dfa: adding new Sheng engine

A new shuffle-based DFA engine, complete with acceleration and smallwrite.

src/nfa/sheng_impl.h

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2016, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * In order to use this macro, the following things need to be defined:
+ *
+ *  - SHENG_IMPL    (name of the Sheng implementation function)
+ *  - DEAD_FUNC     (name of the function checking for dead states)
+ *  - ACCEPT_FUNC   (name of the function checking for accept state)
+ *  - STOP_AT_MATCH (can be 1 or 0, enable or disable stop at match)
+ */
+
+/* byte-by-byte version. we don't do byte-by-byte death checking as it's
+ * pretty pointless to do it over a buffer that's at most 3 bytes long */
+static really_inline
+char SHENG_IMPL(u8 *state, NfaCallback cb, void *ctxt, const struct sheng *s,
+                u8 *const cached_accept_state, ReportID *const cached_accept_id,
+                u8 single, u64a base_offset, const u8 *buf, const u8 *start,
+                const u8 *end, const u8 **scan_end) {
+    DEBUG_PRINTF("Starting DFA execution in state %u\n",
+                 *state & SHENG_STATE_MASK);
+    const u8 *cur_buf = start;
+    if (DEAD_FUNC(*state)) {
+        DEBUG_PRINTF("Dead on arrival\n");
+        *scan_end = end;
+        return MO_CONTINUE_MATCHING;
+    }
+    DEBUG_PRINTF("Scanning %lli bytes\n", (s64a)(end - start));
+
+    m128 cur_state = set16x8(*state);
+    const m128 *masks = s->shuffle_masks;
+
+    while (likely(cur_buf != end)) {
+        const u8 c = *cur_buf;
+        const m128 shuffle_mask = masks[c];
+        cur_state = pshufb(shuffle_mask, cur_state);
+        const u8 tmp = movd(cur_state);
+
+        DEBUG_PRINTF("c: %02hhx '%c'\n", c, ourisprint(c) ? c : '?');
+        DEBUG_PRINTF("s: %u (hi: %u lo: %u)\n", tmp, (tmp & 0xF0) >> 4,
+                     tmp & 0xF);
+
+        if (unlikely(ACCEPT_FUNC(tmp))) {
+            DEBUG_PRINTF("Accept state %u reached\n", tmp & SHENG_STATE_MASK);
+            u64a match_offset = base_offset + (cur_buf - buf) + 1;
+            DEBUG_PRINTF("Match @ %llu\n", match_offset);
+            if (STOP_AT_MATCH) {
+                DEBUG_PRINTF("Stopping at match @ %lli\n",
+                             (u64a)(cur_buf - start));
+                *state = tmp;
+                *scan_end = cur_buf;
+                return MO_MATCHES_PENDING;
+            }
+            if (single) {
+                if (fireSingleReport(cb, ctxt, s->report, match_offset) ==
+                    MO_HALT_MATCHING) {
+                    return MO_HALT_MATCHING;
+                }
+            } else {
+                if (fireReports(s, cb, ctxt, tmp, match_offset,
+                                cached_accept_state, cached_accept_id,
+                                0) == MO_HALT_MATCHING) {
+                    return MO_HALT_MATCHING;
+                }
+            }
+        }
+        cur_buf++;
+    }
+    *state = movd(cur_state);
+    *scan_end = cur_buf;
+    return MO_CONTINUE_MATCHING;
+}