PMAXUB/PMAXUW — Maximum of Packed Unsigned Integers

1. See note in Section 2.5, “Intel® AVX and Intel® SSE Instruction Exception Classification,” in the Intel^® 64 and IA-32 Architectures Software 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 ¶

Description ¶

Performs a SIMD compare of the packed unsigned byte, word integers in the second source operand and the first source operand and returns the maximum value for each pair of integers to the destination operand.

Legacy SSE version PMAXUB: 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 first source and destination operands are XMM registers. The second source operand is an XMM register or a 128-bit memory location. Bits (MAXVL-1:128) of the corresponding destination register remain unchanged.

VEX.128 encoded version: The first source and destination operands are XMM registers. The second source operand is an XMM register or a 128-bit memory location. Bits (MAXVL-1:128) of the corresponding destination register are zeroed.

VEX.256 encoded version: The second source operand can be an YMM register or a 256-bit memory location. The first source and destination operands are YMM registers.

EVEX encoded versions: The first source operand is a ZMM/YMM/XMM register; The second source operand is a ZMM/YMM/XMM register or a 512/256/128-bit memory location. The destination operand is conditionally updated based on writemask k1.

Operation ¶

PMAXUB (64-bit Operands) ¶

IF DEST[7:0] > SRC[17:0]) THEN
    DEST[7:0] := DEST[7:0];
ELSE
    DEST[7:0] := SRC[7:0]; FI;
(* Repeat operation for 2nd through 7th bytes in source and destination operands *)
IF DEST[63:56] > SRC[63:56]) THEN
    DEST[63:56] := DEST[63:56];
ELSE
    DEST[63:56] := SRC[63:56]; FI;

PMAXUB (128-bit Legacy SSE Version) ¶

    IF DEST[7:0] >SRC[7:0] THEN
        DEST[7:0] := DEST[7:0];
    ELSE
        DEST[15:0] := SRC[7:0]; FI;
    (* Repeat operation for 2nd through 15th bytes in source and destination operands *)
    IF DEST[127:120] >SRC[127:120] THEN
        DEST[127:120] := DEST[127:120];
    ELSE
        DEST[127:120] := SRC[127:120]; FI;
DEST[MAXVL-1:128] (Unmodified)

VPMAXUB (VEX.128 Encoded Version) ¶

    IF SRC1[7:0] >SRC2[7:0] THEN
        DEST[7:0] := SRC1[7:0];
    ELSE
        DEST[7:0] := SRC2[7:0]; FI;
    (* Repeat operation for 2nd through 15th bytes in source and destination operands *)
    IF SRC1[127:120] >SRC2[127:120] THEN
        DEST[127:120] := SRC1[127:120];
    ELSE
        DEST[127:120] := SRC2[127:120]; FI;
DEST[MAXVL-1:128] := 0

VPMAXUB (VEX.256 Encoded Version) ¶

    IF SRC1[7:0] >SRC2[7:0] THEN
        DEST[7:0] := SRC1[7:0];
    ELSE
        DEST[15:0] := SRC2[7:0]; FI;
    (* Repeat operation for 2nd through 31st bytes in source and destination operands *)
    IF SRC1[255:248] >SRC2[255:248] THEN
        DEST[255:248] := SRC1[255:248];
    ELSE
        DEST[255:248] := SRC2[255:248]; FI;
DEST[MAXVL-1:128] := 0

VPMAXUB (EVEX Encoded Versions) ¶

(KL, VL) = (16, 128), (32, 256), (64, 512)
FOR j := 0 TO KL-1
    i := j * 8
    IF k1[j] OR *no writemask* THEN
        IF SRC1[i+7:i] > SRC2[i+7:i]
            THEN DEST[i+7:i] := SRC1[i+7:i];
            ELSE DEST[i+7:i] := SRC2[i+7:i];
        FI;
        ELSE
            IF *merging-masking*
                THEN *DEST[i+7:i] remains unchanged*
                ELSE ; zeroing-masking
                    DEST[i+7:i] := 0
            FI
    FI;
ENDFOR;
DEST[MAXVL-1:VL] := 0

PMAXUW (128-bit Legacy SSE Version) ¶

    IF DEST[15:0] >SRC[15:0] THEN
        DEST[15:0] := DEST[15:0];
    ELSE
        DEST[15:0] := SRC[15:0]; FI;
    (* Repeat operation for 2nd through 7th words in source and destination operands *)
    IF DEST[127:112] >SRC[127:112] THEN
        DEST[127:112] := DEST[127:112];
    ELSE
        DEST[127:112] := SRC[127:112]; FI;
DEST[MAXVL-1:128] (Unmodified)

