VAESKEYGENASSIST instruction (AES-NI)

Forms

Every encoding of VAESKEYGENASSIST that Intel XED knows, one row per XED instruction form (iform). How to read the notation.

Instruction	Encoding	Requires
`VAESKEYGENASSIST xmm, xmm, imm8` VAESKEYGENASSIST_XMMdq_XMMdq_IMMb	`VEX.128.66.0F3A.WIG DF /r ib`	AES + AVX
`VAESKEYGENASSIST xmm, m128, imm8` VAESKEYGENASSIST_XMMdq_MEMdq_IMMb	`VEX.128.66.0F3A.WIG DF /r ib`	AES + AVX

Operation

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

x1 = sub_word(src2.d[1])           # SubWord: each byte
x3 = sub_word(src2.d[3])           # through the S-box
xmm1.d[0] = x1
xmm1.d[1] = ror(x1, 8, 32) ^ imm8  # RotWord turns byte 1
xmm1.d[2] = x3                     # into byte 0; imm8 is
xmm1.d[3] = ror(x3, 8, 32) ^ imm8  # zero-extended
# 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.

Operand	Kind	Action
`VAESKEYGENASSIST xmm, xmm/m128, imm8`
`xmm`	explicit	write
`xmm/m128`	explicit	read
`imm8`	explicit	read

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

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.

ISA set	CPUID	Processors
`AVXAES` AES-NI	AES + AVX `CPUID.01H:ECX[25]` AES `CPUID.01H:ECX[28]` AVX	Sandy Bridge, Ivy Bridge, Haswell, Broadwell, Skylake, Comet Lake, Cannon Lake, Ice Lake (client), Tiger Lake, Alder Lake, Arrow Lake, Panther Lake, Nova Lake, Skylake-SP, Cascade Lake, Cooper Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids, Sierra Forest, Clearwater Forest, Knights Landing, Knights Mill, Bulldozer, Piledriver, Zen, Zen+, Zen 2, Zen 3, Zen 4, Zen 5, Zen 6

VAESKEYGENASSIST