PCMPEQB/PCMPEQW/PCMPEQD— Compare Packed Data for Equal

NOTES:

1. See note in Section 2.4, “AVX and SSE Instruction Exception Specification” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 2A and Section 22.25.3, “Exception Conditions of Legacy SIMD Instructions Operating on MMX Registers” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.

Instruction Operand Encoding

Description

Performs a SIMD compare for equality of the packed bytes, words, or doublewords 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 operand is set to all 1s; otherwise, it is set to all 0s.

The (V)PCMPEQB instruction compares the corresponding bytes in the destination and source operands; the (V)PCMPEQW instruction compares the corresponding words in the destination and source operands; and the (V)PCMPEQD instruction compares the corresponding doublewords in the destination and source operands.

In 64-bit mode and not encoded with VEX/EVEX, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

Legacy SSE instructions: The source operand can be an MMX technology register or a 64-bit memory location. The destination operand can be an MMX technology register.

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.

EVEX encoded VPCMPEQD: 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 32-bit memory location. The destination operand (first operand) is a mask register updated according to the writemask k2.

EVEX encoded VPCMPEQB/W: 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. The destination operand (first operand) is a mask register updated according to the writemask k2.

Operation

PCMPEQB (with 64-bit operands)

    IF DEST[7:0] = SRC[7:0]
         THEN DEST[7:0) ← FFH;
         ELSE DEST[7:0] ← 0; FI;
    (* Continue comparison of 2nd through 7th bytes in DEST and SRC *)
    IF DEST[63:56] = SRC[63:56]
         THEN DEST[63:56] ← FFH;
         ELSE DEST[63:56] ← 0; FI;

COMPARE_BYTES_EQUAL (SRC1, SRC2)

    IF SRC1[7:0] = SRC2[7:0]
    THEN DEST[7:0] (cid:197)FFH;
    ELSE DEST[7:0] (cid:197)0; FI;
(* Continue comparison of 2nd through 15th bytes in SRC1 and SRC2 *)
    IF SRC1[127:120] = SRC2[127:120]
    THEN DEST[127:120] (cid:197)FFH;
    ELSE DEST[127:120] (cid:197)0; FI;

COMPARE_WORDS_EQUAL (SRC1, SRC2)

    IF SRC1[15:0] = SRC2[15:0]
    THEN DEST[15:0] (cid:197)FFFFH;
    ELSE DEST[15:0] (cid:197)0; FI;
(* Continue comparison of 2nd through 7th 16-bit words in SRC1 and SRC2 *)
    IF SRC1[127:112] = SRC2[127:112]
    THEN DEST[127:112] (cid:197)FFFFH;
    ELSE DEST[127:112] (cid:197)0; FI;

COMPARE_DWORDS_EQUAL (SRC1, SRC2)

    IF SRC1[31:0] = SRC2[31:0]
    THEN DEST[31:0] (cid:197)FFFFFFFFH;
    ELSE DEST[31:0] (cid:197)0; FI;
(* Continue comparison of 2nd through 3rd 32-bit dwords in SRC1 and SRC2 *)
    IF SRC1[127:96] = SRC2[127:96]
    THEN DEST[127:96] (cid:197)FFFFFFFFH;
    ELSE DEST[127:96] (cid:197)0; FI;

PCMPEQB (with 128-bit operands)

DEST[127:0] (cid:197)COMPARE_BYTES_EQUAL(DEST[127:0],SRC[127:0])
DEST[MAX_VL-1:128] (Unmodified)

VPCMPEQB (VEX.128 encoded version)

DEST[127:0] (cid:197)COMPARE_BYTES_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[VLMAX-1:128] (cid:197) 0

VPCMPEQB (VEX.256 encoded version)

DEST[127:0] (cid:197)COMPARE_BYTES_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] (cid:197)COMPARE_BYTES_EQUAL(SRC1[255:128],SRC2[255:128])
DEST[VLMAX-1:256] (cid:197) 0

