[sql] Import SQLite 3.17.0.

third_party/sqlite/src/src/hash.c

Index: third_party/sqlite/src/src/hash.c
diff --git a/third_party/sqlite/src/src/hash.c b/third_party/sqlite/src/src/hash.c
index b5886e064152b8face140874a447ec596c11832d..62b695a1bb3447b98f7bffb719ecb0a782e13885 100644
--- a/third_party/sqlite/src/src/hash.c
+++ b/third_party/sqlite/src/src/hash.c
@@ -55,8 +55,12 @@ void sqlite3HashClear(Hash *pH){
 static unsigned int strHash(const char *z){
   unsigned int h = 0;
   unsigned char c;
-  while( (c = (unsigned char)*z++)!=0 ){
-    h = (h<<3) ^ h ^ sqlite3UpperToLower[c];
+  while( (c = (unsigned char)*z++)!=0 ){     /*OPTIMIZATION-IF-TRUE*/
+    /* Knuth multiplicative hashing.  (Sorting & Searching, p. 510).
+    ** 0x9e3779b1 is 2654435761 which is the closest prime number to
+    ** (2**32)*golden_ratio, where golden_ratio = (sqrt(5) - 1)/2. */
+    h += sqlite3UpperToLower[c];
+    h *= 0x9e3779b1;
   }
   return h;
 }
@@ -148,7 +152,7 @@ static HashElem *findElementWithHash(
   int count;                     /* Number of elements left to test */
   unsigned int h;                /* The computed hash */
 
-  if( pH->ht ){
+  if( pH->ht ){   /*OPTIMIZATION-IF-TRUE*/
     struct _ht *pEntry;
     h = strHash(pKey) % pH->htsize;
     pEntry = &pH->ht[h];