x86doc › KTESTW/KTESTB/KTESTQ/KTESTD - Packed Bit Test Masks and Set Flags

KTESTW/KTESTB/KTESTQ/KTESTD—Packed Bit Test Masks and Set Flags

Opcode/Instruction	Op En	64/32 bit Mode Support	CPUID Feature Flag	Description
VEX.L0.0F.W0 99 /r KTESTW k1, k2	RR	V/V	AVX512DQ	Set ZF and CF depending on sign bit AND and ANDN of 16 bits mask register sources.
VEX.L0.66.0F.W0 99 /r KTESTB k1, k2	RR	V/V	AVX512DQ	Set ZF and CF depending on sign bit AND and ANDN of 8 bits mask reg-ister sources.
VEX.L0.0F.W1 99 /r KTESTQ k1, k2	RR	V/V	AVX512BW	Set ZF and CF depending on sign bit AND and ANDN of 64 bits mask register sources.
VEX.L0.66.0F.W1 99 /r KTESTD k1, k2	RR	V/V	AVX512BW	Set ZF and CF depending on sign bit AND and ANDN of 32 bits mask register sources.

Instruction Operand Encoding

Op/En	Operand 1	Operand 2
RR	ModRM:reg (r)	ModRM:r/m (r, ModRM:[7:6] must be 11b)

Description

Performs a bitwise comparison of the bits of the first source operand and corresponding bits in the second source operand. If the AND operation produces all zeros, the ZF is set else the ZF is clear. If the bitwise AND operation of the inverted first source operand with the second source operand produces all zeros the CF is set else the CF is clear. Only the EFLAGS register is updated.

Note: In VEX-encoded versions, VEX.vvvv is reserved and must be 1111b, otherwise instructions will #UD.

Operation

KTESTW

TEMP[15:0] := SRC2[15:0] AND SRC1[15:0]
IF (TEMP[15:0] = = 0)
    THEN ZF :=1;
    ELSE ZF := 0;
FI;
TEMP[15:0] := SRC2[15:0] AND NOT SRC1[15:0]
IF (TEMP[15:0] = = 0)
    THEN CF :=1;
    ELSE CF := 0;
FI;
AF := OF := PF := SF := 0;

KTESTB

TEMP[7:0] := SRC2[7:0] AND SRC1[7:0]
IF (TEMP[7:0] = = 0)
    THEN ZF :=1;
    ELSE ZF := 0;
FI;
TEMP[7:0] := SRC2[7:0] AND NOT SRC1[7:0]
IF (TEMP[7:0] = = 0)
    THEN CF :=1;
    ELSE CF := 0;
FI;
AF := OF := PF := SF := 0;

KTESTQ

TEMP[63:0] := SRC2[63:0] AND SRC1[63:0]
IF (TEMP[63:0] = = 0)
    THEN ZF :=1;
    ELSE ZF := 0;
FI;
TEMP[63:0] := SRC2[63:0] AND NOT SRC1[63:0]
IF (TEMP[63:0] = = 0)
    THEN CF :=1;
    ELSE CF := 0;
FI;
AF := OF := PF := SF := 0;

KTESTD

TEMP[31:0] := SRC2[31:0] AND SRC1[31:0]
IF (TEMP[31:0] = = 0)
    THEN ZF :=1;
    ELSE ZF := 0;
FI;
TEMP[31:0] := SRC2[31:0] AND NOT SRC1[31:0]
IF (TEMP[31:0] = = 0)
    THEN CF :=1;
    ELSE CF := 0;
FI;
AF := OF := PF := SF := 0;

Intel C/C++ Compiler Intrinsic Equivalent

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Table 2-63, “TYPE K20 Exception Definition (VEX-Encoded OpMask Instructions w/o Memory Arg).”