Don't check cur_ix_masked against ring_buffer_mask.

`cur_ix_masked` isn't changing from iteration to iteration, and `max_length` ensures we never find a match long enough to walk off the ring buffer. PiperOrigin-RevId: 616440826
google · Mar 17, 2024 · f919c06 · f919c06
1 parent 9717649
commit f919c06
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Showing 4 changed files with 7 additions and 14 deletions.
diff --git a/c/enc/hash.h b/c/enc/hash.h
@@ -586,8 +586,7 @@ static BROTLI_INLINE void FindCompoundDictionaryMatch(
     limit = source_size - offset;
     limit = (limit > max_length) ? max_length : limit;
     if (distance > max_distance) continue;
-    if (cur_ix_masked + best_len > ring_buffer_mask ||
-        best_len >= limit ||
+    if (best_len >= limit ||
         data[cur_ix_masked + best_len] != source[offset + best_len]) {
       continue;
     }
@@ -664,8 +663,7 @@ static BROTLI_INLINE size_t FindAllCompoundDictionaryMatches(
     limit = source_size - offset;
     limit = (limit > max_length) ? max_length : limit;
     if (distance > max_distance) continue;
-    if (cur_ix_masked + best_len > ring_buffer_mask ||
-        best_len >= limit ||
+    if (best_len >= limit ||
         data[cur_ix_masked + best_len] != source[offset + best_len]) {
       continue;
     }

diff --git a/c/enc/hash_forgetful_chain_inc.h b/c/enc/hash_forgetful_chain_inc.h
@@ -255,8 +255,7 @@ static BROTLI_INLINE void FN(FindLongestMatch)(
       prev_ix = (cur_ix - backward) & ring_buffer_mask;
       slot = banks[bank].slots[last].next;
       delta = banks[bank].slots[last].delta;
-      if (cur_ix_masked + best_len > ring_buffer_mask ||
-          prev_ix + best_len > ring_buffer_mask ||
+      if (prev_ix + best_len > ring_buffer_mask ||
           data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
         continue;
       }

diff --git a/c/enc/hash_longest_match64_inc.h b/c/enc/hash_longest_match64_inc.h
@@ -184,8 +184,7 @@ static BROTLI_INLINE void FN(FindLongestMatch)(
     }
     prev_ix &= ring_buffer_mask;
 
-    if (cur_ix_masked + best_len > ring_buffer_mask ||
-        prev_ix + best_len > ring_buffer_mask ||
+    if (prev_ix + best_len > ring_buffer_mask ||
         data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
       continue;
     }
@@ -228,8 +227,7 @@ static BROTLI_INLINE void FN(FindLongestMatch)(
         break;
       }
       prev_ix &= ring_buffer_mask;
-      if (cur_ix_masked + best_len > ring_buffer_mask ||
-          prev_ix + best_len > ring_buffer_mask ||
+      if (prev_ix + best_len > ring_buffer_mask ||
           data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
         continue;
       }

diff --git a/c/enc/hash_longest_match_inc.h b/c/enc/hash_longest_match_inc.h
@@ -181,8 +181,7 @@ static BROTLI_INLINE void FN(FindLongestMatch)(
     }
     prev_ix &= ring_buffer_mask;
 
-    if (cur_ix_masked + best_len > ring_buffer_mask ||
-        prev_ix + best_len > ring_buffer_mask ||
+    if (prev_ix + best_len > ring_buffer_mask ||
         data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
       continue;
     }
@@ -221,8 +220,7 @@ static BROTLI_INLINE void FN(FindLongestMatch)(
         break;
       }
       prev_ix &= ring_buffer_mask;
-      if (cur_ix_masked + best_len > ring_buffer_mask ||
-          prev_ix + best_len > ring_buffer_mask ||
+      if (prev_ix + best_len > ring_buffer_mask ||
           data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
         continue;
       }