VPCMPEQB (EVEX encoded versions)

(KL, VL) = (16, 128), (32, 256), (64, 512)
FOR j (cid:197) 0 TO KL-1
    i (cid:197) j * 8
    IF k2[j] OR *no writemask*
         THEN
              /* signed comparison */
              CMP (cid:197) SRC1[i+7:i] == SRC2[i+7:i];
              IF CMP = TRUE
                    THEN DEST[j] (cid:197) 1;
                    ELSE DEST[j] (cid:197) 0; FI;
         ELSE
                    DEST[j] (cid:197) 0
                                                    ; zeroing-masking onlyFI;
    FI;
ENDFOR
DEST[MAX_KL-1:KL] (cid:197) 0

PCMPEQW (with 64-bit operands)

    IF DEST[15:0] = SRC[15:0]
         THEN DEST[15:0] ← FFFFH;
         ELSE DEST[15:0] ← 0; FI;
    (* Continue comparison of 2nd and 3rd words in DEST and SRC *)
    IF DEST[63:48] = SRC[63:48]
         THEN DEST[63:48] ← FFFFH;
         ELSE DEST[63:48] ← 0; FI;

PCMPEQW (with 128-bit operands)

DEST[127:0] (cid:197)COMPARE_WORDS_EQUAL(DEST[127:0],SRC[127:0])
DEST[MAX_VL-1:128] (Unmodified)

VPCMPEQW (VEX.128 encoded version)

DEST[127:0] (cid:197)COMPARE_WORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[VLMAX-1:128] (cid:197) 0

VPCMPEQW (VEX.256 encoded version)

DEST[127:0] (cid:197)COMPARE_WORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] (cid:197)COMPARE_WORDS_EQUAL(SRC1[255:128],SRC2[255:128])
DEST[VLMAX-1:256] (cid:197) 0

VPCMPEQW (EVEX encoded versions)

(KL, VL) = (8, 128), (16, 256), (32, 512)
FOR j (cid:197) 0 TO KL-1
    i (cid:197) j * 16
    IF k2[j] OR *no writemask*
         THEN
              /* signed comparison */
              CMP (cid:197) SRC1[i+15:i] == SRC2[i+15:i];
              IF CMP = TRUE
                    THEN DEST[j] (cid:197) 1;
                    ELSE DEST[j] (cid:197) 0; FI;
         ELSE
                    DEST[j] (cid:197) 0
                                                    ; zeroing-masking onlyFI;
    FI;
ENDFOR
DEST[MAX_KL-1:KL] (cid:197) 0

PCMPEQD (with 64-bit operands)

    IF DEST[31:0] = SRC[31:0]
         THEN DEST[31:0] ← FFFFFFFFH;
         ELSE DEST[31:0] ← 0; FI;
    IF DEST[63:32] = SRC[63:32]
         THEN DEST[63:32] ← FFFFFFFFH;
         ELSE DEST[63:32] ← 0; FI;

PCMPEQD (with 128-bit operands)

DEST[127:0] (cid:197)COMPARE_DWORDS_EQUAL(DEST[127:0],SRC[127:0])
DEST[MAX_VL-1:128] (Unmodified)

VPCMPEQD (VEX.128 encoded version)

DEST[127:0] (cid:197)COMPARE_DWORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[VLMAX-1:128] (cid:197) 0

VPCMPEQD (VEX.256 encoded version)

DEST[127:0] (cid:197)COMPARE_DWORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] (cid:197)COMPARE_DWORDS_EQUAL(SRC1[255:128],SRC2[255:128])
DEST[VLMAX-1:256] (cid:197) 0

VPCMPEQD (EVEX encoded versions)

