PMULLW — Multiply Packed Signed Integers and Store Low Result

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 signed multiply of the packed signed word integers in the destination operand (first operand) and the source operand (second operand), and stores the low 16 bits of each intermediate 32-bit result in the destination operand. (Figure 4-12 shows this operation when using 64-bit 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 version 64-bit operand: The source operand can be an MMX technology register or a 64-bit memory location. The destination operand is 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 YMM 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 destination YMM register are zeroed. VEX.L must be 0, otherwise the instruction will #UD.

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, a 512/256/128-bit memory location. The destination operand is conditionally updated based on writemask k1.

Operation ¶

PMULLW (with 64-bit operands) ¶

TEMP0[31:0] ←
    DEST[15:0] ∗ SRC[15:0]; (* Signed multiplication *)
TEMP1[31:0] ←
    DEST[31:16] ∗ SRC[31:16];
TEMP2[31:0] ←
    DEST[47:32] ∗ SRC[47:32];
TEMP3[31:0] ←
    DEST[63:48] ∗ SRC[63:48];
DEST[15:0] ←
    TEMP0[15:0];
DEST[31:16] ←
    TEMP1[15:0];
DEST[47:32] ←
    TEMP2[15:0];
DEST[63:48] ←
    TEMP3[15:0];

PMULLW (with 128-bit operands) ¶

    TEMP0[31:0] ←
        DEST[15:0] ∗ SRC[15:0]; (* Signed multiplication *)
    TEMP1[31:0] ←
        DEST[31:16] ∗ SRC[31:16];
    TEMP2[31:0] ←
        DEST[47:32] ∗ SRC[47:32];
    TEMP3[31:0] ←
        DEST[63:48] ∗ SRC[63:48];
    TEMP4[31:0] ←
        DEST[79:64] ∗ SRC[79:64];
    TEMP5[31:0] ←
        DEST[95:80] ∗ SRC[95:80];
    TEMP6[31:0] ←
        DEST[111:96] ∗ SRC[111:96];
    TEMP7[31:0] ←
        DEST[127:112] ∗ SRC[127:112];
    DEST[15:0] ←
        TEMP0[15:0];
    DEST[31:16] ←
        TEMP1[15:0];
    DEST[47:32] ←
        TEMP2[15:0];
    DEST[63:48] ←
        TEMP3[15:0];
    DEST[79:64] ←
        TEMP4[15:0];
    DEST[95:80] ←
        TEMP5[15:0];
    DEST[111:96] ←
        TEMP6[15:0];
    DEST[127:112] ←
        TEMP7[15:0];
DEST[MAXVL-1:256] ← 0

VPMULLW (VEX.128 encoded version) ¶

Temp0[31:0]←SRC1[15:0] * SRC2[15:0]
Temp1[31:0]←SRC1[31:16] * SRC2[31:16]
Temp2[31:0]←SRC1[47:32] * SRC2[47:32]
Temp3[31:0]←SRC1[63:48] * SRC2[63:48]
Temp4[31:0]←SRC1[79:64] * SRC2[79:64]
Temp5[31:0]←SRC1[95:80] * SRC2[95:80]
Temp6[31:0]←SRC1[111:96] * SRC2[111:96]
Temp7[31:0]←SRC1[127:112] * SRC2[127:112]
DEST[15:0] ← Temp0[15:0]
DEST[31:16] ← Temp1[15:0]
DEST[47:32] ← Temp2[15:0]
DEST[63:48] ← Temp3[15:0]
DEST[79:64] ← Temp4[15:0]
DEST[95:80] ← Temp5[15:0]
DEST[111:96] ← Temp6[15:0]
DEST[127:112] ← Temp7[15:0]
DEST[MAXVL-1:128] ← 0

PMULLW (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
            temp[31:0]←SRC1[i+15:i] * SRC2[i+15:i]
            DEST[i+15:i] ← temp[15:0]
        ELSE
            IF *merging-masking* ; merging-masking
                THEN *DEST[i+15:i] remains unchanged*
                ELSE *zeroing-masking*
                        ; zeroing-masking
                    DEST[i+15:i] ← 0
            FI
    FI;
ENDFOR
DEST[MAXVL-1:VL] ← 0

Intel C/C++ Compiler Intrinsic Equivalent ¶

VPMULLW __m512i _mm512_mullo_epi16(__m512i a, __m512i b);

VPMULLW __m512i _mm512_mask_mullo_epi16(__m512i s, __mmask32 k, __m512i a, __m512i b);

VPMULLW __m512i _mm512_maskz_mullo_epi16( __mmask32 k, __m512i a, __m512i b);

VPMULLW __m256i _mm256_mask_mullo_epi16(__m256i s, __mmask16 k, __m256i a, __m256i b);

VPMULLW __m256i _mm256_maskz_mullo_epi16( __mmask16 k, __m256i a, __m256i b);

VPMULLW __m128i _mm_mask_mullo_epi16(__m128i s, __mmask8 k, __m128i a, __m128i b);

VPMULLW __m128i _mm_maskz_mullo_epi16( __mmask8 k, __m128i a, __m128i b);

PMULLW: __m64 _mm_mullo_pi16(__m64 m1, __m64 m2)

(V)PMULLW: __m128i _mm_mullo_epi16 ( __m128i a, __m128i b)

VPMULLW:__m256i _mm256_mullo_epi16 ( __m256i a, __m256i b);

Flags Affected ¶

None.

SIMD Floating-Point Exceptions ¶

None.

Other Exceptions ¶

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

EVEX-encoded instruction, see Exceptions Type E4.nb.