PSUBQ (Subtract Packed Quadword Integers)

Opcodes

Opcode/Instruction Op/En 64/32 bit Mode Support CPUID Feature Flag Description
0F FB /r1 PSUBQ mm1, mm2/m64 RM V/V SSE2 Subtract quadword integer in mm1 from mm2 /m64.
66 0F FB /r PSUBQ xmm1, xmm2/m128 RM V/V SSE2 Subtract packed quadword integers in xmm1 from xmm2 /m128.
VEX.NDS.128.66.0F.WIG FB/r VPSUBQ xmm1, xmm2, xmm3/m128 RVM V/V AVX Subtract packed quadword integers in xmm3/m128 from xmm2.
VEX.NDS.256.66.0F.WIG FB /r VPSUBQ ymm1, ymm2, ymm3/m256 RVM V/V AVX2 Subtract packed quadword integers in ymm3/m256 from ymm2.

NOTES:

1. See note in Section 2.4, “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

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (r, w) ModRM:r/m (r) NA NA
RVM ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA

Description

Subtracts the second operand (source operand) from the first operand (destination operand) and stores the result in the destination operand. When packed quadword operands are used, a SIMD subtract is performed. When a quadword result is too large to be represented in 64 bits (overflow), the result is wrapped around and the low 64 bits are written to the destination element (that is, the carry is ignored).

Note that the (V)PSUBQ instruction can operate on either unsigned or signed (two’s complement notation) inte-gers; however, it does not set bits in the EFLAGS register to indicate overflow and/or a carry. To prevent undetected overflow conditions, software must control the ranges of the values upon which it operates.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

Legacy SSE version: The source operand can be a quadword integer stored in an MMX technology register or a 64-bit memory location.

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

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

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

Note: VEX.L must be 0, otherwise instructions will #UD.

Operation

PSUBQ (with 64-Bit operands)

    DEST[63:0] ← DEST[63:0] − SRC[63:0];

PSUBQ (with 128-Bit operands)

    DEST[63:0] ← DEST[63:0] − SRC[63:0];
    DEST[127:64] ← DEST[127:64] − SRC[127:64];

VPSUBQ (VEX.128 encoded version)

DEST[63:0] ← SRC1[63:0]-SRC2[63:0]
DEST[127:64] ← SRC1[127:64]-SRC2[127:64]
DEST[VLMAX-1:128] ← 0

VPSUBQ (VEX.256 encoded version)

DEST[63:0] ← SRC1[63:0]-SRC2[63:0]
DEST[127:64] ← SRC1[127:64]-SRC2[127:64]
DEST[191:128] ← SRC1[191:128]-SRC2[191:128]
DEST[255:192] ← SRC1[255:192]-SRC2[255:192]

Intel C/C++ Compiler Intrinsic Equivalents

PSUBQ:

__m64 _mm_sub_si64(__m64 m1, __m64 m2)

(V)PSUBQ:

__m128i _mm_sub_epi64(__m128i m1, __m128i m2)

VPSUBQ:

__m256i _mm256_sub_epi64(__m256i m1, __m256i m2)

Flags Affected

None.

Numeric Exceptions

None.

Other Exceptions

See Exceptions Type 4; additionally

#UD If VEX.L = 1.