Speed up maxBetweenExclusive

ConflictSet.cpp

@@ -100,6 +100,8 @@ struct BitSet {
   }
 
   int firstSetGeq(int i) const {
+    assert(0 <= i);
+    assert(i < 256);
     if (i < 128) {
       int a = std::countr_zero(lo >> i);
       if (a < 128) {
@@ -126,7 +128,10 @@ struct Node48 : Node {
   Node *children[48] = {};
   int8_t nextFree = 0;
   int8_t index[256];
-  Node48() { this->type = Type::Node48; }
+  Node48() {
+    memset(index, -1, 256);
+    this->type = Type::Node48;
+  }
 };
 
 struct Node256 : Node {
@@ -443,7 +448,7 @@ void eraseChild(Node *self, uint8_t index) {
   } else if (self->type == Type::Node48) {
     auto *self48 = static_cast<Node48 *>(self);
     self48->bitSet.reset(index);
-    int8_t toRemoveChildrenIndex = self48->index[index];
+    int8_t toRemoveChildrenIndex = std::exchange(self48->index[index], -1);
     int8_t lastChildrenIndex = --self48->nextFree;
     assert(toRemoveChildrenIndex >= 0);
     assert(lastChildrenIndex >= 0);
@@ -730,18 +735,60 @@ downLeftSpine:
 }
 
 int64_t maxBetweenExclusive(Node *n, int begin, int end) {
+  assert(-1 <= begin);
+  assert(begin <= 256);
+  assert(-1 <= end);
+  assert(end <= 256);
+  assert(begin < end);
   int64_t result = std::numeric_limits<int64_t>::lowest();
-  int next = begin;
-  for (;;) {
-    next = getChildGeq(n, next + 1);
-    if (next < 0 || next >= end) {
-      break;
+  {
+    int c = getChildGeq(n, begin + 1);
+    if (c >= 0 && c < end) {
+      auto *child = getChildExists(n, c);
+      if (child->entryPresent) {
+        result = std::max(result, child->entry.rangeVersion);
+      }
     }
-    auto *child = getChildExists(n, next);
-    if (child->entryPresent) {
-      result = std::max(result, child->entry.rangeVersion);
+  }
+  switch (n->type) {
+  case Type::Node4: {
+    auto *self = static_cast<Node4 *>(n);
+    for (int i = 0; i < self->numChildren && self->index[i] < end; ++i) {
+      if (begin < self->index[i]) {
+        result = std::max(result, self->children[i]->maxVersion);
+      }
     }
-    result = std::max(result, child->maxVersion);
+    break;
+  }
+  case Type::Node16: {
+    auto *self = static_cast<Node16 *>(n);
+    for (int i = 0; i < self->numChildren && self->index[i] < end; ++i) {
+      if (begin < self->index[i]) {
+        result = std::max(result, self->children[i]->maxVersion);
+      }
+    }
+    break;
+  }
+  case Type::Node48: {
+    auto *self = static_cast<Node48 *>(n);
+    for (int i = begin + 1; i < end; ++i) {
+      if (self->index[i] != -1) {
+        result = std::max(result, self->children[self->index[i]]->maxVersion);
+      }
+    }
+    break;
+  }
+  case Type::Node256: {
+    auto *self = static_cast<Node256 *>(n);
+    for (int i = begin + 1; i < end; ++i) {
+      if (self->children[i] != nullptr) {
+        result = std::max(result, self->children[i]->maxVersion);
+      }
+    }
+    break;
+  }
+  case Type::Invalid:
+    __builtin_unreachable(); // GCOVR_EXCL_LINE
   }
 #if DEBUG_VERBOSE && !defined(NDEBUG)
   fprintf(stderr, "At `%s', max version in (%02x, %02x) is %" PRId64 "\n",