Add x86 AES-NI vendor intrinsics (#311)

* Define _mm_aes*_si128 intrinsics

* Add tests for _mm_aes*_si128 intrinsics

These tests are based on the examples in Microsoft's documentation.
Same input should result in the same output in any case.

* Constify imm8 argument of aeskeygenassist

* Do not rely on internal layout of __m128

Use _mm_set_epi64x instead to construct constants.

* Move AES vendor intrinsics from x86_64 to i686

Although i686 does not have the AES New Instructions, making code
compatible across x86 and x64_64 tends to be easier if the intrinsics
are available everywhere.

* Pass constant for assert_instr(aeskeygenassist)

Pass a particular value for the disassembly test, so we end up with one
instruction, instead of the match arm that matches on all 256 values.

* Make aeskeygenassist imm8 argument i32, not u8

Intel documentation specifies it as an "8-bit round constant", but then
goes on to give it a type "const int", which translates to i32 in Rust.
The test that verifies the Rust signatures against Intel documentation
failed on this.

For now we will replicate the C API verbatim. Even when Rust could have
a more accurate type signature that makes passing values more than 8
bits impossible, rather than silently mapping out-of-range values to
255.

* Reflow doc comment as proposed by rustfmt

* Add module doc comment for i686::aes

library/stdarch/coresimd/src/x86/i686/aes.rs

@@ -0,0 +1,153 @@
+//! AES New Instructions (AES-NI)
+//!
+//! The intrinsics here correspond to those in the `wmmintrin.h` C header.
+//!
+//! The reference is [Intel 64 and IA-32 Architectures Software Developer's
+//! Manual Volume 2: Instruction Set Reference, A-Z][intel64_ref].
+//!
+//! [intel64_ref]: http://www.intel.de/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf
+use x86::__m128i;
+
+#[cfg(test)]
+use stdsimd_test::assert_instr;
+
+#[allow(improper_ctypes)]
+extern "C" {
+    #[link_name = "llvm.x86.aesni.aesdec"]
+    fn aesdec(a: __m128i, round_key: __m128i) -> __m128i;
+    #[link_name = "llvm.x86.aesni.aesdeclast"]
+    fn aesdeclast(a: __m128i, round_key: __m128i) -> __m128i;
+    #[link_name = "llvm.x86.aesni.aesenc"]
+    fn aesenc(a: __m128i, round_key: __m128i) -> __m128i;
+    #[link_name = "llvm.x86.aesni.aesenclast"]
+    fn aesenclast(a: __m128i, round_key: __m128i) -> __m128i;
+    #[link_name = "llvm.x86.aesni.aesimc"]
+    fn aesimc(a: __m128i) -> __m128i;
+    #[link_name = "llvm.x86.aesni.aeskeygenassist"]
+    fn aeskeygenassist(a: __m128i, imm8: u8) -> __m128i;
+}
+
+/// Perform one round of an AES decryption flow on data (state) in `a`.
+#[inline]
+#[target_feature(enable = "aes")]
+#[cfg_attr(test, assert_instr(aesdec))]
+pub unsafe fn _mm_aesdec_si128(a: __m128i, round_key: __m128i) -> __m128i {
+    aesdec(a, round_key)
+}
+
+/// Perform the last round of an AES decryption flow on data (state) in `a`.
+#[inline]
+#[target_feature(enable = "aes")]
+#[cfg_attr(test, assert_instr(aesdeclast))]
+pub unsafe fn _mm_aesdeclast_si128(a: __m128i, round_key: __m128i) -> __m128i {
+    aesdeclast(a, round_key)
+}
+
+/// Perform one round of an AES encryption flow on data (state) in `a`.
+#[inline]
+#[target_feature(enable = "aes")]
+#[cfg_attr(test, assert_instr(aesenc))]
+pub unsafe fn _mm_aesenc_si128(a: __m128i, round_key: __m128i) -> __m128i {
+    aesenc(a, round_key)
+}
+
+/// Perform the last round of an AES encryption flow on data (state) in `a`.
+#[inline]
+#[target_feature(enable = "aes")]
+#[cfg_attr(test, assert_instr(aesenclast))]
+pub unsafe fn _mm_aesenclast_si128(a: __m128i, round_key: __m128i) -> __m128i {
+    aesenclast(a, round_key)
+}
+
+/// Perform the “InvMixColumns” transformation on `a`.
+#[inline]
+#[target_feature(enable = "aes")]
