Vectorize all bounds checks for Node256 scan

ConflictSet.cpp

@@ -1779,6 +1779,7 @@ bool checkMaxBetweenExclusive(Node *n, int begin, int end,
   }
 
   // [begin, end) is now the half-open interval of children we're interested in.
+  assert(begin < end);
 
   const unsigned shiftUpperBound = end - begin;
   const unsigned shiftAmount = begin;
@@ -1825,31 +1826,54 @@ bool checkMaxBetweenExclusive(Node *n, int begin, int end,
     }
     const int firstPage = begin >> Node256::kMaxOfMaxShift;
     const int lastPage = (end - 1) >> Node256::kMaxOfMaxShift;
+    if (firstPage == lastPage) {
+      if (self->maxOfMax[firstPage] <= readVersion) {
+        return true;
+      }
+      uint64_t conflict = 0;
+      // Check all in page
+      for (int i = 0; i < Node256::kMaxOfMaxPageSize; ++i) {
+        conflict |=
+            (self->childMaxVersion[(firstPage << Node256::kMaxOfMaxShift) + i] >
+             readVersion)
+            << i;
+      }
+      // Mask away out of bounds
+      const int intraPageBegin = begin & (Node256::kMaxOfMaxPageSize - 1);
+      const int intraPageEnd = end - (lastPage << Node256::kMaxOfMaxShift);
+      conflict &= (1 << intraPageEnd) - 1;
+      conflict >>= intraPageBegin;
+      return !conflict;
+    }
     // Check the first page
     if (self->maxOfMax[firstPage] > readVersion) {
-      bool result = true;
+      uint64_t conflict = 0;
       for (int i = 0; i < Node256::kMaxOfMaxPageSize; ++i) {
-        int j = (begin & ~(Node256::kMaxOfMaxPageSize - 1)) + i;
-        result &= !((self->childMaxVersion[j] > readVersion) & inBounds(j));
+        int j = (firstPage << Node256::kMaxOfMaxShift) + i;
+        conflict |= (self->childMaxVersion[j] > readVersion) << i;
       }
-      if (!result) {
-        return result;
+      const int intraPageBegin = begin & (Node256::kMaxOfMaxPageSize - 1);
+      conflict >>= intraPageBegin;
+      if (conflict) {
+        return false;
       }
     }
     // Check the last page
     if (self->maxOfMax[lastPage] > readVersion) {
-      bool result = true;
+      uint64_t conflict = 0;
       for (int i = 0; i < Node256::kMaxOfMaxPageSize; ++i) {
-        int j = ((end - 1) & ~(Node256::kMaxOfMaxPageSize - 1)) + i;
-        result &= !((self->childMaxVersion[j] > readVersion) & inBounds(j));
+        int j = (lastPage << Node256::kMaxOfMaxShift) + i;
+        conflict |= (self->childMaxVersion[j] > readVersion) << i;
       }
-      if (!result) {
-        return result;
+      const int intraPageEnd = end - (lastPage << Node256::kMaxOfMaxShift);
+      conflict &= (1 << intraPageEnd) - 1;
+      if (conflict) {
+        return false;
       }
     }
     uint64_t conflict = 0;
-    // Check all pages
-    for (int i = 0; i < Node256::kMaxOfMaxTotalPages; ++i) {
+    // Check all possible inner pages
+    for (int i = 1; i < Node256::kMaxOfMaxTotalPages - 1; ++i) {
       conflict |= (self->maxOfMax[i] > readVersion) << i;
     }
     // Only keep inner pages