# PCMPEQQ — Compare Packed Qword Data for Equal

Opcode/Instruction | Op/En | 64/32 bit Mode Support | CPUID Feature Flag | Description
--- | --- | --- | --- | ---
66 0F 38 29 /r PCMPEQQ xmm1, xmm2/m128 | A | V/V | SSE4_1 | Compare packed qwords in xmm2/m128 and xmm1 for equality.
VEX.128.66.0F38.WIG 29 /r VPCMPEQQ xmm1, xmm2, xmm3/m128 | B | V/V | AVX | Compare packed quadwords in xmm3/m128 and xmm2 for equality.
VEX.256.66.0F38.WIG 29 /r VPCMPEQQ ymm1, ymm2, ymm3 /m256 | B | V/V | AVX2 | Compare packed quadwords in ymm3/m256 and ymm2 for equality.
EVEX.128.66.0F38.W1 29 /r VPCMPEQQ k1 {k2}, xmm2, xmm3/m128/m64bcst | C | V/V | AVX512VL AVX512F | Compare Equal between int64 vector xmm2 and int64 vector xmm3/m128/m64bcst, and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.
EVEX.256.66.0F38.W1 29 /r VPCMPEQQ k1 {k2}, ymm2, ymm3/m256/m64bcst | C | V/V | AVX512VL AVX512F | Compare Equal between int64 vector ymm2 and int64 vector ymm3/m256/m64bcst, and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.
EVEX.512.66.0F38.W1 29 /r VPCMPEQQ k1 {k2}, zmm2, zmm3/m512/m64bcst | C | V/V | AVX512F | Compare Equal between int64 vector zmm2 and int64 vector zmm3/m512/m64bcst, and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

## Instruction Operand Encoding ¶

Op/En | Tuple Type | Operand 1 | Operand 2 | Operand 3 | Operand 4
--- | --- | --- | --- | --- | ---
A | N/A | ModRM:reg (r, w) | ModRM:r/m (r) | N/A | N/A
B | N/A | ModRM:reg (w) | VEX.vvvv (r) | ModRM:r/m (r) | N/A
C | Full | ModRM:reg (w) | EVEX.vvvv (r) | ModRM:r/m (r) | N/A

## 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 destination 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 (MAXVL-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 (MAXVL-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.

EVEX encoded VPCMPEQQ: The first source operand (second operand) is a ZMM/YMM/XMM register. The second source operand can be a ZMM/YMM/XMM register, a 512/256/128-bit memory location or a 512/256/128-bit vector broadcasted from a 64-bit memory location. The destination operand (first operand) is a mask register updated according to the writemask k2.

## Operation ¶

### PCMPEQQ (With 128-bit Operands) ¶

    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;
    DEST[MAXVL-1:128] (Unmodified)

### COMPARE_QWORDS_EQUAL (SRC1, SRC2) ¶

    IF SRC1[63:0] = SRC2[63:0]
    THEN DEST[63:0] := FFFFFFFFFFFFFFFFH;
    ELSE DEST[63:0] := 0; FI;
    IF SRC1[127:64] = SRC2[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[MAXVL-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])
    DEST[MAXVL-1:256] := 0

### VPCMPEQQ (EVEX Encoded Versions) ¶

    (KL, VL) = (2, 128), (4, 256), (8, 512)
    FOR j := 0 TO KL-1
        i := j * 64
        IF k2[j] OR *no writemask*
            THEN
                IF (EVEX.b = 1) AND (SRC2 *is memory*)
                    THEN CMP := SRC1[i+63:i] = SRC2[63:0];
                    ELSE CMP := SRC1[i+63:i] = SRC2[i+63:i];
                FI;
                IF CMP = TRUE
                    THEN DEST[j] := 1;
                    ELSE DEST[j] := 0; FI;
            ELSE DEST[j] := 0
                        ; zeroing-masking only
        FI;
    ENDFOR
    DEST[MAX_KL-1:KL] := 0

## Intel C/C++ Compiler Intrinsic Equivalent ¶

    VPCMPEQQ __mmask8 _mm512_cmpeq_epi64_mask( __m512i a, __m512i b);

    VPCMPEQQ __mmask8 _mm512_mask_cmpeq_epi64_mask(__mmask8 k, __m512i a, __m512i b);

    VPCMPEQQ __mmask8 _mm256_cmpeq_epi64_mask( __m256i a, __m256i b);

    VPCMPEQQ __mmask8 _mm256_mask_cmpeq_epi64_mask(__mmask8 k, __m256i a, __m256i b);

    VPCMPEQQ __mmask8 _mm_cmpeq_epi64_mask( __m128i a, __m128i b);

    VPCMPEQQ __mmask8 _mm_mask_cmpeq_epi64_mask(__mmask8 k, __m128i a, __m128i b);

    (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 ¶

Non-EVEX-encoded instruction, see Table 2-21, “Type 4 Class Exception Conditions.”

EVEX-encoded VPCMPEQQ, see Table 2-49, “Type E4 Class Exception Conditions.”