- Add noexcept and some constexpr.

- Use BitWord as helper class instead of inheriting in many static methods.

5 files changed, 39 insertions, 38 deletions

diff --git a/searchlib/src/vespa/searchlib/common/bitword.cpp b/searchlib/src/vespa/searchlib/common/bitword.cpp
index fbace5fcc56..8acf3cc3ef4 100644
--- a/searchlib/src/vespa/searchlib/common/bitword.cpp
+++ b/searchlib/src/vespa/searchlib/common/bitword.cpp
@@ -22,6 +22,6 @@ BitWord::Init::Init()
     fillUp(BitWord::_checkTab, std::numeric_limits<BitWord::Word>::max());
 }
 
-BitWord::Word BitWord::_checkTab[BitWord::WordLen];
+constexpr BitWord::Word BitWord::_checkTab[BitWord::WordLen];
 
 }
diff --git a/searchlib/src/vespa/searchlib/common/bitword.h b/searchlib/src/vespa/searchlib/common/bitword.h
index cba6cf7723f..06071e4cae8 100644
--- a/searchlib/src/vespa/searchlib/common/bitword.h
+++ b/searchlib/src/vespa/searchlib/common/bitword.h
@@ -12,16 +12,16 @@ class BitWord {
 public:
     using Word = uint64_t;
     using Index = uint32_t;
-    static Word checkTab(Index index) { return _checkTab[bitNum(index)]; }
-    static Word startBits(Index index) { return (std::numeric_limits<Word>::max() >> 1) >> (WordLen - 1 - bitNum(index)); }
+    static Word checkTab(Index index) noexcept { return _checkTab[bitNum(index)]; }
+    static constexpr Word startBits(Index index) noexcept { return (std::numeric_limits<Word>::max() >> 1) >> (WordLen - 1 - bitNum(index)); }
     static constexpr size_t WordLen = sizeof(Word)*8;
-    static uint8_t bitNum(Index idx) { return (idx % WordLen); }
-    static Word endBits(Index index) { return (std::numeric_limits<Word>::max() - 1) << bitNum(index); }
-    static Word allBits() { return std::numeric_limits<Word>::max(); }
-    static Index wordNum(Index idx) { return idx >> numWordBits(); }
-    static Word mask(Index idx) { return Word(1) << bitNum(idx); }
-    static constexpr uint8_t size_bits(uint8_t n) { return (n > 1) ? (1 + size_bits(n >> 1)) : 0; }
-    static uint8_t numWordBits() { return size_bits(WordLen); }
+    static constexpr uint8_t bitNum(Index idx) noexcept { return (idx % WordLen); }
+    static constexpr Word endBits(Index index) noexcept { return (std::numeric_limits<Word>::max() - 1) << bitNum(index); }
+    static constexpr Word allBits() noexcept { return std::numeric_limits<Word>::max(); }
+    static constexpr Index wordNum(Index idx) noexcept { return idx >> numWordBits(); }
+    static constexpr Word mask(Index idx) noexcept { return Word(1) << bitNum(idx); }
+    static constexpr uint8_t size_bits(uint8_t n) noexcept { return (n > 1) ? (1 + size_bits(n >> 1)) : 0; }
+    static constexpr uint8_t numWordBits() noexcept { return size_bits(WordLen); }
 private:
 
     static Word _checkTab[WordLen];
diff --git a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
index 4203a6361b2..8b8db0f293a 100644
--- a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
+++ b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
@@ -29,12 +29,12 @@ public:
         memset(_lastWords, 0, sizeof(_lastWords));
     }
 protected:
-    void updateLastValue(uint32_t docId);
-    void strictSeek(uint32_t docId);
+    void updateLastValue(uint32_t docId) noexcept;
+    void strictSeek(uint32_t docId) noexcept;
 private:
     void doSeek(uint32_t docId) override;
     Trinary is_strict() const override { return Trinary::False; }
-    bool acceptExtraFilter() const override { return Update::isAnd(); }
+    bool acceptExtraFilter() const noexcept final { return Update::isAnd(); }
     Update              _update;
     const IAccelrated & _accel;
     alignas(64) Word    _lastWords[8];
@@ -42,7 +42,7 @@ private:
 };
 
