XTEST — Test if in Transactional Execution

Opcode/Instruction	Op/En	64/32bit Mode Support	CPUID Feature Flag	Description
NP 0F 01 D6 XTEST	ZO	V/V	HLE or RTM	Test if executing in a transactional region.

Instruction Operand Encoding ¶

Op/En	Operand 1	Operand2	Operand3	Operand4
ZO	N/A	N/A	N/A	N/A

Description ¶

The XTEST instruction queries the transactional execution status. If the instruction executes inside a transactionally executing RTM region or a transactionally executing HLE region, then the ZF flag is cleared, else it is set.

Operation ¶

XTEST ¶

IF (RTM_ACTIVE = 1 OR HLE_ACTIVE = 1)
    THEN
        ZF := 0
    ELSE
        ZF := 1
FI;

Flags Affected ¶

The ZF flag is cleared if the instruction is executed transactionally; otherwise it is set to 1. The CF, OF, SF, PF, and AF, flags are cleared.

Intel C/C++ Compiler Intrinsic Equivalent ¶

XTEST int _xtest( void );

SIMD Floating-Point Exceptions ¶

None.

Other Exceptions ¶

#UD	CPUID.(EAX=7, ECX=0):EBX.HLE[bit 4] = 0 and CPUID.(EAX=7, ECX=0):EBX.RTM[bit 11] = 0.
	If LOCK prefix is used.