PCMPEQB/PCMPEQW/PCMPEQD - Compare Packed Data for Equal

Opcode/ Instruction

Op/ En

64/32 bit Mode Support

CPUID Feature Flag

Description

NP 0F 74 /r1

PCMPEQB mm, mm/m64

A

V/V

MMX

Compare packed bytes in mm/m64 and mm for equality.

66 0F 74 /r

PCMPEQB xmm1, xmm2/m128

A

V/V

SSE2

Compare packed bytes in xmm2/m128 and xmm1 for equality.

NP 0F 75 /r1

PCMPEQW mm, mm/m64

A

V/V

MMX

Compare packed words in mm/m64 and mm for equality.

66 0F 75 /r

PCMPEQW xmm1, xmm2/m128

A

V/V

SSE2

Compare packed words in xmm2/m128 and xmm1 for equality.

NP 0F 76 /r1

PCMPEQD mm, mm/m64

A

V/V

MMX

Compare packed doublewords in mm/m64 and mm for equality.

66 0F 76 /r

PCMPEQD xmm1, xmm2/m128

A

V/V

SSE2

Compare packed doublewords in xmm2/m128 and xmm1 for equality.

VEX.128.66.0F.WIG 74 /r

VPCMPEQB xmm1, xmm2, xmm3/m128

B

V/V

AVX

Compare packed bytes in xmm3/m128 and xmm2 for equality.

VEX.128.66.0F.WIG 75 /r

VPCMPEQW xmm1, xmm2, xmm3/m128

B

V/V

AVX

Compare packed words in xmm3/m128 and xmm2 for equality.

VEX.128.66.0F.WIG 76 /r

VPCMPEQD xmm1, xmm2, xmm3/m128

B

V/V

AVX

Compare packed doublewords in xmm3/m128 and xmm2 for equality.

VEX.256.66.0F.WIG 74 /r VPCMPEQB ymm1, ymm2, ymm3 /m256

B

V/V

AVX2

Compare packed bytes in ymm3/m256 and ymm2 for equality.

VEX.256.66.0F.WIG 75 /r

VPCMPEQW ymm1, ymm2, ymm3 /m256

B

V/V

AVX2

Compare packed words in ymm3/m256 and ymm2 for equality.

VEX.256.66.0F.WIG 76 /r

VPCMPEQD ymm1, ymm2, ymm3 /m256

B

V/V

AVX2

Compare packed doublewords in ymm3/m256 and ymm2 for equality.

EVEX.128.66.0F.W0 76 /r VPCMPEQD k1 {k2}, xmm2, xmm3/m128/m32bcst

C

V/V

AVX512VL AVX512F

Compare Equal between int32 vector xmm2 and int32 vector xmm3/m128/m32bcst, and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.256.66.0F.W0 76 /r VPCMPEQD k1 {k2}, ymm2, ymm3/m256/m32bcst

C

V/V

AVX512VL AVX512F

Compare Equal between int32 vector ymm2 and int32 vector ymm3/m256/m32bcst, and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.512.66.0F.W0 76 /r VPCMPEQD k1 {k2}, zmm2, zmm3/m512/m32bcst

C

V/V

AVX512F

Compare Equal between int32 vectors in zmm2 and zmm3/m512/m32bcst, and set destination k1 according to the comparison results under writemask k2.

EVEX.128.66.0F.WIG 74 /r VPCMPEQB k1 {k2}, xmm2, xmm3 /m128

D

V/V

AVX512VL AVX512BW

Compare packed bytes in xmm3/m128 and xmm2 for equality and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.256.66.0F.WIG 74 /r VPCMPEQB k1 {k2}, ymm2, ymm3 /m256

D

V/V

AVX512VL AVX512BW

Compare packed bytes in ymm3/m256 and ymm2 for equality and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.512.66.0F.WIG 74 /r VPCMPEQB k1 {k2}, zmm2, zmm3 /m512

D

V/V

AVX512BW Compare packed bytes in zmm3/m512 and

zmm2 for equality and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.128.66.0F.WIG 75 /r VPCMPEQW k1 {k2}, xmm2, xmm3 /m128

D

V/V

AVX512VL AVX512BW

Compare packed words in xmm3/m128 and xmm2 for equality and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.256.66.0F.WIG 75 /r VPCMPEQW k1 {k2}, ymm2, ymm3 /m256

D

V/V

AVX512VL AVX512BW

Compare packed words in ymm3/m256 and ymm2 for equality and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

EVEX.512.66.0F.WIG 75 /r VPCMPEQW k1 {k2}, zmm2, zmm3 /m512

D

V/V

AVX512BW Compare packed words in zmm3/m512 and

zmm2 for equality and set vector mask k1 to reflect the zero/nonzero status of each element of the result, under writemask.

