1 files changed, 157 insertions, 0 deletions
diff --git a/third_party/rust/httparse/src/simd/sse42.rs b/third_party/rust/httparse/src/simd/sse42.rs
new file mode 100644
index 0000000000..8caf8f779e
--- /dev/null
+++ b/third_party/rust/httparse/src/simd/sse42.rs
@@ -0,0 +1,157 @@
+use crate::iter::Bytes;
+
+pub unsafe fn parse_uri_batch_16(bytes: &mut Bytes) {
+    while bytes.as_ref().len() >= 16 {
+        let advance = match_url_char_16_sse(bytes.as_ref());
+        bytes.advance(advance);
+
+        if advance != 16 {
+            break;
+        }
+    }
+}
+
+#[target_feature(enable = "sse4.2")]
+#[allow(non_snake_case, overflowing_literals)]
+unsafe fn match_url_char_16_sse(buf: &[u8]) -> usize {
+    debug_assert!(buf.len() >= 16);
+
+    #[cfg(target_arch = "x86")]
+    use core::arch::x86::*;
+    #[cfg(target_arch = "x86_64")]
+    use core::arch::x86_64::*;
+
+    let ptr = buf.as_ptr();
+
+    let LSH: __m128i = _mm_set1_epi8(0x0f);
+
+    // The first 0xf8 corresponds to the 8 first rows of the first column
+    // of URI_MAP in the crate's root, with the first row corresponding to bit 0
+    // and the 8th row corresponding to bit 7.
+    // The 8 first rows give 0 0 0 1 1 1 1 1, which is 0xf8 (with least
+    // significant digit on the left).
+    //
+    // Another example just to drive the point home: in column 15, '>' is
+    // rejected, so the values are 0 0 1 0 1 1 1 1, which gives us 0xf4.
+    //
+    // Thanks to Vlad Krasnov for explaining this stuff to us mere mortals in
+    // a GitHub comment!
+    //
+    // https://github.com/seanmonstar/httparse/pull/89#issuecomment-807039219
+
+    let URI: __m128i = _mm_setr_epi8(
+        0xf8, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc,
+        0xfc, 0xfc, 0xfc, 0xfc, 0xf4, 0xfc, 0xf4, 0x7c,
+    );
+    let ARF: __m128i = _mm_setr_epi8(
+        0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    );
+
+    let data = _mm_lddqu_si128(ptr as *const _);
+    let rbms = _mm_shuffle_epi8(URI, data);
+    let cols = _mm_and_si128(LSH, _mm_srli_epi16(data, 4));
+    let bits = _mm_and_si128(_mm_shuffle_epi8(ARF, cols), rbms);
+
+    let v = _mm_cmpeq_epi8(bits, _mm_setzero_si128());
+    let r = 0xffff_0000 | _mm_movemask_epi8(v) as u32;
+
+    _tzcnt_u32(r) as usize
+}
+
+pub unsafe fn match_header_value_batch_16(bytes: &mut Bytes) {
+    while bytes.as_ref().len() >= 16 {
+        let advance = match_header_value_char_16_sse(bytes.as_ref());
+        bytes.advance(advance);
+
+       if advance != 16 {
+            break;
+       }
+    }
+}
+
+#[target_feature(enable = "sse4.2")]
+#[allow(non_snake_case)]
+unsafe fn match_header_value_char_16_sse(buf: &[u8]) -> usize {
+    debug_assert!(buf.len() >= 16);
+
+    #[cfg(target_arch = "x86")]
+    use core::arch::x86::*;
+    #[cfg(target_arch = "x86_64")]
+    use core::arch::x86_64::*;
+
+    let ptr = buf.as_ptr();
+
+    // %x09 %x20-%x7e %x80-%xff
+    let TAB: __m128i = _mm_set1_epi8(0x09);
+    let DEL: __m128i = _mm_set1_epi8(0x7f);
+    let LOW: __m128i = _mm_set1_epi8(0x20);
+
+    let dat = _mm_lddqu_si128(ptr as *const _);
+    // unsigned comparison dat >= LOW
+    let low = _mm_cmpeq_epi8(_mm_max_epu8(dat, LOW), dat);
+    let tab = _mm_cmpeq_epi8(dat, TAB);
+    let del = _mm_cmpeq_epi8(dat, DEL);
+    let bit = _mm_andnot_si128(del, _mm_or_si128(low, tab));
+    let rev = _mm_cmpeq_epi8(bit, _mm_setzero_si128());
+    let res = 0xffff_0000 | _mm_movemask_epi8(rev) as u32;
+
+    _tzcnt_u32(res) as usize
+}
+
+#[test]
+fn sse_code_matches_uri_chars_table() {
+    match super::detect() {
+        super::SSE_42 | super::AVX_2_AND_SSE_42 => {},
+        _ => return,
+    }
+
+    unsafe {
+        assert!(byte_is_allowed(b'_', parse_uri_batch_16));
+
+        for (b, allowed) in crate::URI_MAP.iter().cloned().enumerate() {
+            assert_eq!(
+                byte_is_allowed(b as u8, parse_uri_batch_16), allowed,
+                "byte_is_allowed({:?}) should be {:?}", b, allowed,
+            );
+        }
+    }
+}
+
+#[test]
+fn sse_code_matches_header_value_chars_table() {
+    match super::detect() {
+        super::SSE_42 | super::AVX_2_AND_SSE_42 => {},
+        _ => return,
+    }
+
+    unsafe {
+        assert!(byte_is_allowed(b'_', match_header_value_batch_16));
+
+        for (b, allowed) in crate::HEADER_VALUE_MAP.iter().cloned().enumerate() {
+            assert_eq!(
+                byte_is_allowed(b as u8, match_header_value_batch_16), allowed,
+                "byte_is_allowed({:?}) should be {:?}", b, allowed,
+            );
+        }
+    }
+}
+
+#[cfg(test)]
+unsafe fn byte_is_allowed(byte: u8, f: unsafe fn(bytes: &mut Bytes<'_>)) -> bool {
+    let slice = [
+        b'_', b'_', b'_', b'_',
+        b'_', b'_', b'_', b'_',
+        b'_', b'_', byte, b'_',
+        b'_', b'_', b'_', b'_',
+    ];
+    let mut bytes = Bytes::new(&slice);
+
+    f(&mut bytes);
+
+    match bytes.pos() {
+        16 => true,
+        10 => false,
+        _ => unreachable!(),
+    }
+}