vpopcntb

Packed Population Count Byte

VPOPCNTB zmm1 {k1}, zmm2/m512

Counts set bits in each byte.

Details

Counts the number of set bits (population count) in each byte of the source, writing the count (0–8) into the corresponding byte of the destination. This operates independently on each of 64 bytes in the ZMM register. No arithmetic flags are modified; the instruction is part of AVX-512-BITALG and supports masking via k1.

Pseudocode Operation

for i = 0 to 63:
  count = 0
  byte_val = zmm2[8*i+7:8*i]
  for bit = 0 to 7:
    if byte_val[bit] == 1:
      count += 1
  zmm1[8*i+7:8*i] ← count & k1_mask[i]

Example

VPOPCNTB zmm1, zmm2/m512

Encoding

Binary Layout

EVEX

Format EVEX

Opcode EVEX.512.66.0F38.W0 54 /r

Extension AVX-512-BITALG

Operands

dest
ZMM
src
ZMM/Mem

Reference (Intel® SDM)

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
EVEX.128.66.0F38.W0 54 /r	VPOPCNTB xmm1{k1}{z}, xmm2/m128	A	V/V	(AVX512_BITALG AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in xmm2/m128 and puts the result in xmm1 with writemask k1.
EVEX.256.66.0F38.W0 54 /r	VPOPCNTB ymm1{k1}{z}, ymm2/m256	A	V/V	(AVX512_BITALG AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in ymm2/m256 and puts the result in ymm1 with writemask k1.
EVEX.512.66.0F38.W0 54 /r	VPOPCNTB zmm1{k1}{z}, zmm2/m512	A	V/V	AVX512_BITALG OR AVX10.1	Counts the number of bits set to one in zmm2/m512 and puts the result in zmm1 with writemask k1.
EVEX.128.66.0F38.W1 54 /r	VPOPCNTW xmm1{k1}{z}, xmm2/m128	A	V/V	(AVX512_BITALG AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in xmm2/m128 and puts the result in xmm1 with writemask k1.
EVEX.256.66.0F38.W1 54 /r	VPOPCNTW ymm1{k1}{z}, ymm2/m256	A	V/V	(AVX512_BITALG AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in ymm2/m256 and puts the result in ymm1 with writemask k1.
EVEX.512.66.0F38.W1 54 /r	VPOPCNTW zmm1{k1}{z}, zmm2/m512	A	V/V	AVX512_BITALG OR AVX10.1	Counts the number of bits set to one in zmm2/m512 and puts the result in zmm1 with writemask k1.
EVEX.128.66.0F38.W0 55 /r	VPOPCNTD xmm1{k1}{z}, xmm2/m128/m32bcst	B	V/V	(AVX512_VPOPCNTDQ AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in xmm2/m128/m32bcst and puts the result in xmm1 with writemask k1.
EVEX.256.66.0F38.W0 55 /r	VPOPCNTD ymm1{k1}{z}, ymm2/m256/m32bcst	B	V/V	(AVX512_VPOPCNTDQ AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in ymm2/m256/m32bcst and puts the result in ymm1 with writemask k1.
EVEX.512.66.0F38.W0 55 /r	VPOPCNTD zmm1{k1}{z}, zmm2/m512/m32bcst	B	V/V	AVX512_VPOPCNTDQ OR AVX10.1	Counts the number of bits set to one in zmm2/m512/m32bcst and puts the result in zmm1 with writemask k1.
EVEX.128.66.0F38.W1 55 /r	VPOPCNTQ xmm1{k1}{z}, xmm2/m128/m64bcst	B	V/V	(AVX512_VPOPCNTDQ AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in xmm2/m128/m32bcst and puts the result in xmm1 with writemask k1.
EVEX.256.66.0F38.W1 55 /r	VPOPCNTQ ymm1{k1}{z}, ymm2/m256/m64bcst	B	V/V	(AVX512_VPOPCNTDQ AND AVX512VL) OR AVX10.1	Counts the number of bits set to one in ymm2/m256/m32bcst and puts the result in ymm1 with writemask k1.
EVEX.512.66.0F38.W1 55 /r	VPOPCNTQ zmm1{k1}{z}, zmm2/m512/m64bcst	B	V/V	AVX512_VPOPCNTDQ OR AVX10.1	Counts the number of bits set to one in zmm2/m512/m64bcst and puts the result in zmm1 with writemask k1.

Instruction Operand Encoding

Op/En	Tuple Type	Operand 1	Operand 2	Operand 3	Operand 4
A	Full Mem	ModRM:reg (w)	ModRM:r/m (r)	N/A	N/A
B	Full	ModRM:reg (w)	ModRM:r/m (r)	N/A	N/A

Description

This instruction counts the number of bits set to one in each byte, word, dword or qword element of its source (e.g., zmm2 or memory) and places the results in the destination register (zmm1). This instruction supports memory fault suppression. VPOPCNT—Return the Count of Number of Bits Set to 1 in BYTE/WORD/DWORD/QWORD Vol. 2C 5-606

Operation

VPOPCNTB
(KL, VL) = (16, 128), (32, 256), (64, 512)
FOR j := 0 TO KL-1:
IF MaskBit(j) OR *no writemask*:
DEST.byte[j] := POPCNT(SRC.byte[j])
ELSE IF *merging-masking*:
*DEST.byte[j] remains unchanged*
ELSE:
DEST.byte[j] := 0
DEST[MAX_VL-1:VL] := 0