 template<typename Update>
-class MultiBitVectorIteratorStrict : public MultiBitVectorIterator<Update>
+class MultiBitVectorIteratorStrict final : public MultiBitVectorIterator<Update>
 {
 public:
     explicit MultiBitVectorIteratorStrict(MultiSearch::Children  children)
@@ -55,36 +55,36 @@ private:
 
 struct And {
     using Word = BitWord::Word;
-    void operator () (const IAccelrated & accel, size_t offset, const std::vector<std::pair<const void *, bool>> & src, void *dest) {
+    void operator () (const IAccelrated & accel, size_t offset, const std::vector<std::pair<const void *, bool>> & src, void *dest) noexcept {
         accel.and64(offset, src, dest);
     }
-    static bool isAnd() { return true; }
+    static bool isAnd() noexcept { return true; }
 };
 
 struct Or {
     using Word = BitWord::Word;
-    void operator () (const IAccelrated & accel, size_t offset, const std::vector<std::pair<const void *, bool>> & src, void *dest) {
+    void operator () (const IAccelrated & accel, size_t offset, const std::vector<std::pair<const void *, bool>> & src, void *dest) noexcept {
         accel.or64(offset, src, dest);
     }
-    static bool isAnd() { return false; }
+    static bool isAnd() noexcept { return false; }
 };
 
 template<typename Update>
-void MultiBitVectorIterator<Update>::updateLastValue(uint32_t docId)
+void MultiBitVectorIterator<Update>::updateLastValue(uint32_t docId) noexcept
 {
     if (docId >= _lastMaxDocIdLimit) {
         if (__builtin_expect(docId >= _numDocs, false)) {
             setAtEnd();
             return;
         }
-        const uint32_t index(wordNum(docId));
+        const uint32_t index(BitWord::wordNum(docId));
         if (docId >= _lastMaxDocIdLimitRequireFetch) {
             uint32_t baseIndex = index & ~(NumWordsInBatch - 1);
             _update(_accel, baseIndex*sizeof(Word), _bvs, _lastWords);
-            _lastMaxDocIdLimitRequireFetch = (baseIndex + NumWordsInBatch) * WordLen;
+            _lastMaxDocIdLimitRequireFetch = (baseIndex + NumWordsInBatch) * BitWord::WordLen;
         }
         _lastValue = _lastWords[index % NumWordsInBatch];
-        _lastMaxDocIdLimit = (index + 1) * WordLen;
+        _lastMaxDocIdLimit = (index + 1) * BitWord::WordLen;
     }
 }
 
@@ -94,7 +94,7 @@ MultiBitVectorIterator<Update>::doSeek(uint32_t docId)
 {
     updateLastValue(docId);
     if (__builtin_expect( ! isAtEnd(), true)) {
-        if (_lastValue & mask(docId)) {
+        if (_lastValue & BitWord::mask(docId)) {
             setDocId(docId);
         }
     }
@@ -102,13 +102,13 @@ MultiBitVectorIterator<Update>::doSeek(uint32_t docId)
 
 template<typename Update>
 void
-MultiBitVectorIterator<Update>::strictSeek(uint32_t docId)
+MultiBitVectorIterator<Update>::strictSeek(uint32_t docId) noexcept
 {
-    for (updateLastValue(docId), _lastValue = _lastValue & checkTab(docId);
+    for (updateLastValue(docId), _lastValue = _lastValue & BitWord::checkTab(docId);
          (_lastValue == 0) && __builtin_expect(! isAtEnd(), true);
          updateLastValue(_lastMaxDocIdLimit));
     if (__builtin_expect(!isAtEnd(), true)) {
-        docId = _lastMaxDocIdLimit - WordLen + vespalib::Optimized::lsbIdx(_lastValue);
+        docId = _lastMaxDocIdLimit - BitWord::WordLen + vespalib::Optimized::lsbIdx(_lastValue);
         if (__builtin_expect(docId >= _numDocs, false)) {
             setAtEnd();
         } else {
diff --git a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.h b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.h
index d75a9ddd357..d99e439af0b 100644
--- a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.h
+++ b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.h
@@ -8,7 +8,7 @@
 