(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j (cid:197) 0 TO KL-1
    i (cid:197) j * 32
    IF k2[j] OR *no writemask*
         THEN
              /* signed comparison */
              IF (EVEX.b = 1) AND (SRC2 *is memory*)
                    THEN CMP (cid:197) SRC1[i+31:i] = SRC2[31:0];
                    ELSE CMP (cid:197) SRC1[i+31:i] = SRC2[i+31:i];
              FI;
              IF CMP = TRUE
                    THEN DEST[j] (cid:197) 1;
                    ELSE DEST[j] (cid:197) 0; FI;
         ELSE
                    DEST[j] (cid:197) 0
                                                    ; zeroing-masking only
    FI;
ENDFOR
DEST[MAX_KL-1:KL] (cid:197) 0

Intel C/C++ Compiler Intrinsic Equivalents

VPCMPEQB __mmask64 _mm512_cmpeq_epi8_mask(__m512i a, __m512i b);

VPCMPEQB __mmask64 _mm512_mask_cmpeq_epi8_mask(__mmask64 k, __m512i a, __m512i b);

VPCMPEQB __mmask32 _mm256_cmpeq_epi8_mask(__m256i a, __m256i b);

VPCMPEQB __mmask32 _mm256_mask_cmpeq_epi8_mask(__mmask32 k, __m256i a, __m256i b);

VPCMPEQB __mmask16 _mm_cmpeq_epi8_mask(__m128i a, __m128i b);

VPCMPEQB __mmask16 _mm_mask_cmpeq_epi8_mask(__mmask16 k, __m128i a, __m128i b);

VPCMPEQW __mmask32 _mm512_cmpeq_epi16_mask(__m512i a, __m512i b);

VPCMPEQW __mmask32 _mm512_mask_cmpeq_epi16_mask(__mmask32 k, __m512i a, __m512i b);

VPCMPEQW __mmask16 _mm256_cmpeq_epi16_mask(__m256i a, __m256i b);

VPCMPEQW __mmask16 _mm256_mask_cmpeq_epi16_mask(__mmask16 k, __m256i a, __m256i b);

VPCMPEQW __mmask8 _mm_cmpeq_epi16_mask(__m128i a, __m128i b);

VPCMPEQW __mmask8 _mm_mask_cmpeq_epi16_mask(__mmask8 k, __m128i a, __m128i b);

VPCMPEQD __mmask16 _mm512_cmpeq_epi32_mask( __m512i a, __m512i b);

VPCMPEQD __mmask16 _mm512_mask_cmpeq_epi32_mask(__mmask16 k, __m512i a, __m512i b);

VPCMPEQD __mmask8 _mm256_cmpeq_epi32_mask(__m256i a, __m256i b);

VPCMPEQD __mmask8 _mm256_mask_cmpeq_epi32_mask(__mmask8 k, __m256i a, __m256i b);

VPCMPEQD __mmask8 _mm_cmpeq_epi32_mask(__m128i a, __m128i b);

VPCMPEQD __mmask8 _mm_mask_cmpeq_epi32_mask(__mmask8 k, __m128i a, __m128i b);

PCMPEQB: __m64 _mm_cmpeq_pi8 (__m64 m1, __m64 m2)

PCMPEQW: __m64 _mm_cmpeq_pi16 (__m64 m1, __m64 m2)

PCMPEQD: __m64 _mm_cmpeq_pi32 (__m64 m1, __m64 m2)

(V)PCMPEQB: __m128i _mm_cmpeq_epi8 ( __m128i a, __m128i b)

(V)PCMPEQW: __m128i _mm_cmpeq_epi16 ( __m128i a, __m128i b)

(V)PCMPEQD: __m128i _mm_cmpeq_epi32 ( __m128i a, __m128i b)

VPCMPEQB:

__m256i _mm256_cmpeq_epi8 ( __m256i a, __m256i b)

VPCMPEQW:

__m256i _mm256_cmpeq_epi16 ( __m256i a, __m256i b)

VPCMPEQD:

__m256i _mm256_cmpeq_epi32 ( __m256i a, __m256i b)

Flags Affected

None.

SIMD Floating-Point Exceptions

None.

Other Exceptions

Non-EVEX-encoded instruction, see Exceptions Type 4.