Extensions
Forms
2 (2 VEX)
Data
Intel XED v2026.08.23

Forms

Every encoding of VAESIMC that Intel XED knows, one row per XED instruction form (iform). How to read the notation.
InstructionEncodingRequires
VAESIMC xmm, xmm VAESIMC_XMMdq_XMMdqVEX.128.66.0F38.WIG DB /rAES + AVX
VAESIMC xmm, m128 VAESIMC_XMMdq_MEMdqVEX.128.66.0F38.WIG DB /rAES + AVX

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 128-bit block of the result comes from the 128-bit block in the same place in each source.
VAESIMC: element by elementResult 128-bit block i comes from 128-bit block i of xmm2. Result 128-bit blocks: r0.0xmm2or m128ar0xmm1

Result 128-bit block i comes from 128-bit block i of xmm2. Result 128-bit blocks: r0.

Operation

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

# a round key of the cipher made one for
# AESDEC, the equivalent inverse cipher's
xmm1.write(inv_mix_columns(src2))
# xmm1 is zeroed from bit 128 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
VAESIMC xmm, xmm/m128
xmmexplicitwrite
xmm/m128explicitread

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-4

Intrinsics

The C intrinsics of Clang 23.1.2 that compile to VAESIMC, 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_aesimc_si128 __m128i _mm_aesimc_si128(__m128i __V)

VAESIMC xmm, xmm VEX.128 -maes -mavxwith AVX enabled

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 AES-NI 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 3-57 (AESIMC)

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.