Use __built_expect() where available (#41411)

diff --git a/CHANGES b/CHANGES
index 019d5479f705dda2fcc8e255d7d54d29c1eb85de..276391de9747dd95195d597f2c13142899bc42d0 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4310.  [performance]   Use __builtin_expect() where available to annotate
+                       conditions with known behavior. [RT #41411]
+
 4309.  [cleanup]       Remove the spurious "none" filename from log messages
                        when processing built-in configuration. [RT #41594]
 

diff --git a/config.h.in b/config.h.in
index 3836450b080ff2929f5353977fd392c1954ac9b2..2fbdba73de4b07bf17f1448a349eaeb6e208c72e 100644 (file)
--- a/config.h.in
+++ b/config.h.in
@@ -191,6 +191,9 @@ int sigwait(const unsigned int *set, int *sig);
    MSVC and with C++ compilers. */
 #undef FLEXIBLE_ARRAY_MEMBER
 
+/* Define to 1 if the compiler supports __builtin_expect. */
+#undef HAVE_BUILTIN_EXPECT
+
 /* Define to 1 if you have the `chroot' function. */
 #undef HAVE_CHROOT
 

diff --git a/configure b/configure
index 15871119d5c88ddc8bf68c62c6010184c133ca8b..38787be92b484e639e25aa5928f70e9c0f456cce 100755 (executable)
--- a/configure
+++ b/configure
@@ -19924,6 +19924,45 @@ fi
 ISC_ARCH_DIR=$arch
 
 
+#
+# Check for __builtin_expect
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking compiler support for __builtin_expect" >&5
+$as_echo_n "checking compiler support for __builtin_expect... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+        return (__builtin_expect(1, 1) ? 1 : 0);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_builtin_expect=yes
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+else
+
+        have_builtin_expect=no
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+if test "$have_builtin_expect" = "yes"; then
+
+$as_echo "#define HAVE_BUILTIN_EXPECT 1" >>confdefs.h
+
+fi
+
 #
 # Activate "rrset-order fixed" or not?
 #

diff --git a/configure.in b/configure.in
index 05b27b0b1ef5e3e899c321b4479f64c5d9246c04..b0523bb4e2b20efbebc61a68fc803489f039c11a 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -3892,6 +3892,23 @@ AC_SUBST(ISC_PLATFORM_USEMACASM)
 ISC_ARCH_DIR=$arch
 AC_SUBST(ISC_ARCH_DIR)
 
+#
+# Check for __builtin_expect
+#
+AC_MSG_CHECKING([compiler support for __builtin_expect])
+AC_TRY_LINK(, [
+        return (__builtin_expect(1, 1) ? 1 : 0);
+], [
+        have_builtin_expect=yes
+        AC_MSG_RESULT(yes)
+], [
+        have_builtin_expect=no
+        AC_MSG_RESULT(no)
+])
+if test "$have_builtin_expect" = "yes"; then
+        AC_DEFINE(HAVE_BUILTIN_EXPECT, 1, [Define to 1 if the compiler supports __builtin_expect.])
+fi
+
 #
 # Activate "rrset-order fixed" or not?
 #

diff --git a/lib/dns/name.c b/lib/dns/name.c
index 68f3180edd318ccc490bb54a9dec65bd9aca67a4..d8d07f9c62c357f11900fa9731f33a4c8e3b64b1 100644 (file)
--- a/lib/dns/name.c
+++ b/lib/dns/name.c
@@ -591,7 +591,7 @@ dns_name_fullcompare(const dns_name_t *name1, const dns_name_t *name2,
        REQUIRE((name1->attributes & DNS_NAMEATTR_ABSOLUTE) ==
                (name2->attributes & DNS_NAMEATTR_ABSOLUTE));
 
-       if (name1 == name2) {
+       if (ISC_UNLIKELY(name1 == name2)) {
                *orderp = 0;
                *nlabelsp = name1->labels;
                return (dns_namereln_equal);
@@ -614,7 +614,7 @@ dns_name_fullcompare(const dns_name_t *name1, const dns_name_t *name2,
        offsets1 += l1;
        offsets2 += l2;
 
