid Move if not overflow (OF=0).
REX.W + 0F 41 /r CMOVNO r64, r/m64 RM Valid N.E. Move if not overflow (OF=0).
0F 4B /r CMOVNP r16, r/m16 RM Valid Valid Move if not parity (PF=0).
0F 4B /r CMOVNP r32, r/m32 RM Valid Valid Move if not parity (PF=0).
REX.W + 0F 4B /r CMOVNP r64, r/m64 RM Valid N.E. Move if not parity (PF=0).
0F 49 /r CMOVNS r16, r/m16 RM Valid Valid Move if not sign (SF=0).
0F 49 /r CMOVNS r32, r/m32 RM Valid Valid Move if not sign (SF=0).
REX.W + 0F 49 /r CMOVNS r64, r/m64 RM Valid N.E. Move if not sign (SF=0).
0F 45 /r CMOVNZ r16, r/m16 RM Valid Valid Move if not zero (ZF=0).
0F 45 /r CMOVNZ r32, r/m32 RM Valid Valid Move if not zero (ZF=0).
REX.W + 0F 45 /r CMOVNZ r64, r/m64 RM Valid N.E. Move if not zero (ZF=0).
0F 40 /r CMOVO r16, r/m16 RM Valid Valid Move if overflow (OF=1).
0F 40 /r CMOVO r32, r/m32 RM Valid Valid Move if overflow (OF=1).
REX.W + 0F 40 /r CMOVO r64, r/m64 RM Valid N.E. Move if overflow (OF=1).
0F 4A /r CMOVP r16, r/m16 RM Valid Valid Move if parity (PF=1).
0F 4A /r CMOVP r32, r/m32 RM Valid Valid Move if parity (PF=1).
REX.W + 0F 4A /r CMOVP r64, r/m64 RM Valid N.E. Move if parity (PF=1).
0F 4A /r CMOVPE r16, r/m16 RM Valid Valid Move if parity even (PF=1).
0F 4A /r CMOVPE r32, r/m32 RM Valid Valid Move if parity even (PF=1).
REX.W + 0F 4A /r CMOVPE r64, r/m64 RM Valid N.E. Move if parity even (PF=1).
0F 4B /r CMOVPO r16, r/m16 RM Valid Valid Move if parity odd (PF=0).
0F 4B /r CMOVPO r32, r/m32 RM Valid Valid Move if parity odd (PF=0).
REX.W + 0F 4B /r CMOVPO r64, r/m64 RM Valid N.E. Move if parity odd (PF=0).
0F 48 /r CMOVS r16, r/m16 RM Valid Valid Move if sign (SF=1).
0F 48 /r CMOVS r32, r/m32 RM Valid Valid Move if sign (SF=1).
REX.W + 0F 48 /r CMOVS r64, r/m64 RM Valid N.E. Move if sign (SF=1).
0F 44 /r CMOVZ r16, r/m16 RM Valid Valid Move if zero (ZF=1).
0F 44 /r CMOVZ r32, r/m32 RM Valid Valid Move if zero (ZF=1).
REX.W + 0F 44 /r CMOVZ r64, r/m64 RM Valid N.E. Move if zero (ZF=1).

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (r, w) ModRM:r/m (r) N/A N/A

Description

Each of the CMOVcc instructions performs a move operation if the status flags in the EFLAGS register (CF, OF, PF, SF, and ZF) are in a specified state (or condition). A condition code (cc) is associated with each instruction to indicate the condition being tested for. If the condition is not satisfied, a move is not performed and execution continues with the instruction following the CMOVcc instruction.

Specifically, CMOVcc loads data from its source operand into a temporary register unconditionally (regardless of the condition code and the status flags in the EFLAGS register). If the condition code associated with the instruction (cc) is satisfied, the data in the temporary register is then copied into the instruction's destination operand.

These instructions can move 16-bit, 32-bit or 64-bit values from memory to a general-purpose register or from one general-purpose register to another. Conditional moves of 8-bit register operands are not supported.

The condition for each CMOVcc mnemonic is given in the description column of the above table. The terms “less” and “greater” are used for comparisons of signed integers and the terms “above” and “below” are used for unsigned integers.

Because a particular state of the status flags can sometimes be interpreted in two ways, two mnemonics are defined for some opcodes. For example, the CMOVA (conditional move if above) instruction and the CMOVNBE (conditional move if not below or equal) instruction are alternate mnemonics for the opcode 0F 47H.

The CMOVcc instructions were introduced in P6 family processors; however, these instructions may not be supported by all IA-32 processors. Software can determine if the CMOVcc instructions are supported by checking the processor’s feature information with the CPUID instruction (see “CPUID—CPU Identification” in this chapter).

In 64-bit mode, the instruction’s default operation size is 32 bits. Use of the REX.R prefix permits access to additional registers (R8-R15). Use of the REX.W prefix promotes operation to 64 bits. See the summary chart at the beginning of this section for encoding data and limits.

Operation

temp := SRC
IF condition TRUE
    THEN DEST := temp;
ELSE IF (OperandSize = 32 and IA-32e mode active)
    THEN DEST[63:32] := 0;
FI;

Flags Affected

None.

Protected Mode Exceptions

#GP(0) If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
If the DS, ES, FS, or GS register contains a NULL segment selector.
#SS(0) If a memory operand effective address is outside the SS segment limit.
#PF(fault-code) If a page fault occurs.
#AC(0) If alignment checking is enabled and an unaligned memory reference is made while the current privilege level is 3.
#UD If the LOCK prefix is used.

Real-Address Mode Exceptions

#GP If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
#SS If a memory operand effective address is outside the SS segment limit.
#UD If the LOCK prefix is used.

Virtual-8086 Mode Exceptions

#GP(0) 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.
#PF(fault-code) If a page fault occurs.
#AC(0) If alignment checking is enabled and an unaligned memory reference is made.
#UD If the LOCK prefix is used.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

#SS(0) If a memory address referencing the SS segment is in a non-canonical form.
#GP(0) If the memory address is in a non-canonical form.
#PF(fault-code) If a page fault occurs.
#AC(0) If alignment checking is enabled and an unaligned memory reference is made while the current privilege level is 3.
#UD If the LOCK prefix is used.