 namespace search::queryeval {
 
-class MultiBitVectorIteratorBase : public MultiSearch, protected BitWord
+class MultiBitVectorIteratorBase : public MultiSearch
 {
 public:
     ~MultiBitVectorIteratorBase() override;
@@ -20,7 +20,8 @@ public:
      */
     static SearchIterator::UP optimize(SearchIterator::UP parent);
 protected:
-    MultiBitVectorIteratorBase(Children hildren);
+    using Word = BitWord::Word;
+    MultiBitVectorIteratorBase(Children children);
     using MetaWord = std::pair<const void *, bool>;
 
     uint32_t                _numDocs;
@@ -29,7 +30,7 @@ protected:
     Word                    _lastValue; // Last value computed
     std::vector<MetaWord>   _bvs;
 private:
-    virtual bool acceptExtraFilter() const = 0;
+    virtual bool acceptExtraFilter() const noexcept = 0;
     UP andWith(UP filter, uint32_t estimate) override;
     void doUnpack(uint32_t docid) override;
     static SearchIterator::UP optimizeMultiSearch(SearchIterator::UP parent);
diff --git a/searchlib/src/vespa/searchlib/queryeval/searchiterator.h b/searchlib/src/vespa/searchlib/queryeval/searchiterator.h
index b58d7ceed43..4ab066727af 100644
--- a/searchlib/src/vespa/searchlib/queryeval/searchiterator.h
+++ b/searchlib/src/vespa/searchlib/queryeval/searchiterator.h
@@ -56,7 +56,7 @@ protected:
      *
      * @param id docid for hit
      **/
-    void setDocId(uint32_t id) { _docid = id; }
+    void setDocId(uint32_t id) noexcept { _docid = id; }
 
     /**
      * Used to adjust the end of the legal docid range.
@@ -64,13 +64,13 @@ protected:
      *
      * @param end_id the first docid outside the legal iterator range
      */
-    void setEndId(uint32_t end_id) { _endid = end_id; }
+    void setEndId(uint32_t end_id) noexcept { _endid = end_id; }
 
     /**
      * Will terminate the iterator by setting it past the end.
      * Further calls to isAtEnd() will then return true.
      */
-    void setAtEnd() { _docid = search::endDocId; }
+    void setAtEnd() noexcept { _docid = search::endDocId; }
 
 public:
     using Trinary=vespalib::Trinary;
@@ -180,7 +180,7 @@ public:
     /**
      * The constructor sets the current document id to @ref beginId.
      **/
-    SearchIterator() : _docid(0), _endid(0) { }
+    SearchIterator() noexcept : _docid(0), _endid(0) { }
     SearchIterator(const SearchIterator &) = delete;
     SearchIterator &operator=(const SearchIterator &) = delete;
 
@@ -192,15 +192,15 @@ public:
      *
      * @return constant
      **/
-    static uint32_t beginId() { return beginDocId; }
+    static uint32_t beginId() noexcept { return beginDocId; }
 
     /**
      * Tell if the iterator has reached the end.
      *
      * @return true if the iterator has reached its end.
      **/
-    bool isAtEnd() const { return isAtEnd(_docid); }
-    bool isAtEnd(uint32_t docid) const {
+    bool isAtEnd() const noexcept { return isAtEnd(_docid); }
+    bool isAtEnd(uint32_t docid) const noexcept {
         if (__builtin_expect(docid >= _endid, false)) {
             return true;
         }
@@ -214,9 +214,9 @@ public:
      *
      * @return current document id
      **/
-    uint32_t getDocId() const { return _docid; }
+    uint32_t getDocId() const noexcept { return _docid; }
 
-    uint32_t getEndId() const { return _endid; }
+    uint32_t getEndId() const noexcept { return _endid; }
 
     /**
      * Check if the given document id is a hit. If it is a hit, the