vpdpbusds

Multiply and Add Unsigned and Signed Bytes with Saturation

VPDPBUSDS zmm1, zmm2, zmm3/m512

Dot product of unsigned/signed bytes, accum to dword (Saturate).

Details

Computes dot product of unsigned and signed bytes, accumulating results into 32-bit signed integers with saturation. Processes 16 pairs of (unsigned byte × signed byte) products per 512-bit vector, summing each group of 4 products and saturating the result to the signed 32-bit range. No flags are affected; operates only on vector registers and memory.

Pseudocode Operation

for i in 0 to 15 {
  prod0 = ZeroExtend(src1[i*32+0:7]) * SignExtend(src2[i*32+0:7]);
  prod1 = ZeroExtend(src1[i*32+8:15]) * SignExtend(src2[i*32+8:15]);
  prod2 = ZeroExtend(src1[i*32+16:23]) * SignExtend(src2[i*32+16:23]);
  prod3 = ZeroExtend(src1[i*32+24:31]) * SignExtend(src2[i*32+24:31]);
  sum = prod0 + prod1 + prod2 + prod3;
  dest[i*32:31] ← SaturateSignedToS32(sum);
}

Example

VPDPBUSDS zmm1, zmm2, zmm3/m512

Encoding

Binary Layout
EVEX
+0
66
+4
0F
+5
38
+6
51
+7
 
Format EVEX
Opcode EVEX.512.66.0F38.W0 51 /r
Extension AVX-512-VNNI

Operands

  • dest
    512-bit ZMM AVX-512 register
  • src1
    512-bit ZMM AVX-512 register
  • src2
    512-bit ZMM AVX-512 register or Memory operand

Reference (Intel® SDM)

Instruction Forms

Opcode Instruction Op/En 64/32-bit Mode CPUID Description
VEX.128.66.0F38.W0 51 /r VPDPBUSDS xmm1, xmm2, xmm3/m128 A V/V AVX_VNNI Multiply groups of 4 pairs signed bytes in xmm3/m128 with corresponding unsigned bytes of xmm2, summing those products and adding them to doubleword result, with signed saturation in xmm1.
VEX.256.66.0F38.W0 51 /r VPDPBUSDS ymm1, ymm2, ymm3/m256 A V/V AVX_VNNI Multiply groups of 4 pairs signed bytes in ymm3/m256 with corresponding unsigned bytes of ymm2, summing those products and adding them to doubleword result, with signed saturation in ymm1.
EVEX.128.66.0F38.W0 51 /r VPDPBUSDS xmm1{k1}{z}, xmm2, xmm3/m128/m32bcst B V/V (AVX512_VNNI AND AVX512VL) OR AVX10.1 Multiply groups of 4 pairs signed bytes in xmm3/m128/m32bcst with corresponding unsigned bytes of xmm2, summing those products and adding them to doubleword result, with signed saturation in xmm1, under writemask k1.
EVEX.256.66.0F38.W0 51 /r VPDPBUSDS ymm1{k1}{z}, ymm2, ymm3/m256/m32bcst B V/V (AVX512_VNNI AND AVX512VL) OR AVX10.1 Multiply groups of 4 pairs signed bytes in ymm3/m256/m32bcst with corresponding unsigned bytes of ymm2, summing those products and adding them to doubleword result, with signed saturation in ymm1, under writemask k1.
EVEX.512.66.0F38.W0 51 /r VPDPBUSDS zmm1{k1}{z}, zmm2, zmm3/m512/m32bcst B V/V AVX512_VNNI OR AVX10.1 Multiply groups of 4 pairs signed bytes in zmm3/m512/m32bcst with corresponding unsigned bytes of zmm2, summing those products and adding them to doubleword result, with signed saturation in zmm1, under writemask k1.

Instruction Operand Encoding

Op/En Tuple Type Operand 1 Operand 2 Operand 3 Operand 4
A N/A ModRM:reg (r, w) VEX.vvvv (r) ModRM:r/m (r) N/A
B Full ModRM:reg (r, w) EVEX.vvvv (r) ModRM:r/m (r) N/A

Description

Multiplies the individual unsigned bytes of the first source operand by the corresponding signed bytes of the second source operand, producing intermediate signed word results. The word results are then summed and accumulated in the destination dword element size operand. If the intermediate sum overflows a 32b signed number the result is saturated to either 0x7FFF_FFFF for positive numbers of 0x8000_0000 for negative numbers. This instruction supports memory fault suppression. VPDPBUSDS—Multiply and Add Unsigned and Signed Bytes With Saturation Vol. 2C 5-484

