From b048af5999061a41e68d1083ef7b0ab2fe75e29d Mon Sep 17 00:00:00 2001
From: "W. Felix Handte" <w@felixhandte.com>
Date: Fri, 14 Sep 2018 15:23:35 -0700
Subject: [PATCH 1/2] ZSTD_fast: Don't Search Dict Context When Mismatch Was
 Found

---
 lib/compress/zstd_fast.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/compress/zstd_fast.c b/lib/compress/zstd_fast.c
index 37a71516..7d7efb46 100644
--- a/lib/compress/zstd_fast.c
+++ b/lib/compress/zstd_fast.c
@@ -124,8 +124,7 @@ size_t ZSTD_compressBlock_fast_generic(
             mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
             ip++;
             ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
-        } else if ( (matchIndex <= prefixStartIndex)
-                 || (MEM_read32(match) != MEM_read32(ip)) ) {
+        } else if ( (matchIndex <= prefixStartIndex) ) {
             if (dictMode == ZSTD_dictMatchState) {
                 U32 const dictMatchIndex = dictHashTable[h];
                 const BYTE* dictMatch = dictBase + dictMatchIndex;
@@ -151,6 +150,11 @@ size_t ZSTD_compressBlock_fast_generic(
                 ip += ((ip-anchor) >> kSearchStrength) + stepSize;
                 continue;
             }
+        } else if (MEM_read32(match) != MEM_read32(ip)) {
+            /* it's not a match, and we're not going to check the dictionary */
+            assert(stepSize >= 1);
+            ip += ((ip-anchor) >> kSearchStrength) + stepSize;
+            continue;
         } else {
             /* found a regular match */
             U32 const offset = (U32)(ip-match);

From b76c88849748935bfd703a0703770d820e75c6b7 Mon Sep 17 00:00:00 2001
From: "W. Felix Handte" <w@felixhandte.com>
Date: Fri, 14 Sep 2018 15:24:25 -0700
Subject: [PATCH 2/2] ZSTD_dfast: Don't Search Dict Context When Mismatch Was
 Found

---
 lib/compress/zstd_double_fast.c | 54 ++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/lib/compress/zstd_double_fast.c b/lib/compress/zstd_double_fast.c
index 7fc11eb4..9231c815 100644
--- a/lib/compress/zstd_double_fast.c
+++ b/lib/compress/zstd_double_fast.c
@@ -141,16 +141,16 @@ size_t ZSTD_compressBlock_doubleFast_generic(
             goto _match_stored;
         }
 
-        /* check prefix long match */
-        if ( (matchIndexL > prefixLowestIndex) && (MEM_read64(matchLong) == MEM_read64(ip)) ) {
-            mLength = ZSTD_count(ip+8, matchLong+8, iend) + 8;
-            offset = (U32)(ip-matchLong);
-            while (((ip>anchor) & (matchLong>prefixLowest)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
-            goto _match_found;
-        }
-
-        /* check dictMatchState long match */
-        if (dictMode == ZSTD_dictMatchState) {
+        if (matchIndexL > prefixLowestIndex) {
+            /* check prefix long match */
+            if (MEM_read64(matchLong) == MEM_read64(ip)) {
+                mLength = ZSTD_count(ip+8, matchLong+8, iend) + 8;
+                offset = (U32)(ip-matchLong);
+                while (((ip>anchor) & (matchLong>prefixLowest)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
+                goto _match_found;
+            }
+        } else if (dictMode == ZSTD_dictMatchState) {
+            /* check dictMatchState long match */
             U32 const dictMatchIndexL = dictHashLong[h2];
             const BYTE* dictMatchL = dictBase + dictMatchIndexL;
             assert(dictMatchL < dictEnd);
@@ -163,13 +163,13 @@ size_t ZSTD_compressBlock_doubleFast_generic(
             }
         }
 
-        /* check prefix short match */
-        if ( (matchIndexS > prefixLowestIndex) && (MEM_read32(match) == MEM_read32(ip)) ) {
-            goto _search_next_long;
-        }
-
-        /* check dictMatchState short match */
-        if (dictMode == ZSTD_dictMatchState) {
+        if (matchIndexS > prefixLowestIndex) {
+            /* check prefix short match */
+            if (MEM_read32(match) == MEM_read32(ip)) {
+                goto _search_next_long;
+            }
+        } else if (dictMode == ZSTD_dictMatchState) {
+            /* check dictMatchState short match */
             U32 const dictMatchIndexS = dictHashSmall[h];
             match = dictBase + dictMatchIndexS;
             matchIndexS = dictMatchIndexS + dictIndexDelta;
@@ -191,16 +191,16 @@ _search_next_long:
             hashLong[hl3] = current + 1;
 
             /* check prefix long +1 match */
-            if ( (matchIndexL3 > prefixLowestIndex) && (MEM_read64(matchL3) == MEM_read64(ip+1)) ) {
-                mLength = ZSTD_count(ip+9, matchL3+8, iend) + 8;
-                ip++;
-                offset = (U32)(ip-matchL3);
-                while (((ip>anchor) & (matchL3>prefixLowest)) && (ip[-1] == matchL3[-1])) { ip--; matchL3--; mLength++; } /* catch up */
-                goto _match_found;
-            }
-
-            /* check dict long +1 match */
-            if (dictMode == ZSTD_dictMatchState) {
+            if (matchIndexL3 > prefixLowestIndex) {
+                if (MEM_read64(matchL3) == MEM_read64(ip+1)) {
+                    mLength = ZSTD_count(ip+9, matchL3+8, iend) + 8;
+                    ip++;
+                    offset = (U32)(ip-matchL3);
+                    while (((ip>anchor) & (matchL3>prefixLowest)) && (ip[-1] == matchL3[-1])) { ip--; matchL3--; mLength++; } /* catch up */
+                    goto _match_found;
+                }
+            } else if (dictMode == ZSTD_dictMatchState) {
+                /* check dict long +1 match */
                 U32 const dictMatchIndexL3 = dictHashLong[hl3];
                 const BYTE* dictMatchL3 = dictBase + dictMatchIndexL3;
                 assert(dictMatchL3 < dictEnd);