Hint at the most likely branches.

1 files changed, 9 insertions, 17 deletions

diff --git a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
index b13bf4a10e2..66f505581c7 100644
--- a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
+++ b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
@@ -20,7 +20,7 @@ struct And {
     void operator () (const IAccelrated & accel, size_t offset, const std::vector<Meta> & src, void *dest) noexcept {
         accel.and64(offset, src, dest);
     }
-    static bool isAnd() noexcept { return true; }
+    static constexpr bool isAnd() noexcept { return true; }
 };
 
 struct Or {
@@ -28,7 +28,7 @@ struct Or {
     void operator () (const IAccelrated & accel, size_t offset, const std::vector<Meta> & src, void *dest) noexcept {
         accel.or64(offset, src, dest);
     }
-    static bool isAnd() noexcept { return false; }
+    static constexpr bool isAnd() noexcept { return false; }
 };
 
 }
@@ -86,21 +86,17 @@ MultiBitVector<Update>::fetchChunk(uint32_t index) noexcept
     _lastMaxDocIdLimitRequireFetch = (baseIndex + NumWordsInBatch) * BitWord::WordLen;
 }
 
-
-
-
 template<typename Update>
 uint32_t
 MultiBitVector<Update>::strictSeek(uint32_t docId) noexcept
 {
     bool atEnd;
     for (atEnd = updateLastValue(docId), _lastValue = _lastValue & BitWord::checkTab(docId);
-         (_lastValue == 0) && __builtin_expect(! atEnd, true);
+         __builtin_expect(_lastValue == 0, Update::isAnd()) && __builtin_expect(! atEnd, true); // And is likely to have few bits, while Or has many.
          atEnd = updateLastValue(_lastMaxDocIdLimit));
-    if (__builtin_expect(!atEnd, true)) {
-        return _lastMaxDocIdLimit - BitWord::WordLen + vespalib::Optimized::lsbIdx(_lastValue);
-    }
-    return _numDocs;
+    return (__builtin_expect(!atEnd, true))
+        ? _lastMaxDocIdLimit - BitWord::WordLen + vespalib::Optimized::lsbIdx(_lastValue)
+        : _numDocs;
 }
 
 template<typename Update>
@@ -108,12 +104,8 @@ bool
 MultiBitVector<Update>::seek(uint32_t docId) noexcept
 {
     bool atEnd = updateLastValue(docId);
-    if (__builtin_expect( ! atEnd, true)) {
-        if (_lastValue & BitWord::mask(docId)) {
-            return true;
-        }
-    }
-    return false;
+    return __builtin_expect( ! atEnd, true) &&
+           __builtin_expect(_lastValue & BitWord::mask(docId), false);
 }
 
 namespace {
@@ -168,7 +160,7 @@ template<typename Update>
 void
 MultiBitVectorIterator<Update>::doSeek(uint32_t docId)
 {
-    if (_mbv.seek(docId)) {
+    if (_mbv.seek(docId)) [[unlikely]] {
         setDocId(docId);
     }
 }