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 transaction- ally 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.