-       while (l > 0) {
+       while (ISC_LIKELY(l > 0)) {
                l--;
                offsets1--;
                offsets2--;
@@ -636,7 +636,7 @@ dns_name_fullcompare(const dns_name_t *name1, const dns_name_t *name2,
                        count = count2;
 
                /* Loop unrolled for performance */
-               while (count > 3) {
+               while (ISC_LIKELY(count > 3)) {
                        chdiff = (int)maptolower[label1[0]] -
                                 (int)maptolower[label2[0]];
                        if (chdiff != 0) {
@@ -665,7 +665,7 @@ dns_name_fullcompare(const dns_name_t *name1, const dns_name_t *name2,
                        label1 += 4;
                        label2 += 4;
                }
-               while (count-- > 0) {
+               while (ISC_LIKELY(count-- > 0)) {
                        chdiff = (int)maptolower[*label1++] -
                                 (int)maptolower[*label2++];
                        if (chdiff != 0) {
@@ -741,7 +741,7 @@ dns_name_equal(const dns_name_t *name1, const dns_name_t *name2) {
        REQUIRE((name1->attributes & DNS_NAMEATTR_ABSOLUTE) ==
                (name2->attributes & DNS_NAMEATTR_ABSOLUTE));
 
-       if (name1 == name2)
+       if (ISC_UNLIKELY(name1 == name2))
                return (ISC_TRUE);
 
        if (name1->length != name2->length)
@@ -754,7 +754,7 @@ dns_name_equal(const dns_name_t *name1, const dns_name_t *name2) {
 
        label1 = name1->ndata;
        label2 = name2->ndata;
-       while (l-- > 0) {
+       while (ISC_LIKELY(l-- > 0)) {
                count = *label1++;
                if (count != *label2++)
                        return (ISC_FALSE);
@@ -762,7 +762,7 @@ dns_name_equal(const dns_name_t *name1, const dns_name_t *name2) {
                INSIST(count <= 63); /* no bitstring support */
 
                /* Loop unrolled for performance */
-               while (count > 3) {
+               while (ISC_LIKELY(count > 3)) {
                        c = maptolower[label1[0]];
                        if (c != maptolower[label2[0]])
                                return (ISC_FALSE);
@@ -779,7 +779,7 @@ dns_name_equal(const dns_name_t *name1, const dns_name_t *name2) {
                        label1 += 4;
                        label2 += 4;
                }
-               while (count-- > 0) {
+               while (ISC_LIKELY(count-- > 0)) {
                        c = maptolower[*label1++];
                        if (c != maptolower[*label2++])
                                return (ISC_FALSE);

diff --git a/lib/dns/rbt.c b/lib/dns/rbt.c
index 86b5183f60a138ad2ffa249187dfc044775817cc..9fb08075f0a10945aa03e23dc6cda17755d999de 100644 (file)
--- a/lib/dns/rbt.c
+++ b/lib/dns/rbt.c
@@ -1136,7 +1136,7 @@ dns_rbt_addnode(dns_rbt_t *rbt, dns_name_t *name, dns_rbtnode_t **nodep) {
        add_name = dns_fixedname_name(&fixedcopy);
        dns_name_clone(name, add_name);
 
-       if (rbt->root == NULL) {
+       if (ISC_UNLIKELY(rbt->root == NULL)) {
                result = create_node(rbt->mctx, add_name, &new_current);
                if (result == ISC_R_SUCCESS) {
                        rbt->nodecount++;
@@ -1377,12 +1377,12 @@ dns_rbt_addnode(dns_rbt_t *rbt, dns_name_t *name, dns_rbtnode_t **nodep) {
 
                }
 
-       } while (child != NULL);
+       } while (ISC_LIKELY(child != NULL));
 
-       if (result == ISC_R_SUCCESS)
+       if (ISC_LIKELY(result == ISC_R_SUCCESS))
                result = create_node(rbt->mctx, add_name, &new_current);
 
