Remove unnecessary ring buffer boundary checks.

PiperOrigin-RevId: 991583282

c/enc/hash.h

diff --git a/c/enc/hash.h b/c/enc/hash.h
index 0340611..35addc8 100644
--- a/c/enc/hash.h
+++ b/c/enc/hash.h
@@ -850,6 +850,8 @@
   }
 #endif
 
+  BROTLI_DCHECK(cur_ix_masked + max_length <= ring_buffer_mask + 1);
+
   for (i = 0; i < 4; ++i) {
     const size_t distance = (size_t)distance_cache[i];
     size_t offset;
@@ -893,7 +895,7 @@
     limit = source_size - offset;
     limit = (limit > max_length) ? max_length : limit;
     if (distance > max_distance) continue;
-    if (best_len >= limit ||
+    if (cur_ix_masked + best_len > ring_buffer_mask || best_len >= limit ||
         /* compare 4 bytes ending at best_len + 1 */
         BrotliUnalignedRead32(&data[cur_ix_masked + best_len - 3]) !=
             BrotliUnalignedRead32(&source[offset + best_len - 3])) {

c/enc/hash_longest_match_simd_opt_inc.h

diff --git a/c/enc/hash_longest_match_simd_opt_inc.h b/c/enc/hash_longest_match_simd_opt_inc.h
index 6c54fae..6985a5d 100644
--- a/c/enc/hash_longest_match_simd_opt_inc.h
+++ b/c/enc/hash_longest_match_simd_opt_inc.h
@@ -190,7 +190,11 @@
     }
     prev_ix &= ring_buffer_mask;
 
-    if (BrotliUnalignedRead16(&data[cur_ix_masked + best_len - 1]) !=
+    if (cur_ix_masked + best_len > ring_buffer_mask) {
+      break;
+    }
+    if (prev_ix + best_len > ring_buffer_mask ||
+        BrotliUnalignedRead16(&data[cur_ix_masked + best_len - 1]) !=
             BrotliUnalignedRead16(&data[prev_ix + best_len - 1])) {
       continue;
     }
@@ -240,7 +244,11 @@
         break;
       }
       prev_ix &= ring_buffer_mask;
-      if (/* compare 4 bytes ending at best_len + 1 */
+      if (cur_ix_masked + best_len > ring_buffer_mask) {
+        break;
+      }
+      if (prev_ix + best_len > ring_buffer_mask ||
+          /* compare 4 bytes ending at best_len + 1 */
           BrotliUnalignedRead32(&data[cur_ix_masked + best_len - 3]) !=
               BrotliUnalignedRead32(&data[prev_ix + best_len - 3])) {
         continue;