Address more missing coverage

cc #3. Found some non-trivial dead code this time!

ConflictSet.cpp

@@ -1243,16 +1243,12 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
                 (parent->numChildren - (nodeIndex + 1)));
 
     --parent->numChildren;
-    if (parent->numChildren == 0 && !parent->entryPresent &&
-        parent->parent != nullptr) {
-      return erase(parent, allocators, impl, dontInvalidate);
-    } else {
+    assert(parent->numChildren > 0 || parent->entryPresent);
     const bool update = result == dontInvalidate;
     maybeDownsize<Type_Node3>(parent, allocators, impl, result);
     if (update) {
       dontInvalidate = result;
     }
-    }
   } break;
   case Type_Node16: {
     auto *parent16 = static_cast<Node16 *>(parent);
@@ -1266,16 +1262,16 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
                 (parent->numChildren - (nodeIndex + 1)));
 
     --parent->numChildren;
-    if (parent->numChildren == 0 && !parent->entryPresent &&
-        parent->parent != nullptr) {
-      return erase(parent, allocators, impl, dontInvalidate);
-    } else {
+
+    // By kMinChildrenNode16
+    assert(parent->numChildren > 0);
+
     const bool update = result == dontInvalidate;
     maybeDownsize<Type_Node16>(parent, allocators, impl, result);
     if (update) {
       dontInvalidate = result;
     }
-    }
+
   } break;
   case Type_Node48: {
     auto *parent48 = static_cast<Node48 *>(parent);
@@ -1293,16 +1289,15 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
     }
 
     --parent->numChildren;
-    if (parent->numChildren == 0 && !parent->entryPresent &&
-        parent->parent != nullptr) {
-      return erase(parent, allocators, impl, dontInvalidate);
-    } else {
+
+    // By kMinChildrenNode48
+    assert(parent->numChildren > 0);
+
     const bool update = result == dontInvalidate;
     maybeDownsize<Type_Node48>(parent, allocators, impl, result);
     if (update) {
       dontInvalidate = result;
     }
-    }
   } break;
   case Type_Node256: {
     auto *parent256 = static_cast<Node256 *>(parent);
@@ -1310,16 +1305,15 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
     parent256->children[parentsIndex].child = nullptr;
 
     --parent->numChildren;
-    if (parent->numChildren == 0 && !parent->entryPresent &&
-        parent->parent != nullptr) {
-      return erase(parent, allocators, impl, dontInvalidate);
-    } else {
+
+    // By kMinChildrenNode256
+    assert(parent->numChildren > 0);
+
     const bool update = result == dontInvalidate;
     maybeDownsize<Type_Node256>(parent, allocators, impl, result);
     if (update) {
       dontInvalidate = result;
     }
-    }
   } break;
   default:                   // GCOVR_EXCL_LINE
     __builtin_unreachable(); // GCOVR_EXCL_LINE
@@ -1358,7 +1352,7 @@ constexpr int kUnrollFactor = 4;
 bool compareStride(const uint8_t *ap, const uint8_t *bp) {
 #if defined(HAS_ARM_NEON)
   static_assert(kStride == 64);
-  uint8x16_t x[4];
+  uint8x16_t x[4]; // GCOVR_EXCL_LINE
   for (int i = 0; i < 4; ++i) {
     x[i] = vceqq_u8(vld1q_u8(ap + i * 16), vld1q_u8(bp + i * 16));
   }
@@ -1368,7 +1362,7 @@ bool compareStride(const uint8_t *ap, const uint8_t *bp) {
             uint64_t(-1);
 #elif defined(HAS_AVX)
   static_assert(kStride == 64);
-  __m128i x[4];
+  __m128i x[4]; // GCOVR_EXCL_LINE
   for (int i = 0; i < 4; ++i) {
     x[i] = _mm_cmpeq_epi8(_mm_loadu_si128((__m128i *)(ap + i * 16)),
                           _mm_loadu_si128((__m128i *)(bp + i * 16)));
@@ -1387,7 +1381,7 @@ bool compareStride(const uint8_t *ap, const uint8_t *bp) {
 int firstNeqStride(const uint8_t *ap, const uint8_t *bp) {
 #if defined(HAS_AVX)
   static_assert(kStride == 64);
-  uint64_t c[kStride / 16];
+  uint64_t c[kStride / 16]; // GCOVR_EXCL_LINE
   for (int i = 0; i < kStride; i += 16) {
     const auto a = _mm_loadu_si128((__m128i *)(ap + i));
     const auto b = _mm_loadu_si128((__m128i *)(bp + i));
@@ -1422,6 +1416,7 @@ int firstNeqStride(const uint8_t *ap, const uint8_t *bp) {
 
 int longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
   assume(cl >= 0);
+  printf("cl: %d\n", cl);
   int i = 0;
   int end;
 
@@ -1429,18 +1424,6 @@ int longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
     goto bytes;
   }
 
-  // Optimistic early return
-  {
-    uint64_t a;
-    uint64_t b;
-    memcpy(&a, ap, 8);
-    memcpy(&b, bp, 8);
-    const auto mismatched = a ^ b;
-    if (mismatched) {
-      return std::countr_zero(mismatched) / 8;
-    }
-  }
-
   // kStride * kUnrollCount at a time
   end = cl & ~(kStride * kUnrollFactor - 1);
   while (i < end) {
@@ -1468,8 +1451,8 @@ int longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
   // word at a time
   end = cl & ~(sizeof(uint64_t) - 1);
   while (i < end) {
-    uint64_t a;
-    uint64_t b;
+    uint64_t a; // GCOVR_EXCL_LINE
+    uint64_t b; // GCOVR_EXCL_LINE
     memcpy(&a, ap, 8);
     memcpy(&b, bp, 8);
     const auto mismatched = a ^ b;
@@ -1624,7 +1607,7 @@ int64_t maxBetweenExclusive(Node *n, int begin, int end) {
     }
   }
   switch (n->getType()) {
-  case Type_Node0:
+  case Type_Node0: // GCOVR_EXCL_LINE
     // We would have returned above, after not finding a child
     __builtin_unreachable(); // GCOVR_EXCL_LINE
   case Type_Node3: {
@@ -1687,7 +1670,7 @@ Vector<uint8_t> getSearchPath(Arena &arena, Node *n) {
   }
   std::reverse(result.begin(), result.end());
   return result;
-}
+} // GCOVR_EXCL_LINE
 
 // Return true if the max version among all keys that start with key + [child],
 // where begin < child < end, is <= readVersion

script_tests/long-common-prefix.txt

@@ -0,0 +1,19 @@
+begin aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+end aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab
+rangeread
+check
+
+begin aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+end aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaazaaaaaaaaaaaaaaaaaaaaaab
+rangeread
+check
+
+begin aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+end aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabaa
+rangeread
+check
+
+begin aaaaaaaaaa
+end aaaaaaabaa
+rangeread
+check