-       if (result == ISC_R_SUCCESS) {
+       if (ISC_LIKELY(result == ISC_R_SUCCESS)) {
 #ifdef DNS_RBT_USEHASH
                if (*root == NULL)
                        UPPERNODE(new_current) = current;
@@ -1465,7 +1465,7 @@ dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, dns_name_t *foundname,
        } else
                dns_rbtnodechain_reset(chain);
 
-       if (rbt->root == NULL)
+       if (ISC_UNLIKELY(rbt->root == NULL))
                return (ISC_R_NOTFOUND);
 
        /*
@@ -1496,7 +1496,7 @@ dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, dns_name_t *foundname,
        current = rbt->root;
        current_root = rbt->root;
 
-       while (current != NULL) {
+       while (ISC_LIKELY(current != NULL)) {
                NODENAME(current, &current_name);
                compared = dns_name_fullcompare(search_name, &current_name,
                                                &order, &common_labels);
@@ -1577,7 +1577,7 @@ dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, dns_name_t *foundname,
                        {
                                dns_name_t hnode_name;
 
-                               if (hash != HASHVAL(hnode))
+                               if (ISC_LIKELY(hash != HASHVAL(hnode)))
                                        continue;
                                /*
                                 * This checks that the hashed label
@@ -1586,12 +1586,12 @@ dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, dns_name_t *foundname,
                                 * match a labelsequence from some other
                                 * subdomain.
                                 */
-                               if (get_upper_node(hnode) != up_current)
+                               if (ISC_LIKELY(get_upper_node(hnode) != up_current))
                                        continue;
 
                                dns_name_init(&hnode_name, NULL);
                                NODENAME(hnode, &hnode_name);
-                               if (dns_name_equal(&hnode_name, &hash_name))
+                               if (ISC_LIKELY(dns_name_equal(&hnode_name, &hash_name)))
                                        break;
                        }
 

diff --git a/lib/isc/hash.c b/lib/isc/hash.c
index 95b573db10cff7430f8d64cbdde9ededee88af48..9fc993c951b47927df90e2cec9c381cbe418ef4f 100644 (file)
--- a/lib/isc/hash.c
+++ b/lib/isc/hash.c
@@ -492,7 +492,7 @@ isc_hash_function_reverse(const void *data, size_t length,
 
        RUNTIME_CHECK(isc_once_do(&fnv_once, fnv_initialize) == ISC_R_SUCCESS);
 
-       hval = previous_hashp != NULL ? *previous_hashp : fnv_offset_basis;
+       hval = ISC_UNLIKELY(previous_hashp != NULL) ? *previous_hashp : fnv_offset_basis;
 
        bp = (const unsigned char *) data;
        be = bp + length;

diff --git a/lib/isc/include/isc/assertions.h b/lib/isc/include/isc/assertions.h
index 2c81b1ae9880cfb51dfdb685d4817006c2be173c..5f264619ff62b746f66c550c52fd9609942f7f3d 100644 (file)
--- a/lib/isc/include/isc/assertions.h
+++ b/lib/isc/include/isc/assertions.h
@@ -83,7 +83,7 @@ isc_assertion_typetotext(isc_assertiontype_t type);
 
 #if ISC_CHECK_REQUIRE != 0
 #define ISC_REQUIRE(cond) \
-       ((void) ((cond) || \
+       ((void) (ISC_LIKELY(cond) || \
                 ((isc_assertion_failed)(__FILE__, __LINE__, \
                                         isc_assertiontype_require, \
                                         #cond), 0)))
@@ -93,7 +93,7 @@ isc_assertion_typetotext(isc_assertiontype_t type);
 
 #if ISC_CHECK_ENSURE != 0
 #define ISC_ENSURE(cond) \
-       ((void) ((cond) || \
+       ((void) (ISC_LIKELY(cond) || \
                 ((isc_assertion_failed)(__FILE__, __LINE__, \
                                         isc_assertiontype_ensure, \
                                         #cond), 0)))
@@ -103,7 +103,7 @@ isc_assertion_typetotext(isc_assertiontype_t type);
 
