On Tue, 2018-09-25 at 16:56 +0200, Jason A. Donenfeld wrote:

This contains two formally verified C implementations of the Curve25519
scalar multiplication function, one for 32-bit systems, and one for
64-bit systems whose compiler supports efficient 128-bit integer types.
Not only are these implementations formally verified, but they are also
the fastest available C implementations. They have been modified to be
friendly to kernel space and to be generally less horrendous looking,
but still an effort has been made to retain their formally verified
characteristic, and so the C might look slightly unidiomatic.

[]

[]

+static __always_inline void fe_freeze(u32 out[10], const u32 in1[10])
+{
+	{ const u32 x17 = in1[9];
+	{ const u32 x18 = in1[8];
+	{ const u32 x16 = in1[7];
+	{ const u32 x14 = in1[6];
+	{ const u32 x12 = in1[5];
+	{ const u32 x10 = in1[4];
+	{ const u32 x8 = in1[3];
+	{ const u32 x6 = in1[2];
+	{ const u32 x4 = in1[1];
+	{ const u32 x2 = in1[0];
+	{ u32 x20; u8/*bool*/ x21 = subborrow_u26(0x0, x2, 0x3ffffed, &x20);
+	{ u32 x23; u8/*bool*/ x24 = subborrow_u25(x21, x4, 0x1ffffff, &x23);
+	{ u32 x26; u8/*bool*/ x27 = subborrow_u26(x24, x6, 0x3ffffff, &x26);
+	{ u32 x29; u8/*bool*/ x30 = subborrow_u25(x27, x8, 0x1ffffff, &x29);
+	{ u32 x32; u8/*bool*/ x33 = subborrow_u26(x30, x10, 0x3ffffff, &x32);
+	{ u32 x35; u8/*bool*/ x36 = subborrow_u25(x33, x12, 0x1ffffff, &x35);
+	{ u32 x38; u8/*bool*/ x39 = subborrow_u26(x36, x14, 0x3ffffff, &x38);
+	{ u32 x41; u8/*bool*/ x42 = subborrow_u25(x39, x16, 0x1ffffff, &x41);
+	{ u32 x44; u8/*bool*/ x45 = subborrow_u26(x42, x18, 0x3ffffff, &x44);
+	{ u32 x47; u8/*bool*/ x48 = subborrow_u25(x45, x17, 0x1ffffff, &x47);
+	{ u32 x49 = cmovznz32(x48, 0x0, 0xffffffff);
+	{ u32 x50 = (x49 & 0x3ffffed);
+	{ u32 x52; u8/*bool*/ x53 = addcarryx_u26(0x0, x20, x50, &x52);
+	{ u32 x54 = (x49 & 0x1ffffff);
+	{ u32 x56; u8/*bool*/ x57 = addcarryx_u25(x53, x23, x54, &x56);
+	{ u32 x58 = (x49 & 0x3ffffff);
+	{ u32 x60; u8/*bool*/ x61 = addcarryx_u26(x57, x26, x58, &x60);
+	{ u32 x62 = (x49 & 0x1ffffff);
+	{ u32 x64; u8/*bool*/ x65 = addcarryx_u25(x61, x29, x62, &x64);
+	{ u32 x66 = (x49 & 0x3ffffff);
+	{ u32 x68; u8/*bool*/ x69 = addcarryx_u26(x65, x32, x66, &x68);
+	{ u32 x70 = (x49 & 0x1ffffff);
+	{ u32 x72; u8/*bool*/ x73 = addcarryx_u25(x69, x35, x70, &x72);
+	{ u32 x74 = (x49 & 0x3ffffff);
+	{ u32 x76; u8/*bool*/ x77 = addcarryx_u26(x73, x38, x74, &x76);
+	{ u32 x78 = (x49 & 0x1ffffff);
+	{ u32 x80; u8/*bool*/ x81 = addcarryx_u25(x77, x41, x78, &x80);
+	{ u32 x82 = (x49 & 0x3ffffff);
+	{ u32 x84; u8/*bool*/ x85 = addcarryx_u26(x81, x44, x82, &x84);
+	{ u32 x86 = (x49 & 0x1ffffff);
+	{ u32 x88; addcarryx_u25(x85, x47, x86, &x88);
+	out[0] = x52;
+	out[1] = x56;
+	out[2] = x60;
+	out[3] = x64;
+	out[4] = x68;
+	out[5] = x72;
+	out[6] = x76;
+	out[7] = x80;
+	out[8] = x84;
+	out[9] = x88;
+	}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}
+}

Unidiomatic might be a stretch here...

[]

and elsewhere...

+static void fe_add_impl(u32 out[10], const u32 in1[10], const u32 in2[10])
+{
+	{ const u32 x20 = in1[9];
+	{ const u32 x21 = in1[8];
+	{ const u32 x19 = in1[7];
+	{ const u32 x17 = in1[6];
+	{ const u32 x15 = in1[5];
+	{ const u32 x13 = in1[4];
+	{ const u32 x11 = in1[3];
+	{ const u32 x9 = in1[2];
+	{ const u32 x7 = in1[1];
+	{ const u32 x5 = in1[0];
+	{ const u32 x38 = in2[9];
+	{ const u32 x39 = in2[8];
+	{ const u32 x37 = in2[7];
+	{ const u32 x35 = in2[6];
+	{ const u32 x33 = in2[5];
+	{ const u32 x31 = in2[4];
+	{ const u32 x29 = in2[3];
+	{ const u32 x27 = in2[2];
+	{ const u32 x25 = in2[1];
+	{ const u32 x23 = in2[0];
+	out[0] = (x5 + x23);
+	out[1] = (x7 + x25);
+	out[2] = (x9 + x27);
+	out[3] = (x11 + x29);
+	out[4] = (x13 + x31);
+	out[5] = (x15 + x33);
+	out[6] = (x17 + x35);
+	out[7] = (x19 + x37);
+	out[8] = (x21 + x39);
+	out[9] = (x20 + x38);
+	}}}}}}}}}}}}}}}}}}}}
+}

etc...