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Source code

VPERMI2B

Full Permute of Bytes From Two Tables Overwriting the Index

stableVMJITAOTinstruction

Encodings

OpcodeInstructionOp/En64-bitCompat/LegacyDescription
EVEX.128.66.0F38.W0 75 /rVPERMI2B xmm1 {k1}{z}, xmm2, xmm3/m128AValidValidPermute bytes in xmm3/m128 and xmm2 using AVX512_VBMI) byte indexes in xmm1 and store the byte results OR AVX10.1 in xmm1 using writemask k1.
EVEX.256.66.0F38.W0 75 /rVPERMI2B ymm1 {k1}{z}, ymm2, ymm3/m256AValidValidPermute bytes in ymm3/m256 and ymm2 using AVX512_VBMI) byte indexes in ymm1 and store the byte results OR AVX10.1 in ymm1 using writemask k1.
EVEX.512.66.0F38.W0 75 /rVPERMI2B zmm1 {k1}{z}, zmm2, zmm3/m512AValidValidPermute bytes in zmm3/m512 and zmm2 using OR AVX10.1 byte indexes in zmm1 and store the byte results in zmm1 using writemask k1.

Operand encoding

Each mode is a value of the Op/En column above. It says which field of the encoded instruction carries each operand, in the order they are written, and whether the instruction reads it, writes it or both.

A

  1. modrm.reg lectura y escrituraModRM byte, reg field (bits 5-3)
  2. evex.vvvv lecturaEVEX prefix, vvvv field (inverted)
  3. modrm.rm lecturaModRM byte, r/m field (bits 2-0); with the SIB byte and the displacement when the mod field asks for them

Tupla: Full Mem

Measured cost

Loading measurements from arch-data...

Description

Permutes byte values in the second operand (the first source operand) and the third operand (the second source operand) using the byte indices in the first operand (the destination operand) to select byte elements from the second or third source operands. The selected byte elements are written to the destination at byte granularity under the writemask k1.

The first and second operands are ZMM/YMM/XMM registers. The first operand contains input indices to select elements from the two input tables in the 2nd and 3rd operands. The first operand is also the destination of the result. The third operand can be a ZMM/YMM/XMM register, or a 512/256/128-bit memory location. In each index byte, the id bit for table selection is bit 6/5/4, and bits [5:0]/[4:0]/[3:0] selects element within each input table.

Note that these instructions permit a byte value in the source operands to be copied to more than one location in the destination operand. Also, the same tables can be reused in subsequent iterations, but the index elements are overwritten.

Bits (MAX_VL-1:256/128) of the destination are zeroed for VL=256,128.

Operation

VPERMI2B (EVEX encoded versions)
(KL, VL) = (16, 128), (32, 256), (64, 512)
IF VL = 128:

    id := 3;
ELSE IF VL = 256:

    id := 4;
ELSE IF VL = 512:

    id := 5;
FI;
TMP_DEST[VL-1:0] := DEST[VL-1:0];
FOR j := 0 TO KL-1

    off := 8*SRC1[j*8 + id: j*8] ;
    IF k1[j] OR *no writemask*:

          DEST[j*8 + 7: j*8] := TMP_DEST[j*8+id+1]? SRC2[off+7:off] : SRC1[off+7:off];
    ELSE IF *zeroing-masking*

          DEST[j*8 + 7: j*8] := 0;
    *ELSE

          DEST[j*8 + 7: j*8] remains unchanged*
    FI;
ENDFOR
DEST[MAX_VL-1:VL] := 0;

Intel C/C++ compiler intrinsics

VPERMI2B __m512i _mm512_permutex2var_epi8(__m512i a, __m512i idx, __m512i b);
VPERMI2B __m512i _mm512_mask2_permutex2var_epi8(__m512i a, __m512i idx, __mmask64 k, __m512i b);
VPERMI2B __m512i _mm512_maskz_permutex2var_epi8(__mmask64 k, __m512i a, __m512i idx, __m512i b);
VPERMI2B __m256i _mm256_permutex2var_epi8(__m256i a, __m256i idx, __m256i b);
VPERMI2B __m256i _mm256_mask2_permutex2var_epi8(__m256i a, __m256i idx, __mmask32 k, __m256i b);
VPERMI2B __m256i _mm256_maskz_permutex2var_epi8(__mmask32 k, __m256i a, __m256i idx, __m256i b);
VPERMI2B __m128i _mm_permutex2var_epi8(__m128i a, __m128i idx, __m128i b);
VPERMI2B __m128i _mm_mask2_permutex2var_epi8(__m128i a, __m128i idx, __mmask16 k, __m128i b);
VPERMI2B __m128i _mm_maskz_permutex2var_epi8(__mmask16 k, __m128i a, __m128i idx, __m128i b);

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type E4NF.nb in Table 2-52, "Type E4NF Class Exception Conditions."

Sources