Operation

VPDPBUSDS dest, src1, src2 (VEX encoded versions)
VL=(128, 256)
KL=VL/32

ORIGDEST := DEST
FOR i := 0 TO KL-1:
// Extending to 16b
// src1extend := ZERO_EXTEND
// src2extend := SIGN_EXTEND

p1word := src1extend(SRC1.byte[4*i+0]) * src2extend(SRC2.byte[4*i+0])
p2word := src1extend(SRC1.byte[4*i+1]) * src2extend(SRC2.byte[4*i+1])
p3word := src1extend(SRC1.byte[4*i+2]) * src2extend(SRC2.byte[4*i+2])
p4word := src1extend(SRC1.byte[4*i+3]) * src2extend(SRC2.byte[4*i+3])
DEST.dword[i] := SIGNED_DWORD_SATURATE(ORIGDEST.dword[i] + p1word + p2word + p3word + p4word)

DEST[MAX_VL-1:VL] := 0

VPDPBUSDS dest, src1, src2 (EVEX encoded versions)
(KL,VL)=(4,128), (8,256), (16,512)
ORIGDEST := DEST
FOR i := 0 TO KL-1:
IF k1[i] or *no writemask*:
// Byte elements of SRC1 are zero-extended to 16b and
// byte elements of SRC2 are sign extended to 16b before multiplication.
IF SRC2 is memory and EVEX.b == 1:
t := SRC2.dword[0]
ELSE:
t := SRC2.dword[i]
p1word := ZERO_EXTEND(SRC1.byte[4*i]) * SIGN_EXTEND(t.byte[0])
p2word := ZERO_EXTEND(SRC1.byte[4*i+1]) * SIGN_EXTEND(t.byte[1])
p3word := ZERO_EXTEND(SRC1.byte[4*i+2]) * SIGN_EXTEND(t.byte[2])
p4word := ZERO_EXTEND(SRC1.byte[4*i+3]) *SIGN_EXTEND(t.byte[3])
DEST.dword[i] := SIGNED_DWORD_SATURATE(ORIGDEST.dword[i] + p1word + p2word + p3word + p4word)
ELSE IF *zeroing*:
DEST.dword[i] := 0
ELSE:     // Merge masking, dest element unchanged
DEST.dword[i] := ORIGDEST.dword[i]
DEST[MAX_VL-1:VL] := 0

Intel C/C++ Compiler Intrinsic Equivalent

VPDPBUSDS __m128i _mm_dpbusds_avx_epi32(__m128i, __m128i, __m128i);
VPDPBUSDS __m128i _mm_dpbusds_epi32(__m128i, __m128i, __m128i);
VPDPBUSDS __m128i _mm_mask_dpbusds_epi32(__m128i, __mmask8, __m128i, __m128i);
VPDPBUSDS __m128i _mm_maskz_dpbusds_epi32(__mmask8, __m128i, __m128i, __m128i);
VPDPBUSDS __m256i _mm256_dpbusds_avx_epi32(__m256i, __m256i, __m256i);
VPDPBUSDS __m256i _mm256_dpbusds_epi32(__m256i, __m256i, __m256i);
VPDPBUSDS __m256i _mm256_mask_dpbusds_epi32(__m256i, __mmask8, __m256i, __m256i);
VPDPBUSDS __m256i _mm256_maskz_dpbusds_epi32(__mmask8, __m256i, __m256i, __m256i);
VPDPBUSDS __m512i _mm512_dpbusds_epi32(__m512i, __m512i, __m512i);
VPDPBUSDS __m512i _mm512_mask_dpbusds_epi32(__m512i, __mmask16, __m512i, __m512i);
VPDPBUSDS __m512i _mm512_maskz_dpbusds_epi32(__mmask16, __m512i, __m512i, __m512i);
VPDPBUSDS—Multiply and Add Unsigned and Signed Bytes With Saturation                                                                   Vol. 2C 5-485

Exceptions

SIMD Floating-Point Exceptions

None.

Other Exceptions

Non-EVEX-encoded instruction, see Table 2-21, “Type 4 Class Exception Conditions.” EVEX-encoded instruction, see Table 2-51, “Type E4 Class Exception Conditions.” VPDPBUSDS—Multiply and Add Unsigned and Signed Bytes With Saturation Vol. 2C 5-486