VPMAXUW (VEX.128 Encoded Version) ¶

    IF SRC1[15:0] > SRC2[15:0] THEN
        DEST[15:0] := SRC1[15:0];
    ELSE
        DEST[15:0] := SRC2[15:0]; FI;
    (* Repeat operation for 2nd through 7th words in source and destination operands *)
    IF SRC1[127:112] >SRC2[127:112] THEN
        DEST[127:112] := SRC1[127:112];
    ELSE
        DEST[127:112] := SRC2[127:112]; FI;
DEST[MAXVL-1:128] := 0

VPMAXUW (VEX.256 Encoded Version) ¶

    IF SRC1[15:0] > SRC2[15:0] THEN
        DEST[15:0] := SRC1[15:0];
    ELSE
        DEST[15:0] := SRC2[15:0]; FI;
    (* Repeat operation for 2nd through 15th words in source and destination operands *)
    IF SRC1[255:240] >SRC2[255:240] THEN
        DEST[255:240] := SRC1[255:240];
    ELSE
        DEST[255:240] := SRC2[255:240]; FI;
DEST[MAXVL-1:128] := 0

VPMAXUW (EVEX Encoded Versions) ¶

(KL, VL) = (8, 128), (16, 256), (32, 512)
FOR j := 0 TO KL-1
    i := j * 16
    IF k1[j] OR *no writemask* THEN
        IF SRC1[i+15:i] > SRC2[i+15:i]
            THEN DEST[i+15:i] := SRC1[i+15:i];
            ELSE DEST[i+15:i] := SRC2[i+15:i];
        FI;
        ELSE
            IF *merging-masking*
                THEN *DEST[i+15:i] remains unchanged*
                ELSE ; zeroing-masking
                    DEST[i+15:i] := 0
            FI
    FI;
ENDFOR;
DEST[MAXVL-1:VL] := 0

Intel C/C++ Compiler Intrinsic Equivalent ¶

VPMAXUB __m512i _mm512_max_epu8( __m512i a, __m512i b);

VPMAXUB __m512i _mm512_mask_max_epu8(__m512i s, __mmask64 k, __m512i a, __m512i b);

VPMAXUB __m512i _mm512_maskz_max_epu8( __mmask64 k, __m512i a, __m512i b);

VPMAXUW __m512i _mm512_max_epu16( __m512i a, __m512i b);

VPMAXUW __m512i _mm512_mask_max_epu16(__m512i s, __mmask32 k, __m512i a, __m512i b);

VPMAXUW __m512i _mm512_maskz_max_epu16( __mmask32 k, __m512i a, __m512i b);

VPMAXUB __m256i _mm256_mask_max_epu8(__m256i s, __mmask32 k, __m256i a, __m256i b);

VPMAXUB __m256i _mm256_maskz_max_epu8( __mmask32 k, __m256i a, __m256i b);

VPMAXUW __m256i _mm256_mask_max_epu16(__m256i s, __mmask16 k, __m256i a, __m256i b);

VPMAXUW __m256i _mm256_maskz_max_epu16( __mmask16 k, __m256i a, __m256i b);

VPMAXUB __m128i _mm_mask_max_epu8(__m128i s, __mmask16 k, __m128i a, __m128i b);

VPMAXUB __m128i _mm_maskz_max_epu8( __mmask16 k, __m128i a, __m128i b);

VPMAXUW __m128i _mm_mask_max_epu16(__m128i s, __mmask8 k, __m128i a, __m128i b);

VPMAXUW __m128i _mm_maskz_max_epu16( __mmask8 k, __m128i a, __m128i b);

(V)PMAXUB __m128i _mm_max_epu8 ( __m128i a, __m128i b);

(V)PMAXUW __m128i _mm_max_epu16 ( __m128i a, __m128i b)

VPMAXUB __m256i _mm256_max_epu8 ( __m256i a, __m256i b);

VPMAXUW __m256i _mm256_max_epu16 ( __m256i a, __m256i b);

PMAXUB __m64 _mm_max_pu8(__m64 a, __m64 b);

SIMD Floating-Point Exceptions ¶

None.

Other Exceptions ¶

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

EVEX-encoded instruction, see Exceptions Type E4.nb in Table 2-49, “Type E4 Class Exception Conditions.”