+#[cfg_attr(test, assert_instr(aesimc))]
+pub unsafe fn _mm_aesimc_si128(a: __m128i) -> __m128i {
+    aesimc(a)
+}
+
+/// Assist in expanding the AES cipher key.
+///
+/// Assist in expanding the AES cipher key by computing steps towards
+/// generating a round key for encryption cipher using data from `a` and an
+/// 8-bit round constant `imm8`.
+#[inline]
+#[target_feature(enable = "aes")]
+#[cfg_attr(test, assert_instr(aeskeygenassist, imm8 = 0))]
+pub unsafe fn _mm_aeskeygenassist_si128(a: __m128i, imm8: i32) -> __m128i {
+    macro_rules! call {
+        ($imm8:expr) => (aeskeygenassist(a, $imm8))
+    }
+    constify_imm8!(imm8, call)
+}
+
+#[cfg(test)]
+mod tests {
+    // The constants in the tests below are just bit patterns. They should not
+    // be interpreted as integers; signedness does not make sense for them, but
+    // __m128i happens to be defined in terms of signed integers.
+    #![allow(overflowing_literals)]
+
+    use stdsimd_test::simd_test;
+
+    use x86::*;
+
+    #[simd_test = "aes"]
+    unsafe fn test_mm_aesdec_si128() {
+        // Constants taken from https://msdn.microsoft.com/en-us/library/cc664949.aspx.
+        let a = _mm_set_epi64x(0x0123456789abcdef, 0x8899aabbccddeeff);
+        let k = _mm_set_epi64x(0x1133557799bbddff, 0x0022446688aaccee);
+        let e = _mm_set_epi64x(0x044e4f5176fec48f, 0xb57ecfa381da39ee);
+        let r = _mm_aesdec_si128(a, k);
+        assert_eq_m128i(r, e);
+    }
+
+    #[simd_test = "aes"]
+    unsafe fn test_mm_aesdeclast_si128() {
+        // Constants taken from https://msdn.microsoft.com/en-us/library/cc714178.aspx.
+        let a = _mm_set_epi64x(0x0123456789abcdef, 0x8899aabbccddeeff);
+        let k = _mm_set_epi64x(0x1133557799bbddff, 0x0022446688aaccee);
+        let e = _mm_set_epi64x(0x36cad57d9072bf9e, 0xf210dd981fa4a493);
+        let r = _mm_aesdeclast_si128(a, k);
+        assert_eq_m128i(r, e);
+    }
+
+    #[simd_test = "aes"]
+    unsafe fn test_mm_aesenc_si128() {
+        // Constants taken from https://msdn.microsoft.com/en-us/library/cc664810.aspx.
+        let a = _mm_set_epi64x(0x0123456789abcdef, 0x8899aabbccddeeff);
+        let k = _mm_set_epi64x(0x1133557799bbddff, 0x0022446688aaccee);
+        let e = _mm_set_epi64x(0x16ab0e57dfc442ed, 0x28e4ee1884504333);
+        let r = _mm_aesenc_si128(a, k);
+        assert_eq_m128i(r, e);
+    }
+
+    #[simd_test = "aes"]
+    unsafe fn test_mm_aesenclast_si128() {
+        // Constants taken from https://msdn.microsoft.com/en-us/library/cc714136.aspx.
+        let a = _mm_set_epi64x(0x0123456789abcdef, 0x8899aabbccddeeff);
+        let k = _mm_set_epi64x(0x1133557799bbddff, 0x0022446688aaccee);
+        let e = _mm_set_epi64x(0xb6dd7df25d7ab320, 0x4b04f98cf4c860f8);
+        let r = _mm_aesenclast_si128(a, k);
+        assert_eq_m128i(r, e);
+    }
+
+    #[simd_test = "aes"]
+    unsafe fn test_mm_aesimc_si128() {
+        // Constants taken from https://msdn.microsoft.com/en-us/library/cc714195.aspx.
+        let a = _mm_set_epi64x(0x0123456789abcdef, 0x8899aabbccddeeff);
+        let e = _mm_set_epi64x(0xc66c82284ee40aa0, 0x6633441122770055);
+        let r = _mm_aesimc_si128(a);
+        assert_eq_m128i(r, e);
+    }
+
+    #[simd_test = "aes"]
+    unsafe fn test_mm_aeskeygenassist_si128() {
+        // Constants taken from https://msdn.microsoft.com/en-us/library/cc714138.aspx.
+        let a = _mm_set_epi64x(0x0123456789abcdef, 0x8899aabbccddeeff);
+        let e = _mm_set_epi64x(0x857c266b7c266e85, 0xeac4eea9c4eeacea);
+        let r = _mm_aeskeygenassist_si128(a, 5);
+        assert_eq_m128i(r, e);
+    }
+}

library/stdarch/coresimd/src/x86/i686/mod.rs

@@ -1,5 +1,8 @@
 //! `i686` intrinsics
 
+mod aes;
+pub use self::aes::*;
+
 mod mmx;
 pub use self::mmx::*;