Extensions
Forms
4 (4 VEX)
Data
Intel XED v2026.08.23

Forms

Every encoding of VADDSUBPD that Intel XED knows, one row per XED instruction form (iform). How to read the notation.
InstructionEncodingRequires
VADDSUBPD xmm, xmm, m128 VADDSUBPD_XMMdq_XMMdq_MEMdqVEX.128.66.0F.WIG D0 /rAVX
VADDSUBPD xmm, xmm, xmm VADDSUBPD_XMMdq_XMMdq_XMMdqVEX.128.66.0F.WIG D0 /rAVX
VADDSUBPD ymm, ymm, m256 VADDSUBPD_YMMqq_YMMqq_MEMqqVEX.256.66.0F.WIG D0 /rAVX
VADDSUBPD ymm, ymm, ymm VADDSUBPD_YMMqq_YMMqq_YMMqqVEX.256.66.0F.WIG D0 /rAVX

Data flow

Where the elements of the sources go, element 0 on the right; results that depend on a control value are drawn for an example. How to read.

Element-wise: each double of the result comes from the double in the same place in each source.
VADDSUBPD: element by elementResult double i comes from double i of xmm2 and xmm3. Result doubles 1 to 0: r1, r0.01xmm2ar0r1xmm101xmm3or m128b

Every double works alike: 2 and 4 doubles in the xmm and ymm forms.

Result double i comes from double i of xmm2 and xmm3. Result doubles 1 to 0: r1, r0.

Operation

What the forms do, in pseudocode that our tests run against results recorded on real processors. How to read.

for i in range(VL // 64):
    a = ymm2.f64[i]
    b = src3.f64[i]
    if i % 2 == 0:
        ymm1.f64[i] = sub(a, b)
    else:
        ymm1.f64[i] = add(a, b)
# ymm1 is zeroed from bit VL up

Run on AMD Zen 5 (EPYC 9645): 4 cases.

Operands

What each form reads and writes, as Intel XED records it: the operands of its syntax, in order, and the implicit ones that the syntax does not name. How to read.
OperandKindAction
VADDSUBPD xmm, xmm, xmm/m128 VADDSUBPD ymm, ymm, ymm/m256
xmm, ymmexplicitwrite
xmm, ymmexplicitread
xmm/m128, ymm/m256explicitread

Flags

None: XED records no flag that the forms test or change.

Exceptions

The exception class is XED's name for the set of exception conditions that a form follows. How to read.

All forms
avx-type-2

Attributes

What else XED records about the forms. How to read.

All forms
follows MXCSR

Intrinsics

The C intrinsics of Clang 23.1.2 that compile to VADDSUBPD, each with the form it compiles to and the Clang options it needs. The forms come from compiling every intrinsic and decoding the result with Intel XED; all intrinsics A–Z explains the method.

IntrinsicCompiles to
_mm_addsub_pd __m128d _mm_addsub_pd(__m128d __a, __m128d __b)

VADDSUBPD xmm, xmm, xmm VEX.128 -mavxwith AVX enabled

_mm256_addsub_pd __m256d _mm256_addsub_pd(__m256d __a, __m256d __b)

VADDSUBPD ymm, ymm, ymm VEX.256 -mavx

CPUID and processors

Each form belongs to an XED ISA set. A form can be used when the processor reports every CPUID bit of one of its ISA set's alternatives.

CPUID requirements and processors of the XED ISA sets above. Alternatives are separated by “or”; processors follow XED’s chip model, whose AMD processors end with Zen 2, and the CPU data of this site for Zen 3 to Zen 6.

More AVX instructions

All 253 AVX instructions

Sources

  1. Intel XED v2026.08.23 (commit 0bcb6237345c): forms, encodings, operands, flags, exception classes, attributes, ISA sets, CPUID bits and chip model.
  2. The CPU data of x86-64.net: Zen 3 to Zen 6, from GCC’s -march feature sets and AMD’s Processor Programming References, which the page of each processor cites.
  3. Clang's x86 intrinsic headers, LLVM 23.1.2 (commit 85ac56026243): the intrinsics, their signatures and doc comments, and the Clang of that release, which compiled each of them.
  4. Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 2 (325383-093, September 2026): Volume 2A, page 3-26 (ADDSUBPD)
  5. Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 1 (253665-093, September 2026)

The tables are derived from Intel XED, Copyright Intel Corporation, licensed under the Apache License 2.0; x86-64.net converted and reformatted them. The intrinsics and their signatures come from Clang, part of the LLVM Project, licensed under the Apache License 2.0 with LLVM Exceptions. The text is our own.