NOTES:

1. See note in Section 2.5, "Intel® AVX and Intel® SSE Instruction Exception Classification," in the Intel® 64 and IA-32 Architectures Soft-

ware Developer's Manual, Volume 2A, and Section 23.25.3, "Exception Conditions of Legacy SIMD Instructions Operating on MMX

Registers," in the Intel® 64 and IA-32 Architectures Software Developer's Manual, Volume 3B.

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

D

Full Mem

ModRM:reg (w)

EVEX.vvvv (r)

ModRM:r/m (r)

N/A

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

COMPARE_WORDS_EQUAL (SRC1, SRC2)

   IF SRC1[15:0] = SRC2[15:0]
   THEN DEST[15:0] := FFFFH;
   ELSE DEST[15:0] := 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] := FFFFH;
   ELSE DEST[127:112] := 0; FI;

COMPARE_DWORDS_EQUAL (SRC1, SRC2)

   IF SRC1[31:0] = SRC2[31:0]
   THEN DEST[31:0] := FFFFFFFFH;
   ELSE DEST[31:0] := 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] := FFFFFFFFH;
   ELSE DEST[127:96] := 0; FI;

PCMPEQB (With 128-bit Operands)

DEST[127:0] := COMPARE_BYTES_EQUAL(DEST[127:0],SRC[127:0])
DEST[MAXVL-1:128] (Unmodified)

VPCMPEQB (VEX.128 Encoded Version)

DEST[127:0] := COMPARE_BYTES_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[MAXVL-1:128] := 0

VPCMPEQB (VEX.256 Encoded Version)

DEST[127:0] := COMPARE_BYTES_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] := COMPARE_BYTES_EQUAL(SRC1[255:128],SRC2[255:128])
DEST[MAXVL-1:256] := 0

VPCMPEQB (EVEX Encoded Versions)

(KL, VL) = (16, 128), (32, 256), (64, 512)
FOR j := 0 TO KL-1
   i := j * 8
   IF k2[j] OR *no writemask*
       THEN 
            /* signed comparison */
            CMP := SRC1[i+7:i] == SRC2[i+7:i];
            IF CMP = TRUE
                THEN DEST[j] := 1;
                ELSE DEST[j] := 0; FI;
       ELSE     DEST[j] := 0                ; zeroing-masking onlyFI;
   FI;
ENDFOR
DEST[MAX_KL-1:KL] := 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] := COMPARE_WORDS_EQUAL(DEST[127:0],SRC[127:0])
DEST[MAXVL-1:128] (Unmodified)

VPCMPEQW (VEX.128 Encoded Version)

DEST[127:0] := COMPARE_WORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[MAXVL-1:128] := 0

VPCMPEQW (VEX.256 Encoded Version)

DEST[127:0] := COMPARE_WORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] := COMPARE_WORDS_EQUAL(SRC1[255:128],SRC2[255:128])
DEST[MAXVL-1:256] := 0

VPCMPEQW (EVEX Encoded Versions)

(KL, VL) = (8, 128), (16, 256), (32, 512)
FOR j := 0 TO KL-1
   i := j * 16
   IF k2[j] OR *no writemask*
       THEN 
            /* signed comparison */
            CMP := SRC1[i+15:i] == SRC2[i+15:i];
            IF CMP = TRUE
                THEN DEST[j] := 1;
                ELSE DEST[j] := 0; FI;
       ELSE     DEST[j] := 0                ; zeroing-masking onlyFI;
   FI;
ENDFOR
DEST[MAX_KL-1:KL] := 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] := COMPARE_DWORDS_EQUAL(DEST[127:0],SRC[127:0])
DEST[MAXVL-1:128] (Unmodified)

VPCMPEQD (VEX.128 Encoded Version)

DEST[127:0] := COMPARE_DWORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[MAXVL-1:128] := 0

VPCMPEQD (VEX.256 Encoded Version)

DEST[127:0] := COMPARE_DWORDS_EQUAL(SRC1[127:0],SRC2[127:0])
DEST[255:128] := COMPARE_DWORDS_EQUAL(SRC1[255:128],SRC2[255:128])
DEST[MAXVL-1:256] := 0

VPCMPEQD (EVEX Encoded Versions)

(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
   i := j * 32
   IF k2[j] OR *no writemask*
       THEN 
            /* signed comparison */
            IF (EVEX.b = 1) AND (SRC2 *is memory*)
                THEN CMP := SRC1[i+31:i] = SRC2[31:0];
                ELSE CMP := SRC1[i+31:i] = SRC2[i+31: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 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 Table 2-21, "Type 4 Class Exception Conditions." EVEX-encoded VPCMPEQD, see Table 2-49, "Type E4 Class Exception Conditions." EVEX-encoded VPCMPEQB/W, see Exceptions Type E4.nb in Table 2-49, "Type E4 Class Exception Conditions."