 #if ISC_CHECK_INSIST != 0
 #define ISC_INSIST(cond) \
-       ((void) ((cond) || \
+       ((void) (ISC_LIKELY(cond) || \
                 ((isc_assertion_failed)(__FILE__, __LINE__, \
                                         isc_assertiontype_insist, \
                                         #cond), 0)))
@@ -113,7 +113,7 @@ isc_assertion_typetotext(isc_assertiontype_t type);
 
 #if ISC_CHECK_INVARIANT != 0
 #define ISC_INVARIANT(cond) \
-       ((void) ((cond) || \
+       ((void) (ISC_LIKELY(cond) || \
                 ((isc_assertion_failed)(__FILE__, __LINE__, \
                                         isc_assertiontype_invariant, \
                                         #cond), 0)))

diff --git a/lib/isc/include/isc/error.h b/lib/isc/include/isc/error.h
index e0cdfa83e7cba52142aed71131956eeaba685082..5f13d5ed4124b816516fd40528434adae3d3e9d5 100644 (file)
--- a/lib/isc/include/isc/error.h
+++ b/lib/isc/include/isc/error.h
@@ -55,7 +55,7 @@ void
 isc_error_runtimecheck(const char *, int, const char *);
 
 #define ISC_ERROR_RUNTIMECHECK(cond) \
-       ((void) ((cond) || \
+       ((void) (ISC_LIKELY(cond) || \
                 ((isc_error_runtimecheck)(__FILE__, __LINE__, #cond), 0)))
 
 ISC_LANG_ENDDECLS

diff --git a/lib/isc/include/isc/magic.h b/lib/isc/include/isc/magic.h
index 073de90dcc9257e1fd35be2b6179c54f04f5ccfc..635d70f774f63cd57742d7b3fcd7c11d2572de18 100644 (file)
--- a/lib/isc/include/isc/magic.h
+++ b/lib/isc/include/isc/magic.h
@@ -20,6 +20,8 @@
 #ifndef ISC_MAGIC_H
 #define ISC_MAGIC_H 1
 
+#include <isc/util.h>
+
 /*! \file isc/magic.h */
 
 typedef struct {
@@ -33,8 +35,8 @@ typedef struct {
  * The intent of this is to allow magic numbers to be checked even though
  * the object is otherwise opaque.
  */
-#define ISC_MAGIC_VALID(a,b)   (((a) != NULL) && \
-                                (((const isc__magic_t *)(a))->magic == (b)))
+#define ISC_MAGIC_VALID(a,b)   (ISC_LIKELY((a) != NULL) && \
+                                ISC_LIKELY(((const isc__magic_t *)(a))->magic == (b)))
 
 #define ISC_MAGIC(a, b, c, d)  ((a) << 24 | (b) << 16 | (c) << 8 | (d))
 

diff --git a/lib/isc/include/isc/util.h b/lib/isc/include/isc/util.h
index 6baf786bdeab5a18668dbdca8e4a5cac9b693ac7..2f4fd3b7f4b53fab7a61bf7b387007921abb9c3f 100644 (file)
--- a/lib/isc/include/isc/util.h
+++ b/lib/isc/include/isc/util.h
@@ -206,6 +206,17 @@
 #define INSERTAFTER(li, a, e, ln)      ISC_LIST_INSERTAFTER(li, a, e, ln)
 #define APPENDLIST(list1, list2, link) ISC_LIST_APPENDLIST(list1, list2, link)
 
+/*%
+ * Performance
+ */
+#ifdef HAVE_BUILTIN_EXPECT
+#define ISC_LIKELY(x)            __builtin_expect(!!(x), 1)
+#define ISC_UNLIKELY(x)          __builtin_expect(!!(x), 0)
+#else
+#define ISC_LIKELY(x)            (x)
+#define ISC_UNLIKELY(x)          (x)
+#endif
+
 /*
  * Assertions
  */