Remove zero initialization of large buffers

Profiles show that an high amount of CPU time spent in memset.
By removing zero initalization of certain large buffers we improve
performance in certain authoritative workloads.

lib/dns/qp.c

@@ -1789,10 +1789,9 @@ dns_qpchain_init(dns_qpreadable_t qpr, dns_qpchain_t *chain) {
 	REQUIRE(QP_VALID(qp));
 	REQUIRE(chain != NULL);
 
-	*chain = (dns_qpchain_t){
-		.magic = QPCHAIN_MAGIC,
-		.qp = qp,
-	};
+	chain->magic = QPCHAIN_MAGIC;
+	chain->qp = qp;
+	chain->len = 0;
 }
 
 unsigned int
@@ -1825,10 +1824,11 @@ dns_qpiter_init(dns_qpreadable_t qpr, dns_qpiter_t *qpi) {
 	dns_qpreader_t *qp = dns_qpreader(qpr);
 	REQUIRE(QP_VALID(qp));
 	REQUIRE(qpi != NULL);
-	*qpi = (dns_qpiter_t){
-		.qp = qp,
-		.magic = QPITER_MAGIC,
-	};
+
+	qpi->qp = qp;
+	qpi->sp = 0;
+	qpi->magic = QPITER_MAGIC;
+	qpi->stack[qpi->sp] = NULL;
 }
 
 /*

lib/dns/qpcache.c

@@ -1598,11 +1598,17 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 		now = isc_stdtime_now();
 	}
 
-	search = (qpc_search_t){
-		.qpdb = (qpcache_t *)db,
-		.options = options,
-		.now = now,
-	};
+	search.qpdb = (qpcache_t *)db;
+	search.options = options;
+	/*
+	 * qpchain - Init by dns_qp_lookup
+	 * qpiter - Init by dns_qp_lookup
+	 */
+	search.need_cleanup = false;
+	search.now = now;
+	search.zonecut = NULL;
+	search.zonecut_header = NULL;
+	search.zonecut_sigheader = NULL;
 
 	TREE_RDLOCK(&search.qpdb->tree_lock, &tlocktype);
 

lib/dns/qpzone.c

@@ -3379,13 +3379,23 @@ qpzone_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 		close_version = true;
 	}
 
-	search = (qpz_search_t){
-		.qpdb = (qpzonedb_t *)db,
-		.version = (qpz_version_t *)version,
-		.serial = ((qpz_version_t *)version)->serial,
-		.options = options,
-	};
+	search.qpdb = (qpzonedb_t *)db;
+	search.version = (qpz_version_t *)version;
+	search.qpr = (dns_qpread_t) {};
+	search.serial = ((qpz_version_t *)version)->serial;
+	search.options = options;
+	/*
+	 * qpchain -- init in dns_qp_lookup
+	 * qpiter -- init in dns_qp_lookup
+	 */
+	search.copy_name = false;
+	search.need_cleanup = false;
+	search.wild = false;
+	search.zonecut = NULL;
+	search.zonecut_header = NULL;
+	search.zonecut_sigheader = NULL;
 	dns_fixedname_init(&search.zonecut_name);
+	search.now = 0;
 
 	if ((options & DNS_DBFIND_FORCENSEC3) != 0) {
 		dns_qpmulti_query(qpdb->nsec3, &search.qpr);

lib/dns/rdataset.c

@@ -54,11 +54,20 @@ dns_rdataset_init(dns_rdataset_t *rdataset) {
 
 	REQUIRE(rdataset != NULL);
 
-	*rdataset = (dns_rdataset_t){
-		.magic = DNS_RDATASET_MAGIC,
-		.link = ISC_LINK_INITIALIZER,
-		.count = DNS_RDATASET_COUNT_UNDEFINED,
-	};
+	rdataset->magic = DNS_RDATASET_MAGIC;
+	ISC_LINK_INIT(rdataset, link);
+	rdataset->count = DNS_RDATASET_COUNT_UNDEFINED;
+
+	rdataset->methods = NULL;
+
+	rdataset->rdclass = 0;
+	rdataset->type = 0;
+	rdataset->ttl = 0;
+	rdataset->trust = 0;
+	rdataset->covers = 0;
+	rdataset->attributes = 0;
+	/* TODO should rdataset->count be initialized to zero? */
+	rdataset->resign = 0;
 }
 
 void
@@ -70,11 +79,18 @@ dns_rdataset_invalidate(dns_rdataset_t *rdataset) {
 	REQUIRE(DNS_RDATASET_VALID(rdataset));
 	REQUIRE(rdataset->methods == NULL);
 
-	*rdataset = (dns_rdataset_t){
-		.magic = 0,
-		.link = ISC_LINK_INITIALIZER,
-		.count = DNS_RDATASET_COUNT_UNDEFINED,
-	};
+	rdataset->magic = 0;
+	ISC_LINK_INIT(rdataset, link);
+	rdataset->count = DNS_RDATASET_COUNT_UNDEFINED;
+	
+	rdataset->rdclass = 0;
+	rdataset->type = 0;
+	rdataset->ttl = 0;
+	rdataset->trust = 0;
+	rdataset->covers = 0;
+	rdataset->attributes = 0;
+	/* TODO should rdataset->count be initialized to zero? */
+	rdataset->resign = 0;
 }
 
 void
@@ -89,11 +105,7 @@ dns__rdataset_disassociate(dns_rdataset_t *rdataset DNS__DB_FLARG) {
 	if (rdataset->methods->disassociate != NULL) {
 		(rdataset->methods->disassociate)(rdataset DNS__DB_FLARG_PASS);
 	}
-	*rdataset = (dns_rdataset_t){
-		.magic = DNS_RDATASET_MAGIC,
-		.link = ISC_LINK_INITIALIZER,
-		.count = DNS_RDATASET_COUNT_UNDEFINED,
-	};
+	dns_rdataset_init(rdataset);
 }
 
 bool