fixed incorrect rowlog initialization

the variable has only very limited usage,
being only used once at the beginning of the block for prefetching only,
hence the error had no impact on compression ratio.

lib/compress/zstd_lazy.c

@@ -1440,8 +1440,15 @@ ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_HC_VTABLE)
 *********************************/
 typedef enum { search_hashChain=0, search_binaryTree=1, search_rowHash=2 } searchMethod_e;
 
+/**
+ * This table is indexed first by the four ZSTD_dictMode_e values, and then
+ * by the two searchMethod_e values. NULLs are placed for configurations
+ * that should never occur (extDict modes go to the other implementation
+ * below and there is no DDSS for binary tree search yet).
+ */
 
-static ZSTD_LazyVTable const* ZSTD_selectLazyVTable(ZSTD_matchState_t const* ms, searchMethod_e searchMethod, ZSTD_dictMode_e dictMode)
+static ZSTD_LazyVTable const*
+ZSTD_selectLazyVTable(ZSTD_matchState_t const* ms, searchMethod_e searchMethod, ZSTD_dictMode_e dictMode)
 {
     /* Fill the Hc/Bt VTable arrays with the right functions for the (dictMode, mls) combination. */
     ZSTD_LazyVTable const* const hcVTables[4][3] = GEN_ZSTD_VTABLE_ARRAY(GEN_ZSTD_HC_VTABLE_ARRAY);
@@ -1475,19 +1482,10 @@ ZSTD_compressBlock_lazy_generic(
     const BYTE* ip = istart;
     const BYTE* anchor = istart;
     const BYTE* const iend = istart + srcSize;
-    const BYTE* const ilimit = searchMethod == search_rowHash ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8;
+    const BYTE* const ilimit = (searchMethod == search_rowHash) ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8;
     const BYTE* const base = ms->window.base;
     const U32 prefixLowestIndex = ms->window.dictLimit;
     const BYTE* const prefixLowest = base + prefixLowestIndex;
-    const U32 rowLog = ms->cParams.searchLog < 5 ? 4 : 5;
-
-
-    /**
-     * This table is indexed first by the four ZSTD_dictMode_e values, and then
-     * by the two searchMethod_e values. NULLs are placed for configurations
-     * that should never occur (extDict modes go to the other implementation
-     * below and there is no DDSS for binary tree search yet).
-     */
 
     searchMax_f const searchMax = ZSTD_selectLazyVTable(ms, searchMethod, dictMode)->searchMax;
     U32 offset_1 = rep[0], offset_2 = rep[1], savedOffset=0;
@@ -1524,6 +1522,7 @@ ZSTD_compressBlock_lazy_generic(
     }
 
     if (searchMethod == search_rowHash) {
+        const U32 rowLog = MAX(4, MIN(6, ms->cParams.searchLog));
         ZSTD_row_fillHashCache(ms, base, rowLog,
                             MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */),
                             ms->nextToUpdate, ilimit);