PCMPEQQ (Compare Packed Qword Data for Equal)

Opcodes

Opcode/Instruction Op/En 64/32 bit Mode Support CPUID Feature Flag Description
66 0F 38 29 /r PCMPEQQ xmm1, xmm2/m128 RM V/V SSE4_1 Compare packed qwords in xmm2/m128 and xmm1 for equality.
VEX.NDS.128.66.0F38.WIG 29 /r VPCMPEQQ xmm1, xmm2, xmm3/m128 RVM V/V AVX Compare packed quadwords in xmm3/m128 and xmm2 for equality.
VEX.NDS.256.66.0F38.WIG 29 /r VPCMPEQQ ymm1, ymm2, ymm3 /m256 RVM V/V AVX2 Compare packed quadwords in ymm3/m256 and ymm2 for equality.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (r, w) ModRM:r/m (r) NA NA
RVM ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA

Description

Performs an SIMD compare for equality of the packed quadwords in the destination operand (first operand) and the source operand (second operand). If a pair of data elements is equal, the corresponding data element in the desti-nation is set to all 1s; otherwise, it is set to 0s.

128-bit Legacy SSE version: The second source operand can be an XMM register or a 128-bit memory location. The first source and destination operands are XMM registers. Bits (VLMAX-1:128) of the corresponding YMM destination register remain unchanged.

VEX.128 encoded version: The second source operand can be an XMM register or a 128-bit memory location. The first source and destination operands are XMM registers. Bits (VLMAX-1:128) of the corresponding YMM register are zeroed.

VEX.256 encoded version: The first source operand is a YMM register. The second source operand is a YMM register or a 256-bit memory location. The destination operand is a YMM register.

Note: VEX.L must be 0, otherwise the instruction will #UD.

Operation

IF (DEST[63:0] = SRC[63:0])
    THEN DEST[63:0] ← FFFFFFFFFFFFFFFFH;
    ELSE DEST[63:0] ← 0; FI;
IF (DEST[127:64] = SRC[127:64])
    THEN DEST[127:64] ← FFFFFFFFFFFFFFFFH;
    ELSE DEST[127:64] ← 0; FI;

VPCMPEQQ (VEX.128 encoded version)

DEST[127:0] ←COMPARE_QWORDS_EQUAL(SRC1,SRC2)
DEST[VLMAX-1:128] ← 0

VPCMPEQQ (VEX.256 encoded version)

DEST[127:0] ←COMPARE_QWORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] ←COMPARE_QWORDS_EQUAL(SRC1[255:128],SRC2[255:128])

Intel C/C++ Compiler Intrinsic Equivalent

(V)PCMPEQQ:

__m128i _mm_cmpeq_epi64(__m128i a, __m128i b);

VPCMPEQQ:

__m256i _mm256_cmpeq_epi64( __m256i a, __m256i b);

Flags Affected

None.

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type 4; additionally

#UD If VEX.L = 1.