VPOPCNTW
(KL, VL) = (8, 128), (16, 256), (32, 512)
FOR j := 0 TO KL-1:
IF MaskBit(j) OR *no writemask*:
DEST.word[j] := POPCNT(SRC.word[j])
ELSE IF *merging-masking*:
*DEST.word[j] remains unchanged*
ELSE:
DEST.word[j] := 0
DEST[MAX_VL-1:VL] := 0

VPOPCNTD
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1:
IF MaskBit(j) OR *no writemask*:
IF SRC is broadcast memop:
t := SRC.dword[0]
ELSE:
t := SRC.dword[j]
DEST.dword[j] := POPCNT(t)
ELSE IF *merging-masking*:
*DEST..dword[j] remains unchanged*
ELSE:
DEST..dword[j] := 0
DEST[MAX_VL-1:VL] := 0





VPOPCNT—Return the Count of Number of Bits Set to 1 in BYTE/WORD/DWORD/QWORD                                                     Vol. 2C 5-607
VPOPCNTQ
(KL, VL) = (2, 128), (4, 256), (8, 512)
FOR j := 0 TO KL-1:
IF MaskBit(j) OR *no writemask*:
IF SRC is broadcast memop:
t := SRC.qword[0]
ELSE:
t := SRC.qword[j]
DEST.qword[j] := POPCNT(t)
ELSE IF *merging-masking*:
*DEST..qword[j] remains unchanged*
ELSE:
DEST..qword[j] := 0
DEST[MAX_VL-1:VL] := 0

Intel C/C++ Compiler Intrinsic Equivalent

VPOPCNTW __m128i _mm_popcnt_epi16(__m128i);
VPOPCNTW __m128i _mm_mask_popcnt_epi16(__m128i, __mmask8, __m128i);
VPOPCNTW __m128i _mm_maskz_popcnt_epi16(__mmask8, __m128i);
VPOPCNTW __m256i _mm256_popcnt_epi16(__m256i);
VPOPCNTW __m256i _mm256_mask_popcnt_epi16(__m256i, __mmask16, __m256i);
VPOPCNTW __m256i _mm256_maskz_popcnt_epi16(__mmask16, __m256i);
VPOPCNTW __m512i _mm512_popcnt_epi16(__m512i);
VPOPCNTW __m512i _mm512_mask_popcnt_epi16(__m512i, __mmask32, __m512i);
VPOPCNTW __m512i _mm512_maskz_popcnt_epi16(__mmask32, __m512i);
VPOPCNTQ __m128i _mm_popcnt_epi64(__m128i);
VPOPCNTQ __m128i _mm_mask_popcnt_epi64(__m128i, __mmask8, __m128i);
VPOPCNTQ __m128i _mm_maskz_popcnt_epi64(__mmask8, __m128i);
VPOPCNTQ __m256i _mm256_popcnt_epi64(__m256i);
VPOPCNTQ __m256i _mm256_mask_popcnt_epi64(__m256i, __mmask8, __m256i);
VPOPCNTQ __m256i _mm256_maskz_popcnt_epi64(__mmask8, __m256i);
VPOPCNTQ __m512i _mm512_popcnt_epi64(__m512i);
VPOPCNTQ __m512i _mm512_mask_popcnt_epi64(__m512i, __mmask8, __m512i);
VPOPCNTQ __m512i _mm512_maskz_popcnt_epi64(__mmask8, __m512i);
VPOPCNTD __m128i _mm_popcnt_epi32(__m128i);
VPOPCNTD __m128i _mm_mask_popcnt_epi32(__m128i, __mmask8, __m128i);
VPOPCNTD __m128i _mm_maskz_popcnt_epi32(__mmask8, __m128i);
VPOPCNTD __m256i _mm256_popcnt_epi32(__m256i);
VPOPCNTD __m256i _mm256_mask_popcnt_epi32(__m256i, __mmask8, __m256i);
VPOPCNTD __m256i _mm256_maskz_popcnt_epi32(__mmask8, __m256i);
VPOPCNTD __m512i _mm512_popcnt_epi32(__m512i);
VPOPCNTD __m512i _mm512_mask_popcnt_epi32(__m512i, __mmask16, __m512i);
VPOPCNTD __m512i _mm512_maskz_popcnt_epi32(__mmask16, __m512i);
VPOPCNTB __m128i _mm_popcnt_epi8(__m128i);
VPOPCNTB __m128i _mm_mask_popcnt_epi8(__m128i, __mmask16, __m128i);
VPOPCNTB __m128i _mm_maskz_popcnt_epi8(__mmask16, __m128i);
VPOPCNTB __m256i _mm256_popcnt_epi8(__m256i);
VPOPCNTB __m256i _mm256_mask_popcnt_epi8(__m256i, __mmask32, __m256i);
VPOPCNTB __m256i _mm256_maskz_popcnt_epi8(__mmask32, __m256i);
VPOPCNTB __m512i _mm512_popcnt_epi8(__m512i);
VPOPCNTB __m512i _mm512_mask_popcnt_epi8(__m512i, __mmask64, __m512i);
VPOPCNTB __m512i _mm512_maskz_popcnt_epi8(__mmask64, __m512i);
VPOPCNT—Return the Count of Number of Bits Set to 1 in BYTE/WORD/DWORD/QWORD                                                     Vol. 2C 5-608

Exceptions

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Table 2-51, “Type E4 Class Exception Conditions.” VPOPCNT—Return the Count of Number of Bits Set to 1 in BYTE/WORD/DWORD/QWORD Vol. 2C 5-609