Get back to 100% line coverage locally

The latter somehow generated a vmovdqa64 instruction that segfaulted on
unaligned memory, with gcc and --coverage. Hmm.

ConflictSet.cpp

@@ -720,16 +720,18 @@ struct ReadContext {
 struct WriteContext {
 
   struct Accum {
-    int64_t entries_erased = 0;
-    int64_t insert_iterations = 0;
-    int64_t entries_inserted = 0;
-    int64_t nodes_allocated = 0;
-    int64_t nodes_released = 0;
-    int64_t point_writes = 0;
-    int64_t range_writes = 0;
-    int64_t write_bytes = 0;
+    int64_t entries_erased;
+    int64_t insert_iterations;
+    int64_t entries_inserted;
+    int64_t nodes_allocated;
+    int64_t nodes_released;
+    int64_t point_writes;
+    int64_t range_writes;
+    int64_t write_bytes;
   } accum;
 
+  WriteContext() { memset(&accum, 0, sizeof(accum)); }
+
   template <class T> T *allocate(int c) {
     ++accum.nodes_allocated;
     if constexpr (std::is_same_v<T, Node0>) {
@@ -1967,6 +1969,9 @@ downLeftSpine:
   return n->entry.rangeVersion <= readVersion;
 }
 
+// Only one of these is ever exercised. I'm not worried about somehow not
+// calling one of these though.
+// GCOVR_EXCL_START
 #ifdef HAS_AVX
 uint32_t compare16_32bit(const InternalVersionT *vs, InternalVersionT rv) {
   uint32_t compared = 0;
@@ -1986,14 +1991,14 @@ uint32_t compare16_32bit(const InternalVersionT *vs, InternalVersionT rv) {
 
 __attribute__((target("avx512f"))) uint32_t
 compare16_32bit_avx512(const InternalVersionT *vs, InternalVersionT rv) {
-  __m512i w;
-  memcpy(&w, vs, sizeof(w));
   uint32_t r;
   memcpy(&r, &rv, sizeof(r));
-  return _mm512_cmpgt_epi32_mask(_mm512_sub_epi32(w, _mm512_set1_epi32(r)),
+  return _mm512_cmpgt_epi32_mask(
+      _mm512_sub_epi32(_mm512_loadu_epi32(vs), _mm512_set1_epi32(r)),
       _mm512_setzero_epi32());
 }
 #endif
+// GCOVR_EXCL_STOP
 
 // Returns true if v[i] <= readVersion for all i such that begin <= is[i] < end
 // Preconditions: begin <= end, end - begin < 256
@@ -2048,9 +2053,9 @@ bool scan16(const InternalVersionT *vs, const uint8_t *is, int begin, int end,
 
   uint32_t compared = 0;
   if constexpr (kAVX512) {
-    compared = compare16_32bit_avx512(vs, readVersion);
+    compared = compare16_32bit_avx512(vs, readVersion); // GCOVR_EXCL_LINE
   } else {
-    compared = compare16_32bit(vs, readVersion);
+    compared = compare16_32bit(vs, readVersion); // GCOVR_EXCL_LINE
   }
   return !(compared & mask);
 
@@ -2076,10 +2081,11 @@ bool scan16(const InternalVersionT *vs, const uint8_t *is, int begin, int end,
 // Returns true if v[i] <= readVersion for all i such that begin <= i < end
 //
 // always_inline So that we can optimize when begin or end is a constant.
+// gcovr exclude annotation necessary because of always_inline?
 template <bool kAVX512>
 inline __attribute__((always_inline)) bool
-scan16(const InternalVersionT *vs, int begin, int end,
-       InternalVersionT readVersion) {
+scan16(const InternalVersionT *vs, int begin, int end, // GCOVR_EXCL_LINE
+       InternalVersionT readVersion) {                 // GCOVR_EXCL_LINE
   assert(0 <= begin && begin < 16);
   assert(0 <= end && end <= 16);
   assert(begin <= end);