Improve performance of H48 solver with prefetching

With this commit we re-structure how the node expansion in the
H48 solution search works to allow prefetching of pruning values,
showing performance improvements in the range of 30-45% on x86,
depending on table size and solution length.

A small bug fix related to appending solutions is included in this commit.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/solvers/solutions.h b/src/solvers/solutions.h
index d92d5ad..8817348 100644
--- a/src/solvers/solutions.h
+++ b/src/solvers/solutions.h
@@ -108,7 +108,7 @@ last_solution_is_duplicate(const solution_list_t l[static 1])
                 j--;
                 for (i = l->used-2; l->buf[i] == l->buf[j]; i--, j--) {
                         if (l->buf[i-1] == '\n') {
-                                if (l->buf[j-1] == '\n' || j == 0)
+                                if (j == 0 || l->buf[j-1] == '\n')
                                         return true;
                                 else break;
                         }